SYNCHROPHASOR TECHNOLOGY FOR ISLANDING AND RESTORATION OF SMART DISTRIBUTED GENERATION SYSTEM

Abstract

With the increasing population and industrialization, electricity demand is increasing day by day. The traditional way of electricity generation from the limited non-renewable resources failed to meet this increasing electricity demand. Therefore, the application of renewable energy resources for electricity generation gains the attention of researchers. This electricity is supplied to the end-user by a very complex transmission and distribution network. The network is equipped with different protection devices to keep the system protected from various unwanted scenarios such as line outages, unwanted tripping of the circuit breakers, bus faults, etc. With the occurrence of a fault in the system, the protection devices operate to isolate the faulty sections from the remaining healthy portion of the network. When a healthy portion of the network operates independently with the local Renewable energy sources (RES) supplying the local loads, it is called “Islanding”. Further, the islanding is classified into unintentional and intentional islanding. While intentional islanding may be used as a last means to secure a sub-section of the network from a major blackout condition, unintentional islanding may cause several undesirable concerns such as; equipment failure at both grid and customer sides, the safety of the repair personnel, deterioration of the system power quality, etc. Unintentional islanding must be detected as quickly as possible in order to avoid major system-wide blackouts. In the event of any system disturbances, the faults must be cleared as soon as possible by the protection devices to avoid any further damage to the other system equipment. After clearance of faults and the faulty sections get isolated, restoration of the system should be carried out as soon as possible so that the end-user gets the power supply with no further delay. Thus, the effectiveness of the restoration process plays a vital role in power system network stability and efficiency as well as customer satisfaction. The networks need to be restored back to their normal operation after the clearance of the faults. In the same process, the restoration process has to be carried out after the islanding event occurs in a microgrid environment. RES integrated with the grid is known as a microgrid. Now, when a RES operates in isolation from the rest of the system and supplies to its local loads, it is called islanding. Once the islanding event is detected and the system is brought back to its normal operating condition, the islanded portion must be restored back with its original grid.