百兆瓦级非稳态运行变流系统低次谐波形成、传导及耦合机理研究

The harmonic problem of high power pulsation supply is directly related to the operation safety for power supply device and power grid. Especially the low-order harmonics, which tend to occur resonance but difficult to filter out, could be one of the key challenges of the research on system compatibility for hundred-megawatt converter system. Meanwhile, many domestic and foreign converter devices and harmonic filtering platforms are forced outage and optimization due to the harm of the low-order harmonics. Therefore, the proposal aims at this urgent technical challenge. Then, three kinds of modulation function: steady-state-transfer function, asymmetrical-impulse function and phase correction function will be further studied to explain the formation, conduction and coupling mechanism of low-order harmonics by combining rapid changes of the trigger angle, DC bias and AC/DC system harmonic coupling. The results will be carried out on ITER and EAST experiments. Finally, an analysis model will be established to accurately judge the formation and ratio of low-order harmonics and this will provide a scientific foundation and theory evidence basically to solve the low-order harmonic and other issues.

大功率脉冲电源谐波问题直接关系到电源本身及电网的运行安全，尤其是极易谐振，极难治理的低次谐波是百兆瓦级变流系统兼容性研究的关键问题之一。低次谐波危害大、影响深、事故多发，迫使国内外一些大型变流装置及配套谐波抑制系统多次停运改造，饱受其害。因此本申请瞄准这一亟待解决技术难题，立足非稳态运行变流系统低次谐波发射机理与特性，紧密围绕磁约束聚变低次谐波抑制的迫切需要，拟采用稳态、脉动及换相修正调制函数相结合的方法，统一考虑触发角快速调节、直流偏磁和交、直流动态耦合等因素，对低次谐波形成原因、传导机理及耦合方式进行深入、系统地理论分析和建模仿真，并通过EAST和ITER变流系统实验进行验证，准确判定此类谐波的成因及其权重，为从根本上解决低次谐波及其相关问题提供科学基础和理论依据。

低次谐波威胁高功率变流系统运行安全，是磁约束聚变装置与电网兼容亟待解决的关键问题之一。本项目紧密围绕EAST国家大科学装置和ITER国际重大科技合作项目的需求，在低次谐波形成原因、传导方式、耦合机理及抑制策略方面开展了相关研究工作。计及触发快速调节、换相非线性、电网谐波、直流电动势等非稳态实际工况，将稳态、脉动及换相修正函数有机结合，建立了聚变变流系统低次谐波非稳态数学模型；建立了ITER PF整流变压器直流偏磁等值参数电路，推导了交流侧2次谐波与直流侧基波电流之间的关系，并通过理论计算和实验测试排除了聚变电源低次谐波是由直流偏磁传导引起的；建立了变流系统交直流耦合低次谐波时域模型，基于移频函数理论将时域非线性特征转化为频域线性函数，据此推导出交直流耦合低次谐波频域模型，给出了其稳定性特征方程和稳定性判据方法；发展了谐振注入混联并网的低次谐波抑制拓扑，提出了多参考量改进型PR复合控制方法，开展了有源变流单元输出滤波器研究，设计了基于椭圆数字带通滤波器和单频陷波器的组合检测系统，研制了一套低次谐波混联滤波实验装置，可解决无源易谐振、低频效果差，有源高压直挂难、容量成本高的问题，为从根本上解决聚变电源低次谐波难题提供了科学基础和抑制方法。