Improved Frequency Regulation in an Islanded Mixed Source Microgrid Through Coordinated Operation of DERs and Smart Loads

The advent of microgrids paved the way for energy decentralization and self-sufficiency among consumers. Reciprocating engine-driven synchronous generators (also known as gensets) are one of the most commonly found distributed energy resources (DERs) installed in a microgrid. A key concern in microgrid operation is the frequency regulation, especially when it is islanded from the main grid. In recent years, the inverter-based DERs have witnessed huge growth. When fast-responding inverter-based DERs are working in parallel with the slow-acting gensets within the islanded mixed source microgrid, many challenges exist in coordinating their operation. In particular, an inverter-based DER is susceptible to collapse due to its large transient loading and this can bring down the entire system. This paper investigates load sharing and proposes new techniques for improved frequency regulation in an islanded mixed source microgrid. An improved coordination scheme between DERs is presented in this paper by accounting for their inertial and governor response characteristics. The unequal transient load sharing between gensets and inverter-based DERs is redistributed to prevent system collapse as well as achieve desired frequency regulation. For dealing with extreme scenarios, a smart load shedding scheme is integrated into the coordinated operation of DERs.