配电网故障时逆变型分布式电源的运行特性及短路电流计算方法研究

With the rapid development of distributed new power generation technologies, the problems of the energy shortage and environmental pollution have been effectively solved. However, due to a large number of Inverter Interfaced Distributed Generations(IIDGs) are incorerprated into the distribution network, it would change the fault operation characteristics of the distribution network, and affect the traditional stage current protection. As a result, network accidents occur in a large range, and that brings great challenges to the safe and reliable operation of distribution network. Firstly, the high performance adaptive phase-locked method of IIDG is explored in this project, to assure the control of low voltage ride through; Secondly, the operation characteristics of IIDG on distribution network fault are studied, and the relationships between its operation characteristic and control strategy, switching mode, power and current constraints, and the type of short circuit , are also analyzed, and then a reasonable and effective operation strategy of IIDG is proposed; Thirdly, comprehensively considering the influence of DG dynamic process, the DC bus voltage fluctuation, the inverter dead time and other factors, a precise fault equivalent model of distribution network with IIDG operation characteristics is established; Finally, the solution method of nonlinear fault current of distribution network with IIDG is proposed, so as to reveal the short-circuit distribution regularity, and provide effective guidance to the relay protection configuration of distribution network. The research results of this project will be helpful to improve the operation reliability of distribution network with IIDGs, and could be applied to power quality control or other electrical engineering areas. That would eventually promote the development of distributed power generation technologies. The research is with important scientific significance and research value.

新能源分布式发电技术的快速发展，有效地解决了能源不足和环境污染问题，但逆变型分布式电源IIDG的大量接入，改变了配网故障运行特性，影响了传统的阶段式电流保护，大范围脱网事故时有发生，给配网的安全可靠运行带来巨大挑战。项目首先探索IIDG的高性能自适应锁相方法，保证低压穿越过程的有效性；其次，研究配网故障时IIDG的运行特性规律，分析IIDG运行特性与控制策略、模式切换、功率电流约束、及短路类型等的关系，提出有效的IIDG运行策略；再次，综合考虑DG动态过程、直流母线电压波动、逆变器死区时间等因素的影响，建立计及IIDG运行特性的配网故障等效精确模型；最后，提出含IIDG配网故障电流的非线性求解方法，揭示配网的短路分布规律，为继电保护提供有效指导。研究成果有助于提高含IIDG配电网的运行可靠性，可应用于电能质量控制与其他电气工程领域，促进分布式发电技术的发展，具有重要的科学意义和研究价值。

项目遵循由简单到复杂、由点及面、先静态后动态的研究思路，针对逆变型分布式电源运行特性进行研究，主要从分布式电源并网时高性能锁相环探索、分布式电源逆变器控制策略、分布式电源逆变器延时补偿控制、级联型变换器的均压均功率控制、微网短路特性分析及其保护等几个方面开展工作。.1）高性能锁相环探索方面：提出了基于Hilbert变换和预设旋转频率的无锁相环电网同步基准正弦信号检测方法和基于改进型自适应陷波器和多变量滤波器的锁相方法（IDANF-MVF-PLL）；.2）分布式电源逆变器控制策略方面：提出了一种基于分裂电容中间电流控制无源阻尼优化方法和一种无频差的有功-频率控制算法；.3）分布式电源逆变器延时补偿控制方面：针对LCL型三相并网逆变器数字单环控制延时影响及稳定域进行了分析，提出了基于占空比预测与零极点结合的LCL型逆变器延时补偿方法；.4）级联型变换器均压均功率控制方面：提出了基于预测功率模型的级联整流器均压新方法，针对级联H桥整流器的直流侧电压与无功平衡控制问题，提出了一种新型控制策略及基于最小功率回流的均压均功率控制策略。.本项目的研究成果具有现实意义，可直接应用于电能质量分析与控制、分布式发电领域，在目前含微网的配电网、电气化铁路牵引供电系统、电动汽车充放电及大规模储能并网系统、HVDC中均将有着广泛的应用前景。.