Research On Control Strategy Of Active And Reactive Power For Photovoltaic Power Station In Energy Coordinated Control System

Energy is essential in the development of the world economy. As the traditional fossil energy is drying up and environment pollution problem is increasingly serious, people pay more and more attention to renewable energy sources such as solar energy, wind energy. Using the solar energy which is lean, environmental friendly and without any pollution, photovoltaic power has become one of the fastest growing new energy power generation technologies in the world. However, photovoltaic power is intermittent, randomness and volatility. With the growing capacity, photovoltaic system will bring a series of problems of power balance and voltage stability to the grid. The difficulties of photovoltaic power prediction as well as bad performance of stability and accommodation make this problem even more severe. So strengthening the research on the control of photovoltaic’s active and reactive power in energy coordinated control systems is not only conducive to the security and stability of the power grid, but also the foundation of photovoltaic industry’s healthy development.Firstly, the basic principle of photovoltaic battery components and three-phase inverter is analyzed in this paper. A grid-connected PV model is established using the PSASP software and simulation results verify the volt-ampere characteristic of the photovoltaic modules and the control strategy of the inverter. To solve the problem of traditional active power dispatching strategy of photovoltaic power station, a new active power dispatching strategy is proposed, which is based on the short-term weather forecast data of photovoltaic arrays and considers of the reliability and risk of the photovoltaic power station’s active output and the volatility of the photovoltaic arrays’ active output to scheduling power output of the photovoltaic arrays. Then, according to the fact that there are a lot of cascaded hydro-plants in northwest areas of China, a dispatching strategy for power pool composed of photovoltaic power station and cascaded hydro-plants is proposed. This strategy considers the risk reserve constraint of photovoltaic power station and the "water waste" constraint of hydro-plants to make more sufficient and reasonable use of the light and water resources. Finally, the paper studies the reactive power regulation ability of the photovoltaic inverter under different conditions. On this basis, a reactive power and voltage control strategy is proposed to coordinate the photovoltaic power station substation control compensation devices and photovoltaic inverters. By solving the multi-objective optimization model of photovoltaic power plants eventually get the optimal reactive allocation scheme of photovoltaic power station.