混合直流系统中基于平波电抗器与限流电抗器参数优化的限流策略

Current Limiting Strategy Based on Parameter Optimization of Smoothing Reactor and Current Limiting Reactor in Hybrid HVDC System

直流线路正常运行过程中,平波电抗器可以减小电流纹波。当直流线路发生故障时,限流电抗器的快速投入可以抑制故障电流的上升速度。因此,考虑限流电抗器与平波电抗器的协同,不仅可以抑制故障电流的上升速度,而且能够降低直流断路器的切断容量。然而,受到投资成本和系统动态特性的制约,平波电抗器与限流电抗器的电感容量需要保持在合理的范围内。因此,对直流输电系统中平波电抗器和限流电抗器的容量进行优化配置,在保证限流能力的同时降低投资是十分有意义的。首先,建立了交直流混联系统的故障等效模型,并分析直流线路发生双极性短路时两端故障电流的特性。其次,建立了平波电抗器和限流电抗器的优化配置数学模型。最后,基于MATLAB仿真试验对所提限流策略进行了验证。

During normal operation of DC lines,the smoothing reactor can reduce current ripple.When a DC line fails,the rapid operation of the current limiting reactor can suppress the rising speed of the fault current.Therefore,considering the collaboration between current limiting reactors and smoothing reactors can not only suppress the rising speed of fault current,but also reduce the cutting capacity of DC circuit breakers.However,due to investment costs and system dynamic characteristics,the inductance capacity of smoothing reactors and current limiting reactors needs to be maintained within a reasonable range.Therefore,it is very meaningful to optimize the capacity configuration of smoothing reactors and current limiting reactors in the HVDC transmission system,while ensuring the current limiting capacity and reducing investment.Firstly,a fault equivalent model for the AC/DC hybrid power grid is established and the characteristics of the fault current at both ends when a bipolar short circuit occurs in the DC line are analyzed.Secondly,a mathematical model for optimizing the configuration of smoothing reactors and current limiting reactors is established.Finally,the proposed current limiting strategy is validated through MATLAB simulation experiments.