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Using Innovative Technologies to ease Wind

Resource penetration into Power Grid

Damien THOLOMIER Jorge ROLA Carlyle WILLEMSE

AREVA T&D Automation AREVA T&D Automation AREVA T&D Automation

5845, boulevard Couture, Montreal,

H1P 1A8, Canada 5845, boulevard Couture, Montreal, H1P 1A8, Canada 5845, boulevard Couture, Montreal, H1P 1A8, Canada

damien.tholomier@areva-td.com jorge.rola@areva-td.com carlyle.willemse@areva-td.com 1. INTRODUCTION

With the penetration of wind resources in European and North American Grid networks, the need of adapting network’s stability and control principles has significantly increase. This has resulted into the progressive development of adequate Grid Codes setting with some acceptable operational bandwidth to wind generators as far as fault levels, power quality and supply stability. These have to be strictly follow by every independent power producer setting indirectly new technical constraints such as to forecast and curtail a wind farm energy output under certain conditions or to improve the plant response to network faults especially VAR flows.

On the other hand the same wind farms offer new VAR injection opportunities at lower network levels which theoretically could reduce the investment need in network reinforcement or dedicated VAR compensation devices assuming the plant VARs can be as flexibly controlled as for conventional plants. Energy regulators are developing innovative rewarding schemes against such specific VAR control scenarios.

While the wind turbine technology has now moved to levels raising promising results on the turbine side, the latest technological developments in the Energy Management Software has opened the Optimization software modules traditionally used by Transmission or Distribution Operators into the lower SCADA platforms used by traders and associated generation portfolio operators to track their assets through real-time market constraints (intra-day and balancing) bringing them new opportunities to control their portfolio as a coordinated system. As a direct result of this technical feasibility stage being reached energy regulators today propose various market mechanisms to insure a financial return to Generation portfolio players investing in the extra amount of technology required to offer these new network technical services. These new constraints and incentives are raising new energy control challenges within wind industry, especially for large wind farms which face the most demanding Grid Code constraints. In the meantime, it is interesting to notice that Energy Management soft technologies have been employed over the past 20 years into larger network and generation context against similar requirements.

A new standard called IEC 61400-25 has been also designed to unify all the communication systems in wind power plants, both for internal exchange of information and for remote control. Most of the current control and monitoring systems used in wind farms are vendor-specific and the protocols and data provided by these systems are therefore dependent on their manufacturer. The new IEC61400-25 standard is derived from IEC61850, and has been developed to modularize

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object models, to model information exchanges and map communication profiles related to wind turbine.

This paper proposed to summarize the various innovative concepts brought through Substation Automation and Energy management software allowing in the future a better wind generation integration to power grid systems as close as possible to conventional plant models while taking into account the need for coordinated control between wind generator excitation system, static or dynamic VAR compensation equipment as well as the latest developments in the area of wind forecasting applications. In a second part, this paper will not only explain the main features of the standard IEC 61400-25, but also highlight its advantages for the integration of wind farms into the electric system

2. MAJOR CHALLENGES

The total capacity of all wind farms in Canada is approximately 1,856 MW (see figure 1). The United States (see figure 2) has the third most installed capacity of wind power in the world with a combined capacity of 16,818 MW after Germany and Spain.

Figure 1: Map of installed windfarms in Canada – Sources Canwea

There are more than 5,500 MW of future developments of windfarm in Canada. A large contribution from wind energy to power generation is technically and economically feasible. This will result in a power generation in the same order of magnitude as the individual contributions from conventional technologies developed over the past century. These large shares – about 20% in 2020/30 - can be achieved, while maintaining a high degree of system security in the power systems. The constraints of increasing wind power penetration are not inherently technical problems with wind technology. The barriers are mainly a matter of regulatory, institutional and market modifications, and should be dealt with in a broader power market context.

At the end of 2007, worldwide capacity of wind-powered generators was 94.1 Gigawatts. Although wind currently produces just over 1% of world-wide electricity use, it accounts for approximately 19% of electricity production in Denmark, 9% in Spain and Portugal, and 6% in Germany and the Republic of Ireland. Globally, wind power generation more than quadrupled between 2000 and 2006. Wind power is produced in large scale wind farms connected to electrical grids, as well as in individual turbines for providing electricity to isolated locations. USA, Germany and Spain account for more than 58% of the worldwide wind energy capacity.

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Figure 2: US Wind Energy projects (AWEA 4th Quarter 2007 Market Report)

In order to properly assess the scope of integration of wind power, a system-wide approach should be adopted. Wind cannot be analysed in isolation from other parts of the power system. The size and inherent flexibility of the power system are crucial aspects in determining the system’s ability to accommodate a high share of wind power. The role of a variable output power source, like wind energy, needs to be considered as one aspect of a variable supply and demand electricity system. The already established control methods and backup, available for coping with variable demand and supply, are more than adequate for dealing with the additional variable supply of wind power, at penetration levels of up to around 20% of supply, depending on the nature of the system. For larger penetration levels, some changes may be needed in power systems and their method of operation to accommodate the further integration of wind energy. In addition, network infrastructure needs to be upgraded to accommodate the increased power flows and to access the offshore wind resources.

The major challenges of wind power integration are: Design and operation of the power system, Grid infrastructure,

Connection requirements for wind power plants, System adequacy and the security of supply, Electricity market design,

Institutional and legal barriers 3. GRID CODES

Clear rules are required to ensure that the power system operates efficiently and safely. In this respect, wind energy technology is evolving to keep up with ever stricter technical requirements. There are continuous changes in grid codes, technical requirements and related regulation, often introduced at very short notice and with minimum involvement of the wind power sector.

Grid codes and other technical requirements should reflect the true technical needs for system operation and should be developed cooperatively between TSOs, the wind energy sector and authorities. Costly technical requirements should only be applied if they are based on a truly

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technical rationale and if their introduction is required for reliable and stable power system operation. As large energy systems operate with little storage capacities mostly for economic reasons, the guiding principle is to balance demand and supply continuously and, where necessary, to replace other capacity within very short lead times. As each national electricity system operates under tight security and quality standards, these so-called “ancillary services” have to be relied on to “secure” and “fine-tune” the electricity provided, independent of whether intermittent renewable are connected to the grid or not.

Security standards dictate that the electricity grid must be designed to withstand outages of certain magnitude and high loads without losing service, so-called 'N-1' or 'N-2' events. Overall system reliability is determined by the “loss-of-load probability” which can be defined as "the probability that the load will exceed the available generation".

Quality standards define the exact nature of the electricity service delivered, the frequency and voltage being two important variables of this. This mandates that the operator keeps variations in frequency and voltage within specified limits so as not to damage electrical appliances.

Keeping these two above criteria in mind, an operator has to enable enough reserve capacity to be able to maintain the specified security and quality of electricity supply in the face of major events. Two commonly considered events are the outage of the largest individual generating unit on the grid or the loss of the most significant transmission line.

AWEA identified on last 2004, more than 4 major technical areas of concern:

Low voltage ride-through (LVRT) capability for wind plants and wind turbines: AWEA recommended adoption of an LVRT requirement developed by E.ON Netz (Figure 3), if required, on a case-by-case basis. E.ON Netz is a German grid operator faced with a significant and growing penetration of asynchronous wind generation capacity on the German grid. The E.ON Netz standard requires that the machine stay connected for voltages at the terminals as low as 15% of nominal per unit for approximately 0.6 s.

Supervisory control and data acquisition (SCADA) equipment for remote control: AWEA recommended the requirement of equipment to enable remote command and control for the limitation of maximum plant output during system emergency and system contingency events and telemetry equipment to accommodate reliable scheduling and forecasting information exchange.

Reactive power capability: AWEA recommended that wind plants connected to the transmission system be capable of operating over a power factor range of ±0.95.

Current wind turbine simulation models: AWEA recommended that transmission providers and wind turbine manufacturers participate in a formal process for developing, updating, and improving engineering models and turbine specifications used for modeling the wind plant interconnection.

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Figure 3: LVRT requirement for wind generation facilities per FERC

4. BALANCING INTERMITTENT GENERATION AT TRANSMISSION SYSTEM OPERATOR LEVEL

Due to climate change, the decision of European governments to approve the Kyoto protocol and the associated cost of carbon emission is creating promising economical incentives to further develop alternate CO2 free energy sources and reach the objective of having around 15% (as for

instance in the United Kingdom) of the country’s electricity production generated from renewable energy sources such as wind energy.

Like any other form of generation, wind power will have an impact on power system reserves and will also contribute to a reduction in fuel usage and emissions. The impact of wind power depends mostly on the wind power penetration level, but also on the power system size, generation capacity mix, the degree of interconnection to neighbouring systems and load variations.

When about 10% of total electricity consumption is produced by wind power, the increase in extra reserves is estimated at 2-4 % of installed wind power capacity, assuming proper use of forecasting techniques. For the purposes of balancing, the qualities of wind energy must be analysed in a directly comparable way to that adopted for conventional plants. Balancing solutions involve mostly existing conventional generation units (thermal and hydro as in Canada). In future developments, increased flexibility should be encouraged as a major design principle (flexible generation, demand side management, interconnections, storage etc.) in order to manage the increased variability induced by renewable energies.

The balance market rules must be adjusted to improve accuracy of forecasts and enable temporal aggregation of wind power output forecasts. Curtailment of wind power production should be managed according to least-cost principles from a complete-system point of view.

In the same time the lands offering sufficient wind opportunities to reach the expected financial rate of return starts saturating, raising new interests towards coastal areas presenting the combined interest of reducing the associated visual and noise disturbance to the public as well as showing promising wind potential (see figure 4). Building wind farms offshore however requires larger initial

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investments and so the associated return on investment equation directly results in a need to increase the associated site generation density.

This situation has raised new electrical network connection challenges as the new offshore wind farms will soon reach similar sizes as conventional power plants operating in transmission networks. As a result, their configuration and operational model shall be adapted as compared to the traditional wind farms connected to distribution networks whose reduced capacity have been ignored in the generation response models used by transmission network operator.

Figure 4: Off and Onshore Wind farm

These large size offshore wind farms raises new control challenges to Transmission System Operators as summarised through the following diagram (figure 5):

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Optimal Scheduling Generation

Availability Week, Day, Hour

Minute Second MilliSecond

Load Forecast Stochastic Generation availability Local Primary Turbine Control Network Security Constraint Optimum Active Power Sharing Spinning Reserve Secondary Reserve Tertiary Reserve Congestions How to Share MW Between Scheduled Generation

Optimally ? Unit Commitment Close Loop Frequency Control How to maintain frequency within limits ? Economic Dispatch Automatic Generation Control Blade Pitching Mechanisms

Figure 5: Impact on Transmission Systems

As a consequence large wind generation patterns need to be integrated within the traditional generation scheduling and real-time economic dispatch programs. This impacts the area of wind generation forecast where weather based forecasting techniques will have to be deployed in coordination with real-time data measurements for short-term error correction.

The new exposed through Grid Codes for Generation of that size are key to reduce the amount of reserve having to be operated in parallel of unpredictable resource to balance for short-term deviations. Longer term the innovation seen in the wind turbine control technology (blade pitching) will for sure allow large wind generating plant to flexibly operate through automatic load-frequency control schemes.

5. FORECASTING AND CURTAILING WINDGENERATION

As expressed in the previous paragraph it is the responsibility of the network operator to ensure that the generation injections constantly match the demand while keeping sufficient reserve to allow safe network operation.

This approach obliges the network operator to keep some amount of reserve generation on-line for network stability purposes and manage errors in its short-term demand forecast as well as generation availability plans (or forecasts in the case of unpredictable generation such as wind generation). In the same time the optimisation of its network operational costs drives the minimisation of generation reliability costs, turning into minimisation of available reserve.

From a grid management point of view, changes in electricity production are typically observed over short time-intervals (minutes, half-hourly or hourly intervals). Thus, for example, if current wind energy production runs at 2,000MW, the question a system operator might ask is what will be

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the output in one hour? On the basis of weather forecasts and modelling results, the likely output is calculated and the operational reserve is planned accordingly.

The interest in wind forecasting has been growing over recent years along with the recognition of technical implications of higher penetrations of wind power. For wind penetrations of below around 5%, wind forecasting is generally believed as not necessary, since "deviations in wind output fail to show up in thee flow of daily operation with such small grid penetrations". As wind penetration rises, wind forecasting increasingly adds value to wind power.

As shows in Figure 6, using both weather based prediction methods correlated with short-term historical values acquired through real-time, Generation software has recently well improved the quality of wind generation forecasts improving the visibility of the network Operator on the amount of wind generation distributed in its network, and so in return reducing the need for operating parallel costly stand-by reserve units.

This recent progress is therefore seen as the way forward by Transmission System operator to allow for larger penetration of intermittent generation while maintaining generation reserve costs (usually uplifted at the level of all generation player network access costs) within reasonable levels. It justifies the recent changes observed into the Grid Codes of Transmission System Operators operating large amount of generation resources (such as for instance Spain).

LF UC/ED Weather Forecast Conventional Plant Basepoints (MW) SCADA Real-time measurements - Wind - Loads - Generation Wind Power Forecast (MW) WGF xml files xml files setpoints measurements Monitoring

Figure 6: Wind forecasting

Electricity generation from wind turbines will always vary with weather conditions but the more precise the forecasting and modelling becomes, the smaller will be the error margin in forecasting this variability and thus the lower the requirements can become for operational reserves and

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balancing energy. A second difficulty encountered in the management of wind generation is related to the fact that “optimized” wind locations are usually remote in weak transmission access areas. In these cases, the existing transmission lines may not always offer sufficient power evacuation possibility, requiring the network operator to curtail wind generation programs during certain days of the year when for instance insufficient loads at the proximity of the wind farm requires excessive wind power flows through the line.

This situation may therefore requires wind and network operators to agree on days when wind generation can produced but is not allowed to for congestion reasons, directly impacting the overall wind project Business Case considering the lack of revenues during these days. Cases were for instance observed in France were this situation blocked some wind projects.

In this case the traditional Energy Management automated control functionality offer distributed interfacing down to individual windturbine controllers (using IEC61400-25 communication protocol) as well as standard ICCP interfaces to Regional or National Control Centers. This for instance allows dynamic windturbine curtailment reacting in real-time to the curtailment thresholds received from the network operator. This solution guarantees the maximum revenue stream during the congested periods directly impacting the associated project return.

The associated system infrastructures are typically based on State of the Art Ethernet 100Mbit/s IEC61850 communication protocol between energy applications and individual turbine controllers as shown in Figure 7.

Figure 7: Wind Plan Generation Control

The technology employed is derived from conventional Substation automation technology where IEC61850 have already mapped the specific Wind generation data models and offer fast communication capability between controlling devices, while integrating network application

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software as well as traditional protocol to interconnect with Energy Management Systems, typically Ethernet ICCP.

6. COMMUNICATION DATA EXCHANGE REQUIREMENTS

Some utility grid codes specify that it must be possible to transmit data with real time stamps to a regional or national control center. The grid code gives a list of data that must be transmitted as for example:

Plant status information:

o Signalling or status alarm (protective relay trip, relay watchdog, teleprotection, SF6 pressure, CB status, turbine status, etc.)

General information

o Real time measurement data (voltage, current, frequency, active / reactive power, etc.)

o Command and feedback-signal of CB control and compensation equipment,

Generally the grid codes make demands for active and reactive power, voltage and meteorological data (wind speed, wind direction and ambient temperature). The grid codes then include data exchange demands for plant alarms, connectivity, wind turbine availability etc. as listed bellows:

General information

o Active power production at connection point, Possible production at connection point, Lost production as time series, Reactive power production at connection point, Voltage at the connection point, Grid transformer tap position, Circuit-breaker position indication, Fault indication for the grid transformer, Current measurements, Frequency, Status of compensation equipment,

Plant Status information

o Number of turbines stopped due to low and high wind, Number of turbines stopped due to maintenance, Number of turbines stopped due to forced outage, Total number of turbines out of operation, Number of turbines with limited capacity, Relevant information topology for the internal network, Relevant plant alarms, Frequency response system mode signal, Frequency response system mode status indication,

Metrological information

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Figure 8: Substation Automation System for the Electrical part

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7. NEW IEC61400-25 COMMUNICATION PROTOCOL

A new standard called IEC 61400-25 has been also designed to unify all the communication systems in wind power plants as shown in Figure 8 and 9, both for internal exchange of information and for remote control. Most of the current control and monitoring systems used in wind farms are vendor-specific and the protocols and data provided by these systems are therefore dependent on their manufacturer.

The new IEC61400-25 standard is derived from IEC61850, and has been developed to modularize object models, to model information exchanges and map communication profiles related to wind turbine.

The focus of IEC61400-25 is on the communications between wind power plant components such as wind turbines and actors such as SCADA or/and Digital Control Systems. The standard is composed of 6 parts:

Part 1 (Overall description of principles and models) provides an overview of the standard, defines some of the terminology used in the following parts and outlines the underlying modelling concept. The schematic in Figure 10 illustrates the client-server pattern behind the communication architecture, whose three parts - object model, information exchange model and communication profile mappings - are modularised and modelled separately. This benefits the flexibility and modularity of implementations.

Figure 10: Conceptual communication model of IEC61400-25

Part 2 (Information models) introduces and defines the data objects - referred to as logical nodes - specific to wind turbine communication. All data objects and data types are self-describing through embedded meta-data such as scaling and unit information for measured values. This enables e.g. the self-configuration of SCADA systems.

Figure 11 gives an overview of the available objects and their logical node names. The minimal configuration requires an object model which at least contains information about the rotor, the generator(s), the yawing system, the nacelle and the turbine as a whole.

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Figure 11: Wind turbines and electrical substation modelling (logical node)

IEC61400-25 inherits a significant number of data types, as well as some nodes, from its “parent standard” IEC61850, which in turn inherits data types and performance definitions from its predecessor IEC60870 (“Telecontrol equipment and systems”).

Part 3 (Information exchange models) describes the required mechanisms and protocols of data exchange, such as authenticating a client, sending a control command, subscribing to a monitoring data feed or accessing the self-description of a device.

Part 4 (Mapping to communication profiles) defines the message format of the individual data exchange transactions. Several such mappings may be supported by a single implementation, and each mapping specifies which services of the information exchange model will be supported. The current version of the standard defines a mandatory mapping to web services using SOAP, an XML-based protocol. Additional mappings are expected to be defined in the final version. Currently planned mappings are web services, IEC 61850-8-1 MMS, OPC XML DA, IEC 60870-5-104, and DNP3.

Part 5 (Conformance testing) specifies standardised procedures for verifying that a given implementation adheres to the standard, as well as specific measurement techniques to be applied when declaring performance parameters.

Part 6 is currently underway in a separate process from parts 1-5. It is called “Communications for monitoring and control of wind power plants – Logical node classes and data classes for condition monitoring”. It extends the defined name spaces with logical nodes and possibly new data classes for condition monitoring.

The integration of substation automation system and wind farm control based on IEC61850 could provide a more efficient control, monitoring and collection of data to be exchanged as there is

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today a stronger need for communication and access to Distributed Energy Resource information with increased influence on electricity trading and trading of environmental benefits.

Some specific logical nodes have been defined for Wind turbine application: WTUR Wind Turbine General Information,

WROT Wind turbine rotor information

WTRM Wind turbine transmission information WGEN Wind turbine generator information WCNV Wind turbine converter information WTRF Wind turbine transformer information WNAC Wind turbine nacelle information WYAW Wind turbine yawing information WTOW Wind turbine tower information WALM Wind turbine alarm information WSLG Wind turbine state log information WALG Wind turbine analog log information WREP Wind turbine report information

In addition, the use of IEC GOOSE message over an Ethernet network provides a cost effective solution for the implementation of communication aided protection and control schemes for wind farm applications.

The figure 12 illustrates the present mapping of IEC61850/IEC61400-25 to wind farm applications:

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This new standard will facilitate communications among a collection of wind machines and other equipment within a wind power plant as well as with equipment and systems external to the WPP. The development of the standard (IEC 61400-25) is requirements driven but through participation of WG members familiar with IEC 61850 a high degree of re-use and compatibility with IEC 61850 is anticipated.

8. LEVERAGING NEW REACTIVE POWER CONTROL OPPORTUNITY

While small scale wind farms implies reduced “in-fence” network configuration, developing large off-shore wind farms requires much longer cable connections whose cable impedance have influence on reactive power flows within the wind farm as well as with the outside world.

In the same time the physical reactive compensation (typical the wind generation controllers, shunt reactors, tap changers) is naturally installed far away from the interconnecting nodal point with the Transmission or Distribution System Operator where the reactive is to be controlled. As a matter of fact, the Transmission or Distribution network operator expectations are defined at the substation interconnection point, raising first new needs in coordinating in an optimal manner VAR compensating device within the plant.

Optimal Voltage VAR Dispatch applications have historically been used by network operators to define optimised reactive/voltage control strategies (capacitors banks, active compensation and transformers tap changers settings) within real-time network state estimations while minimising active power losses or correct voltage deviations.

The same tool are applicable at the level of a large wind farm “in-fence” network where VAR strategies are to be defined through real-time wind generation operation especially under the constraints of having to potentially supply fluctuating VAR set-points at the interconnecting point (in line with what large generating plant can offer).

The same technology also offers new control possibilities from transmission operators to Distributed Generation although located through distributed networks. In this scenario the software offers VAR control coordination among the wind generation plants connected to a certain Transmission Node in line with the target nodal VAR set-points established by the Transmission System Operator. This tool can typically be operated by a generation operator offering coordination services among a portfolio or by the underlying Distribution Network operator depending on the associated market structure.

9. TRADING & SCHEDULING WINDGENERATION INTO MARKETS

The deregulation process developed through the various European energy markets has created new market environments where energy transactions are managed through transparent market based mechanisms. In other words conventional generation asset players are given opportunity to contract their physical portfolio through various opportunities ranging from bilateral deals through various time scales to day-ahead, intra-day, balancing and ancillary services markets as per the typical following European market framework:

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Figure 13: Wind Trading

While wind generation has historically been analysed in a scenario of reduced penetration into networks it has originally been considered with a special market regime where Distribution System Operators have obligations to buy contracts under fixed tariff conditions, the associated financial impact being returned from market participant through general network access costs.

Wind generation portfolios however reached sufficient penetration scales in some countries to create some market distortions if wind generation is not dealt as part of conventional wind portfolios. In some cases regulators therefore changed their market strategy forcing the reintegration of wind generation (from a certain size) into markets.

This recent change directly transfers the wind generation control strategy and risks related to poor short-term forecast at the participant levels who then look for new software tools to better mitigate their wind generation forecasting risks as a Balancing Responsible Party role (integrating their intermittent generation into a larger portfolio of controllable resources) within balancing market mechanisms. As a result of that the traditional trading & risk management tools operated by asset-based traders tend to move closer to real-time time frames while looking at better scheduling, visualization and optimisation techniques to maximise their market revenues.

These new tools typically cover the following key operational trading functionality:

Defining an optimum trading strategy for a given commodity deployed through various instrument opportunities (Day-head, balancing, reserve, VARs, …),

Real-time electronic bidding,

Accurate forecasting of the physical energy dispatched and close control of the associated imbalances

Distribution / Retail Transmission / Wholesale

TSO

TSO RegulatorRegulator

Infrastructures, Municipalities SME Balancing Responsible Party Balancing Responsible Party Large Consumers Large Consumers DNO DNO Traditionnal Retailers Traditionnal Retailers New Entrants New Entrants Generators Generators Traders, Brokers, Market Makers Traders, Brokers, Market Makers Derivative Market Futures, Option Derivative Market Futures, Option

Day Ahead Market Day Ahead Market

Balancing Market Balancing Market Ancillary Services Ancillary Services M ar ke t O pe ra to r M ar ke t O pe ra to r S ys te m O pe ra to r S ys te m O pe ra to r Distribution / Retail Transmission / Wholesale TSO

TSO RegulatorRegulator

Infrastructures, Municipalities SME Balancing Responsible Party Balancing Responsible Party Large Consumers Large Consumers DNO DNO Traditionnal Retailers Traditionnal Retailers New Entrants New Entrants Generators Generators Traders, Brokers, Market Makers Traders, Brokers, Market Makers Derivative Market Futures, Option Derivative Market Futures, Option

Day Ahead Market Day Ahead Market

Balancing Market Balancing Market Ancillary Services Ancillary Services M ar ke t O pe ra to r M ar ke t O pe ra to r S ys te m O pe ra to r S ys te m O pe ra to r

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Management of new Green energy opportunities appearing not only through wholesale with Green Certificates but also through retailers who tend to differentiate through Green tariff offering

Monitoring further demand-side opportunities as good curtailment alternatives to hedge the wind energy uncertainty.

Figure 14: Counter Party Energy Volume

When the wind generation operates as part of a deregulated market player portfolio, the benefit of improving generation forecasting finally impacts the participant bottom line directly, improving its capacity to trade energy within day ahead and balancing market mechanisms where deviations between day-ahead commitments and real-time dispatch directly result into market imbalance penalties.

In this later case large windgeneration operators progressively move their operational strategy towards the aggregation of generation and demand portfolios and so off-setting unpredictable generation imbalances through dispatchable generation units or demand-side participation.

In this case the traditional Energy Management applications such as Generation Optimal Scheduling and Economic Dispatch tools become directly applicable to support portfolio players (to define their optimum dispatching configuration.

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UC/

ED

Load & Wind forecast Unit model

Optimum

Generation Schedule Current unit production

Adjustment on wind production forecast

Day ahead prediction

Cycle: 1 day

Unit production target Reserve requirement Other adjustment of production Transactions forecast

Wind forecast

Cycle: ½ hour to minute

Figure 15: New Trading Opportunities

10. CONCLUSION

A new standard for the communication with wind turbines has bee finalised by the IEC. This standard allows vendor-independent data access to and command of the wind farm via remote links, but also for additional equipment in the wind farm itself. This new IEC61400-25 standard is derived from IEC61850, and has been developed to modularize object models, to model information exchanges and map communication profiles related to wind turbine. The focus of IEC61400-25 is on the communications between wind power plant components such as wind turbines and actors such as SCADA or/and Substation Automation Systems.

Several field proven Energy Management as well as Trading & Risk Management applications are existing and have recently been adapted to better incorporate for wind generation models and smaller network configurations. These tools offer promising alternative soft methods to improve large wind farm dispatchability as alternatives to more conventional network reserve management or network reinforcement.

The progress of these technologies within the wind area would simply require regulators to establish suitable market frameworks for wind operators to receive the required financial incentives to invest, which in return would naturally result in a better wind generation integration. This would also require a closer co-operation between real-time automation experts and wind turbine suppliers to progress into the development of innovative wind farm control strategies.

References

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