Research On Volt-Var Control For Distribution Networks With Distributed Renewable Energy Generation

With the rapid development of China's power system, power loads and distributed generation(DG) in distribution networks increase greatly at the same time. It has led to the fact that the operation of power grid is consequently meeting increasingly sophisticated challenge of security. On the one hand, DG can improve the reliability of system power supply, alleviate energy crisis and can be conducive to environmental protection. On the other hand, DG's output power is probabilistic, affecting the whole system safe and stable operation to a certain extent. To reduce DG's adverse effects, effective monitor and management of power system are needed. At the same time, the advancement of computer science and network communication technology gives rise to intelligent trend for monitoring and control of power system. This provides an important technical support for online stability monitoring, and reduces the impact of distributed generation power fluctuations on the system.This dissertation mainly presents a Volt-Var control method in distribution networks to reduce the adverse influences of distributed generation power fluctuations. Based on system load voltage characteristics, it regulates voltage appropriately and makes the load changes track the output power of distributed generations, thus it could mitigate output power fluctuations of distributed generations effectively. The analysis indicates that the Volt-Var control method in this paper could reduce the influence of distributed renewable energy power fluctuations on the stability of power system. It could also reduce whole system peak load without cutting user loads. So the method is practical and feasible. Finally, some promising aspects on DG's parallel operation and control are discussed.