Research of the Efficiency of Under-Frequency Load Shedding and Special Automatics Switching-off of Load in Case of Large Shortages of Active Power in Micro-Power Systems with MINI-HPPS

The occurrence of emergency power shortages in micro-power systems with mini-hydroelectric power plants (HPPs) during the transition from parallel operation with an electric power system to an autonomous mode is investigated. For a qualitative assessment and analysis of the properties of micro-power systems with mini-hydroelectric power plants, they differ in terms of power shortage in the Power Systems Computer Aided Design (PSCAD) software package (PC) developed a calculation model of a synchronous generator (SG) and special load automation (SAON). The simulation results show that in micro-power systems with mini-HPPs, with a large emergency power shortage, the efficiency of the under-frequency load shedding decreases, since the under-frequency load shedding does not provide the necessary and sufficient amount of electrical load to be turned off during the transient process. Therefore, it is proposed to jointly work with under-frequency load shedding (UFLS) and special automatics switching-off of load (SASL) to ensure the stability of the operation of micro-power systems with mini-HPPs in emergency modes and to ensure the continuity of power supply to consumers of the first category. However, after carrying out an economic calculation, it was found that the introduction of the existing system of UFLS and SASL in the analyzed micro-power system does not provide the required technical and economic efficiency. Therefore, it is necessary to refine this type of device, which combines the functions of UFLS and SASL, taking into account the characteristics of the power supply area in order to obtain an economically viable option for implementation.