一种无需线路参数的输电线路故障定位算法

提出了一种新的输电线路故障定位算法,该算法利用故障时正、负序网络中各自电压、电流间的关系,导出了故障定位方程.无需线路参数,只需借助GPS实现同步采集线路两端的电压、电流数据,并作相关处理,即可实现故障定位.与传统方法相比,该算法不受线路参数变化、故障发生地点环境以及故障过度电阻等的干扰,实现简单、灵活,实用性更强.同...     

配电网线路开断后潮流的新算法

在配电网回路阻抗法潮流算法的基础上,提出了一种新的配电网线路开断后潮流算法:对应取零法.该算法通过对已有的基态潮流方程的矩阵经过适当的变形,得到所求的因子表,从而节约了大量计算机时.对一个35节点配电网实例计算与比较的结果证明了"对应取零法"的可行性和正确性.     

Problem-specific genetic algorithm for power transmission system planning

A hypothesis is proposed that the only way for Turing computers to solve efficiently NP complete problems and NP hard problems is to use randomization techniques. By comparison of the popular randomization techniques, it is concluded that genetic algorithm may be the best choice until now. To overcome the disadvantages of conventional genetic algorithms, problem-specific genetic algorithm is suggested. Then, a problem-specific genetic algorithm that is developed specially for power transmission system planning problems is proposed. The algorithm searches global optimum from local optimums instead of from all feasible solutions, while the local optimums are found by a more efficient linear iterative minimum-cost-flow algorithm. Furthermore, the network flow model for power transmission system planning is improved so that the capacities and locations of transmission lines, substations and power plants can be optimized simultaneously. Results from a comparative study have proved the reasonableness and efficiency of the proposed model and algorithm.     

A new single ended fault location algorithm for combined transmission line considering fault clearing transients without using line parameters

In this paper a new single ended fault location method is proposed for underground cable combined with overhead lines. In this algorithm fault clearing high frequency transients are used instead of fault-generated transients and the line parameters are not needed. In the proposed algorithm, samples just from voltage transients generated by fault clearing action of circuit breaker are taken from the sending end of the cable line. Applying wavelet transform, the first three inceptions of traveling waves to the fault locator are detected. Using these, the proposed algorithm at first identifies fault section, overhead or cable, and then wave speed is calculated and at last location of fault is determined accurately. Because of using only voltage samples taken from one terminal, it is simple and economic and does not need to GPS and data communication and synchronization. Extensive simulations carried out using SimPowerSystem toolbox of MATLAB, confirm the capabilities and high accuracy of the proposed method under different system and fault conditions.     

高压输电线路单端故障测距新方法

提出了一种新的单端故障测距的方法,根据故障发生后的故障附加网络,利用单端故障电压电流计算沿线故障电压对距离的导数,然后再求其范数在线路上的分布,根据其分布特点确定故障点的位置,实现测距.仿真证明该新方法具有较高的准确度和稳定性.     

高压输电线路单端故障测距新方法

提出了一种新的单端故障测距的方法,根据故障发生后的故障附加网络,利用单端故障电压电流计算沿线故障电压对距离的导数,然后再求其范数在线路上的分布,根据其分布特点确定故障点的位置,实现测距。仿真证明该新方法具有较高的准确度和稳定性。     

输电线路长度和参数的校正方法

提出了一种线路长度和参数的在线估计方法,利用区内出现的缺相运行情况对线路正、负、零序参数和线路长度同时进行校正。该方法适用于装设单相自动重合闸的架空输电线路,利用现有的硬件设备,可以有效地削弱线路长度和参数变化对测距精度的影响,对于故障测距和线路保护均具有较重要的意义。     

输电线路长度和参数的校正方法

提出了一种线路长度和参数的在线估计方法,利用区内出现的缺相运行情况对线路正、负、零序参数和线路长度同时进行校正.该方法适用于装设单相自动重合闸的架空输电线路,利用现有的硬件设备,可以有效地削弱线路长度和参数变化对测距精度的影响,对于故障测距和线路保护均具有较重要的意义.     

Optimization method for reactive power planning by using a modifiedsimple genetic algorithm

This paper presents an improved simple genetic algorithm developed for reactive power system planning. Successive linear programming is used to solve operational optimization sub-problems. A new population selection and generation method which makes the use of Benders' cut is presented in this paper. It is desirable to find the optimal solution in few iterations, especially in some test cases where the optimal results are expected to be obtained easily. However, the simple genetic algorithm has failed in finding the solution except through an extensive number of iterations. Different population generation and crossover methods are also tested and discussed. The method has been tested for 6 bus and 30 bus power systems to show its effectiveness. Further improvement for the method is also discussed     

A new control algorithm of active power line conditioner for improving power quality

In this paper, a new control algorithm for active power line conditioner (APLC) is proposed. The proposed APLC contains two power converters, a series power converter and a shunt power converter. The series power converter is operated as a current source, and it has the function of a harmonic isolation to block the harmonic current from the nonlinear load to mains and the harmonic voltage from the mains to load. The shunt power converter is operated as a voltage source to supply a clean and regulated output voltage to the load. Both power converters use the same dc bus. To demonstrate its performance, a prototype is developed and tested. The tested results show that the proposed APLC has the expected performance.     

A new method for the analysis of cross-country multifaults in a double-circuit transmission line

To analyze multifaults on a power line, many complex calculations must be performed. Hence, in many cases, computers are employed in the actual phase domain. However, it is difficult to determine the property and/or the physical meaning of the calculated results because the computer method is based on many complex numerical calculations. This paper represents a new analytical method for short-circuit studies which can deal with cross-country multifaults in a double-circuit transmission line with zero-sequence mutual coupling. This method is based on the well-known “two-component network theory” for a balanced three-phase double-circuit. Procedure steps are: (1) represent the network as seen from the faulted points with symmetrical component impedance; (2) construct the symmetrical equivalent circuits for faults with imaginary phase-shifting transformers; (3) combine these equivalents with each other and erase the symmetrical voltages at faulted points because the phase voltages at such points are known; and (4) calculate the currents at the faulted points by solving the simultaneous linear equations. This method is applied to an investigation of distance-relay “underreach” phenomena where crosscountry multifault occurred on a double-circuit transmission line. Effects of line constants on these phenomena have been well understood.     

基于后向预测Prony算法的超高压输电线路暂态量保护方案

提出了一种基于故障后暂态电流信号的保护方案,利用运算法详细推导了分布参数下超高压输电线路各种故障类型时电流暂态信号的成分,分析结果表明故障后的暂态信号包含谐波形式的高频分量,其频率和相位特征能够可靠区分区内、外故障和各种故障类型.使用后向预测Prony算法作为提取暂态电流特征的工具,并对方程组的求解使用QR分解以缩短算...     

一种识别电网关键输电断面的新方法

快速、准确、完整地识别出电网关键输电断面,对于提高电网运行的稳定性及防止大停电事故的发生意义重大。首先,综合考虑电网拓扑结构和支路潮流分布状态,以线路导纳模值与其有功潮流幅值之比即导流比作为线路权重,建立了电网的加权网络模型,使其更符合复杂多变的实际电网;其次,针对已有电网关键输电断面搜索方法的局限性,提出了一种基于改进Floyd算法搜索前k最小权路径的方法,克服了仅搜索第一最短路径上的线路造成的漏选;最后通过层层递进的筛选方法快速完整地识别出关键输电断面,同时也能对潮流反向增大的线路有效识别。在新英格兰39节点系统的仿真结果中验证了所提方法的正确性和有效性。     

电力线路工频参数测量装置中通道测量误差的多重校准方法

分析了电力线路工频参数测量装置中相差测量对阻抗测量精度的影响,在此基础上提出将基于最小二乘原理的分段线性数据拟合方法应用到装置通道的校准中,实现包括通道幅值、相差及幅值一相差关系的多重校准的新方法。该方法通过分段线性拟合建立测量值和实际值的关系函数实现测量数据的校准,原理简单、校准效果好,对电力现场的多种参数测量有一定参考价值。     

电力中性线电流计算新法

低压配电系统三相负载基本上都不平衡,中性线有电流通过,计算该电流的方法有2种:几何法和投影法.2种计算方法比较复杂.笔者不断探索,提出一新的计算方法,即根据负载的性质不同,计算方法也不同,现阐述如下.     

An improved algorithm for rational approximation of transfer functions

The calculation of a rational transfer function is considered using a Laguerre expansion of the impulse response. An algorithm is proposed that avoids the appearance of high-order surplus factors. Results of computer experiments are presented.     

基于抗差估计理论的输电线路故障定位新型算法

针对采样中出现的粗差,提出了一种基于抗差估计理论的故障定位算法.通过等价权原理,将抗差估计理论和最小二乘法有机的结合起来,有效地避免了粗差的影响.算法采用微分方程作为数学模型,并利用相模变换解耦;然后,在模域采用输电线路双端信号列写故障点方程;最后,用抗差最小二乘法求解.经过RTDS实验表明,该算法结果稳定,具有很好的准确性和抗干扰能力.     

一种计及微地形修正的输电线台风风险预警方法

台风过境时,较大的风力往往会引发风偏放电、断线、倒塔等事故,是对沿海地区电网安全可靠运行威胁最大的自然灾害之一。由于台风灾害的高风险性,建立台风预警体系能更经济有效的提升电网抵御台风灾害的能力。现有的电网台风风险预警方法直接使用气象局提供的区域性预测风速,并未考虑具体线路所处的微地形环境对风速的影响,易出现漏警以及虚警。因此,提出一种计及微地形影响的输电线台风风险预警方法。该方法把预警区域按经纬度划分为0.01°×0.01°的网格,将网格内的输电设备与网格微气象、微地形信息关联,建立了输电线微地形条件下的风速修正系数计算方法,可更准确地辨识遭受台风灾害影响的线路集并按风险等级进行预警。实例验证了方法的可行性和有效性。     

A new decoupling method for double‐circuit transmission lines with asymmetrical parameters

The six‐sequence component method is widely used in short‐circuit calculation of double‐circuit lines. However, this method can be used to decouple only two parallel transmission lines whose parameters are exactly the same. In this paper, a new sequence component method is introduced to deal with the lines whose parameters are not exactly the same. Mutual impedances between phases of the same line are decoupled first, and then the zero‐sequence mutual impedances between different lines are decoupled. Six new independent components are obtained after decoupling. System impedances are modified based on the relationship between voltages and currents of the new sequence components and the traditional sequence components. According to the boundary conditions of the faults, the characteristics of new sequence components are studied, and the corresponding sequence networks are discussed. According to the combined sequence network, new sequence currents can be calculated, and the phase currents can be obtained easily from the new sequence currents by a transformation matrix. PSCAD simulation results demonstrate that the short‐circuit calculation method proposed in this paper is appropriate and practical to deal with the two parallel transmission lines with different parameters and partially coupled transmission lines. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.