One VSC is connected to in shunt to the transmission line via a shunt transformer and other one is connected in series through a series transformer. The DC terminal of two VSCs is coupled and this creates a path for active power exchange between the converters. VSC provide the main function of UPFC by injecting a voltage with controllable magnitude and phase angle in series with the line via an injection transformer. This injected voltage act as a synchronous ac voltage source. The transmission line current flows through this voltage source resulting in reactive and active power exchange between it and the ac system. The reactive power exchanged at the dc terminal is generated internally by the converter. The real power exchanged at the ac terminal is converted into dc power which appears at the dc link as a real power demand and VSC1 is to supply or absorb the real power demanded by converter2 at the
DVR is of great importance in present day’s powersystem. DVR is used to protect sensitive loads against voltage disturbance can occurs into two forms either voltage or voltage swell. it is a type of forceful or solution of powersystem application fault at either the transmission or distribution level may cause voltage sag and swell in the entire system or a large part of it. Voltage sag occurs at any time in the system. The ratio of the amplitude is 10-90% and the time duration can take a half cycle of one minute .
Abstract —Simulating a powersystem with both transmis- sion and distribution networks modeled in detail is a huge computational challenge. In this paper, we propose a Schur- complement-based domain decomposition algorithm to provide accurate, detailed dynamic simulations of the combined system. The simulation procedure is accelerated with the use of parallel programming techniques, taking advantage of the parallelization opportunities inherent in domain decomposition algorithms. The proposed algorithm is general, portable and scalable on inex- pensive, shared-memory, multi-core machines. A large-scale test system is used for its performance evaluation.
In present-day dynamic security assessment of a large-scale powersystem, it is common to represent the bulk generation and higher voltage (transmission) levels accurately, while the lower voltage (distribution) levels are equivalenced. On the other hand, when concentrating on a DN, the TN is often repre- sented by a Thévenin equivalent. The prime motivation behind this practice has been the lack of computational resources. Indeed, fully representing the entire powersystem network was historically impossible given the available computing equipment (memory capacity, processing speed, etc.) . Even with current computational resources, handling the entire, detailed model with hundreds of thousands of Differential and Algebraic Equations (DAE) is extremely challenging , . As modern DNs are evolving with power-electronics inter- faces, DGUs, active loads, and control schemes, more detailed and elaborate equivalent models would be needed to encom- pass the dynamics of DNs and their impact on global system
With the increased loading of transmission and distribution lines, voltage instability problem has become a concern and serious issue for powersystem planners and operators. The main challenge of this problem is to narrow down the locations where voltage instability could be initiated and to understand the origin of the problem. One effective way to narrow down the workspace is to identify weak buses in the systems, which are most likely to face voltage collapse. The weakest bus has been identified as the bus, which lacks reactive power support the most to defend against voltage collapse. Network configuration, R/X ratio of interconnections, load models, load directions, presence of generators and compensators are most influential factors of the strength of a bus in a distributionsystem. In turn, identifying weak buses can give correct information for the optimal reactive power planning involved that would decide which buses are the most severe and need to have new reactive power sources installed . Ranking of bus based on strength has also been found useful in determining location for distributed generator to enhance loadability of the system . Different voltage stability indices have been developed to determine the strength of load buses in a system, which has been explained in brief in the next section.
Besides the function of wireless monitoring, the SEMS based on Zigbee wireless transmission proposed in this paper also possesses the important functions of intelligent energy management and power usage safety protection. For the convenience of applying the developed system onto buildings, the wireless transmission function is adopted in the system so that the system could be used and installed at any location within the interior space without any need of wiring, which realizes the intelligent power usage management, monitor and safety protection at any place and effectively improves the convenience of system utilization . The system concept is as shown in Figure1. As shown in the figure, consumer end receiver board and distribution end transmitter board are plugged onto the designed intelligent outlet module.
Energy shortage has become a global challenge. As the country economy is mostly dependent on electrical en- ergy, each and every nation is trying to recover their en- ergy crisis. A developing country like Bangladesh needs an efficient energy system to minimize the losses and proper utilization of generated power. Smart Grid system is the only one and proper solution. Bangladesh has bet- ter prospect to implement Smart Grid technology. It is possible to manufacture the equipments required to im- plement Smart Grid in Bangladesh. Only some alteration is needed to make it happen. At the same time some moderation in transmission and distributionsystem can be done. So Smart Grid can be a proper solution for Ban- gladesh to overcome the power crisis problem and to face the future impacts in power sector [1-4].
Abstract: Congestion is severe problem that affects the powersystem security as it violates the various operating limits of the powersystem so congestion management is an important task for independent system operator. For managing congestion, smart wire module has been used in series with transmission line. When smart wire is connected in series with most congested line, there is improvement in voltage profile, reduction in transmission line loading and losses. Transmission Congestion Distribution Factor (TCDF) is calculated to know congestion in lines and congestion is managed with the help of smart wire module. It is observed that value of TCDF also reduced when smart wire is connected. Work has been carried out on IEEE 15 bus system on MATLAB.
Paper  discussed the application of series-shunt compensation. TCSC and SVC, which are two members of FACTS devices, used to improve powertransmission capability of EWIs (East-West Interconnectors) (from Ghorasal to Ishurdi) of Bangladesh PowerTransmissionSystem. 71.8% of capacity has been enhanced after compensating the transmission line. In paper , it has been focused on using series compensation on a specific area in Canada, Hydro-Quebec, long distribution line. The study was done on 60 km distributionsystem supplying industrial and household customers. Three levels of compensation had been tested, 0% (non-compensated), 36% and 60%. This paper shows that the series compensation improves the powertransmission capability as well as the transient and steady-state stability of the voltage profile. In paper , a technique of power transfer capability improvement of powertransmission line using
Major concern in photovoltaic power plants these days is how much is the maximum allowable penetration level. Photovoltaic Power Generation (PPG) has now become a significant source in powerdistribution systems. However, PPG may bring both positive and negative effects to the distributionsystem. But extracting power from solar photovoltaic arrays according to the demand of the load under changing grid conditions and environmental conditions has been a challenge. In this work, active/reactive power control and maximum power point tracking control strategies are investigated. The developed solar array is investigated under varying solar irradiation and varying temperatures. The effect of these factors on voltage, current and consequently on power is observed. The power at AC and DC sides of the inverter is verified. This two stage configuration is more complex in nature with three control loops.
Abstract: The energy transition towards renewable and more distributed power production triggers the need for grid and storage expansion on all voltage levels. Today’s powersystem planning focuses on certain voltage levels or spatial resolutions. In this work we present an open source software tool eGo which is able to optimize grid and storage expansion throughout all voltage levels in a developed top-down approach. Operation and investment costs are minimized by applying a multi-period linear optimal power flow considering the grid infrastructure of the extra-high and high-voltage (380 to 110 kV) level. Hence, the common differentiation of transmission and distribution grid is partly dissolved, integrating the high-voltage level into the optimization problem. Consecutively, optimized curtailment and storage units are allocated in the medium voltage grid in order to lower medium and low voltage grid expansion needs, that are consequently determined. Here, heuristic optimization methods using the non-linear power flow were d eveloped. Applying the tool on future scenarios we derived cost-efficient grid and storage expansion for all voltage levels in G ermany. Due to the integrated approach storage expansion and curtailment can significantly lower grid expansion costs in medium and low voltage grids and at the same time serve the optimal functioning of the overall system. Nevertheless, the cost-reducing effect for the whole of Germany was marginal. Instead, the consideration of realistic, spatially differentiated time series lead to substantial overall savings. Keywords: power grid modelling; transmission grid planning; distribution grid planning; optimization; linear optimal power flow; power flow; grid expansion; storage expansion; renewable energy
information system (GIS) for DG system was conducted. Monitoring, analysis, and evaluation associated with DG has been performed for individual distribution systems, assuming that in practice the power flow is unidirectional in a distributionsystem. Conventional radial distribution systems have been able to operate using separate methods, but as the DG connection increases, there is a need to accurately monitor and analyze such systems. In separate analysis and monitoring, DG could be connected and operated in a distributionsystem without considering the actual effects on other distribution feeders and transmission systems. Therefore as the installed DG has increased, the necessity to transmit and distribute integrated analysis has occurred . This paper presents a new transmission and distribution integrated monitoring and analysis system and methodology to evaluate the effects of DG in integrated system, and it recommends a method for the optimal operation of DG. The proposed system is new concept of grid operating for practical DG penetrated power systems. In previous grid operating systems, transmission and distribution systems are managed separately and the effect of DG cannot be analyzed properly. To analyze the effects of DG in real powersystem operations, the transmission and distribution integrated monitoring and analysis system is connected to a distribution automation system (DAS) and supervisory control and data acquisition (SCADA). When transmission and distribution integrated systems analyze DG connected power systems, both the SCADA and DAS system data are automatically combined. A new methodology and automated process for preliminary evaluation of DG connection also proposed in the paper. Case studies performed using practical data from Jeollanam-do Province in South Korea show the effectiveness and differences of the integrated system.
of disturbances on electrical power systems. CORBA architecture is utilized as communication interface by the Transient meter, wavelet-based techniques for automatic signal classification and characterization, and a smart trigger circuit for the detection of disturbances. A measurement algorithm, developed by using the wavelet transform and wavelet networks, had been adopted for the automatic classification and measurement of disturbances . L.W. Coombe and D. G. Lewis explained severity of the fault depends on the short-circuit location, the path taken by fault current, the system impedance and its voltage level. In order to maintain the continuation of power supply to all customers which is the core purpose of the powersystem existence, all faulted parts must be isolated from the system temporary by the protection schemes. When a fault exists within the relay protection zone at any transmission line, a signal will trip or open the circuit breaker isolating the faulted line. To complete this task successfully, fault analysis has to be conducted in every location assuming several fault conditions. The goal is to determine the optimum protection scheme by determining the fault currents & voltages. In reality, powersystem can consist of thousands of buses which complicate the task of calculating these parameters without the use of computer software such as MATLAB .The controlling and monitoring of electrical distribution line is also possible using IOT (internet on things). It is capable of effective integrate of the infrastructure resources in communications manage for electrical powersystem, make the information and communication services manage for electrical powersystem, increase the level of powersystem information and to get better the utilization efficiency of infrastructure in the existing powersystem . But the problem associated with this approach is that it cannot deal with real time simulation and failures or abnormal conditions of powersystem.
In bulk powertransmissionsystem planning and ope- ration, the present practice is to carry out an N-1 con- tingency analysis . Occasionally, an N-2 security ana- lysis is employed in some stringent cases. However, it is implemented not via an exhaustive search but rather via a partial assessment of the system reserves over a small portion of the transmission network. An N-k security analysis for k > 1 is perceived as being impossible to achieve due to the huge number of cases that need to be investigated. In fact, under the assumption of independ- ence between successive events, it would require check- ing the impact on the system reserve margins of the loss of every k out of N pieces of equipment, which yields a number of cases to be tested that grow exponentially with N. However, it is clear that this chain of contingencies is dependent on each other due to the protection-system interactions, either directly or indirectly via the changes in the distribution of power through the network or due to the possible multiple impacts of a triggering event, such as lightning or other natural hazards. Consequently, the probability of the occurrence of cascading failures is much higher than the probability of a random (i.e. inde- pendent) tripping of k out of N components of the sys- tem.
The powerdistributionsystem is made up of sub- transmission lines, power transformers, 33kV lines, 15kV lines, distribution transformers, LV Lines, etc. Currently Ethiopian Electric Powersystem has 400kV, 230kV, 132 kV primary transmission systems and 66kV, 45kV as sub transmissionsystem and 33kV and 15kV as distributionsystem. At all the 66 or 45kV substations power transformers of various ratings like 25 /12 /6.3/3MVA are installed for step down of voltage to 15kV for feeding to Distribution Transformers. Once the voltage has been lowered at the distribution substation, the electricity flows to industrial, commercial, and residential centers through the distributionsystem. Conductors called feeders reach out from the distribution substation to carry electricity to customers. Customers require higher quality service due to more sensitive electrical and electronic equipment. The effectiveness of a powerdistributionsystem is measured in terms of efficiency, service continuity or reliability, service quality in terms of voltage profile and stability and powerdistributionsystem performance .
The power source or power generation system generates power for the transmission and reception system. This power source is different for the three systems: an a.c (alternating current) source and a dc source. For the purpose of achieving the desired result for this project, a DC (Direct Current) power source for the transmissionsystem and an a.c source for the reception, alert and actuation system was used. The power supply stage provides the appropriate DC voltage requirements to ensure the circuit components are powered properly. The ATMEGA8 requires a maximum voltage of +5.5V, which makes 5V power supply okay for the circuit. The power supply stage is a linear power supply type and involves in step down transformer, rectifier, filter capacitor and voltage regulators, to give the various voltage levels. The transmissionsystem comprises the electrical components that influence the remote control to transmit signals through radio frequency signals to the radio frequency receiver. The components of the transmissionsystem are simply the components of the remote control. These white box components are: 9V dc source, 470µF capacitor, ATMEGA8 microcontroller, Push button (12), HT12E RF encoder, RF transmitter, 10k Resistor, Antenna, Electronic chip board, Transparent plastic 8 by 4 ft for housing, LCD LED (2)
Large wind farms consist of hundreds of individual wind turbines which are connected to the electric powertransmission network. For new constructions, onshore wind is an inexpensive source of electricity, competitive with or in many places cheaper than fossil fuel plants. Offshore wind is steadier and stronger than on land, and offshore farms have less visual impact, but construction and maintenance costs are considerably higher. Small onshore wind farms can feed some energy into the grid or provide electricity to isolated off-grid locations.
Figure 9 is a comparison curve of experimental and simulated data of ultrasonic energy under diﬀerent excitation source amplitudes. The experimental data are the ultrasonic power measured at the receiving end at diﬀerent excitation voltages when the transmitting transducer frequency is 28 kHz through 3 cm of pork tissue. The simulation data are the sound intensity of the transmitting transducer when the source frequency of the transducer is 28 kHz, and the vibration velocity is changed from 30 V to 50 V. In Fig. 9, the horizontal axis of the bottom end is the excitation level applied by the COMSOL simulation transmitting end; the left vertical axis represents the sound intensity of the COMSOL simulation part; the top horizontal axis is the excitation voltage of the transmitting transducer in the experiment; and the right vertical axis represents the ultrasonic power obtained by the receiving transducer in the experiment. Fig. 9 shows that experimental and simulated data are consistent with trends in sound source size. In the far ﬁeld, the energy tends to increase with the increase of the excitation source at the transmitting end.
Green energy is a need of present time. The development of any country largely depends upon the accessibility and convention for use of energy and its energy efficiency. No country can, therefore, afford to think of not using the energy. In related to efficiency of power generation, its transmission and distribution, improvement of power quality become priorities in the field of electric power industry in the today’s time. Requirements to natural resource saving aspects at all phases of energy production, transmission and distribution are simultaneously raised. Continual improvement of technologies for the safe use of energy resources is a key to sustainable development of a human society. In particular, high temperature superconductivity (HTS) should be used to meet the growing needs of the energy industry. It is known that HTS power cables allow us to increase the level of transmitted power to several W at a voltage of 66-110kV. Technology of HTSing systems and equipment are characterized by high critical current carrying density (J c ), high critical temperature (T c ),