Renewables at >50% in European grids

Introduction

Higher penetration of renewables will lead to new flexibility and ancillary services requirements to ensure the reliability of the power system. The provision of the system services such as frequency and voltage controls – so far mainly supplied by conventional synchronous units – would also be required for variable renewable generation connection or supplied by storage.

In previous studies and demonstrations worldwide, the ability of these new assets to provide individually system services has been investigated. However, the services provision may be restricted and intermittent by using single units’ abilities only, due notably to unfavorable wind/solar conditions or limited storage capacity. The performance and reliability of the procured services are therefore expected to be highly enhanced, from a local point of view, by aggregating renewable energy sources (RES) and storage abilities. Furthermore, cost-benefit analysis often shows that the revenues of a single service are not sufficient to cover the investment and operating costs. The provision of multiple services can help overcome this barrier thanks to additional revenue streams.

In this context, an aggregation approach based on the concept of Virtual Power Plant (VPP), allowing the aggregator to provide multiple services and flexibility products to the power system, was proposed in the Work Package (WP) 8 demonstration of EU-SysFlex project. The partners involved in this demonstration are EDF and ENERCON, with several of their branches and research teams cooperating for the needs of the demonstration work.

The multi-resources multi-services demonstration

The main facilities and testing means for the demonstration are shown in Figure 1. The portfolio of resources comprises:

  • a 12-MW wind farm of 6 x 2000-KW turbine, located in the department of “Marne” and connected to the French distribution grid;
  • a full storage system including a 2 MW / 2.9 MWh lithium-ion battery as well as an ENERCON E-Storage 2300 power conversion system;
  • photovoltaic panels and a variable load test bench installed at Concept Grid, which was set up by EDF R&D in the site of Les Renardières south-east of Paris and developed to study the integration of renewable energy resources in the electric system as well as new uses such as electric vehicles or heat pumps.

Figure 1. Means and facilities of the WP8 demonstration

The services that can be procured from the VPP are well aligned with the power system scarcities at high RES penetration rates, identified in WP2 and in WP3 of the EU-SysFlex project, in terms of future needs of ancillary services and flexibilities. These services are classified into 4 categories as summarized in Table 1.

Table 1. Multi-services provided by the WP8 multi-resources VPP

Operating principle and control layers

To operate the WP8 demonstration composed of multi-resources of different nature as a whole and to ensure the optimal coordination of multi-services provision, centralized control functions are built, including renewable generation forecasting tools as well as the Energy Management System (EMS) providing both day-ahead / intraday schedules and short-term program adjustment capacities.

The operation of the demonstration is achieved using a dedicated three-level supervisory control as illustrated in Figure 2. First, a remote supervision performs day-ahead scheduling of generation planning and services allocation to maximize profitability while satisfying different constraints (e.g., battery state of charge) and requests from the system operators. Secondly, the layer of Short-Term Control (STC) is necessary to ensure the continuous and correct operation of the VPP by handling unexpected program deviations, or unsatisfying performance of the provided services, inside each scheduling step. Ultimately local controllers of each resource will autonomously manage the execution of the services allocated by the EMS and send active and reactive power references to the resources, depending on local measurement such as frequency and voltage.

Figure 2. General control layers of the WP8 demonstration

To ensure the communication within different control layers and assets, a new full IEC 61850 based and hardware-agnostic communication platform developed by EDF is used. This platform presents several advantages, when compared with the traditional ones, such as the flexibility to manage the software, firmware and configurations on remote devices with an increased level of cybersecurity. Another important aspect is the evolutivity of the proposed platform since the evolutions of its software and hardware are mostly independent. This aspect allows to enhance the management of an increasing number of devices being deployed on the field for automation and of distributed energy resources on all voltage levels.

State of development

The main objectives of the WP8 VPP demonstration are:

  • to demonstrate the technical feasibility of performing optimal management and coordinated control of the multi-resources VPP to provide multi-services to the power system;
  • to assess the performances of different services and flexibility solutions that can be procured from the VPP by considering the power system’s needs and grid codes’ requirement.

Main hardware and software components of the demonstration have been set up and commissioned since 2019. Before starting the experiments in the overall environment of the VPP, the capability of the installed storage system as well as of the wind farm to provide individually frequency support services is being demonstrated locally. EDF and ENERCON continue focusing on integrating progressively the different assets and components into the whole WP8 VPP and intend to draw technical and economic conclusions from the experimental tests.

 

Written by: Dr. Ye Wang, EDF, WP8 leader of the EU-SysFlex project.

EDF is the largest producer of renewable electricity in Europe. Two priorities are at the heart of its research: preparing the flexible and adaptable electrical systems and grids of tomorrow, and consolidating and developing competitive and low-carbon energy generation mixes.

For further information please follow us on www.eusysflex.com, LinkedIn, Twitter and Facebook.

Disclaimer: blog entries reflect individual views of the author(s) that may not reflect official positions or communication of the project / project consortium.

 

 

 

 

 

 

 

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