【作者】 倪云峰；

【导师】 刘健；

【作者基本信息】 西安科技大学 ， 安全技术及工程， 2010， 博士

【摘要】 为了对接地网中的导体支路和引下线的腐蚀状况进行故障诊断,及时发现接地网的缺陷,确保人身、设备和电力系统的安全,对接地网的腐蚀故障诊断理论与方法进行了深入研究。为了将大规模接地网撕裂成若干小规模子网络分别进行测试和诊断,提出了接地网的分块模型。将一个接地网分解为若干相互独立的块,定义了块的原型和投影等概念,并将块分类为明晰块、不确定块和混合块三类。指出:以块为单位对接地网进行撕裂才能够保持撕裂前后的可测性不变,为接地网的分块测试和腐蚀故障诊断奠定了基础。提出了一种接地网的分块故障诊断方法。提出了一种基于节点分区的测试方法和块内本征支路电阻的线性求解方法,不仅能够避免块间测试数据的交叉干扰和提高求解效率,而且有助于减小传统非线性方法中本征支路电阻诊断结果对量测误差的敏感程度。基于所测试的子网络的投影中的本征支路电阻的诊断结果,采用逐层上溯的方法求解出该子网络中各条支路电阻反映其腐蚀状况,从而实现接地网的分块故障诊断和局部故障诊断。为了测试接地引下线的腐蚀状况,提出了两种测试与诊断方法。方法一:首先在避免接地引下线影响的条件下对接地网整体进行充分测试,并诊断出其全部本征支路电阻,然后分别测试各个可及节点间的输入阻抗,测试中确保每条接地引下线参与两次,求解得到的关于接地引下线电阻的线性方程组,诊断出各条接地引下线的电阻,从而反映其腐蚀状况。方法二:基于分块故障诊断方法。首先在避免接地引下线影响的条件下诊断出本征支路电导的比例关系,再进行包含接地引下线影响的测试,从而建立关于接地引下线电导的线性方程组,求解该线性方程组得出接地引下线的诊断结果。为了减小诊断过程中的测试工作量,基于接地网的分块故障诊断方法,提出了测试方案的优化方法。定量分析了采用常规测试设备和采用自动化测试系统时的测试工作量,提出了一种基于动态规划思想的测试方案优化方法,能够有效减小测试工作量。为了解决接地网测试中可及节点偏移的影响,采用蒙特卡罗方法,研究了可及节点位置偏移对支路电阻诊断准确性和可测性的影响,提出了一种以实际观测电压向量与修正后的电压向量之差的二阶范数最小为目标函数、采用禁忌搜索算法对故障诊断结果进行修正的方法,并对修正效果进行了定量评价,表明其是有效的。在实验室60支路的实验接地网和渭南东330kV变电站内的38支路的接地网上进行了实验验证,结果表明本文所提出的理论和方法是正确的和可行的。更多还原

【Abstract】 In order to diagnose the corrosion of the grounding grid and down lead lines conveniently, find out the defects in time and ensure the safety of power apparatus, electric power system and the personal safety, the following contributions have been made:To benefit for dividing a large grounding grid into several small grounding grids, based on hierarchical simplification model, a novel block model for grounding grids is proposed. The originalshape and projection concept of block are defined in the block. According to the block model, the grounding grid can be divided into different scale blocks, which are independent each other and can be classified into different kinds blocks such as clear block,uncertain block and mixed block, the different methods for different kinds of block is presented, which the diagnosing the corrosion of grounding grids can be achieved. Using the splitting method based on the block model, the testability of grounding grids can be kept identical all time.The block diagnosing method based on the block model for grounding grids is put forward. A linear new approach is presented, which the intrinsic branch resistances can be solved accurately. The cross-interferences of testing data between the blocks are reduced and the efficiency is improved rapidly, meanwhile it is helpful to reduce the sensitivity from intrinsic branch resistance measurement error. The branch resistances of actual grounding grids can be solved by the tracing method to calculate the current branch resistance according to the upper level branch resistances. So, the corrosion diagnoses of partition and part block can be acheived.To diagnose the corrosion of down lead lines, two novel methods are proposed. One method is to achieve the resistances of the horizon conductors firstly based on the sufficient test data avoiding the effect of the down lead lines. Then, the linear equation group of down lead line resistances are established based on the test data of resistances between each two touchable nodes. The other method is based on the proposed block model. The ratios of the intrinsic branch resistances are achieved firstly based on the sufficient test data. Then, the linear equation group of down lead line resistances and the resistance of a certain intrinsic branch can be established based on the test data including the influence of the down lead lines; the resistances of the down lead lines can be thus solved.The amount of test work is calculated for the cases of using normal measurement equipments and with automatic testing system, respectively. An optimization approach of test schemes based on dynamic programming is put forward to reduce the amount of test work in the process of grounding grid corrosion diagnosis.In the practice of grounding grid test, the down lead lines are used as touchable nodes and normalized into the nearby cross nodes of the network, respectively, resulting in touchable nodes deviation problems. The influences of touchable nodes deviation on the accuracy and the testability of the results of grounding grids corrosion diagnosis are analyzed. A Tabu search based on correction approach is put forward. The diagnosis results in case of deviation are used as the initial solution. The index is to minimize the summation of the squared differences between the observed voltages and the voltages after correction. A method to access the correction in quantity is suggested.Experiments are made on the test grounding grid with sixty branches and the thirty-eight grounding grid buried in Weinan 330kV Substation are tested and diagnosed, respectively, the diagnose results of which show that the proposed approaches and algorithms are correct and feasible.更多还原