Effective energy storage power control to extend the acceptable range of generator frequency in distributed generation

Gas-turbine and gas-piston generator sets (GS) are widely used at distributed generation (DG) facilities. International GS manufacturers configure relay protections (RP) in a way that narrows the acceptable range (AR) and causes properly functioning RPs to effect unnecessary disconnections. It has been shown that the worst disturbances are observed when a microgrid that carries a DG facility is islanded, and power imbalance occurs; when motors start in groups; when the GS’s shed 95% of their output; and when a 3-phase short-circuit occurs in an islanded grid segment. Energy storage units (ESU) are the most recent and highly successful solution to many problems of power engineering. The authors hereof have developed a method that controls active and reactive power of an ESU independently to avoid unnecessary GS disconnections that would otherwise be caused by a short-term deviation in frequency; this will help reliably deliver electricity to the users of an islanded microgrid. Simulation results show that the use of ESUs helps to effectively extend the acceptable range for generator sets. There are recommendations on drawing technical requirements to ES. An important advantage of the proposed ESU power control method is that it does not need to adjust ES-received control actions (CA) online for frequency deviation.