The Interaction Of Photovoltaic Power Station Reactive Compensation Devices And Coordination Control

The large-scale utilization of solar energy becomes one of the important ways to optimize resource allocation and improve environmental quality. PV power stations are generally located in remote areas, so high-voltage long-distance transmission is adopted to transport the rich light resource from the western to the eastern load center; in addition, the photovoltaic grid-connected inverter is usually run in the unit power factor mode, therefore, PV power stations prefer to select FACTS device, which has significant advantages in terms of controllability, operating range and response speed, to guarantee the normal operation of the PV power stations with the reactive power needs and to restrain the voltage fluctuation or even out of voltage limit at the grid connection point led by the variation of active power output. However, many inevitable problems come along. In view of this, this paper will study the interaction and the coordination control of the reactive power compensation devices within and between PV power stations.First of all, a mathematical model of the system is built in regard to the interaction between each controllers when different types of FACTS devices are in the grid voltage fluctuations among the PV power stations. Simulink and RGA theory are also applied to conduct Simulation test and quantitative calculation, to further confirm that there is an interaction between the FACTS controllers, and the degree of influence is related to the electrical distance.Secondly, aiming at the causes of the interaction, in consideration of the correlation between the FACTS controllers from an overall angle, a global coordination controller is designed to effectively weaken the interaction between FACTS controllers in the PV power stations and improve the control performance of the system.Thirdly, aiming at the coordination control of the reactive power and voltage in the PV power stations, the equivalent circuit model is established based on the topology of PV power station,the relevant technical parameters are given and the control scheme of grid-connected inverter is put forward. The simulation model is built via Simulink to verify the correctness of each design parts.Finally, specific to the randomness and uncontrollability of the output of PV power source,the paper analyzes the problems such as the decrease of power quality and the poor stability, and proposes the coordination control strategy of grid-connected inverter and FACTS device,optimizes the reactive power distribution scheme of the PV power station, and applies Simulink to carry out the instance simulation, verifying the correctness and feasibility of the control strategy.