Catastrophic impacts of geomagnetic disturbances on power system operation: Analysis and Mitigation

太阳爆发活动引起的太阳风暴可能会导致地磁扰动(GMD)。在GMD期间，大量带电的太阳高能粒子从太阳的光晕中逃脱，旅行到地球，扰乱地球的磁场，并在电力系统中产生不受欢迎的直流电流。这会导致电力系统设备过热、超载和不正常运行。因此，GMD已经证明有能力扰乱电网的正常运行，并导致大范围停电。魁北克水电系统的崩溃就是一个突出的例子，600多万用户断电，电力系统主要设备受损；这一事件造成了约3亿美元的经济损失。专家估计，严重的GMD有可能造成广泛的长期损失，恢复时间为4至10年，经济损失达1至2万亿美元。该项目的主要目标是准确模拟GMD对大容量电力系统正常运行的影响，并开发系统的方法来缓解这些影响，包括电网重构和确定闭塞装置的适当位置。为了实现本研究项目的主要目标，定义了以下两个目标：准确的GMD对电力系统的影响建模和分析，以及基于电力系统重构和闭锁装置安装的GMD影响的系统缓解。为此，本项目对科学界的主要贡献如下：1)电力变压器的频谱元素分析：这将是将频谱元素方法应用于电力变压器和一般电机的首次尝试。与传统的有限元方法相比，这种方法的计算公式紧凑，使用的是高次基函数，所需的内存和计算时间大大减少，从而为电机的分析提供了更准确的结果和更好、更高效的平台。该项目通过更好地建立变压器饱和模型而受益于这项任务的结果；GMD对变压器的影响是所有GMD不利影响的根本原因。2)非线性谐波潮流分析：某些非线性现象，如变压器饱和，会引起电力系统的谐波。该项目旨在开发一种在这些情况下估计系统电压和电流的谐波含量的综合方法。尽管在这个问题上做了大量的努力，并且在该领域取得了过去的进展，但到目前为止，还没有针对大规模问题的强大的解决技术。3)基于优化的GMD缓解：为了防止GMD造成大范围停电，可以采取电力系统重构和安装闭路器等措施。电力系统重构的目的是通过设备计划停运来提高电力系统的稳定裕度或防止不良直流电流在系统中传播。阻挡装置安装旨在通过安装高阻抗硬件设备来阻止GIC在电网中循环。该项目将创建基于优化技术的系统方法，以确定最优缓解策略，同时确保考虑电力系统稳定性和设备负载限制。总而言之，该项目将创建准确的建模技术和缓解方法，以防止GMD对电网产生严重影响。此外，该项目的成果还将有助于在一般电力系统建模和分析中得到更广泛的应用。

Solar storms, caused by the violent outburst of explosive activities on the sun, may lead to geomagnetic disturbances (GMDs). During GMDs, a large mass of charged solar energetic particles escapes from the sun's halo, travels to Earth, perturbs Earth's magnetic field, and gives rise to undesirable dc currents in power systems. This results in overheating, overloading, and abnormal operation of power system equipment. As a result, GMDs have demonstrated the ability to disrupt the normal operation of power grids and cause widespread blackouts. The collapse of the Hydro-Quebec system is a prominent example, where more than six million customers were left without power, and major power system equipment was damaged; this episode resulted in economic damages of approximately $300 million. Experts estimate that a severe GMD has the potential to cause widespread, long-term losses with a recovery time of four to ten years and staggering economic losses of $1-2 trillion. The main goal of this project is to accurately model the impacts of GMDs on the normal operation of bulk electric power systems and develop systematic approaches to mitigate these impacts, including power grid reconfiguration and determining proper placement of blocking devices.To achieve the main goal of this research project, the following two objectives are defined: Accurate modeling and analysis of GMD impacts on power systems, and systematic mitigation of GMD impacts based on power system reconfiguration and blocking device installation. To this end, the major contributions of this project to the scientific community are as follows: 1) Spectral element analysis of power transformers: This will be the first attempt in applying spectral element method to power transformers and generally to any electric machine. Due to its compact formulation and use of high order basis functions, this technique requires much less memory and CPU time compared to traditional finite element methods and hence provides more accurate results and a better and more efficient platform for the analysis of electric machines. This project benefits from the results of this task by better transformer saturation modeling; impact of GMDs on transformers is the root cause of all GMD adverse impacts. 2) Nonlinear harmonic power flow analysis: Certain nonlinear phenomena, such as transformer saturation, can give rise to power system harmonics. This project seeks to develop a comprehensive approach for estimating the harmonic content of system voltages and currents under these circumstances. Despite the great deal of effort on this problem and past advancements in the area, to date no robust solution technique exists for large-scale problems. 3) Optimization-based GMD mitigation: To prevent GMDs from causing widespread blackouts, measures such as power system reconfiguration and blocker device installation can be taken. Power system reconfiguration aims to provide an improved stability margin to the power system or prevent the propagation of undesirable DC currents in the system by means of equipment planned outages. Blocker device installation aims to block the GICs from circulating in the grid by installing high-impedance hardware devices. This project will create systematic approaches based on optimization techniques to determine optimal mitigation strategies while ensuring consideration of power system stability and equipment loading limits. In summary, this project will create accurate modeling techniques and mitigation approaches to prevent GMD from having severe impact on the grid. Moreover, the deliverables of this project will also contribute to broader applications in general power system modeling and analysis.