计及储能协调控制的经济型限流器在高渗透微电网故障穿越中的应用

In the case of that a micro-grid with high penetration of renewable resources is accessed into a power distribution network, the micro-grid’s treatment mode and transient performance under the short-circuit fault condition will affect the power distribution network’s operation characteristics dramatically. Regarding that how to ensure the secure and reliable operation of the micro-grid and distribution network under the fault condition, researching an effective and feasible solution is required. In this project, our research group will investigate the fault ride-through (FRT) characteristics of a high penetration micro-grid where an external short-circuit fault occurs. An economical fault current limiter (FCL) will be proposed for the micro-grid, and this FCL will coordinate closely with a hybrid energy storage system allocated inside the micro-grid. According to the coordination effect, not only reduction of fault current and improvement of voltage sag can be achieved, but also inhibition of power fluctuation and enhancement of power quality can be obtained. The detailed research contents will cover the following aspects. Our research group will firstly study a mathematical analysis method suitable for deducing the fault voltage and fault current of the micro-grid, and quantificationally analyze the transient characteristics of the micro-grid and related distribution network by the electro-magnetic transient simulation software. Consequently, a few of technical indexes, which are used for determining whether the micro-grid will carry out the fault-ride-through operation or switch to the islanded mode, can be provided. Further, our research group will suggest an economical FCL which is installed at the point of common coupling (PCC) between the micro-grid and distribution network, and propose the coordinated control strategy where the super capacitor and battery hybrid energy storage system is taken into consideration. At the last, from the point of view of facilitating the FCL’s engineering application in the micro-grid, our research group will discuss the capacity optimization scheme of the FCL, where the multi-objectives constraints and intelligence artificial algorithms will be adopted. Based on the above-mentioned studies, it is expected to actively strengthen the micro-grid’s FRT capability as far as possible. And for some specific faults, the micro-grid should disconnect from the main network, and the coordinated control strategy can make the micro-grid implement a smooth transition between its grid-connected and islanded modes. In the light of the project, it can provide a solid technical foundation for guaranteeing the secure and reliable operation of the micro-grid and distribution network.

高渗透微电网在短路故障时的应对机制及暂态性能将对配电网的运行产生重要影响，确保故障下微电网与配电网的安全可靠运行具有极强的理论和现实意义。本项目围绕外部短路时高渗透微电网的故障穿越问题开展研究，引入经济型限流器并结合微电网内配置的复合储能进行协调控制，以期在限制短路电流和改善耦合点电压跌落的同时，也在平抑功率波动和提高电能质量方面发挥积极作用。研究内容包括：研究求取微电网故障电流/电压的解析方法，仿真分析高渗透微电网的故障暂态特征及对配电网运行的影响，给出微电网故障穿越/孤岛运行的量化指标；设计应用于微电网与配电网耦合接口处的经济型限流器，提出结合蓄电池-超级电容复合储能的协调控制策略；应用多目标约束和人工智能算法探索经济型限流器的容量优化方案。本项目的研究有望使高渗透微电网在无需孤岛运行时实现故障穿越，在应转为孤岛运行时实现平稳过渡，为保障微电网与配电网的安全可靠运行奠定坚实的技术基础。

高渗透微电网在短路故障时的处理方式及暂态性能将对配电网的运行产生重要影响，如何确保故障下微电网与配电网的安全可靠运行是亟待解决的关键问题。本项目围绕外部短路时高渗透微电网的故障穿越问题开展研究工作，引入经济型限流器并结合微电网储能系统进行协调控制，以期在限制短路电流和改善耦合点电压跌落的同时，也在平抑功率波动和提高电能质量方面发挥积极作用。本项目的主要研究内容包括：（1）高渗透微电网的故障暂态特征及对配电网运行特性的影响；（2）适用于高渗透微电网的经济型故障限流器技术方案；（3）考虑主动控制切换的经济型限流器-微网储能协调动作策略；（4）基于多目标约束及人工智能算法的经济型限流器容量优化方法。本项目的核心研究结果为：（1）针对高渗透微电网的电压等级与短路容量，提出了一种基于快速开关的磁通耦合式经济型限流器，比较了其与动态电压恢复器在故障限流及电压支撑方面的性能差异，论证了所提限流器的技术可行性和经济优越性；（2）计及高渗透微电网在故障穿越全过程的暂态特性，提出了一种基于P-Q/V-F主动切换的经济型限流器-超导磁储能协调控制方法，探讨了蓄电池-超导磁储能复合储能在微电网暂态稳定中的功能定位和动作重叠时域，验证了所提协调控制方法的有效性和先进性；（3）针对含不同类型分布式电源的复杂微电网，采用多目标粒子群算法，给出了经济型限流器应用于复杂微电网的帕累托优化方案。本项目的研究使得高渗透微电网在无需孤岛运行时实现故障穿越，在应转为孤岛运行时实现平稳过渡，有力提升了微电网应对外部短路故障的灵活性，为保障微电网与配电网的安全稳定运行奠定了坚实的技术基础。