超导磁控串联补偿限流技术的机理研究

This project researches a technology which can both achieve the series compensation and fault current limitation . Using the combination of superconducting magnetically controlled reactor and capacitive circuit, a technology with a series compensation during normal operation of the grid and a large inductance to limit the fault current in the case of a fault is realized through controlling the output reactor of magnetically controlled reactor. A reasonable gap structure is introduced through analyzing the effect of gap structure on flux inkage-current curve and the optimization of the control to the magnetically controlled reactor is carried out. The high current density which introduced by the air gap is reduced through optimizing the structure of the core. Taking the advantage of MgB2 superconducting materials, the core flux is maximized while magnetic flux density on superconducting coil is minimized through improving the structure of DC coil and optimizing the distribution of Magnetic field. After analyzing The steady-state and transient characteristics of the grid. an adjustble capacitance circuit is researched to presents a large capacitive reactance while the grid is normal, and when the grid is in fault, the capacitive reactance quickly reduces to a very low value even zero. A coordination control method and system is designed to realize rapid state transition. A prototype and a platform will be achived and tested. It provides some research basis for MgB2 in series compensation application.

本项目研究一种可以同时实现串联补偿和故障限流的技术。该技术组合超导磁控电抗器和电容电路，通过控制磁控电抗器的输出电抗，实现电网非故障运行时的串联补偿作用；当电网发生故障时，系统快速输出较大的感抗，限制故障电流。项目通过分析气隙结构对磁链—电流曲线的影响，引入合理的气隙结构，优化磁控电抗器的控制曲线；通过优化铁芯结构，降低因引入气隙而提升的直流电流密度；研究利用MgB2新型超导材料的优势，设计直流线圈结构，通过优化磁场分布，最大化铁芯磁通并最小化分布在超导线圈的磁感应强度；分析电力系统暂态和稳态特性，研究不同的容性电路拓扑结构，实现容性电路在电网非故障运行时呈现较大的容抗，当电网发生故障后，容性电路的容抗值迅速降至很低或者为零；研究统一的协调控制方法及其控制系统，实现快速的状态转换；制作样机并搭建样机平台，测试系统性能。为MgB2在串补应用提供一定的研究基础。

本项目拟研究的基于 MgB2 的 MSCFCL 系统兼具串联补偿控制和故障限流功能，其基本原理是通过切换磁化曲线工作点，改变铁芯工作点磁导率进而改变输出电抗大小。实现直流小电流对交流大电流的控制，根据电网要求进行潮流控制、电压动态灵活调整、线路容量调节以及故障限流。