磁控式并联电抗器（MCSR）可实现无功功率的大范围平滑调节,但现有研究中MCSR容量调节暂态特性及其对保护的影响尚不清晰。因此,该文对MCSR容量调节过程展开研究,首先分析了磁控式并联电抗器的稳态运行特性,引入磁饱和度概念,在此基础上,对其容量调节暂态过程特性展开讨论。调容暂态过程中,由于心柱间磁饱和度的差异,三相控制绕组电流及控制绕组总电流的基波分量将会增加,导致基于控制绕组总电流基波分量的匝间保护误动。为解决该问题,根据MCSR调容过程中三相控制绕组电流基波分量平均值近似相等的特点,利用三相控制绕组电流基波分量差异度,可以准确识别出容量调节过程,从而有效解决了MCSR容量调节过程中匝间保护误动的问题。基于Matlab/Simulink的仿真及1.5kV MCSR样品的动模实验,验证了所提方案的正确性。

实际工程中对于特高压磁控式并联电抗器（MCSR）控制绕组接地故障配置直流母线过压保护,然而发生控制绕组端部接地故障时,母线极对地电压无交流过电压特征,导致保护无法识别该故障。针对该问题,分析了控制绕组接地故障及稳态运行、2种方式合闸、区外故障工况下母线极对地电压变化情况,基于此提出一种基于直流母线不平衡电压的控制绕组接地保护方案。该方案利用正、负极直流母线电压之和构造直流母线不平衡电压,基于故障下直流母线不平衡电压明显上升的特征识别故障。方案原理简单、易于实现,解决了现有保护无法识别控制绕组端部接地故障问题。在MATLAB/Simulink软件中搭建了750 kV三相MCSR仿真模型,大量仿真结果验证了该保护方案的有效性。

超/特高压磁控式并联电抗器（Magnetically Controlled Shunt Reactor,MCSR）是柔性交流输电设备中重要的一员,其结构特殊、故障特性极其复杂,对保护可靠性要求较高。本文以MCSR控制绕组保护为研究核心,围绕MCSR工作原理及仿真建模、励磁系统故障对匝间保护影响及解决策略、控制绕组故障分析及保护新方案和物理模型内部故障实验这四部分开展研究。本文首先对MCSR及其励磁系统的结构、工作原理及稳态运行特性做了简要说明,并介绍了当前基于有限元分析法和磁路分解法的两种MCSR建模方法。根据投运于青海省鱼卡站750kV MCSR的额定参数,基于磁路分解法在MATLAB/Simulink搭建了 750kV三相MCSR五分段磁路仿真模型;基于课题组设计和定制的500V MCSR样机模型,在ANSYS有限元分析软件中搭建了该样机的二维有限元仿真模型。其次,针对MCSR励磁系统故障在直流母线电流中引入基频分量后导致控制绕组匝间保护误动的问题,详细分析了几种常见的励磁系统故障发展过程,总结了两种不同类型的直流侧电流基频分量的产生机理,进一步解释了基于基频分量的匝间保护误动原因;分析了匝间故障与励磁系统故障时直流母线电流二次谐波衰减速度的差异性特征,提出了基于二次谐波衰减速度的匝间保护防误动策略,有效地识别了励磁系统故障,解决了匝间保护误动问题。针对现有母线过电压保护无法识别无交流过电压特征的控制绕组端部接地故障问题,本文提出了一种基于直流母线不平衡电压的控制绕组接地保护方案,基于故障时母线不平衡电压明显上升的特征识别控制绕组接地故障,方案原理简单易于实现,解决了现有保护无法识别控制绕组端部接地故障问题。最后,为了检验两种不同的模型对于内部故障特性仿真的准确性,利用真空断路器搭配上高时间精度可编程PLC控制器,搭建了 MCSR模型样机内部故障实验平台,实现了故障时段的精确把握和故障过程的自动控制。仿真与实验结果验证了两种建模方法的准确性。

磁控式并联电抗器（Magnetically controlled shunt reactor,MCSR）作为超/特高压输电系统中重要的无功补偿设备,其安全与稳定运行对于系统的无功平衡及电压稳定至关重要。然而,MCSR本体结构复杂,绕组匝间故障几率高,在交直流励磁的共同作用影响下,匝间故障特性与固定式高抗不同,增加了匝间保护设计的难度。本文以MCSR匝间保护为核心,围绕当前匝间保护配置及性能分析、合闸暂态特性及其对匝间保护的影响与对策、容量大范围调节特性及其对匝间保护的影响与对策、基于等效漏电感参数的匝间保护新原理四部分展开研究。首先,在介绍MCSR的工作原理及模型搭建的基础上,对当前MCSR匝间保护配置及其性能展开了研究。研究发现,MCSR匝间保护尚有以下问题待解决:①匝间保护可靠性、灵敏性不足;②复杂运行工况下匝间保护的适应性不明确。然后,针对MCSR的一种复杂工况—合闸暂态过程,研究了 MCSR合闸暂态特性及其对匝间保护的影响及对策。分析了 MCSR合闸场景下主要电气量的暂态特性,发现基于总控电流基波分量的匝间保护在合闸过程中容易发生误动。为解决上述问题,分别从频域和时域的角度,提出了基于控制绕组电流与总控电流基波分量比值以及基于控制绕组电流波形自相关的合闸防误动策略。仿真及试验结果表明,这两种策略有效解决了 MCSR合闸过程中匝间保护误动的问题。其次,针对MCSR另一种复杂工况—容量调节,研究了容量调节暂态特性及其对匝间保护的影响及对策。分析了容量调节过程中主要电气量的暂态特性,发现基于总控电流基波分量的匝间保护在在容量调节过程中易发生误动。为解决上述问题,根据调容过程中三相控制绕组电流基波分量近似相等的特点,构建了基于控制绕组电流基波分量三相差异度的容量调节识别判据。仿真及试验结果表明,所提方案有效解决了 MCSR容量调节中匝间保护误动的问题。最后,提出了一种基于等效漏电感参数辨识的MCSR匝间保护新原理。在构建等效漏电感参数计算模型的基础上,利用递推最小二乘法对等效漏电感参数进行辨识,最后利用故障前后等效漏电感参数的变化,提出了基于等效漏电感参数变化率及三相差异度的匝间保护新原理。仿真及试验结果表明,保护新原理解决了匝间保护可靠性、灵敏性不足的难题,在合闸、容量调节等复杂工况下适应性较强,且能识别故障绕组,对实际工程具有重要的参考价值。

Shunt reactors are used in long transmission lines and distribution networks to absorb the extra reactive power generated due to the existence of capacitive charging current.The MCSR is a type of continuously controllable shunt reactors used for reactive power compensation and voltage control.From a power system reliability point of view,continuous operation of MCSR is needed.Therefore,special attention should be given to protect the equipment from all types of possible faults.Due to the design and functional differences from fixed type shunt reactors and power transformers,the protection task becomes more challenging for MCSR.The major faults which cause high magnitude fault current are phase-to-phase and phase-to-ground faults.The level of fault current is dependent upon the location of the fault.The T2TF（fault between turns within the phase winding）is not only the most common failure in shunt reactors,but it is also the most challenging fault type to detect.Once the arc between some turns has been initiated,the fault may develop to flashover the entire winding.If not detected at an incipient stage,this resulting into phase fault that can harm the healthy phases as well.Even one shorted turn will cause a high magnitude circulating current in the fault location.However,seen from the outside,the magnitudes of phase currents and the voltages do not change very much from the normal steady-state operational limits.Due to the presence of MCSR windings inside the oil tank,detection of the low-level T2TF becomes a challenging task,especially in case of a CtrW T2TF where DC is flowing and have a special configuration.The Buchholz or pressure relief protection（i.e.,mechanical way of faults protection）presents a quite dependable protection for this type of fault in case of oil-based shunt reactors.Many utilities consider mechanical protection is a main protection function due to the limitations from electrical protection schemes.However,new methods for detecting T2TFs that benefit from the possibilities offered by numerical protection have been developed in recent years.The fundamental objective of this research work is to model and design a sensitive and applicable T2TF electrical protection scheme for MCSR that can protect the equipment from all possible T2TFs.Therefore,two new protection schemes are proposed and tested in this thesis mainly.The uniqueness of the proposed protection schemes in this work are their abilities to detect the faulty phase,faulty winding,differentiation between different windings T2TFs,differentiation of T2TF from energization conditions,internal,and external faults.Moreover,these schemes can be applied on the existing MCSR without changing the basic windings configuration,body structure,or mechanical design,which is a real challenge.For this research work,the first 750kV MCSR installed in Yuqia substation having a rated voltage of 800kV and a rated capacity of 330 MVAr,is chosen as a case study.The following approaches are used to achieve the ultimate goal of modelling and designing these unique T2TFs protection schemes.First of all,basic understanding of the mathematical background of existing EHV MCSR model and its implementation in MATLAB/Simulink platform is performed.Faults analysis of the model is carried out and a comprehensive protection package for all kind of possible internal and external faults is formulated and validated through numerous simulation results.The symmetrical components behavior under PWs,CtrWs,and CpWs T2TFs is evaluated and defined a protection scheme based on angle of the negative sequence voltage（∠3V2）,and magnitude of the negative sequence current（|3I2|）.The usefulness of the proposed symmetrical components-based protection scheme is validated through simulations.Moreover,mathematical modelling is performed for developing an algorithm for T2TF protection based on the current’s magnitudes comparison at different buses,and evaluated the fundamental laws comprising of basic electric and magnetic circuit parameters.This protection scheme is also tested on the simulation model and validated its usefulness.