Coordinated Centralized Control Scheme for Voltage Regulation of Bus Voltages using PV Sources

Nowadays, there is a significant concern about voltage deviation in power systems during overloading and light load conditions. To address this issue, PV sources are used to compensate for voltage deviation within the specified range. While voltage regulation in transmission networks depends largely on reactive power, sub-transmission or distribution networks with resistive or mixed (L and R) lines depend on both active and reactive power. Existing control schemes, such as P-Q-V droop and network agonist adaptive PQ method, are uncoordinated and can lead to overloading and stress on the system. There is a need for coordinated control schemes that inject active and reactive power in a controlled manner, which is not sufficiently discussed in the literature. To address this need, a centralized supervisory voltage controller (CSVC) is proposed in this paper to minimize voltage deviations at various buses. The CSVC uses a Wide Area Measurement System (WAMS) to obtain information on bus voltage. Based on the available voltage deviations, the CSVC assigns reference active and reactive power signals to each local controller of the distributed PV source. The proposed CSVC can regulate the voltage of the buses within the required limits during underload and overload conditions. The reference signals allocated by the proposed CSVC are designed in such a way that each PV source supplies active and reactive power in proportion to its rated capacity. This helps reduce the overloading of PV source converters. The converter is controlled intelligently to maintain bus voltages within the specified limit, considering the IEEE standard 1547–2018.