Evaluation of first power
simulation
The New Line Copenhagen – Ringsted
Alignment and Railway Technology
Evaluation of first power simulation
The New Line Copenhagen – Ringsted
Alignment and Railway Technology
Copenhagen – Ringsted Team
Arne Jacobsens Allé 172300 København S
Version history of the document
1 First draft – issued for Banedanmark
control 20130212 ZMAJR XJGAD VPE
Content:
1
Introduction to the study ... 5
1.1
Foreword ... 5
1.2
Resume of the study ... 5
2
Objective of the study ... 6
2.1
Documents of relevance ... 6
2.2
Glossary of terms... 7
3
Requirements for the traction power systems ... 8
4
Method of study ... 9
4.1
Limitations of simulation... 9
5
Description of the traction power systems ... 11
5.1
Overhead catenary system ... 11
5.1.1 Existing overhead catenary system ... 12
5.1.2 Future overhead catenary system ... 13
5.2
Traction power systems ... 14
5.2.1 Supply scenarios ... 15
5.3
Demands imposed on the TPS from the 132 kV grid ... 16
5.3.1 Power supplying technologies ... 17
5.4
Simulated traction power substations... 19
5.4.1 Vigerslev Fordelingsstation (IGF) ... 20
5.4.2 Kildebrønde Fordelingsstation (KILF) ... 20
5.4.3 Bjæverskov Fordelingsstation (BJÆF) ... 21
5.4.4 Roskilde Fordelingsstation (ROF) ... 21
5.4.5 Ringsted Fordelingsstation (RGF) ... 22
5.4.6 Slagelse Fordelingsstation (SGF) ... 22
5.4.7 Lov Fordelingsstation (LOF) ... 23
5.4.8 Masnedø Fordelingsstation (MNF) ... 23
5.4.9 Toreby Fordelingsstation (TORF) ... 24
5.4.10 Rødby Fordelingsstation (RFF) ... 24
5.4.11 Haslev Fordelingsstation (HZF) ... 24
5.4.12 Kastrup Fordelingsstation (CPHF) ... 25
5.4.13 Kokkedal Fordelingsstation (OKF) ... 25
6
Timetable ... 26
7
Results ... 28
7.1
General discussion of the results ... 30
7.1.1 Power demand ... 30
7.1.2 Voltage quality ... 31
7.1.3 Current ... 33
8
Result analysis of TPS transformer sizes ... 34
8.1
Vigerslev Fordelingsstation (IGF) ... 34
8.1.1 IGF T25 ... 34
8.1.2 IGF T26 ... 38
8.2
Kildebrønde Fordelingsstation (KILF)... 38
8.3
Bjæverskov Fordelingsstation (BJÆF) ... 38
8.4
Roskilde Fordelingsstation (ROF) ... 38
8.5
Ringsted Fordelingsstation (RGF) ... 39
8.5.1 RGF T25 ... 39
8.5.2 RGF T26 ... 40
8.6
Slagelse Fordelingsstation (SGF) ... 40
8.7
Lov Fordelingsstation (LOF) ... 40
8.8
Masnedø Fordelingsstation (MNF) ... 40
8.9
Toreby Fordelingsstation (TORF) ... 41
8.10
Haslev Fordelingsstation (HZF) ... 41
8.11
Kastrup Fordelingsstation (CPHF) ... 41
8.12
Kokkedal Fordelingsstation (OKF) ... 41
9
The simulated power demand to be supplied by the 132 kV grid ... 42
10
Conclusion ... 46
11
Recommendations for second run ... 46
1 Introduction to the study
1.1
Foreword
Due to the ongoing railway projects in eastern Denmark, among others the new line between Copenhagen and Ringsted and the fixed link connection from Denmark to Germany over Femern Belt, several existing and new mainline railways will be electrified, and in year 2020 almost all traffic on the railway will be handled by electric trains. To ensure that both the new and the existing traction power supply is
dimensioned to support this increase in electric traffic density, several simulations are carried out. This report describes and analyses the result of the first simulation – an analysis of the needed traction power supply in year 2020 - and make suggestions how to improve the traction power system.
1.2
Resume of the study
The traction power system study was implemented as a simulation, where a model of the traction power system was built and the traffic, a future timetable delivered from Banedanmark, gave an estimated power demand.
The results of the simulation shows that both the existing and the anticipated future traction power system in eastern Denmark is under dimensioned in several locations, if the planned traffic density materializes.
Even though the power demand in an abnormal or backup scenario can be hard to predict, it seems given that almost all of the existing electrified lines need to undergo changes if the future traffic is to be supported.
The suggested transformer sizes on the new electrified lines are in general fine, but the continued weakening of the 132 kV grid is a big issue, and as a minimum some kind of balancing or compensation will be needed.
The rated current of the booster transformers is also a matter of concern in most of the system.
2 Objective of the study
The Danish electrified mainline railways are mainly built with overhead catenary system type TFZF160St with booster transformers, but other systems as TFZF160St and TFZF200St without booster transformers are also employed. Two phase
transformers on the 132 kV grid supplies the catenary system with 25 kV 50 Hz. The electrification of the new line between Copenhagen and Ringsted as well as the new connection to Germany and electrification of the existing line from Ringsted to Rødby will result in a significant increase in the demand for traction power. The purpose of this first study is to determine the best suited system to supply and distribute the power. The best suited traction power distribution system will not necessarily be the same at all locations. The choice will be made between the following systems. Overhead catenary system:
TFZF160St with booster transformers TFZF200St with booster transformers TFZF160St without booster transformers TFZF200St without booster transformers Autotransformer system
For all of the mentioned systems, there will also be the possibility of adding one or more reinforced feeder wires and/or return wires to lower the impedance.
Traction power supply:
Two phase direct transformers Three phase direct transformers Autotransformer system
Static frequency converter
For both two and three phase transformers and autotransformers, unbalances can be compensated by various means of active/passive components on one or both sides of the transformer.
The keywords in choosing systems are the design and complexity of the system, the system reliability and quality in distributing traction power and the overall cost in investment and maintenance.
This report will only describe solutions for the traction power substation and the overhead contact system which has influence on either the new line Copenhagen – Ringsted or the "Sydbanen" path.
2.1
Documents of relevance
While this document only describes the technical conditions and prerequisites of the simulation briefly, the following documents have previously been introduced to the project, and will describe the conditions for the simulation in details. The documents
define all methods and metadata for the simulation model such as timetables, train models, the traction power supply system and geographic conditions.
"Forudsætninger Øst simulering" ver. 2, date 2013.02.12
The document and its annexes describe all the conditions for the simulation e.g. the impedance and the system configuration of the overhead catenary system, the simulated timetables and the requirements on the output of the simulation.
"TARTE_6_XXXXXX_002" ver. B, date 2013.02.12
Drawing of the future traction power feeder system in eastern Denmark, as described in "Forudsætninger Øst simulering" ver. 2, date 2013.02.12. "Lokalitetsforkortelser for kørestrømsanlæg", ver. 2, date 2013.02.12 The document is an explanation of abbreviations for all the sites concerned, such as station abbreviations or site names in the traction power grid used in the simulation. Please note that only the Danish station and site names will be used in this report.
2.2
Glossary of terms
The following terms are used in this report:
132 kV grid: The system that in east Denmark supplies the traction power transformers with power.
Neutralsection: A small section without power supply in the OCS, 0,2 to 0,5 km long that separates the transformers. Through switchgear some neutral sections can be energized if necessary (if a train is stopped in the section).
ONAF: Oil Natural Air Forced – a cooling technology for a transformer (forced
cooling enhancing the transformers capacity).
ONAN: Oil Natural Air Natural – a cooling technology for a transformer. Overhead catenary system (OCS): The wire system over the railway that let the current flow from the transformer to the train.
Path: A continuous railway line, for example the mainline from København to Jylland.
Railway substation (RRS): A building that contains switchgear and devises to monitor and supervise the traction power.
Section: A part of a path. When talking about traction power supply, a section is normally between 5 and 25 km long with a typical length of 10 to 17 km.
Traction power substation (TPS): Common for RSS and the supplying transformers.
Traction power system: Term for the overall system which consist of both TPS and OCS.
Transformer: An electrical unit that transforms a voltage level up or down. The currently used railway transformers in east Denmark is 132/27,5 kV transformers.
Utility substation (USS): A 132 kV grid owner substation. The railway transformers are normally located in a USS.
Path names
Figure 1 shows the path name of the main lines that will be used in the simulation.
Figure 1: Path names in the simulation
3 Requirements for the traction power systems
The requirements for the traction power systems can be summarized to:
According to EN 50163 table 1:
Nominal voltage UN [V] and frequency [Hz] 25000 V and 50 Hz
Lowest permanent voltage Umin1 19000 V
Lowest non permanent voltage Umin2 17500 V
Highest permanent voltage Umax1 27500 V
Highest non permanent voltage Umax2 29000 V
Lowest/highest frequency fmin/fmax 49/51 Hz
Time interval with voltage between Umin1- Umin2 may not exceed 2 min
Time interval with voltage between Umax1- Umax2 may not exceed 5 min
In a normal supply scenario, the voltage shall be between Umin1- Umax1
In an abnormal / backup supply scenario, may voltage between Umin2- Umin1 not
cause any damage or errors.
The lowest voltage, where electric traction trains are expected to function, is Umin2.
According to EN 50388 table 2:
At any given time, and under any supply scenario, the trains should require 500 A from the traction power system on existing path, and 800 A on new path.
According to EN 50388 table 3:
Electric trains have to be equipped with current limiting devices, to avoid voltage collapse at low voltages. The current is to be limited in the voltage area from 22000 V to 17500 V. At 17500 V only power to aux. equipment is allowed.
4 Method of study
An analysis of such a complex system as the entire traction power system in eastern Denmark cannot be carried out by simple hand calculations but requires a simulation tool. Therefore a model of the system has been established in the simulation software tool Trackfeed® simulation. The model contains data which makes it possible to simulate the power consumption of the trains. The most important components are:
Infrastructure data such as gradients, speed limits, tunnel design, stationing for public platforms and other sites of interest.
Traction and utility power system with information on configuration of the systems, impedance and short circuit levels.
Overhead catenary system with information on impedance and configuration of the overhead contact system.
Traffic data such as timetables with start, stop, dwell and passing times. Train data with characteristics of each type of train such as weight, acceleration and retardation characteristics and maximum speed.
The collected results are power, voltage and current at the points of interest in the traction power system. These points are on both sides of the transformers and at the longest distance from the transformers - typically at the end of a supply section.
4.1
Limitations of simulation
The simulation is carried out for the future electrified rail system in eastern Denmark at year 2020. The geographical boundaries for the simulation are shown in Figure 2.
The boundaries for the simulations are: North: Helsingør station East: Lernacken neutralsection South: Rødby fordelingsstation West: Marslev fordelingsstation Northwest: Roskilde fordelingsstation
The size of a traction power feeder station in Denmark is normally determined by the power demand from the trains under the three different modes of operation: normal supply, abnormal supply and backup supply, see chapter 5.2.1 Supply scenarios. Many of the traction power substations are new and the purpose of this first simulation is mainly to determine if the suggested overall traction power system seems able to handle the necessary power. Therefore this first simulation only describes the traction power feeder substations in their normal supply situation. Simulation 2 will include both the abnormal and backup supply situations.
The accuracy of the results depends to a large extent on the quality of the input data. While gradients, distances and impedance in the traction power system, train
characteristics and timetables are the most significant components, it has been decided to leave out the impact of curvature of the rail lines in the simulation. Curvature is complex to handle in the model and of relatively little relevance to the results. Previous simulations show that the curves affect the accuracy with less than 1 %.
The trains in the simulation are operated in a way that gives the highest possible power demand on the traction power substation. This occurs when the trains accelerate and brake at capacity, and run as fast as they are allowed to on the line. Under normal operation, it is estimated that the power consumption from the trains is about 90 % of the simulated results.
5 Description of the traction power systems
5.1
Overhead catenary system
The overhead catenary system, hereafter OCS, distributes the traction power from the traction power substations to the trains.
The types of OCS differ from one another by the complexity of design, the impedance, the electric influence on surrounding environment and not at least the cost.
Construction: A simple construction requires a smaller pole and will be easier to both build and maintain than a complex construction. If additional feeder or return conductors are used, it can by necessary to reinforce the supporting construction.
Impedance: A larger cross section of the contact and catenary wires will result in lower impedance. Low impedance reduces the voltage drop, and thereby makes it possible to transport traction power over a longer distance. BT represents a large internal impedance.
Electric influence on surrounding environment: A magnetic field can induce unwanted current in longitudinal conductive objects near the railway. The unwanted current can erode metal or lead to dangerous touch voltage levels for humans and animals. The same thing can occur with stray current.
Cost: The cost of the OCS is proportional with complexity of the system. Unfortunately it is not possible to choose a single type of OCS that fulfills all success criteria for the perfect OCS. From an electric point of view, the perfect OCS will have low impedance, low magnetic influence on third part equipment and low stray current. For reasons of effective construction and maintenance a simple OCS is preferred. Table 1 compares the different types of OSC.
Type Design Impedance Electric influence
Cost TFZF160st +BT Simple Highest Lowest Medium
TFZF200st +BT Simple High Lowest Medium
TFZF160st –BT Simplest Medium Highest Lowest
TFZF200st –BT Simplest Medium High Low
Autotransformer Complex Lowest Low Highest
TFZF160st +FL/RL Advanced Low High Medium
Table 1: Advantages and disadvantages on different OCS
There are ongoing projects that analyses the electromagnetic emission and the stray current from OCS. These projects will partly clarify if the booster transformers are
necessary and make recommendations for the future OCS. These recommendations will be available before the second simulation run.
5.1.1 Existing overhead catenary system
OCS in Denmark today consists of three different types, as shows in Figure 3.
Figure 3: Types of OCL in year 2013
Normally the OCS is TFZF160st, also known as Bane 160, with booster transformers, hereafter BT. This type of OCL is sometimes described as 100/50 BT-RR and it consists of four main elements: 100 mm² contact wire, 50 mm² messenger wire, 327 mm² return wire and booster transformer. The BT, which is placed every third km, secures that all return current utilizes the return conductor on its way back to the traction power transformer instead of flowing in unwanted return paths such as earth and other low impedance connections e.g. pipelines and telephone, signal or power cables. To get the return current from rail to return wire, there is a connection from the rail to the return conductor between every BT. The speed limit with TFZF160st is 180 km/h.
BT's are not installed in the Copenhagen area because of the close proximity to the 1500 V DC commuter railway. The BT is likely to saturate when installed close to a DC railway.
On the Storebælt and Øresund connections OCS TFZF160st is not used due to the relative high impedance that the combination of BT's and the OCS itself is a result of. Furthermore the maximum speed on parts of the Øresund connection is 200 km/h which is more than TFZF160st is designed for. Instead the TFZF200st, also known as Bane 200 or 120/70 RR-RR, is used. That system has a heavier contact and
messenger wire (120/70). By coincidence, on all existing TFZF200st lines BT's are omitted, even though the BT is a part of the Bane 200 system as well. Speed limit for TFZF200st is 200 km/h.
5.1.2 Future overhead catenary system
The future OCS, as planned in year 2020, is shown in Figure 4.
Figure 4: OCL types in east Denmark year 2020, as used in first simulation
The existing electrification paths are kept with the same type of OCS as today. The biggest challenges will be paths equipped with BT's, because of the impedance from both the transformers and the OCS. Furthermore the BT's installed on existing railways, are rated for 255 A. Even though they can be overloaded during shorted periods of time, it is most likely that many of them must be replaced with larger ones, due to the intense traffic density with electrical traction in the near future.
The new line Copenhagen-Ringsted has OCS type TFZF200st without BT. Trains on the line will operate with speeds up to 250 km/h, and parts of the path are close to the urban DC railway.
The path between Ringsted and Rødby is equipped with TFZF200st with BT. Speed limit is 200 km/h. There are no DC railway lines in the area of this path and BT can therefore be installed.
The path on "Lille Syd" is initially set to TFZF160st with BT. The path is a single track railway with many small stations, and the current speed limit of 120 km/h is expected to continue.
Results from the simulation will show if the anticipated OCS on both the new and the existing railways can handle the traction power demand without unacceptable voltage drops.
5.2
Traction power systems
The traction power supply feeds the OCS on the mainline railway with 25 kV 50 Hz. A simple diagram showing the currently employed traction power supply is found in Figure 5.
Figure 5: Traditional traction power supply setup in Denmark
In eastern Denmark, the transformers are fed from the 132 kV grid. The two phased railway transformers are placed in the utility substation, hereafter USS. Each transformer is connected with the railway substation, hereafter RSS, trough two 1 x 800 mm² cables. The distance between USS and RSS vary from location to location; from less than a hundred meters to more than three kilometres. The RSS consists of HV switchgear and devices to control and monitor the traction power. The RSS is normally placed right next to the railway, but at some locations the distance can be higher than 1000 meters. The connection is trough two 1 x 800 mm² cables. The RSS and connected transformers will be described as the traction power substation or TPS in this document.
The transformers are separated by neutral sections out on the railway line. In case of an abnormal or a backup supply situation where a path section is left without traction power, the HV switchgear at a RSS or at the neutral section between RSS can switch between "adjacent" transformers and that way secure a continued power supply of the trains.
5.2.1 Supply scenarios
The traction power supply system can operate in three different modes as shown in Figure 6.
Figure 6: Simplified visualization of the three supply scenarios
They are:
Normal supply scenario
The normal supply scenario is the most common and is estimated to be the supply scenario on a TPS more than 355 days a year.
Abnormal supply scenario
In an abnormal supply situation, one of the transformers in a TPS is out of service. Mostly this is due to maintenance but can also be the result of unforeseen failures. In an abnormal supply situation the remaining transformer in the TPS, supplies the affected supply section. On a TPS with only one transformer, the abnormal supply scenario cannot occur. Estimated abnormal supply scenario on a TPS is between five and ten days a year.
Backup supply scenario
In a backup supply scenario, a whole TPS is out of duty. In this case, one or more nearby TPS's (the two adjacent) will supply the affected TPS supply sections. That operating mode is estimated to occur with only a maximum of one day a year.
Although the normal supply scenario is by far the most common, the dimensioning of the transformers is based on the power demand in the abnormal and backup
scenarios. With two phase transformers a good rule of thumb is that a transformer in normal supply scenario shall not be loaded with more than 50 % of the installed power. In most cases, a 50 % reserve capacity will be enough to supply in both the abnormal and the backup supply scenario.
5.3
Demands imposed on the TPS from the 132 kV grid
One of the challenges for the future traction power supply is the traditional two phased transformers. The 132 kV grid owner Energinet.dk, estimates that parts of the grid will not be able to support the unbalance caused by the transformers. The acceptable unbalance from an arbitrary installation on the 132 kV grid, shall not exceed 1,4 %, and can be calculated with the formula
Formula 1
Where
Eui = The limit for the contribution to voltage imbalance for each
installation, as the inverse voltage with respect to synchronous voltage at a given point in the transmission grid.
Eu = The limit for voltage unbalance, here 1,4%, given as inverse voltage
in relation to the synchronous voltage at a given point in the transmission grid.
Si = The maximum instantaneous power load for the installation in the
connection point.
Smax = The maximum load from a 132 kV USS, here set to 100 MVA.
α = Summation exponent α is set to 2, which takes into account the simultaneity between unbalances from several installations.
While Formula 1 describes the unbalance from an instantaneous load on the 132 kV grid in general, Formula 2 describes the unbalance from a load at a given location on the 132 kV grid.
Formula 2
Where
ELocation = The unbalance at a given point
Sk, min = The minimum shortcircuit power level at the given location
SL = The maximum instantaneous load at the given location
It is required that the result from Formula 2 is less than the result from Formula 1, if the power shall be supplied from a two phase transformer without any compensation. Both formulas require knowledge about the instantaneous load from the transformer and are therefore further discussed in chapter 9.
5.3.1 Power supplying technologies
The continued weakening of the 132 kV supply grid (decreasing short circuit levels due to abandonment of large thermal power plants and increased use of renewable sources) will most likely lead to stricter and - depending on actual location of RSS - differentiated requirements on supply technologies. The different technologies are briefly described in the following.
5.3.1.1 Two phased transformers
In the conventional traction power supply system, 132 kV is transformed to 27,5 kV by a two phase transformer. All of the existing railway transformers are conventional two phase transformers.
The two phased transformers are the simplest way of supplying the OCS. The transformers can without any problem be overloaded with a factor 2 of the installed power for shorter time intervals.
The downside of the two phased transformer is, that the power is tapped from only two phases on the supplying 132 grid, resulting in an unbalance of the 132 kV grid. Also the high internal impedance of the transformer, which for a 23 MVA transformer is 0,36+j4,656 Ω, can be a problem as it can result in excessive voltage drop over the transformer.
5.3.1.2 Three phased transformers
It is possible to use transformers that have three phased input at the primary side, and a two phased output at the secondary side. These are normally constructed as a Scott transformer. Three phased transformers are more complex to construct than two phased transformers, which makes them more expensive. Although a three phased transformer to a certain extent balances the load at all three phases on the primary side, a means of compensation will still be necessary. The three phase transformer will in addition to the 50 Hz output, produce rather powerful harmonics, 100 Hz and higher, which have to be filtered.
5.3.1.3 Static Frequently Converter
Static Frequency Converters (SFC) converts through a DC link the three phased 132 kV AC to single phased 27,5 kV AC. The 132 kV has to be stepped down with a transformer, to a level where the AC/DC converter is able to make the conversion to DC. The DC/AC also requires a transformer to smoothen the AC to an acceptable quality.
As the SFC works as an AC/DC – DC/AC circuit, the voltage level at the railway side of the SFC is very steady in comparison to a two phased transformer, as it to a certain extent is independent of the load. The SFC is also able to work together with a traditional transformer – or another SFC - at the opposite end of the supplied section, as the SFC is not directly connected to the 132 kV grid. This makes the neutral section between the SFC and the connected traditional transformer unnecessary. That again improves the voltage quality considerably, as it is possible to split the power supply into a double sided system.
The AC/DC as well as the DC/AC conversion requires filters to reduce harmonics and flickers. A SFC cannot be overloaded the same way as a conventional two phase transformer, and must therefore be dimensioned to the maximum expected load – which normally is found as the instantaneous load in either abnormal or backup mode.
5.3.1.4 Active balancing
The produced unbalance from a two phased – or for that matter a three phased transformer – can be compensated by adding an active balancer to the system. Active balancing compensates all three phases on the 132 kV grid, either on the secondary side of two phased transformer or directly on the 132 kV grid. It compensates the load using power electronics, and in addition to reduce the unbalance, it is able to reduce the reactive power consumption from the transformer considerably.
5.4
Simulated traction power substations
In eastern Denmark there is currently located five TPS. These TPS supports "Vestbanen", "Kystbanen" and "Øresundsbanen", see Figure 1. Initially these TPS's are not changed for the first simulation. In order to supply the new line between Copenhagen and Ringsted, "Sydbanen" and "Lille Syd", it is suggested to build an additional eight TPS's; two on the new line Copenhagen – Ringsted, five on "Sydbanen" and a single one on the "Lille Syd". Figure 7 shows TPS locations and their connected path sections.
Figure 7: Existing and future traction power substations and related path sections in eastern Denmark
The primary task of this first simulation is to study the power demand from the trains and the voltage quality in the TPS. It has been chosen to simulate all TPS according to the existing power supply philosophy, namely with two phased transformers. This makes is possible to see the effects of changing the OCS and TPS at the second simulation run on locations, where supply problems have been detected.
The size and location of each transformer is based upon the power consumption in their respective path sections and the voltage drop within the section. The power consumption and voltage drop are primarily determined by traffic density, the number and location of train stops and the length and the geographical conditions in the section. Each TPS will be described regarding this in the following.
5.4.1 Vigerslev Fordelingsstation (IGF)
IGF was established in 1995 and is supplied from two 23 MVA transformers (18 MVA ONAF). The substation supplies the main part of the Copenhagen area and therefore supports a part of all the main lines in eastern Denmark, namely "Kystbanen", "Vestbanen", "Øresundsbanen", traffic on "Sydbanen" and traffic to the new line Copenhagen – Ringsted. The OCS in the entire area that IGF covers is TFZF160St without BT.
IGF T25
Transformer T25 supplies the sections between HIFN and Kh, Kh-SJÆN, Kh-TÅTN, Kh-HGLN and KLV-KLVN. The sections see the highest traffic levels in all Denmark and generate the most stops, mainly because of the stations København H, Nørreport, Østerport, Ørestad and Tårnby. Even though the longest distance from the
transformer is less than 10 km, the total supplied area is quite large with just over 26 km. It is therefore expected that T25 will be one of the most strained transformers in the simulation.
Backup for T25 is initially OKF T26. IGF T26
The section from IGN to HIFN and from HIFN to HHN is supplied from transformer T26. The transformer is currently also supplying the sections from KLVN to SJÆN and from SJÆN to IGN, but the new TPS KILF is taking over the supply of these sections. The section from HIFN to HHN is quite long, almost 19 km, and a station, Høje
Taastrup, at the end of the section generates quite a few stops. The long distance and the dense traffic are expected to challenge the transformer and give cause to severe voltage drop in the long section.
Backup for T26 is ROF T25.
5.4.2 Kildebrønde Fordelingsstation (KILF)
KILF is a new RSS which being located at km 14,478 on the new line Copenhagen – Ringsted. KILF is thought to be supplied from two 23 MVA (18 MVA ONAF) on Ishøjgård USS. The distance from USS is approximately 1200 m. The traffic in the supplied sections is rather limited.
KILF T25
T25 will be supplying the first nearly 15 km of the new line as well as the sections KLVN –SJÆN and SJÆN – IGN currently supplied from IGF T26. There is only one minor station, Ny Ellebjerg, in the area. The OCL is TFZF160st without BT on the existing sections, and TFZF200st without BT on the new sections.
KILF T26
T26 supplies the section from KILF to KJNN, approximately 13 km. No stations are found within the section and the OCS is TFZF200St without BT. Due to the rather short supplied section and the limited traffic, T26 is expected to be one of the least loaded transformers in the simulation.
BJÆF T25 is backup for T26.
5.4.3 Bjæverskov Fordelingsstation (BJÆF)
BJÆF is a new RSS located at km 43,226 on the new line Copenhagen – Ringsted. The RSS is to be supplied from two 31 MVA (31 MVA ONAN) transformers on the USS Bjæverskov. The distance from USS is approximately 1100 m. The traffic in the sections is rather limited.
BJÆF T25
T25 is set to supply the section from KJNN to BJÆF as well as the section on "Lille Syd" from KJN to HFN. Even though the total length of the sections is considerable, more than 22 km, and there is a minor station, Køge Nord, in the area, the rather light traffic will probably not cause any major problems. The OCS is TFZF200st without BT on the new line Copenhagen – Ringsted and TFZF160St with BT on "Lille Syd". BJÆF T25 is in backup supplied from KILF T26.
BJÆF T26
T26 supplies the section on the new line from BJÆF to RGØN. Because it is a short section, less than 10 km, and the fact that there is no station on it, the transformer is not expected to represent a problem. The OCS is TFZF200St without BT.
T26 section is backup supplied from RGF T25.
5.4.4 Roskilde Fordelingsstation (ROF)
ROF was established during the electrification of "Vestbanen" in the nineties. The RSS is currently supplied from two 18 MVA transformers on the USS Kamstrup, but in the simulation they are set to be equipped with ONAF increasing the possible output to 23 MVA. Cabling from USS is quite long with 3000 m. ROF is supplying a large part of "Vestbanen" that sees a rather heavy traffic load and the transformers are therefore challenged.
If the path towards Holbæk and Kalundborg is electrified, a minor part of the path is set to be supplied from ROF T26.
ROF T25
T25 is feeding the section from HHN to ROF, which is a 4 track section. The total length is 21 km – 2 times 10,5 km double track – and there is one large station with numerous stops. The OCS is TFZF160St with BT.
ROF T26
T26 is supplying the section from ROF to KYN, a new neutral section that separates ROF T25 with the new RGF railway substation. The section is long, 21,5 km, and the OCS is TFZF160st with BT.
T26 sections are backup supplied from RGF T25.
5.4.5 Ringsted Fordelingsstation (RGF)
During the electrification of "Vestbanen" in the nineties, RGF was initially planned to be established, but due to light electric traffic the RSS was later skipped. However, the future electrification of both "Sydbanen" and the new line Copenhagen – Ringsted, leaves no doubt that RGF is necessary now. RGF is set to be placed in km 66,2, right next to USS Ringsted. USS Ringsted will supply RGF with two 31 MVA (31 MVA ONAN) transformers.
RGF T25
T25 supplies the sections on "Vestbanen" from KYN to RGF, on the new line from RGØN to Ringsted and on "Sydbanen" from RGSN to RMN. The supplied area is the largest in the simulation with 34,5 km. All traffic, except traffic from Sweden to
Helsingør, is passing through the area at some point. There is also one larger station, Ringsted, in the area. It is therefore expected that the transformer will be challenged. The OCS is TFZF160St with BT on "Vestbanen", TFZF200St with BT on "Sydbanen" and TFZF200St without BT on the new line.
Backup for T25 is BJÆF T26. RGF T26
T26 is set to supply the section from RGF to a new neutralsection, SON, located between RGF and SGF. The section is nearly 17 km long, and there are only a few minor stations. The OCS is TFZF160st with BT.
T26 supply section is during backup supplied from SGF T25.
5.4.6 Slagelse Fordelingsstation (SGF)
SGF was build during the electrification of "Vestbanen", and is supplied from two 18 MVA transformers on the USS Hejninge. In the simulation the transformers are set to be equipped with ONAF which increases the output to 23 MVA. The distance between USS and SGF is about 600 m.
SGF T25
T25 is supplying the section from the new neutralsection SON, to SGF. The section is short, less than 14 km, and equipped with OCS TFZF160st with BT. There are one minor station in the section.
T25 section is in backup supplied from RGF T26. SGF T26
T26 is supplying the section from SGF to SPRN. The section is quite long with 24 km and runs to a large part in tunnel, part of the Storebælt Fixed Link between Sjælland
and Fyn. The tunnel gradients combined with the long distance will probably cause some issues regarding voltage drop. The OSC is from SGF to the tunnel TFZF160St with BT, and hereafter TFZF200St without BT.
T26's section is backup supplied from MVF KT3D, which is almost 60 km away and therefore also an issue.
5.4.7 Lov Fordelingsstation (LOF)
LOF is a new RSS planned to supply a part of the new electrification path on "Sydbanen". LOF is supposed to be supplied from transformers on USS Blangslev, and will in km 99,4 be located close to that station. The transformers are initially set to 31 MVA (31 MVA ONAN) for T25 and 23 MVA (18 MVA ONAF) for T26.
LOF T25
T25 will supply the section from RMN to LOF as well as a small section on the "Lille Syd" path. The total length of the supplied sections is about 17 km, and Næstved station in located near the transformer. Except the small section on "Lille Syd", OCS is TFZF200St with BT.
Backup is supplied from RGF T25. LOF T26
The section from LOF to KRN is supplied from T26. The section is short, 10,6 km, and there is only a minor station on it. OCS is TFZF200st with BT.
MNF T25 is backup supply for T26.
5.4.8 Masnedø Fordelingsstation (MNF)
MNF is a new RSS set to supply a part of "Sydbanen". It is supplied from USS Masnedøværket, and is planned to be located right next to it. The transformers are of to two different sizes; T25 being a 23 MVA (18 MVA ONAF) and T26 a 31 MVA (31 MVA ONAN). The OCS is on the entire path is TFZF200St with BT, and the traffic density is quite low.
MNF T25
T25 is set to supply the section from KRN to MNF. The total length that T25 supplies is with only 10,4 km one of the smallest supply areas in the simulation. There are only minor stations in the area.
T25 is backup supplied from LOF T26. MNF T26
T26 is planned to supply the section from MNF to EKN. The section is almost 20 km long and thereby the longest on "Sydbanen". On the section the bridge
Storstrømsbroen is located. Today the bridge is a single track bridge but is expected to be replaced by a double tracked bridge. The simulation is based on the latter. There are only minor stations in the section.
5.4.9 Toreby Fordelingsstation (TORF)
TORF is a new RSS planned to supply a section of the "Sydbanen" path. The RSS is supplied from USS Radsted and located near by it, at km 150,6. Transformers are initially planned to be a 25 MVA (25 MVA ONAN) for T26 and a 31 MVA (31 MVA ONAN) for T26. The entire area has low traffic density, mostly freight trains, and OCS is set to TFZF200St with BT.
TORF T25
T25 is set to supply the section from EKN to TORF. The section is short, 10,7 km and there are only minor stations on it.
The section is backup supplied from MNF T26. TORF T26
T26 is planned to supply the section between TORF and LLMN. The section has no stations and is short with a total length of 16,8 km.
In backup, the section is supplied from RFF T25.
5.4.10 Rødby Fordelingsstation (RFF)
RFF is a new RSS set to supply both the last part of the "Sydbanen" path, as well as the tunnel under Femern bælt to Germany. The RSS will consist of three transformers, where two of them are supplying the tunnel towards Germany. These two
transformers, T26 and T27 is not part of the simulation, and will therefore not be described. The T25 transformer is supplied from USS Rødby, and initially set to 25 MVA (25 MVA ONAN). The RSS is located right next to it on km 182.
RFF T25
T25 supplies the section from LLMN to RFF that has a length of nearly 15 km. The traffic density is low; mostly freight trains and the OCS is TFZF200St with BT. Backup for T25 section is TORF T26.
5.4.11 Haslev Fordelingsstation (HZF)
HZF is a planned new RSS on the path "Lille Syd". HZF is set to be supplied from the USS Haslev by two 12 MVA (10 MVA ONAF) transformers. The location is right next to the USS and initially at km 73. The OCS is on all "Lille Syd" TFZF160St with BT. The path is a single line railway and the traffic density is low.
HZF T25
T25 is set to supply the section between HFN and HZF. The section is 17 km long and there are only minor stations.
The section is backup supplied from BJÆF T25. HZF T26
T26 is planned to supply the section from HZF to NÆNN, which is 17 km long. There are only minor stations in the section.
Backup is supplied from LOF T25.
5.4.12 Kastrup Fordelingsstation (CPHF)
CPHF is an existing RSS that was established around the year 2000, and supplies a part of "Øresundsbanen" as well as the connection to Sweden. CPHF is the only RRS in Denmark not owned by Banedanmark but instead owned by the Danish-Swedish state owned Øresundsbro Konsortiet. CPHF is therefore not supposed to backup other TPS in Denmark in any backup scenarios. Nevertheless it is simulated because of the possibility that IGF's supply area needs to either be revised or the supply technology changed, which can influence CPHF.
CPHF is supplied from a single transformer on USS Kastrup. The transformer is set to 23 MVA (18 MVA ONAF).
CPHF T25
T25 supplies the section from TÅTN to LKN. The section has a total length of 20 km and is running in both tunnel and across the Øresunds bridge. The OCS is partly TFZF160St without BT and partly TFZF200St without BT. There is one major station in the section, namely Kastrup, and the traffic density on the path is quite high.
The section is supplied alternately from T25 and from Lernacken RSS, which is located in Sweden. In case of a backup scenario it is simply the unaffected RSS that provides the section with traction power.
5.4.13 Kokkedal Fordelingsstation (OKF)
OKF is located in km 28,189 on the "Kystbanen" path. It was the first TPS established in Denmark. The power demand from OKF was simulated in 2009 and therefore initially not a part of this simulation, but since OKF is backup for IGF (and the other way around), it is simulated with the same timetable as well.
OKF is supplied from two 23 MVA transformers (18 MVA ONAF) on USS Stasevang. The distance between RSS and USS is rather long, approximately 3300 m. The traffic density is quite high, even though there are no freight trains on the path.
OKF T25
T25 supplies the section from Helsingør to OKF. The section is 18 km, and there are many stops on the six stations. The OCS is TFZF160st with BT.
T25's section is backup supplied from IGF T25. The distance from IGF is nearly 50 km and therefore a challenge.
OKF T26
T26's section is from HGLN to OKF. The section is one of the longest with a total length of nearly 24 m. There are five stations in the sections generating quite a lot of stops. The OCS is partly TFZF160St with BT, partly TFZF160St without BT.
6 Timetable
The simulation follows the timetable "Køreplan 250 med ekstra tog" received from Banedanmark 2012.11.28. For further information, please see Annex 3. A graphic overview of the timetable is shown in Figure 8.
Figure 8: Received timetable from Banedanmark
All Banedanmark paths, except the path "Lille Syd" from Roskilde to Køge, are simulated with electric traction. The sections with highest traffic density is København H – Østerport (20 trains each hour/ each direction), and København - Roskilde (12 trains each hour/ each direction). In the received timetable, not all trains were
expected to run by electric traction. In the simulation these trains have been replaced with electric trains with an equal number of seats.
Most intercity trains on the new line Copenhagen - Ringsted, trains from København to Jylland and Germany, are simulated with trains that are capable of running 250 km/h. Some sections of the path permit operation in a speed of 250 km/h.
6.1
Used train models
The timetable is simulated with two types of passenger trains and one type of freight train:
Passenger trains
o ET
All regional trains; from København towards Roskilde, Holbæk, Kalundborg, Ringsted, Næstved, Nykøbing Falster and Sweden. The ET is simulated with either 3 or 4 multiple units, depending on the specific path the trains follow.
o ICE-3
A major part of the intercity trains from København to Jylland or Germany.
Freight trains
o 2 x BR 185
Freight trains on the path Rødby – Køge Nord - Kalvebod – Sweden are simulated with 2500 t train weight, and the freight trains Jylland – Odense – Roskilde – Vigerslev – Sweden is simulated with 2300 t train weight.
7 Results
Simulation results are shown in Table 2.
Table 2: Results from simulation. The table is ranked after the power demand vs. the installed power.
The following colours are used as an indication of the load and the voltage quality:
The voltage quality is coloured, as EN 50163 requires.
The 30 min power demand is coloured according to "the rule of thumb", which says that the power demand shall not exceed 50 % of the installed power in normal supply scenario. The 1 min power demand is coloured red if over 200% of the installed capacity, because the protective relays on the transformer normally is rated to this power (actually at the current that corresponds the power).
The size of the current is not coloured, because the limits for the acceptable current is dependent on the type of OCS in the sections.
An overview of the voltage quality in the traction power system and the load on the transformers are shown in Figure 9.
Figure 9: Overview of the simulation results.
The sections are coloured, because the power demand from the respective sections in some places calls for measures to deal with overloaded transformers. A possible reconfiguration of the sections, where excessive loads on the transformer occurs, will in some locations be an acceptable solution.
7.1
General discussion of the results
The simplest way to make the traction power system functional is to reduce the traffic density and the power consumption from the trains (shorter trains). This will without doubt reduce the power demand. It is actually possible to change the timetable without reducing it, and still see an effect on the power demand. A possible way to do this is to make sure that there is not more than one train that accelerates within a supplied section at any given time. This can of course only be done if the traffic density is sufficient light and there are not too many stations in the section. For example will it most likely be possible on Storebælt, but impossible on sections supplied by IGF T25. There is unfortunately always the risk that the trains differ from the timetable, and thereby the voltage drop and power demand problems reoccurs.
However, it is not desirable to have the timetable restricted because of the traction power system, which is why the solutions in the following only regard the traction power system.
Solutions will in this report only concern the TPS's that is part of either "Sydbanen" or the new line Copenhagen – Ringsted.
7.1.1 Power demand
Excessive power demand is critical to the supplying transformer and must be dealt with in one of the following ways:
Changing the size of the transformer. Changing the type of transformer.
Compensate the reactive power from the transformer.
The restrictions put on the supply system from the 132 kV grid owner regarding unbalance, rules out the conventional two phase transformer supply at several locations. This means that even though the installed power in the transformer is acceptable according to the simulated power demand, there could still be a need for additional measures to secure a stable supply. Solutions could be switching the transformer to a three phased transformer or install active balancing / capacitive compensating.
In general, the results show that theexisting transformers on both "Vestbanen" and "Kystbanen" are loaded beyond the "the rule of thumb", namely 50 % of the installed power. That will cause problems during an abnormal or backup supply scenario.
The suggested transformer sizes on the new TPS seem in general reasonably, even though certain transformers sizes are likely to be exaggerated.
7.1.1.1 Direct and indirect feeding
The supply technology has to be chosen with respect to the location of the RSS, and the power demand from the supplied sections. Figure 10 indicates how the supply technology depends on power demand.
Figur 10: Power demand and supply technology.
There are two major types of supply technology seen from the 132 kV grid; direct feeding or indirect feeding. Direct feeding is directly dependent of the strength of the 132 kV grid, because the railway is a two phase system on a three phase supplying grid. Different solutions with three phase transformers, compensation and active balancing can help the a weak 132 kV grid coping with the unbalance the railway produce, but if the power demand is to high, the only solution is to chose a system with indirect feeding.
The power values written in the figure is an overall estimate, and is very dependent of the short circuit value at a given location.
7.1.2 Voltage quality
The high internal impedance of the conventional transformer, 0,36+j4,656 Ω, can be a problem, as it, with high current, results in a large voltage drop over the transformer. At the rated current for the conventional OCS without BT, 500 A, the voltage drop over the transformer is 2,3 kV and results in a voltage on the secondary side of the
transformer of 25,4 kV. A capacitive compensation on the secondary side of the transformer will reduce the voltage drop dramatically.
The conventional OCS, especially OCS with BT, also has a rather high impedance - 0,2371+j0,676 Ω/km. With the rated current for the BT transformers, 255 A, that results in a voltage drop of 180 V/km.
Figure 11 shows the longest permissible distance to power supply, if the voltage at the OSC shall not subside under 22,5 kV, which is the lowest voltage a train can operate under without reduction in power (ET and freight trains).
Figure 11: The longest possible distance to power supply regarding voltage drop. The impedance of the OCS and the transformer is included.
If the voltage drop over a section is too big, there are two different solutions regarding the OCS; either the length or the impedance of the section must be reduced.
The simulation results shows that there are problems with the voltage quality in the existing sections supplied by IGF, at OKF supply sections and on the section on Storebælt supplied from MVF. The voltage drop on IGF T25 sections is caused by the considerable overload on the transformer. Solutions aimed at the transformer will likely to solve the problem. The transformers on rest of the sections with to high voltage drop are not overloaded, and it is recommended that actions here involve the OCS.
In general it is not recommended that an autotransformer system be applied at the existing electrified paths, one of the major reasons being that it most certainly will require a total rebuild of the masts due to the weight of the heavier system. Instead is suggested a solution that involves removal of the BT where it is possible and
otherwise reinforce the OCS with extra feeder and return conductors. 0,0 10,0 20,0 30,0 40,0 50,0 60,0 200 400 600 800 D IS TA N CE (K M ) CURRENT (I) TFZF160st +BT TFZF200st +BT TFZF160st -BT TFZF200st -BT
Except from IGF's sections, both the new line Copenhagen – Ringsted as well as "Sydbanen", have no problem with the voltage quality.
7.1.3 Current
The only way to improve the OCS rated current level, is to increase the area of the OCS conductors. An overview of the rated current for OCS can be seen in Table 3.
Type Max. Current (30 min RMS) TFZF160st +BT 255 A* TFZF200st +BT 255 A* TFZF160st –BT 500 A TFZF200st –BT 800 A Autotransformer To be determined. TFZF160st +FL/RL To be determined.
Table 3: Rated current in different types of OCS.
* the maximum current is determined by the rated current of the BT.
For existing OCS, the best solution is to add one or more feeder and/or return conductors. It must be confirmed that the mechanical strength of the existing poles is sufficient to carry additional conductors.
Throughout most of the sections in the simulation, the results show a general problem with the current regarding the prevalent used BT. If the BT cannot be removed, they must be replaced by other BT's rated for a higher current.
A critical current caused by excessive power demand is often combined with a critical voltage drop. Solutions aimed at solving the voltage and power problem will often reduce the current to a level that will make other actions unnecessary.
8 Result analysis of TPS transformer sizes
In this chapter results for analyzed transformers are presented. For further information on specific transformers, please see Annex 1 and 2.
8.1
Vigerslev Fordelingsstation (IGF)
Both transformers on IGF see power demands higher than the acceptable load. The voltage quality and the current is also a problem at all supplied sections, but the solutions which will be described regarding the power demand, are likely to solve the other issues as well.
8.1.1 IGF T25
T25 is by far the most loaded transformer in the entire simulation. The 30 min load of 34,9 MVA exceeds the installed power by more than 50%. The transformer is therefore not even in the normal supply scenario capable of supplying its connected sections. If the previously mentioned rule of thumb is followed, the installed power shall be twice the size of the load under normal operating conditions, which in this case is almost 70 MVA. Since the section that T25 supplies in the abnormal and backup supply scenario is smaller than T25's sections, it is likely that 50 – 60 MVA will be sufficient. Unfortunately this cannot be provided by any conventional two phase transformer due to the restrictions from the 132 kV grid owner. That leaves only two solutions; either the sections must be reduced dramatically, or the supply must be switched to SFC.
8.1.1.1 Solutions regarding the extension of sections.
Figure 12: T25's currently supplied sections
Sections supplied by T25 totals 26 km and have a very high traffic density with a total of 175 stops and 508 train km pr. hour. The supplied area is in the middle of
Copenhagen, something that severely reduces the number of possible solutions regarding a reconstruction of the area. With some difficulties it could perhaps be possible to install two new neutral sections at the locations shown in Figure 13.
Figure 13: Possible new configuration of T25 supplied section.
A new neutral section between Nørreport and Østerport would reduce the stops in T25 sections from 175 to 136 and the train km from 508 to 446 in a rush hour.
Unfortunately the section from the new neutral section and northwards cannot be supplied from OKF T26, because the load on OKF T26 is already too high. It is therefore necessary to install a new transformer on HGLF to supply the section. There is a small transformer today on HLGL that only supplies the tracks in the yard for passenger equipment. A new transformer could also supply a part of the section that OKF T26 today supplies and thereby reducing the load of OKF T26 to an acceptable level.
Another new neutral section could be installed on the path from København H to Ørestad. This will separate the two stations Ørestad and Tårnby from T25's supply section. Furthermore all freight traffic will be separated as well. This will reduce the number of stops by 16 % (from 175 to 147) and the train km from 508 to 330 in a rush hour. CPHF T25 is not a Banedanmark transformer, and it would therefore be
necessary to install a new transformer on CHPF to supply the new section.
The best solution regarding a new configuration would be to introduce both changes. This will result in a reduction in train km on 48 % and a stop reduction on 39 %. The power demand on IGF T25 is likely to be reduced by 40 % (estimated value) to 21 MVA. This solution will therefore solve the problems that occur under normal operating conditions, but not in the other supply scenarios. The only solution will be to match one of the new transformers, either the one on HLGF or CHPF, with T25 regarding installed power, thus securing sufficient backup power for T25
The effect of reconfiguring the supply area of T25 as described above is only estimation. Before any final decisions are made another simulation must be run.
8.1.1.2 Solutions regarding the supply technology.
Another solution for T25 is to change the supply technology. It is likely that the
currently installed supply with two phase transformers cannot be supported by the 132 kV grid as the power demand increases as indicated by the simulated timetable. The high power demand requires a supply with a type of SVC or more likely through a SFC supply. A solution is shown in Figure 14.
Figure 14: IGF T25 sections supplied from a SFC.
There are various supply scenarios for IGF T25's sections with SFC that can be suggested. The solution on Figure 14 is only one of them. Other solutions with SFC include another location of a single SFC or two larger SFC's.
A SFC is normally configured with a number of SFC cells which each delivers up to 20 MVA. As the SFC cannot be overloaded the same way as the conventional
transformer can, it must be dimensioned by the highest instantaneous power demand. This is for IGF T25 about 73 MVA and the supplying SFC must therefore consist of four SFC cells, totaling 80 MVA.
The SFC supplied area can, as previously mentioned, be supplied in combination with traditional transformers and thereby secure a better overall voltage quality.
Additional simulations must be carried out, before the best solution with SFC can be found. Generally speaking, a SFC solution will be about two to three times the cost of a new traditional TPS.
8.1.2 IGF T26
IGF T26 is delivering 22 MVA (30 min RMS). This is almost the entire installed power, leaving no extra power for backup supply if necessary. The voltage quality is also unacceptable, especially at HHN where the voltage is below the limit on which
electrical traction power can be operated. The current can also be a matter of concern with a 1 min value of 904 A.
Actions are needed to be taken, shall the simulated timetable be used.
8.2
Kildebrønde Fordelingsstation (KILF)
Both transformers on KILF have acceptable loads in the simulation. The most loaded is T25 with 49%, and the suggested size of the transformers seems therefore
acceptable.
Due to the large power demand from IGF T26 sections, it seems unlikely that T25 is able to supply that one in a backup mode.
The voltage quality is good in the entire supplied area, but the current on parts of T25's sections is too large for the suggested OCS. Specific parts of the OCS need to be reinforced with extra feeder and return conductors.
8.3
Bjæverskov Fordelingsstation (BJÆF)
Though T25's section show a little more power demand (12,76 MVA) than the "rule of thumb" limit of 50 % of the installed power (12,5 MVA), it can be accepted due to the limited demand from the sections to be supplied in both an abnormal and a backup supply mode (KILF T26 and BJÆF T26).
The size of T26 has in normal supply scenario an overcapacity of 76 %, but the size seems reasonably regarding the supply of T25 sections in an abnormal supply situation. A backup supply of RGF T25 sections seems unlikely regarding RGF T25's load.
The voltage quality and current is over the entire area acceptable in the normal supply scenario.
8.4
Roskilde Fordelingsstation (ROF)
Both transformers on ROF are delivering over the acceptable limit of 50 % in the normal supply scenario; the load on T25 is 88 % and the load of T26 is 69% of the installed power. This will cause problems in the abnormal supply scenario for both transformers. The voltage quality is overall good, but the current flow is an issue. Actions need to be taken before the transformers can supply the intended traffic density.
8.5
Ringsted Fordelingsstation (RGF)
8.5.1 RGF T25
T25 is using 88 % the installed power in the normal supply scenario and the power demand is therefore critical. The voltage quality is fine, which indicates that the supplied area is not too wide spread, but as the overall traffic density is quite intense, it could perhaps still be worth considering a reconfiguring of the supplied sections. An overview of the area supplied by RGF T25 and the surrounding transformers can be seen in Figure 15.
Figure 15: RGF T25 and surrounding transformers as stipulated in simulation.
8.5.1.1 Solution regarding reconfiguration of sections supplied by RGF T25
ROF T26 is already loaded beyond the acceptable limit, so an extension of the sections supplied by ROF T26 in order to offload RGF T25 is not a valid option. LOV T25 is acceptable loaded, but switching the supply of the section from RGSN - RMN to LOF does not seem a feasible option because of the long distance from LOV (total 33,2 km). This will probably leave the voltage quality at RGSN unacceptable. An option could be to let the neutral section RGØN separate the "Vestbanen" path as well. BJÆF T26 sees only a small power demand, and the extra section from RGØN to KYN will not be any problem. Unfortunately it will only reduce the supplied area from 34,5 km to 29,6 km reducing traffic in the supplied area with 16 % (from 432 to 363,4 train km). The major power demand is found where train accelerates, which is in Ringsted, the only major station in the supplied area with 14 stops pr. hour. Reducing the area by introducing a new neutral section at RGØN is unlikely to have a larger effect on RGF T25 than 2 or 3 MVA.
There is also a chance that RGF T26 could supply the RGSN to RMN section. The section will extend the total supply area for RGF T26 by a factor 2, but as there is almost no stops on the section it could be a possible solution. Especially if RMN could be moved a few km north and SON some km east the solution seems interesting.
Adopting this solution means that T26 must be upgraded to be able to supply the needed amount of power under a non normal supply conditions. For RGF T25, the reconstruction of the section would mean a reduction of the supplied area by almost 49 % and traffic reduction of 47 %. As the one major stop station remains in the section supplied by T25, the power demand will not drop by the same percentage, but it seems likely that the adjustment will result in a decrease in the power demand of an estimated 15 MVA.
However, this solution only focuses on the problem matching the size of transformers with the power demand. The right solution will have to deal with the 132 kV grid as well, and that leaves no doubt that the only solution is by installing another supply technology than the 2 phased transformer. This will be discussed further in chapter 9.
8.5.2 RGF T26
The power demand on RGF T26 is 10,9 MVA and therefore seems acceptable according to the installed power (23 MVA). There are not any problems with the voltage quality, but the current is higher than the rated current for the installed BT's.
8.6
Slagelse Fordelingsstation (SGF)
Overall the power demand from SGF is considered acceptable.
The demand on T26 exceeds the "rule of thumb" by a few percent, but seems reasonable in the normal supply scenario. The long distance to MVF is most likely to give cause to a need for actions in the backup supply mode regarding both the power demand and especially the voltage quality.
I normal supply scenario the voltage quality is fine, but the current is too large in the parts of the OCS where BT's are installed.
8.7
Lov Fordelingsstation (LOF)
The power demand on LOF is less than the currently planned sizes of the
transformers are able to supply. The load leaves an overcapacity of at least 67 % in normal supply scenario, and even in the abnormal supply scenario installed power is excessive.
The voltage quality is good in the entire supply area, but the current is too big for the currently used BT's.
8.8
Masnedø Fordelingsstation (MNF)
The power demand on MNF is well under the limit of 50 % of the installed power, as both transformers have an overcapacity of about 65 %. The largest transformer, T26 on 31 MVA, is not likely to exceed the installed power under any supply scenarios, and is probably oversized.
The voltage is not critical in the normal supply scenario, but the BT's must be switched to some with a larger current rating.
8.9
Toreby Fordelingsstation (TORF)
Both transformers on TORF seem to be oversized, as the power demand does not exceed 34 % of the installed power. A more appropriate size will possibly be 23 MVA. The current is possibly too high for the BT's installed on T25's supply sections, and it may require action. The voltage quality is almost perfect throughout the supplied area for both transformers.
8.10
Haslev Fordelingsstation (HZF)
The two transformers on HZF have a power demand on 35 and 44 % respectively of the installed power. The transformers are the smallest in the simulation, 12 MVA, and as the abnormal power demand can be hard to predict, it is not recommended that the transformer size is downscaled further.
Both the voltage quality and the current are at an acceptable level.
8.11
Kastrup Fordelingsstation (CPHF)
CPHF T25 is loaded with 10,57 MVA in 30 min RMS, and due to the fact that the transformer is not supposed to operate in any abnormal or backup supply scenario, the transformer is suggested left untouched.
8.12
Kokkedal Fordelingsstation (OKF)
Both transformers on OKF are in the normal supply scenario loaded beyond the limit where they can supply in any abnormal or backup mode. Action needs to be taken to secure this.
Both voltage and current level is critical, and at least the BT's needs to be removed before an acceptable level can be reached.
9 The simulated power demand to be supplied by the 132 kV
grid
Results from the calculated unbalance are shown in Table 4.
Table 4: Calculated unbalance from 2 phased supply.
While the transformers are dimensioned by the highest 30 min load, the effect on the 132 kV grid is calculated by the highest instantaneous load from the transformers. If the calculated unbalance at a given location (the "Allowed unbalance without compensation (EU=1,4% and α=2)" column) exceeds the calculated unbalance from a load (the "2-phase Unbalance (%) column), the cell in the table is highlighted with a yellow background. At these locations, the created unbalance must be compensated. If the unbalanced load in column "2-phase Unbalance (%)" exceeds the given limit of 1,4%, the cell in the table is highlighted with a red background, and the traction power supply cannot be established with a conventional two phased transformer.
The locations where the calculated unbalance in one or the other way necessitates some kind of action are shown in Figure 16.
Figure 16: Transformers where load leads to action vs. the 132 kV grid.
The simulated power demand and the calculated unbalance are both dependent of the strength of the 132 kV grid. The short circuit levels used in the simulation, and
therefore also in the calculation, are estimated. Newer short circuit levels provided by Energinet will influence the results, but unlikely to an extent, that the conclusions will be any different.
The future traction power system needs to take into account the weak 132 kV grid. Solutions to this problem are several, but a system with SFC seems the most feasible as it does not affect the 132 kV grid with unbalance as the other systems do.
A solution for new line Copenhagen – Ringsted and for "Sydbanen" needs to be seen as an integral part of the overall traction power system in all eastern Denmark. An immediate possible solution is suggested in Figure 17.
