Studies On Distributed Model Predictive Based AGC In Power Systems With Intermittent Power Generation

Energy shortage and environment pollution are the urgent problems to be solved now. As an important way of solving the global energy and environmental crisis, the renewable energy sources, such as the wind energy, solar energy, sea energy, geothermal energy, may be a partial substitute for fossil fuels as primary energy for electric generation. Fluctuation and intermittence are the common characteristics of renewable energy. Integration of large-scale intermittent power generation will bring great challenges to security operation and power quality of power systemsWind power is a typical representative of the intermittent power generation, which has also developed fastest in the renewable energy generation. Large-scale wind farm integration is an effective way for the utilization of wind energy. However wind power has the characteristics of intermittence and random fluctuations, and it is very difficult to maintain the power output controllability and predictability. With the wind power capacity increasing, integration of wind power will lead to frequency fluctuations, and increases the burden of ancillary services, such as peak and frequency regulation, operating and scheduling. It is necessary to study and control the frequency fluctuations impact of power system with large scale wind farms integration. In the current study, the wind farm model is still relatively rough, and can not fully reflect the actual wind farm output power characteristics. In addition, the traditional PID based AGC system may be insufficient when it is used to reduce frequency fluctuations of power system with large scale wind farms integration.Taking wind power as the representative of the intermittent power generation, this paper analyzes the impact of large scale wind farms integration to power system active power/frequency and the corresponding control measures.Firstly, considering the energy loss by wake effect, impact of topographical factor on wind speed of wind turbine in different location and delay of the wind, an accurate equivalent model of wind farm is established. The simulation results show that the model considering aggregation effects of wind turbines, has better precision and reduces the complexity.Secondly, an improved automatic generation control based on distributed model predictive control algorithm is proposed. The simulation results of two area system show that the improved automatic generation control system, which resolves the conflict between speed and accuracy, has better control performance.Finally, based on the accurate equivalent model of wind farm, the improved automatic generation control system is applied to reduce the frequency fluctuations of power system with high penetration of wind power. The simulation results of two area system with four generators and IEEE43 bus system show the feasibility and practicability of the improved automatic generation control system.