Unified compensation control of a hybrid energy storage system for enhancing power quality and operation efficiency in a diesel and wind-turbine based stand-alone microgrid

An intermittent power of renewable sources such as wind turbine and photovoltaic system can damage power quality and operation efficiency of generator. Specially, in case of standalone microgrid such as island power system, this intermittent characteristic of renewable resource can lead to severe problems, such as frequency oscillation and power fluctuation. This frequency oscillation and power fluctuation can be a cause of system stability problem and operation efficiency drop. This paper presents unified compensation control strategy of a hybrid electric energy storage system in order to improve power quality and operating efficiency in a diesel and wind-turbine based stand-alone microgrid. This study addressed an AC hybrid energy storage system which was composed of lead acid battery storage and electric double layered capacitor, and presented a compensation control strategy with modified droop and wind power compensation for damping system frequency and power fluctuation. Usefulness of the proposed control algorithm is verified by experimental test results for system frequency, voltage, power fluctuation of the generator, and operation efficiency. Comparison tests with conventional compensation methods were performed to validate the effectiveness of the proposed control method.