含PQ控制逆变型分布式电源的配电网故障分析

发布时间：2018-04-18 03:28

本文选题：逆变型分布式电源 + 控制策略　；参考：《华南理工大学》2014年硕士论文

【摘要】：随着能源危机和环境污染的加剧以及传统电网安全稳定问题的凸显，以清洁能源为基础的分布式电源（distributed generation，DG）接入配电网已成为电网发展的必然趋势。大量分布式电源的接入，使得传统配电网的故障特征，如短路电流的大小和方向等发生了变化。目前广泛使用的逆变型分布式电源（inverter interfaced distributed generation，IIDG）具有输出响应快的特点，要实现其故障特性的准确分析必须充分计及控制策略的影响。另外，最新的并网规定要求IIDG在故障时不仅保持并网运行，还需向电网注入无功功率，以支撑电网电压。为此，本文计及IIDG的控制特性，提出了一种适用于最新并网规定的含PQ控制IIDG的配电网故障分析方法。针对并网运行时广泛采用PQ控制策略的IIDG，基于其数学模型，采用双环控制方式，并对其输出特性进行分析；针对不对称条件下，传统PI环节不能实现无静差控制以及IIDG注入负序电流带来的问题，在双同步旋转dq坐标系下，采用消除IIDG负序电流控制策略，减轻对逆变器和电网的负面影响；计及最新并网规定，对IIDG采用具有电压支撑能力的故障穿越控制策略，仿真结果验证了策略的有效性。基于电力系统仿真平台DIgSILENT，搭建了含PQ控制策略IIDG的配电网模型，利用仿真分析方法，对IIDG的故障暂态特性进行研究；计及控制策略的影响，通过分析IIDG的控制系统响应过程，提出IIDG在对称故障和不对称故障情况下的故障等值模型，，并通过仿真验证了所提等值模型的准确性。针对含多个IIDG的配电网模型，利用本文提出的计及控制特性的IIDG故障等值模型，建立故障下的节点电压方程，并针对不同IIDG间的相互耦合关系以及IIDG并网点电压与IIDG故障电流的非线性关系，提出相应的迭代修正求解方法，最后通过仿真算例，验证了所提方法的可行性和有效性。
[Abstract]:With the aggravation of energy crisis and environmental pollution as well as the security and stability of traditional power grid, distributed generation based on clean energy (DGG) has become an inevitable trend in the development of power grid.With the access of a large number of distributed power sources, the fault characteristics of traditional distribution network, such as the size and direction of short-circuit current, have changed.Inverter interfaced distributed Generation (IIDG), which is widely used at present, has the characteristics of fast output response. In order to realize accurate analysis of its fault characteristics, the influence of control strategy must be fully taken into account.In addition, the latest grid-connected regulations require IIDG not only to maintain grid-connected operation in the event of failure, but also to inject reactive power into the power grid to support the grid voltage.In this paper, considering the control characteristics of IIDG, a fault analysis method for distribution network with PQ controlled IIDG is proposed.In view of IIDG, which widely adopts PQ control strategy in grid-connected operation, based on its mathematical model, the double loop control method is adopted and its output characteristics are analyzed.The traditional Pi link can not realize the problems caused by no static error control and IIDG injection negative sequence current. In the double synchronous rotating DQ coordinate system, the negative sequence current control strategy of eliminating IIDG is adopted to reduce the negative influence on inverter and power grid.Considering the latest grid-connected regulations, a fault crossing control strategy with voltage support capability is adopted for IIDG. The simulation results verify the effectiveness of the strategy.Based on the power system simulation platform, the distribution network model with PQ control strategy IIDG is built, and the transient characteristics of IIDG are studied by using simulation analysis method, considering the influence of control strategy, the response process of IIDG control system is analyzed.The equivalent fault model of IIDG in the case of symmetric fault and asymmetric fault is proposed, and the accuracy of the proposed equivalent model is verified by simulation.For the distribution network model with multiple IIDG, the nodal voltage equation under the fault is established by using the IIDG fault equivalent model which takes into account the control characteristics proposed in this paper.According to the mutual coupling relationship between different IIDG and the nonlinear relation between IIDG parallel dot voltage and IIDG fault current, the corresponding iterative correction method is proposed. Finally, the feasibility and effectiveness of the proposed method are verified by a simulation example.
【学位授予单位】：华南理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM711

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