Monitoring compliance with requirements and standards for 200 MW wind farm

Design of a wind farm involves a range of electrical requirements. Any project connected to the transmission network requires approval from the transmission network operator. Compliance with required standards is a must for approval. A 308 MW wind park required harmonic study compliance in order to receive approval from the transmission network operator. The customer asked HyTEPS to perform the modeling, simulation and analysis to check for compliance with the grid norms. Harmonic analysis has to be performed for individual harmonic orders and inter-harmonics.

Challenge

To perform the harmonic study, the entire wind farm was modelled in power system analysis software. Tests and analysis were performed to identify whether the wind farm was compliant with all requirements, and does not inject harmonics beyond the limits into the HV grid. Modelling the wind farm posed several challenges. Wind farms can operate in different topologies, each with a different harmonic injection profle. Therefore, a few network topologies have to be defned to perform worst-case scenario analysis. In addition, the high voltage (HV) grid is not a static system, but has changing characteristics. Harmonic injection from a wind turbine also changes depending on the power it is injecting. Taking different topologies, varying HV grid confgurations, power injection of each wind turbine and multiple orders of harmonics into account would require running hundreds of thousands of simulations to perform a complete harmonic study. Furthermore, a large pool of data has to be verifed for compliance.

Objectives

• Define wind farm network topologies, and possible HV grid confgurations to give an adequate representation of harmonic injection for accurate simulation.
• Define parameters and harmonic orders required for harmonic compliance check with the customer. 
• Combining defined grid confgurations, network topologies, and required parameters for compliance into thousands of load flow studies for each individual harmonic order (inter harmonic included). 
• Analyze results from harmonic load flow studies and to identify whether these comply with the regulations required by the TSO.

Solution

Eight network topologies were chosen for calculation for simulation. In addition, the behavior of the HV grid was divided into 75 different operating points for each harmonic order. Three harmonic Power Quality parameters were chosen with the client, and to check for compliance. When performed for each individual harmonic (including intra harmonics), a total of 865,800 harmonic load flows had to be performed. After a model of the wind farm was created, with 61 wind turbines, the harmonic load flows were run. To improve eficiency of the simulation and results analysis, the entire process was automated using the Python programming language. The efficiency of the simulations was also improved by using “parallel processing”, which allows running several simulations together. This reduces the total time required for simulations of such large size. Results were compiled, analyzed and compared with the transmission system operator’s compliance regulations to create a complete understanding of harmonic injection in the network for the customer and grid operator. 

Results

Based on the 865,800 individual simulation results, data was run through a compliance check to identify individual cases of non-compliance as compared to the grid requirements. This helps pinpoint specifc case scenarios to avoid. Visualizations were provided to the customer to improve their understanding of the results, and to provide a quick visual check of case scenarios where compliance is not achieved. This helps the customer save time and effort sifting through vast amounts of data. The whole project took some fve months. HyTEPS is proud of its knowledge and ability to fnd innovative solutions such as automation and parallel processing to signifcantly reduce the time taken for simulations.