基于超短期负荷预测的电力系统动态状态估计

在常规动态状态估计的基础上,引入高精度的超短期负荷预测数据,将预测的节点注入功率作为滤波步的输入,实现了系统状态的实时跟踪预测。仿真表明,基于超短期负荷预测的电力系统动态状态估计算法提高了动态状态估计的计算精度．具有一定的现实意义和理论价值。     

A fuzzy-logic-supported weighted least squares state estimation

This paper presents a new approach to power system state estimation based on the application of fuzzy logic. Significant improvements in state estimates are achieved (relative to the weighted least squares algorithm) by using a hybrid estimator incorporating fuzzy-logic concepts. The design of the fuzzy estimator is described. The approach is illustrated for two sample systems: a 6-bus network and the 30-bus IEEE test system. Numerical and graphical results are presented to illustrate the superiority of the new method.     

Advanced modeling of the multicontrol functional static synchronous series compensator (SSSC) in Newton power flow

The static synchronous series compensator (SSSC) is one of the recently developed flexible AC transmission system (FACTS) controllers. The SSSC coupled with a transformer is connected in series with a transmission line. This paper describes a multicontrol functional model of the SSSC for power flow analysis, which can be used for steady state control of one of the following parameters: (1) the active power flow on the transmission line; (2) the reactive power flow on the transmission line; (3) the voltage at the bus; and (4) the impedance (precisely reactance) of the transmission line. Furthermore, the model can also take into account the voltage and current constraints of the SSSC. The detailed implementation of such a multicontrol functional model in Newton power flow algorithm is presented. A special consideration of the initialization of the variables of the SSSC in power flow analysis is also proposed. Numerical examples on the IEEE 30-bus system, IEEE 118-bus system, and IEEE 300-bus system are used to illustrate the feasibility of the SSSC model and performance of the Newton power flow algorithm.     

A new numerical algorithm to check the observability and bad-data processing ability of the metering scheme

This paper provides a unified approach for the optimization of measurements placements employed for power system online monitoring through state estimation. The proposed methodology, which can be suitable for the mixed measure system, preserves state estimation observability and bad-data processing capability by employing numerical algorithms for observability checking, critical measurements and critical couple identification. First, node injection radix measurements and measurement categories are defined. According to the above definitions, the coefficient matrix can be solved. The analysis on the column vectors of the coefficient matrix can determine each measurement classification. Furthermore, the numbers of each measurement class contains can determine bad-data processing capability. The observability can be checked by the type number of measurements. The proposed method is illustrated with the IEEE39-bus system and the IEEE118-bus system. Results from the case studies are presented to demonstrate that the approach adequately fulfills the desired properties related to observability, bad-data processing, cost, and robustness.     

电力系统多区域分布式状态估计方法

提出了一种电力系统多区域分布式状态估计方法,各区域估计器利用其数据采集与监视控制系统提供的量测数据进行本地状态估计,并通过平均一致性算法获取全局信息进行系统级状态估计。建立了基于拉格朗日乘子法的状态估计模型并设计了基于一致性的全局信息交换协议,给出了多区域分布式状态估计算法的实现流程。通过IEEE 14节点和118节点系统中的仿真算例验证了所提方法的正确性和有效性,并就估计精度和计算效率与现有状态估计方法进行了比较。仿真结果表明分布式状态估计方法可有效提高集中式状态估计系统的计算效率及可靠性,适用于结构更加复杂、量测数据体量更大电网的状态估计。     

Integration of HVDC control dynamics into transient energy functions

A common approximation used in the formulation of transient energy functions (TEFs) for ac/dc power systems involves the omission of dc control dynamics. The differential equations representing the dc system dynamics are used to track the fault-on trajectory, but not to derive the TEF. This approach leads to an error in TEF-based stability prediction. In this paper, a method is presented to derive the TEF with dc system dynamics explicitly integrated. By using this comprehensive transient energy function, the accuracy of the stability prediction in ac/dc systems is improved. In addition, because differential equations representing dc dynamics are included directly in the TEF, the calculation of the post-fault equilibrium point is done only once. This leads to a considerable reduction in CPU time. The method is validated by comparing results from 12-bus and 30-bus ac/dc test systems with those obtained from time simulation.     

A novel fuzzy index for steady state voltage stability analysis and identification of critical busbars

In this paper, a novel fuzzy index is proposed for the prediction of steady state voltage stability conditions in transmission networks. The uncertainties in the input parameters are efficiently modeled in terms of fuzzy sets by assigning trapezoidal and triangular membership functions. The results include fuzzy load flow solutions for the base case and critical conditions with and without contingencies. The proposed fuzzy voltage stability index clearly indicates the location and status of critical busbars. Case studies have been conducted on standard test systems (IEEE 14-bus, 30-bus, and 57-bus) with proper validation of the results.     

ANN for transmission system static security assessment

This paper presents computationally efficient artificial neural network technique for assessing the security of the power system against line outages. Performance index (PI), which accounts for various line limit violations per contingency, is defined. The basic purpose of ANN is to assess the severity of line outages in terms of PI, based on training examples from off-line analysis. The selection of input signals for ANN is influenced by the operating state of the system and the contingency in question which determines the extent of line power limit violations. In an attempt to attain perfection in PI prediction, suitable architecture and topology for the network is investigated. To expedite learning process, saturating linear coupled neuron model (sl-CONE) is also tried out. The effectiveness of proposed technique is demonstrated on 5-bus (7-line) and IEEE 14-bus (21-line) test systems. Computation efficiency of the method makes it potential candidate for inclusion in on-line comprehensive security analysis package.     

静态电压稳定域边界的切平面分析

提出了基于全参数空间的静态电压稳定域的2种切平面计算方法：特征向量法和隐函数求导法。2种方法均可考虑各种因素对于电压稳定域的影响。其中隐函数求导法还能够计算状态变量对于独立参数变量的偏导数。在此基础上,建立了从功率注入空间到线路传输功率空间的映射关系,可以解析求出割集功率空阎电压稳定域的超平面近似表达式,从而避免了现有数据拟合算法的局限性,提高了计算速度。此外,文中考虑电力系统运行限制对于电压稳定的影响,提出了实用电压稳定域的概念,并计算了相应的切平面。进一步在电压静态稳定域切平面分析的基础上,提出了3类电压稳定指标,有利于综合评估系统电压稳定水平。IEEE9和IEEE39节点系统的仿真分析表明,所提出的电压静态稳定域的切平面分析法可准确评估系统的电压稳定水平,为电力系统的安全运行提供了决策依据。     

Analysis of confidence bounds in power system state estimation with uncertainty in both measurements and parameters

A method for uncertainty analysis in power system state estimation is proposed. The uncertainty is expressed in both measurements and network parameters. Uncertainties in both measurements and parameters are known and bounded. The problem is formulated as a constrained non-linear optimization problem. To find the tightest possible upper and lower bounds of any state variable, the problem is solved by sequential quadratic programming (SQP) techniques. When applied to the 6-bus, IEEE 14-bus and IEEE 30-bus networks, the proposed method shows reliability and accuracy in estimating the uncertainty bounds in power system state estimation. In addition, assessment of time performance is carried out to demonstrate that the proposed method is suitable for either an on-line or an off-line application.     

基于态势感知的智能配电网运行状态评估

围绕智能配电网的态势感知关键技术,综合考虑安全性、供电可靠性和经济性,提出了基于态势感知的智能配电网运行状态综合评估方法。研究基于量测系统的态势要素采集方案,对配电网运行状态进行实时评估和态势理解,进而基于负荷的超短期预测进行态势预测,并建立了配电网运行状态评估指标体系,从不同层次、不同角度反映系统当前与未来时刻的运行状态以及故障发生后系统所面临的风险,并通过IEEE 33节点配电系统对所提出的方法进行验证。结果表明,该方法可准确反映配网的运行状态,判断系统态势发展的趋势,为配电网安全运行提供一定参考。     

Decentralized unscented Kalman filter based on a consensus algorithm for multi-area dynamic state estimation in power systems

A decentralized unscented Kalman filter (UKF) method based on a consensus algorithm for multi-area power system dynamic state estimation is presented in this paper. The overall system is split into a certain number of non-overlapping areas. Firstly, each area executes its own dynamic state estimation based on local measurements by using the UKF. Next, the consensus algorithm is required to perform only local communications between neighboring areas to diffuse local state information. Finally, according to the global state information obtained by the consensus algorithm, the UKF is run again for each area. Its performance is compared with the distributed UKF without consensus algorithm on the IEEE 14-bus and 118-bus systems. The low communication requirements and high estimation accuracy of the decentralized UKF make it an alternative solution to the multi-area power system dynamic state estimation.     

基于变参数追踪的暂态稳定分析与预防控制方法

采用了一种基于变参数追踪的电力系统暂态仿真算法.该算法将时间维作为微分代数-差分方程组的一个普通参数来处理,通过预估-校正的计算环节,连续求解得到系统在暂态过程中的轨迹.从该算法出发,提出了一类状态变量限值和约束函数对控制参数的灵敏度并推导了其公式.基于该灵敏度,提出了一种暂态稳定预防控制方法.该方法以控制总成本最小为目标,综合考虑多故障的协调.通过新英格兰10机39节点系统的算例,验证了文中方法的有效性.     

交直流输电系统潮流计算中换流器运行方式的转换策略

分析了多端直流输电系统和多馈入直流输电系统控制运行方式,提出了采用计算机进行控制方式转换的方法。在考虑各种控制方式的控制作用和转换条件的基础上计算交直流系统潮流。该方法用加入2条直流输电线路的IEEE 300节点算例系统和加入三端直流输电系统的IEEE 118节点算例系统进行测试,计算效果较好,能够处理运行条件改变导致的运行方式发生的转换。     

考虑风电接入的电网静态电压安全域计算

实现快速、有效的系统安全裕度评估,能够为系统运行控制提供决策指导。为掌握电网的安全运行态势,提出一种考虑风电接入的电网静态电压安全域计算方法。首先,利用连续潮流模型并结合电压安全约束,构建系统电压安全裕度指标,用于衡量运行点的安全状态。其次,融合灵敏度方程和启发式算法求得电压安全裕度,实现负荷裕度量化评估。然后,通过引入考虑相关性的风速预测方法,为态势预测奠定基础。最后,通过IEEE 118节点测试系统验证所提方法的有效性和可行性。通过算例仿真可知,当风电渗透率较高时,风电场出力之间的相关度越大,电压安全裕度的波动范围也越大。     

基于传输块的暂态稳定建模

针对暂态稳定分析中发电机和相关控制系统的具体特点,将传输模块划分为大量的线性和少量的非线性表达。利用小干扰稳定分析中的插入式建模技术处理线性部分,先将发电机及辅助控制设备转化为两类基本的传输块,形成相应的数学表达,结合网络方程构成全系统计算模型。与常规的方法相比,在发电机建模、模型修改和状态变量的初值计算方面更为方便。该方法的有效性在一22节点6机系统上进行了验证。     

Sequential bad data analysis in state estimation using orthogonaltransformations

The sequential identification of multiple bad data in power system state estimation using orthogonal transformations is described. The method involves iteratively building a list of suspect bad data based on their normalized residuals. The measurements are then analyzed for their estimated errors, and the suspect list is pruned to reveal the bad data. Valid measurements are then returned to the system for completing the solution. As part of this development, a new method of computing and updating the residual covariance matrix is also presented. Test results on the IEEE 30-bus system are presented     

基于无迹卡尔曼滤波的电力系统抗差动态估计

为解决电力系统动态状态估计准确性易受量测不良数据影响的问题,提出基于无迹卡尔曼滤波(Unscented Kalman Filter,UKF)的电力系统抗差动态估计方法。在预测过程中引入时变噪声估计器处理未知系统噪声;利用新息向量判断量测是否存在异常,并使用基于测点正常率最大的静态估计方法辨识不良数据;然后构建更新因子矩阵降低不良数据在动态估计更新过程中的影响。将算法运用于IEEE 14节点标准系统中,仿真结果表明该方法估计结果准确且抗差效果良好。     

电力系统安全预警评估指标及其应用

电力系统运行状态的转换直接关系到系统安全性能分析及调度操作策略,在系统状态转移之前分析状态转移的可能性以及对系统造成的危害程度,对电力系统的安全稳定有着重要的意义.文中在基于风险理论的预警评估指标体系基础上,提出了对电力系统运行状态进行定量风险分析的安全预警评估指标,对状态变化的风险做出预警,也可为电力系统的低电压预防、过负荷预防、系统电压失稳预防的决策提供支持.以上海电网84节点的仿真分析表明了其可行性和实用性.     

一种改进的相量测量装置最优配置方法

以电力系统状态完全可观测和相量测量装置(PMU)配置数目最小为目标,提出了一种改进的PMU最优配置方法.将启发式方法和模拟退火方法有效结合以确保得到最优解,提高了基于启发式方法的初始PMU配置方案的质量,通过改进配置模型缩小了模拟退火方法的寻优范围,从而提高了求解速度.还提出了一种基于节点邻接矩阵的快速可观测性分析方法.最后采用IEEE 14、IEEE 30、IEEE 118节点系统和新英格兰39节点系统对该方法进行了验证.