中低纬地磁扰动感应地电场与电网GIC分布特征研究

Although China is located in the mid-low latitudes, the geomagnetically induced currents (GIC) due to strong geomagnetic disturbances (GMD) are still potential threats to the safe operation of the power grid. It is of great importance to know the distribution characteristics of harmful GIC in the large-scale power grid for the purpose of accessing and controlling the risk of extreme space weather. The project proposes to investigate the occurrence and distribution characteristics of GIC in the Chinese EHV and UHV power grid through the following methods: .1. Create a large-scale 3D conductivity model based on the magnetotelluric data for the key areas where the transmission corridors are located, and propose a numerical method to calculate the GMD induced geoelectric field in the 3D structure of the earth conductivity; .2. Establish a fine GIC circuit model with considering the comprehensive effect of geoelectric field distribution, power grid structure and the electrical parameters for simulating GIC in the complex multi-voltage level large-scale power grid; .3. Simulate the long-term performance of geoelectric field and GIC in the power grid by using GMD historical observation data, and establish the corresponding statistical model so that the distribution characteristics and occurrence probability of harmful GIC can be obtained. .The research results of this project will deepen our understanding on the generation mechanism of the GMD disaster at mid-low-latitude power grid, and provide the basic data as well as analysis tools for the risk assessment and designing prevention measures.

虽然我国位于中低纬度，但是强烈地磁扰动（GMD）产生的地磁感应电流（GIC）对电网的安全运行仍构成潜在威胁。了解灾害性GIC在我国大规模电网中的分布特征对于评估、防范极端空间天气导致的安全风险具有重要意义。本项目以未来特高压、超高压大规模电网为研究对象，基于大地测深数据构建输电走廊重点区域的大尺度三维电导率模型，提出GMD在三维大地导电结构中感应电场的数值计算方法；综合考虑地电场的分布性和电网结构、参数的共同作用建立电网GIC精细计算模型，实现多电压等级大规模复杂电网GIC的仿真计算；通过GMD的历史观测数据仿真模拟感应地电场和电网GIC的长期表现，并对仿真结果建立统计模型，探明GIC的分布规律和高危因素，给出危害性GIC的发生概率与分布特征。本项目的研究成果可加深我们对中低纬电网GMD灾害产生机理的理解，为电网风险评估和有针对性地设计防治措施提供基础数据和分析工具。

随着电网规模的持续扩大和电网结构的日趋复杂，强烈地磁扰动（GMD）导致的地磁感应电流（GIC）及其引起的电网无功波动屡有发生，给电网的安全运行带来不利影响。为了防范空间天气导致的电网安全风险，了解灾害性GIC在我国大规模电网中的分布特征具有重要意义。在国家自然科学基金的支持下，本项目开展的主要工作及成果如下：.1.针对大规模电网对应区域的复杂地质结构，考虑大地电导率的纵向、横向突变，提出了3D大地电导率建模方法，基于有限元法和无网格有限差分法发展了GMD感应地电场的数值计算方法。.2.基于3D大地电导率模型，求解了GMD感应地电场的局部增强，得出了电导率、频率、分界面距离等因素对感应地电场畸变的影响规律，通过输电线路模型和电网模型定量分析了海岸效应和电网GIC增强现象之间的关系。.3.建立了中低纬电网GIC计算的精细等效电路模型，应用完整太阳活动周期内发生的多次强磁暴数据计算了电网的GIC，以这些数据作为统计样本分析得出了中低纬电网GIC的发生规律，并由概率模型预测了极端情况下我国特高压电网的GIC水平。.4.建立了变压器电路-电磁场-机械场耦合模型，研究了GIC对变压器无功损耗、铁芯振动、噪声增强之间的定量关系，基于磁暴对电网安全产生影响的因果链，提出了GMD危害电网的风险评估方法与优化防治策略。.本项目研究加深了对中低纬电网GMD灾害机理及其影响因素的认识，掌握了GMD感应地电场和GIC的分布特征和发生规律，可为评估和防范大规模复杂电网中的GIC风险提供仿真分析方法。