Demonstration of

coordinated ancillary services covering different voltage levels and the integration in future markets

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Innovation Cell Germany

The IC Germany focuses on the provision of reactive power within and across grid levels in the context of a comprehensive operational planning process for local virtual power plants (LVPP). The IC builds on the IRENE and IREN2 projects, in which a LVPP in a local LV-grid is set up. In DeCAS, the LVPP will be scaled up by including distributed energy resources (DER) connected to the medium voltage (MV-) grid. Additionally, the IC Germany will add new DER in the LV-grid expanding the demonstrator from the projects IRENE and IREN2. Furthermore, the operational planning process will be extended by an intraday planning process to make better use of short-time generation and load forecasts. In general, virtual power plants (VPPs) are a concept to improve market participation of DER. The IC partners include Allgäu Netz GmbH, University of Applied Sciences Kempten and RWTH Aachen.

Technical Requirements

The LVPP set up in the IC Germany includes various DER units, e.g. photovoltaic (PV), combined heat and power (CHP) and storage units, which are controlled according to the planned day-ahead schedule via a control system. The operational planning process uses day-ahead generation forecasts as well as real-time grid measurements. Based on this data, a reactive power demand, that represents the demand of the transmission system operator, is derived and an optimal aggregated reactive power schedule is calculated. The scale up in DeCAS requires several extensions of the technical infrastructure as well as of the operational planning software (see figure below). 

The extension of the existing microgrid consists of a nanogrid and a controllable biogas combined heat and power plant (biogas-CHP). The nanogrid is implemented as a smart home including a home battery system, a controllable photovoltaic system (PV system), and a power-to-heat system (P2H). The integration of MV-units requires a communication interface to the distribution system operator’s (DSO) SCADA system. Due to network security issues, a direct control of DER in the MV-grid is not possible. Therefore, an open loop control via the DSO’s control system will be installed, during which the DSO tries to carry out the planned schedule. The expansion of the metering infrastructure to higher grid levels is necessary to analyse the potential of the LVPP’s reactive power provision not only from the LV- to the MV-grid but also to the HV-level. Aside from measurements in the MV-feeder, the power flow across the HV/MV-transformer is an important evaluation criterion to assess the potential.

The extensions regarding the operational planning aim at complementing the day-ahead planning process (once every 24h) by an intraday planning process (hourly). Further automation of the planning process is necessary to realize the short-term planning stage. This relates mainly to the data transfer from and to the control system as well as to the planning algorithm itself. Furthermore, intraday planning requires the update of day-ahead generation forecasts to generate the required input for the planning process. For this purpose, real time data can be used to correct the day-ahead forecasts’ deviations, yielding updated and more accurate intraday forecasts.

Stakeholder Adoption

The realisation of the scale up to the MV-grid level requires additional participants compared to the existing LVPP at LV-level. Therefore, the owners of generation units connected to the MV-grid, i.e. large scale PV and CHP units, willing to participate in the field test must be recruited. The participation entails allowing the remote control of reactive power feed-in during the field test as well as the installation of additional metering equipment.

Additionally, further involvement of the DSO is necessary to enable control of units at MV-grid level. The DSO has to dispatch the planned schedules to the respective generation units. Hence, a communication interface in form of an open loop control between the operational planning software and the DSO’s control system is necessary.

Market Requirements

In addition to the grid-oriented provision of reactive power, the IC Germany aims to investigate the market integration of DER into the energy markets. This investigation is carried out within a simulation environment, independently from the field test. The current market framework with high requirements regarding minimum volume, block offers and the compliance with the reported schedule obstruct the market participation of VPPs including intermittent generation. Therefore, two approaches to further improve the market participation of VPPs are investigated in this project. The first approach targets the mitigation of market risks caused by intermittent generation. Possible countermeasures include the regional distribution of generation as well as the use of new developed futures products to hedge against risks. The second approach investigates the impact of different market frameworks on the market integration of VPPs. Therefore, frameworks from various European market areas are analysed and included in the simulation environment. The efficiency of the two approaches regarding the market participation of VPPs is analysed and compared using the simulation environment. The investigation requires an adequate data basis for:

  • local forecasting errors of intermittent generation
  • market data of futures products
  • market data of different European market areas