The generic schematic diagram of a converter-based test bench.

Advanced Test Methods and Generic Models for Wind Energy

Background:

The increasing installed capacity of variable renewable generation, including Wind Power Plants (WPP), has concerned power system operators in terms of harmonic resonances, control interactions, stability issues and reliability of the overall system. Wind energy must be integrated into the power systems under appropriate circumstances, which is called network connection requirements.

The electrical test and assessment of wind turbines are going hand in hand with standards and network connection requirements. This way, wind turbine models and proper test and validation methods are needed to evaluate the impacts of wind power generation on the power system. For this purpose, in recent years, generic dynamic models of wind power plants have been defined by several organizations, mainly IEC and WECC. However, harmonic interactions and WPP stability issues, as increasing challenges, have not been completely solved and analyzed yet. 

The IEC 61400-21-1 includes standard IEC test methods for harmonics, but the test results are not sufficient for validation of harmonic models. Therefore, it is essential to create an experimental environment to perform standard tests and validations on harmonic models for wind turbines and their sub-systems, for troubleshooting of design and experimental analysis of WPPs. Most of the available advanced test sites are developed based on full-converters. Figure 1 illustrates the general structure of advanced converter-based test benches, which consists of three main parts: Grid Emulator, Wind Torque Emulator and Device Under Test. This way, the characteristics of a real power system, that device under test is exposed to, can be emulated by converters coupled with RTDS systems through a high-bandwidth PHIL interface. Harmonic injection tests are one of the promising applications of full-converter CGIs for harmonic interaction studies.

PhD Objectives:

This doctorate project aims to research WT and WPP harmonic models and develop practical test methods for the validation of wind turbine harmonic models. The harmonic studies would combine the probabilistic and stochastic data analysis methods with deterministic models. In addition, this project would involve establishing a wind energy prototype laboratory to make experimental works possible. Steady-state and transient interactions of offshore wind power plants and wind turbine converters with DC-interconnected HVDC networks and high-frequency harmonics influences on the grid and wind turbines would be considered.

Research activities:

The PhD study would bring contributions to the research related to:

  1. Overview of generic test equipment, and test and validation methods for wind energy.
  2. Generic EMT modeling of WTs and WPPs, focus on HVDC-connected and other converter-based systems.
  3. Development of advanced test methods for harmonics providing test results, which can be applied for validation of harmonic models.
  4. Experimental analysis and demonstration in AC/DC laboratory, research wind turbine(s), and controllable grid interface.

This PhD project is part of the large Horizon 2020 - Project “PROgress on Meshed HVDC Offshore Transmission Networks” – PROMOTioN.

Contact

Behnam Nouri
PhD student
DTU Wind Energy
+45 31 96 49 56