Dynamic Enhancement and Protection of Power Systems with Large Penetration of Renewable Energy

***应对全球气候变化这一影响到地球上每一个人的全球性环境现象的需要，是利用可再生能源的最公开的推动力。电网整合大容量可再生能源和利用大容量电能储能现已成为现实。然而，这些类型的电网需要新的方法来增强和保护系统的动态。申请人计划进行的研究工作将在两个主要推动力下推进。***推力1：可再生能源大容量电力系统的动态增强***该推力将探索双馈感应发电机（DFIG）和全尺寸变频器（FFC）风电场补充控制的潜在用途，以减轻次同步共振（SSR：串联电容器补偿传输系统与涡轮发电机轴系统之间的相互作用）和次同步相互作用(SSI：串联电容补偿输电系统和基于dfig的风电场之间的相互作用)。***由于大多数大型风电场采用DFIG和FFC风力涡轮机，它们基于电压源变流器的背靠背（BtBs）提供了实功率和无功功率的解耦控制。这些控制能力的使用最近被提议用于阻尼功率波动，区域间振荡和SSI。在串联电容补偿输电线路和高渗透风电转换系统的综合电力系统中，在某些系统突发事件中，SSR和SSI可能同时存在。因此，减轻SSR和SSI一直是一个有吸引力的研究和开发领域，旨在制定切实有效的对策。***推力2：大容量可再生能源电力系统的保护***中点STATCOM对发电机相备保护和发电机失磁保护性能影响的研究结果表明，中点STATCOM对这类保护具有不良影响，可能以欠伸、过伸或延时的形式出现。***由于DFIG和FFC风力涡轮机的并网侧变流器对发电机来说是STATCOMs，这些类型的可再生能源转换系统的高渗透率预计会对发电机距离继电器的性能产生不利影响。***本课题的一项主要研究是探讨风能转换系统的高穿深对发电机距离、缺相保护和失磁保护的影响，以确定保护工程师在设计和设置保护系统时需要考虑的重要问题。此外，还将探讨切实可行的解决方案，以减轻可再生能源转换系统对发电机和输电线路距离保护的不利影响

***The need to address global climate change, a worldwide environmental phenomenon that will affect everyone on earth, is the most public driving force for the utilization of renewable energy. Grid integration of large capacity of renewable energy sources and the use of large capacity of electrical energy storage is now a reality. These types of grid require, however, new approaches for system dynamic enhancement and protection. The research work that the applicant is planned to undertake will advance upon two major thrusts.***Thrust 1: Dynamic Enhancement of Power Systems with Large Capacity of Renewable Energies***This thrust will explore the potential use of supplemental controls of Doubly-Fed Induction Generator (DFIG) and Full-Scale Frequency Converter (FFC) wind farms for the mitigation of subsynchronous resonance (SSR: the interaction between series capacitor compensated transmission systems and turbine-generator shaft system) and subsynchronous interaction (SSI: the interaction between series capacitor compensated transmission systems and DFIG-based wind farms).***As most large wind farms employ DFIG and FFC wind turbines, their voltage-sourced converter-based back-to-backs (BtBs) offer decoupled control of the real and reactive power. The use of these control capabilities have been recently proposed for damping power swings, inter-area oscillations and SSI. In integrated power systems incorporating series capacitor compensated transmission lines and high penetration of wind energy conversion systems, SSR and SSI could exist simultaneously during some system contingences. Thus, alleviating SSR and SSI has been an attractive area of research and development targeting at developing practical and effective countermeasures.***Thrust 2: Protection of Power Systems with Large Capacity of Renewable Energies***The results of the investigations on the impact of midpoint STATCOM on the performance of generator phase backup protection and generator loss of excitation protection have revealed that the midpoint STATCOM has an adverse effect on such protections which can be in the form of underreach, overreach or a time delay.***As the Grid-Side Converters of DFIG and FFC wind turbines appear to the generators as STATCOMs, high penetration of these types of renewable energy conversion systems is expected to have an adverse effect on the performance of generator distance relays.***A major investigation in this thrust is exploring the impact of high penetration of wind energy conversion systems on generator distance phase backup protection and loss of excitation protection in order to identify the important issues that protection engineers need to consider when designing and setting the protection system. In addition, practical and feasible solutions to mitigate the adverse impact of renewable energy conversion systems on generator and transmission line distance protection will be explored.**