分布式电源对配电网电压的影响分析及其优化控制策略

Analysis of the Impact of Distributed Generation on Distribution Network Voltage and Its Optimal Control Strategy

针对配电网中分布式电源(DG)接入渗透率不断提高带来的电压波动、电压越限等电能质量问题,首先从理论上较全面地推导分析分布式电源接入对配电网电压的影响,包括对接入点电压和对电压分布的影响,并通过仿真对比分析了不同DG渗透率和不同DG功率因数下的电压变化情况,指出了全局电压控制的必要性。在此基础上,综合考虑配电网中分布式电源和储能的有功、无功电压调节能力,提出一种基于模型预测控制(MPC)的电压优化控制方案,通过计算各节点电压灵敏度,建立各节点电压预测模型,提前感知各节点电压变化趋势,以各节点预测电压与额定电压之间偏差最小为控制目标,实现了控制成本最低的协调电压控制策略。通过IEEE33节点配电网系统仿真算例分析,结果表明:本文提出的方法能更大限度地消除配电网中分布式可再生能源随机波动带来的影响,具有较好的电压控制灵活性和鲁棒性。

With an increasing penetration of distributed generation (DG) into distributionnetworks, problems regarding voltage fluctuations and over-limit voltage has become a major concern.In this paper, Firstly, the impacts of DG on voltage level at both the injection nodes of DG and at othernodes of the system is analyzed by conducting a series of simulations with different DG penetrationrates and different DG power factors, which proves the necessity of global voltage control in the case ofDG penetration. Secondly, a model predictive control-based optimal voltage control scheme is proposedby utilizing the active/reactive power regulation capability of DGs and energy storages. By calculatingthe voltage sensitivity at each node and sensing the potential voltage variation tendency, the proposedscheme establishes a voltage prediction model with the aim of minimizing the deviation between thepredicted node voltage level and the rated node voltage level to realize a coordinated voltage control atthe lowest cost. Finally, the simulation tests are carried out on the IEEE 33-bus distribution system.Simulation results show that the proposed method could efficiently eliminate the influence of randomfluctuations of DG in the distribution network, and also possesses considerable voltage controlflexibility and robustness.