Siemens will focus primarily on the technical realization of the project. In particular the development and testing of methods that allow the implementation of micro-grids in low-voltage and medium-voltage grids, their use as topological power plants and supply of grid services to parent grid levels. Furthermore, Siemens investigates methods to stabilize power grids in the presence of fast transient processes as well as slow interaction processes between grid, generation units, loads and storage. Ensuring a stable grid operation as well as an optimized operational strategy (in an economic sense) is a further important goal. Especially the optimization plays a vital role in the cost-effectiveness of island grid as well as grid-connected operation of micro-grids.
Novel grid services, which can be provided by topological power plants of the future, should enable the distribution grid operator to reduce the amount of conventional must-run reserves significantly. This will increase the usable share of renewable energy resources substantially.
IREN2 is a contribution to the vision of supplying Germany entirely from renewable energy sources. For this purpose Siemens intends to develop the basis for an innovative micro-grid system technology and to market this technology globally. In this context Germany plays a vital role since it is pioneering the area of renewable energy on an international level.
Siemens will focus on the following goals:
1 Analysis and control of the fast dynamic behavior of micro-grids
In the considered grid section, we will couple actuators with a diverse dynamic behavior. Different diesel generators, storage and photovoltaic inverters and load combined with the power grid form a complex dynamical system.
To ensure a stable grid-tied operation, real-world measurements and simulations, exposing the dynamical behavior of the system, will have to be analyzed. The focus hereby is on fast control actions in the region of a few milliseconds to a few seconds. This allows the derivation of feed-back control structures, parameterizations as well as robustness margins.
The goal is to validate a feed-back control technology developed by Siemens by means of simulation and practical testing. The technology must guarantee a stable micro-grid operation and, at the same time, implement a desired behavior on (external) request. This technology will provide the basis for the island-grid operation as well as the provision of grid services.
2 Integration and Test of algorithms for operational planning
In IREN2 we implement and test technologies that are indispensable to a planned and/or long-term operation of micro-grids and topological power plants. Load, generators, storage, and the grid are to be operated in a way that allows the realization of planned processes, such as the dis-/connection of grid section, grid services, etc. whilst respecting the constraints posed by system and control related issues.
The goal is to validate a pre-existing technology developed by Siemens and to adapt that technology to the new requirements. More precisely, we want to prove that the operation of micro-grids and topological power plants is indeed feasible from a planning perspective and show where the system-limits in terms of grid services are.
3 Interaction of topological power plants with the distribution grid operator
Given the described system-related limits and the grid services realized by the topological power plant, it is to be discussed with the distribution grid operator how this technology may be integrated into their operational concept. Business cases and cost-effectiveness of the approach will be evaluated based on this insight. If regulatory barriers for a cost effective or technological integration exist, modifications proposals will be developed to address the identified issues.
4 Dis-/connection to/from the main grid
Since micro-grids may be temporarily disconnected from the main grid, we will investigate the mechanisms of that play a role in this process. Hereby it is important to define the preconditions for a connection or disconnection, as well as the methodology of re-synchronizing an island grid comprising of multiple, distributed inverter-based in-feed units with the supply grid.
5 Sensitivity of the micro-grid
The operation of a micro-grid necessitates a stable behavior in the presence of disturbances. The functioning of the island-grid as well as the topological power plant in respect to electrical and communication related disturbances are to be investigated. We will investigate system-related limits and develop appropriate counter measures.
6 Black start
In the prospect of increasing the security of supply with the help of micro-grids, we investigate the energizing of the grid in a bottom-up kind of way. In particular, we investigate how a micro-grid can achieve an isolated back start.