Testing the Performance of Battery Energy Storage in a Wind Energy Conversion System

This article examines the dynamic and transient performances of a battery energy storage system (BESS) connected with the output of a wind energy conversion system to smoothen the short-term fluctuations in the output power. A low-power experimental real-time testbed, using battery storage and representative power converters, is interfaced with a real-time digital simulator for the reduced-scale power hardware-in-the-loop simulation. Different configurations, where the energy storage system is integrated on the ac side via static synchronous compensator and directly at the dc link of the frequency converter using back-to-back converters, are examined under both constant and variable references. For each case, the resulting error in the net power flow, the operation of the battery, and the conduction losses in the power conversion stage are examined. The performances using the constant and variable reference of the storage device with full and reduced-order hardware stage of a storage element are demonstrated. The low-voltage transient performance of the BESS is also tested and the results are presented. The novel approach of the real-time low-power BESS testbed opens the door for in-lab testing of the energy storage devices for large wind or solar photovoltaic farms to save time and money.