Emergency load control for power system flexibility

The study is aimed at proposing and researching a method of emergency load control for electricity consumers in real time by automatically transferring the power supply of controlled load receivers from the period of the daily maximum to the minimum of power consumption. The studies were carried out using the RuStab software package applicable for simulating electromechanical transients in electric power systems in time by modelling scenarios of the effect caused by relay protection disturbances and operation, as well as emergency control equipment, on the system for maintaining the stability of electric power systems. The studies were carried out on a test circuit representing a real power supply system in isolation mode as a result of a disturbance with a power shortage. In the case of a power supply system in isolated mode with a power shortage after an emergency disconnection of communication with the external power system, an analysis is performed to consider problems in ensuring the stability of the power supply system with distributed generation installations operating in normal mode synchronously with the external power system. In terms of ensuring the stability of the power supply system, negative factors involve the small constant inertia of the generator rotors and simplified control systems. The main control actions for eliminating power shortages are traditionally associated with automatic under-frequency load shedding. A proposed anti-emergency load control automation process consists in transferring controlled power consumers from the period of daily maximum load to the minimum. At the same time, the volume of the load disconnected by under-frequency load shedding is reduced with the released generated power used for maintaining the power supply to critical load. A scenario of an emergency situation with a simulation of the proposed emergency control automation is presented. As a result, the electricity supply is additionally preserved for 17% of critical load. In terms of providing power supply to critical load, the performed studies have demonstrated the potential effectiveness of the proposed emergency load control automation in emergency modes. Future research will focus on a specification of the operating conditions for automation under various emergency situations and its practical implementation.

distributed generation, electricity supply, real-time load control, flexibility, power systems, transient stability