Under-frequency load shedding technique considering response based for islanding distribution network connected with mini hydro

Abstract

One of the biggest challenge in an islanding operation is to sustain the frequency stability. A large power imbalance following islanding would cause under-frequency, hence an appropriate control is required to shed certain amount of load. Under-frequency load shedding (UFLS) scheme is commonly adopted for grid transmission system of which requires particular consideration for application on an isolated/islanded system. The main objective of this research is to develop an adaptive UFLS technique for an islanding system. The technique is designed considering response based for any disturbance during islanding operation. The disturbance magnitude is determined from the swing equation in which relies on frequency and rate of change of frequency measurement for shedding the required amount of load. The technique is modeled by using PSCAD simulation tool. A simulation study on a distribution network connected with mini hydro generation is carried out to evaluate the UFLS model. It is performed under different load condition: peak load, base load and overload scenario. The results have shown that the load shedding technique have successfully shed certain amount of load and stabilized the system frequency following overload.