The new technology of grid-forming wind turbines will mean new regulations and compliance testing. Verification through Controller Hardware-in-Loop (C-HIL) aims to prototype a method to test and verify the electrical characteristics of wind turbines.
In the future, to ensure the stability of the electrical grid with an increasing volume of renewables, grid regulations will demand that wind turbines (WTs) have grid-forming capabilities, like forming system voltage and contributing to system inertia, and fault currents. However, compliance testing and assuring the grid-forming capabilities of a WT are not possible using traditional field testing, and reliable solutions and testbenches are required.
Additionally, a wind turbine includes several sub-systems, such as blades, a pitch system, gear box, generator, controls, and grid protection, which make building a comprehensive testbench a challenging and multidisciplinary task. New multidisciplinary cyber-physical testbenches are needed to accelerate the testing of grid-forming wind turbines.
Testbench to study all scenarios
This project successfully prototyped a testbench to verify the grid-forming capabilities of a WT in a controlled environment. To include different sub-systems of the WT, a co-simulation-based testbench was developed which also allows the integration of actual hardware replica of the controller in a Controller Hardware-in-Loop (C-HIL) type setup.
The aerodynamic and mechanical systems of the WT are simulated using DNV’s wind turbine design software Bladed. The wind turbine’s generator, the frequency converter power stage, and the electrical network are modelled to run in real-time or a real-time simulator. The electrical model includes interfaces with the mechanical model and the hardware replica of the wind turbine controller under test.
The testbench can simulate different subsystems of a WT in detail such that the characteristics of the turbine can be studied in scenarios where electrical and mechanical dynamics are strongly coupled. Examples include extreme conditions, faults, and wind turbine self-energization through pitch control. It also offers a flexible test environment where actual controller hardware replicas are integrated in the testbench.
The benefits
Several requirements of the grid-forming WT and its functions are either very difficult or unfeasible to validate by the field tests. To test those functions in a physical testbench is also very demanding in terms of infrastructure, and the manufacturers might need to wait for very long times to get a test spot. The prototyped testbench and test method offer a flexible, faster, and reliable way to test the advanced functionality of a grid-forming WT and check its grid-code compliance. This will not only be a cheaper alternative but will also save a lot of time, which is key to advancing the energy transition.
Market potential
With growing demand for accelerated testing and deployment of grid-forming and other advanced functionalities of WTs, DNV expects and already sees interest in this solution from WT manufacturers. The solution is also ideal for manufacturers in other renewable sectors such as solar and battery energy storage systems.
