X-in-the-Loop Test Environment for Standardized Development of Photovoltaic Inverters

The current transformation of the energy system, driven by the energy transition, brings new challenges in the areas of supply security, reliability, and efficiency. The increasing number of small, decentralized power generation plants with a decreasing number of centralized and grid-forming large power plants requires the provision of system services from all grid users. This requires an intelligent energy management and actively optimized distribution grid operation. To investigate the behavior of a plant before commissioning on a resulting dynamic and complex overall system, X-in-the-Loop methods can be used. In this approach, the real environment or a part of it is simulated on a simulator and coupled with the plant under investigation. This approach is followed in this work to develop a test platform for photovoltaic inverters. According to the German standard, Photovoltaic systems must provide system services through frequency-dependent active power control, static voltage maintenance, reactive power provision, and dynamic grid support. The test platform can be used to test and validate these specifications during the development of a photovoltaic inverter control systems. The last part of the paper deals with the validation of the test platform. For this purpose, the Power Hardware-in-the-Loop setup is put into operation and tested. By evaluating measurement signals, results about the accuracy and dynamic behavior of the system are presented.