Fault location of untransposed double-circuit transmission lines based on an improved Karrenbauer matrix and the QPSO algorithm

Some double-circuit transmission lines are untransposed,which results in complex coupling relations between the parameters of the transmission lines.If the traditional modal transformation matrix is directly used to decouple the parameters,it can lead to large errors in the decoupled modal parameter,errors which will be amplified in the fault location equation.Consequently,it makes the fault location results of the untransposed double-circuit transmission lines less accurate.Therefore,a new modal transformation method is needed to decou-ple the parameter matrix of untransposed double-circuit transmission lines and realize the fault location according to the decoupled modal parameter.By improving the basis of the Karrenbauer matrix,a modal transformation matrix suitable for decoupling parameters of untransposed double-circuit transmission lines is obtained.To address the dif-ficulties in solving the fault location equation of untransposed double-circuit transmission lines,a new fault location method based on an improved Karrenbauer matrix and the quantum-behaved particle swarm optimization(QPSO)algorithm is proposed.Firstly,the line parameter matrix is decomposed into identical and inverse sequence compo-nents using the identical-inverse sequence component transformation.The Karrenbauer matrix is then transformed to obtain the improved Karrenbauer matrix for untransposed double-circuit transmission lines and applied to identi-cal and inverse sequence components to solve the decoupled modal parameter.Secondly,based on the principle that voltage magnitudes at both ends are equal,the fault location equation is expressed using sequence compo-nents at each end,and the QPSO algorithm is introduced to solve the equation.Finally,the feasibility and accuracy of the proposed method are verified by PSCAD simulation.The simulation results fully demonstrate that the innova-tive improvement on the basis of the traditional modal transformation matrix in this paper can realize the modal transformation of the complex coupling parameters of the untransposed double-circuit transmission lines.It causes almost no errors in the decoupling process.The QPSO algorithm can also solve the fault location equation more accu-rately.The new fault location method can realize the accurate fault location of untransposed double-circuit transmis-sion lines.

计及短线路同杆并架双回线的输电网混合状态估计

提出计及短线路同杆并架双回线参数不对称的输电网精确快速混合状态估计模型及算法。首先通过机理分析获得导致输电网采用单相状态估计进行包括短线路不换位同杆并架双回线估计时,短线路不换位同杆并架双回线中无功功率估计与其实际量测值偏差大的原因:双回线之间因自感和互感不相等导致参数不对称;并用仿真方法分析其传输功率差的影响因素。基于所得到的上述原因,提出实现输电网中短线路不换位同杆并架双回线无功功率准确估计须采用三相状态估计方法。进而提出基于Π型等效接口的输电网单三相混合状态估计的快速算法及Π型等效接口位置自动确定策略。采用IEEE118系统对模型的机理、模型及算法的可行性和有效性进行分析验证。