This paper presents the concept, architecture, and application of a Power Plant Controller (PPC) Hardware-in-the-loop (HIL) test bench developed to support standardized control and performance testing of wind power plants in accordance with IEC 61400-21-2 and FGW Technical Guideline TR3 (Rev.26). The PPC HIL test bench, hereafter referred to as the Plant Simulator is designed as a modular, scalable, and high-fidelity test bench that emulates the electrical behavior of an entire wind power plant, including wind turbine generators (WTGs), the collector grid, additional plant components (e.g. STATCOMs, MSUs, breakers), power meters, and the external grid, while interfacing directly with the real Power Plant Controller (PPC) and SCADA system under test.

The Plant Simulator directly supports the execution of IEC 61400-21-2 functionality tests, such as active / reactive ramp rate limitation, frequency control, voltage control Q(U), power factor control and communication fallback scenarios. These tests are not site dependent, hence can be performed in a controlled and repeatable HiL environment, as specified by IEC 61400-21-2 for PPC validation. Performance tests such as active / reactive power control and controlled shutdown are site dependent (i.e., collector grid and point of connection (POC) characteristics), but still supported by the Plant Simulator under consideration of simplifications (e.g., power losses). In addition, the simulator enables FGW TR3 plant controller tests, such as determination of switchover behaviour and reconnection after grid protection events, by emulating grid disturbances, protection triggers, and recovery conditions.

Moreover, Plant Simulator facilitates the systematic comparison and validation of PPC behavior represented in OEM electrical models. HiL test results (i.e., measurements) can be compared with simulation results from offline electromagnetic transient models (e.g. PSCAD models) or real-time software in the loop solutions (e.g., RSCAD on RTDS). Importantly, these OEM reference models are derived from source code aligned with real products (PPC and WTG), enabling a consistent and traceable validation chain from component level models to plant level controller performance. The presented Plant Simulator therefore provides a robust foundation for standard compliant testing, early integration verification, and model validation of modern wind power plants.