Control Strategies for Electric Spring in an Islanded Microgrid: A Comparative Evaluation

Islanded operation of microgrid is sensitive to frequency and voltage fluctuations due to lack of inertia. This makes it vulnerable to disturbances and intermittent renewable generation. Integration of energy storage devices is an effective but expensive solution to stabilize the microgrid. Electric Spring (ES) is a new power electronic based smart grid technology which can be used to provide voltage support at the point of common coupling and improvise frequency profile of the system. In this paper, electric spring is connected to an islanded single phase microgrid, and simulated with two different control approaches; to regulate voltage, and to regulate frequency. The effectiveness of ES in terms of voltage regulation achieved and the spinning reserve required is analysed for both the scenarios and conclusions are presented. It is shown that the electric spring employing just reactive power compensation and involved in the function of voltage regulation needs additional storage for ensuring stability. Also, it is shown that ES with reactive compensation employed to support frequency regulation, aids in reducing the reserve storage capacity at the cost of poorer voltage regulation.