直流线路继电保护解析分析方法与新型保护原理研究

发布时间：2018-05-21 00:35

本文选题：高压直流输电 + 直流线路保护　；参考：《华南理工大学》2014年博士论文

【摘要】：直流线路是直流输电系统的核心元件之一，长期以来一直存在故障率高、保护正确动作率低的问题，给直流输电系统以及整个电网的安全稳定运行带来重大影响。一方面，与传统交流继电保护不同，直流线路保护与直流控制强相关，并且受行波色散、边界条件等影响，尚未建立完备的分析方法体系。目前，直流线路保护分析主要基于数值仿真采用反复试验的研究模式进行，保护动作边界、关键因素作用机理等淹没于海量的数值仿真之中，不利于保护动作性能的评估与优化。另一方面，直流线路保护存在固有性能缺陷，主保护易受过渡电阻影响、后备保护动作延时过长，大量的高阻接地故障由控制系统动作造成直流闭锁。本文密切结合我国直流输电工程安全稳定的重大需求，在直流线路故障计算与保护分析的解析方法、直流线路新型保护原理等方面展开研究。本文主要工作包括：（1）提出了直流输电系统线路故障的解析计算方法。在分析直流输电系统线路故障暂态过程的基础上，推导了单极和双极直流输电系统的线路故障解析模型。由于直流线路参数的频变特性、直流控制作用的强非线性，难以对直流线路故障解析模型进行精确的时域求解。因此，研究了故障行波的衰减和畸变特征，提出采用惯性环节对解析模型中的行波色散进行等值；研究了直流控制对线路故障的响应规律，提出采用比例积分环节对解析模型中直流控制进行等值。基于行波色散和直流控制等值，对直流线路末端短路、平波电抗器阀侧短路等典型故障情况下的故障电气量进行时域解析，并与数值仿真结果进行比对，验证了解析计算方法的有效性。（2）提出了直流线路保护的解析分析方法。基于直流线路故障时域解析，分析了直流线路保护的实现原理，推导得到了保护特征量的时域解析函数。在区外故障情况下，求取解析函数的最大值，得到保护特征量的区外边界；在区内故障情况下，通过对解析函数与给定宽度标尺进行对标，得到保护特征量的区内边界。基于保护特征量变化边界，通过引入可靠系数、灵敏系数等，，提出了行波保护的电压变化率判据、电压变化量判据、电流变化量判据的整定计算方法。对南方电网直流输电系统的线路保护进行了整定计算，并与实际工程定值进行比对，实现了保护动作性能的定量评估。（3）提出了基于高频采样的新型直流线路行波保护方案，通过提高保护采样频率充分利用暂态故障信息构成保护判据保证了保护的灵敏性，采用行波保护的电压变化率理念以保证保护的速动性。提出了检测电流首峰值时间的直流线路保护新原理，将易受过渡电阻影响的电气量检测问题转换为不易受过渡电阻影响的时间检测问题从而提高保护的灵敏性，仅在线路末端故障时需要对端信息保证了保护的速动性。本文的新型直流线路保护方案有效解决直流线路保护速动性和灵敏性的矛盾，（4）为解决直流线路行波测距中波速选择带来的测距结果精确度较低、对运行工况和故障条件适应性差的问题，提出了基于宽频信息的直流线路故障测距方案。研究了故障行波变波速特性与宽频故障信息、故障特征之间的内在联系，提出了基于宽频故障信息的行波测距变波速处理方案，有效提高了现有测距算法的测距精度。将该方案与模量传输时间差原理相结合，提出了无需检测故障行波第二波头的新型单端测距算法。将基于宽频信息的故障测距方案应用于天广直流输电系统线路故障测距之中，测距结果验证了所提方法的有效性和实用性。本文得到国家高技术研究发展计划项目（“863计划”）（项目编号：2012AA050209）以及国家自然科学基金项目（项目编号：51077055）的资助。部分研究成果已经南方电网实际直流工程中得到应用，并获得南方电网公司科学技术进步二等奖，取得了良好的技术和经济效益，验证了本文工作的正确性和有效性。
[Abstract]:DC line protection is one of the core elements of DC power transmission system . It has long existed fault rate and low protection operation rate . On the other hand , the protection of DC line is mainly based on the research mode of repeated test , protection action boundary , key factor action mechanism and so on . On the other hand , DC line protection is mainly based on numerical simulation .

The main work of this paper is as follows :

On the basis of analyzing the transient process of DC power transmission system , the line fault analysis model of single pole and bipolar DC power transmission system is deduced . Because of the frequency change characteristic of DC line parameter and the strong nonlinearity of DC control function , it is difficult to solve the direct current line fault analysis model accurately .
In this paper , the response rule of direct current control on line fault is studied , and the equivalent value of DC control in analytical model is presented by proportional integral . Based on the equivalent of traveling wave dispersion and DC control , the fault electrical quantity in the typical fault condition such as short circuit of DC line end and short circuit of flat wave reactor is analyzed in time domain , and compared with the result of numerical simulation , the validity of analytical calculation method is verified .

( 2 ) The analysis method of DC line protection is put forward . Based on the analysis of DC line fault time domain , the principle of DC line protection is analyzed , and the time domain analytic function of protection feature quantity is deduced . In case of out - of - area fault , the maximum value of the analytic function is obtained , and the outer boundary of the protection feature quantity is obtained .
in that case of a fault in the area , the area boundary of the protection feature quantity is obtain by comparing the analytic function with a given width scale . based on the change boundary of the protection feature quantity , a set method for determining the voltage change rate criterion , the voltage variation quantity criterion and the current change amount criterion of the traveling wave protection is put forward based on the change boundary of the protection feature quantity , and the line protection of the DC power transmission system of the south grid is calculated and compared with the actual engineering fixed value , and the quantitative evaluation of the protection action performance is realized .

( 3 ) A novel direct current line protection scheme based on high frequency sampling is proposed , which ensures the sensitivity of protection by increasing the protection sampling frequency and making full use of transient fault information .

( 4 ) In order to solve the problem of poor accuracy of distance measurement result brought by wave velocity selection in direct current line traveling wave distance measurement , a direct current line fault location scheme based on broadband information is put forward . A new single - end ranging algorithm based on broadband fault information is proposed . A new single - end ranging algorithm based on broadband fault information is proposed .

This paper is supported by the National High - Tech Research Development Program ( " 863 Plan " ) ( Project No . 2012AA050209 ) and the National Natural Science Foundation Project ( Project No . : 51077055 ) . Some of the research achievements have been applied in the real direct current project of the Southern Power Grid , and the second prize of the Science and Technology Progress of the Southern Power Grid Corporation has been obtained . Good technical and economic benefits have been obtained , and the correctness and effectiveness of the work are verified .
【学位授予单位】：华南理工大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TM773

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