基于潮流越限量的阻塞费用分摊方案研究

提出一种基于潮流跟踪原理,在双边交易模式下按阻塞线路上各交易导致线路阻塞的潮流越限量占线路潮流总越限量的比例分摊阻塞费用。由于线路潮流在达到线路容量上限之前,不存在阻塞,各交易成交量的变化不对阻塞承担责任。在达到线路容量上限后,交易量的增加使得线路发生阻塞,则这部分潮流增量就应承担阻塞的全部责任。采用该方法分摊阻塞成本,能准确地反映引起阻塞的责任,并公平地对待各市场参与者,消除阻塞对市场的不利影响。4节点系统算例表明该算法可行。     

基于SRMC的区域电力市场输电定价方案

从我国区域电力市场的运行实际出发,提出一种基于SRMC的输电定价方案,该方案不仅可以向发电厂和用户提供有效的经济信号,引导短期市场效率,而且可以保证电网公司的年收支平衡,并为电网扩建积累专项资金,具有一定的合理性和实用性.     

New reactive power flow tracing and loss allocation algorithms for power grids using matrix calculation

A novel simple method is suggested in this paper to evaluate the contributions of the sources (including the generators and branches’ charging capacitances) or the loads to the branches’ reactive flows and losses separately as well as to calculate the sources’ shares in providing the loads’ reactive powers. In the method, the study system is first converted to the system, each branch of which only has reactive loss, using a new technique for modeling the generating branches based on the AC load flow results. The properties of two new matrices (i.e. injection-bus and absorption-bus matrices), which are constituted for the obtained system, are then used to derive three other matrices. These matrices, which express reactive power productions of the sources in terms of reactive power consumptions of the demands (viz. the loads and branches’ losses) and vice versa, contain the intended contributory factors. Three-bus system is applied to demonstrate the computing process of the method whereas several IEEE systems are used to show its capability to implement on the transmission systems with arbitrary topologies and sizes. Some advantages of the method compared to the earlier methods are also illustrated.     

基于潮流跟踪的电力市场电价研究

我国现在正处在电力市场开放的前夕 ,厂网分开 ,竞价上网。如何公正、合理地确定电价是电力市场的一个核心问题。文中使用矩阵法进行系统潮流跟踪 ,确定用户对系统网络资源、发电资源的占用 ,以及应分摊的网损 ,依此为基础提出一种电力市场定价方式 ,真正体现根据资源占用比例计算费用的原则 ,同时还讨论了无功电价的计算方法。一个 2 2节点的算例计算显示 ,该方法是可行的。     

Load flow tracing in power systems with circulating power

Power flow tracing is very important to open access for loss allocation, congestion analysis and reactive power pricing, etc. In a previous paper, power flow tracing of power systems without circulating power has been implemented. In this paper, two lemmas have been proved first which show the reasons for circulating power. Then graph theory is applied to detect the existence of circulating power. After that optimal power flow (OPF) approach is suggested to eliminate circulating power. The sequential quadratic programming is used for OPF solution. The computer tests on a 6-bus system and the IEEE 30-bus power system yield satisfactory results. The suggested method is suitable for both active and reactive power flow tracings of power systems with circulating active and reactive power.     

Considering system non-linearity in transmission pricing

In this paper a new approach for transmission pricing is presented. The contribution of a contract on power flow of a transmission line is used as extent-of-use criterion for transmission pricing. In order to determine the contribution of each contract on power flow of each transmission line, first the contribution of each contract on each voltage angle is determined, which is called voltage angle decomposition. To this end, DC power flow is used to compute a primary solution for voltage angle decomposition. To consider the impacts of system non-linearity on voltage angle decomposition, a method is presented to determine the share of different terms of sine argument in sine value. Then the primary solution is corrected in different iterations of decoupled Newton–Raphson power flow using the presented sharing method. The presented approach is applied to a 4-bus test system and IEEE 30-bus test system and the results are analyzed.     

Comparison of transmission pricing models

In this paper we make a comparison of three transmission pricing models: the Wangensteen model, the optimal power flow model and the Hogan model. The similarities among the models are that all can be used in locational pricing systems. In these systems the prices are calculated as the marginal cost that in turn equals the marginal benefit to load. In the Wangensteen model and the original optimal power flow model, the locational prices are equal to the Lagrange multipliers associated with the power flow equations. On the contrary, Hogan’s model and the modified optimal power flow model express the locational prices as equal to the reference bus (node) price, the marginal costs of losses, and the marginal costs of congestion. The Wangensteen model is used for educational purposes and considers elastic load. The optimal power flow model has been widely used in electrical engineering and dispatch of power systems. Load is assumed to be inelastic. Hogan’s model is an economist’s version of the optimal power flow model and considers elastic load. It also gives an expression for the locational prices in terms of an equilibrium equation.     

A PSO based approach for multi-stage transmission expansion planning in electricity markets

This paper presents a particle swarm optimization (PSO) based approach to solve the multi-stage transmission expansion planning problem in a competitive pool-based electricity market. It is a large-scale non-linear combinatorial problem. We have considered some aspects in our modeling including a multi-year time horizon, a number of scenarios based on the future demands of system, investment and operating costs, the N − 1 reliability criterion, and the continuous non-linear functions of market-driven generator offers and demand bids. Also the optimal expansion plan to maximize the cumulative social welfare among the multi-year horizon is searched. Our proposed PSO based approach, namely modified PSO (MPSO), uses a diversity controlled PSO to overcome the problem of premature convergence in basic PSO (BPSO) plus an initial high diversity swarm to cover the search space efficiently. The MPSO model is applied to the Garver six-bus system and to the IEEE 24-bus test system and compared to the BPSO model and a genetic algorithm based model.     

基于潮流跟踪的网损分摊新方法

基于复合功率潮流跟踪算法,提出了一种新的网损分摊方法。首先对输电线路构建了一种新的解析模型,解析模型的参数是由线路潮流来决定的;其次,线路模型可以更合理地量化解决有功和无功潮流所引起的有功和无功损耗交叉影响;证明所提出的方法可以解决网络存在环流时网损分摊问题。     

Possibilistic programming approach for mid-term electric power planning in deregulated markets

The mid-term electric power planning problem under uncertainty for a generation company (GenCo) in a deregulated market having some thermal, hydro and wind power plants is addressed. We propose a novel possibilistic price-based mixed integer linear programming approach to solve the considered problem. Because the uncertainties especially those are related to market could not usually be based upon probabilities, the possibilistic distribution functions are used to simulate some key imprecise/ambiguous parameters: GenCo’s electricity market share; electricity, fuel and emission market prices; possible wind electric power; availability of generating units; available water reservoir for hydro units. To solve the proposed model, we develop an interactive possibilistic solution method based upon two recent solution approaches. Finally, we use a real-world case study to show the ability and appropriateness of our model and report computational results. Notably, the proposed approach can be easily applied for a regulated environment.     

基于最优潮流的无功定价方法探讨

电力市场环境下精确可行的无功服务定价是近年来研究的热点问题。将无功发电机会成本和无功补偿设备的投资加入到最优潮流的目标函数中,并考虑旋转备用的重要性,加入旋转备用约束条件,提出了新的基于最优潮流的无功功率实时定价模型。并对IEEE4-57节点系统进行了测试,所得的无功电价既能涵盖大部分的无功生产费用,又能提供足够的经济信息。     

An optimal power flow plus transmission costs solution

This paper is aimed at the solution of the optimal power flow (OPF) problem with embedded security constraints (OPF-SC) by the particle swarm optimizer. The major objective is to minimize the overall operating cost while satisfying the power flow equations, system security, and equipment operating limits. The overall operating cost is composed by the generation cost, transmission cost, and the consumer benefit. A modification of the conventional particle swarm optimizer (PSO) has been used as the optimization tool, which uses reconstruction operators and dynamic penalization for handling constraints. The reconstruction operators allow the increase of the number of particles within the feasible region. The power equations mismatch, loss active power transmission, and voltages are calculated by the Newton–Raphson method. To demonstrate its robustness, the proposed algorithm was tested on systems from the open literature. Several cases have been studied to test and validate the proposed approach.     

区域电力市场阻塞管理方法评述

电力市场化改革要求开放本地市场,开展跨区交易,促进竞争,其主要目的是提高市场效率,降低电价。但是,跨区交易同时也带来了一些重要问题,区域间的阻塞就是一个不可忽视的问题。对近年来国外提出的跨区域阻塞管理方法进行评述,比较了他们的特点,从中得出了一些结论,为进一步研究跨区交易的输电服务、制定合理的跨区交易的输电价格提供参考。并对我国的跨区域阻塞管理提出一些建议。     

潮流追踪的实用化研究

输电系统开放后，潮流追踪的实用化研究是十分必要的，对潮流追踪的实用化进行了深入的分析，对实际电网潮流追踪中的追踪顺序采用二次排序的方法，保证了追踪顺序的快速性和正确性，对线路两端对地电容充电功率采取在线路两端加入无功功率电源的方法，在处理变压器支路负阻抗时采取将此负阻抗支路进行等效变换的方法，以某省电网系统（155个节点）作为算例进行计算，计算精度完全满足工程要求，验证了所提出方法的正确性与可行性。     

Optimal power flow by a fuzzy based hybrid particle swarm optimization approach

This paper presents a fuzzy based hybrid particle swarm optimization (PSO) approach for solving the optimal power flow (OPF) problem with uncertainties. Wind energy systems are being considered in the study power systems. OPF is an optimization problem which minimizes the total thermal unit fuel cost, total emission, and total real power loss while satisfying physical and technical constraints on the network. When performing the OPF problem in conventional methods, the load demand and wind speed must be forecasted to prevent errors. However, actually there are always errors in these forecasted values. A characteristic feature of the proposed fuzzy based hybrid PSO method is that the forecast load demand and wind speed errors can be taken into account using fuzzy sets. Fuzzy set notations in the load demand, wind speed, total fuel cost, total emission, and total real power loss are developed to obtain the optimal setting under an uncertain environment. To demonstrate the effectiveness of the proposed method, the OPF problem is performed on the IEEE 30- and 118-Bus test systems.     

Scenario selection in composite reliability assessment of deregulated power systems

Power market analysis should be incorporated in reliability assessments of deregulated power systems. For the Nordic power system, this is done by using The Multi-area Power-market Simulator (EMPS) for long-term power market analysis, where EMPS finds the optimal socio-economic dispatch on a weekly basis, with respect to, e.g., hydro reservoir levels. The EMPS analysis results in a set of load and generation scenarios, and these scenarios are interpreted as a sample of future power market behaviour, and is used as basis for a reliability assessment. These load and generation scenarios are referred to as power market scenarios.The power market analysis produces a large number of power market scenarios, and to include all these scenarios in a reliability assessment results in excessive computation time. The scenario selection method is presented and discussed. Scenario selection is used to pick out a subset of the generated power market scenarios, to only use this subset of scenarios as a basis for the reliability assessment. The paper provides some general guidelines for application of the scenario selection method. It is shown that the scenario selection method can reduce the scenario set by about 90%, with little loss of accuracy in the reliability assessment.     

A power flow tracing method focused on reactive power and SC

“Tracing the power flow of electricity” is a concept that has become the focus of attention recently, as the deregulation or the liberalization of the electric power market proceeds. Although a number of methods, such as “tracing method by power flow contribution,” have already been published, reactive power contribution has been little studied to date. However, applying “tracing the power flow of electricity” to ancillary service, for example compensation of reactive power, is very important. In this paper, we focus on line flows and static capacitors in particular, and study how to deal with the problem. We perform a computer simulation using a simple system and show the tracing results. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 156(1): 33–43, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/ eej.20118     

Analytical model and algorithm for tracing active power flow based on extended incidence matrix

This paper proposes an analytical model and algorithm for tracing power flow (TPF). The concept, construction approach and properties of extended incidence matrix (EIM) are developed. By using results of an AC or DC power flow solution from any off-line program or state estimation, the extended incidence matrix, generation and load power vectors, and distribution factor matrix are derived so that the analytical model of power transfers between generators and loads can be built. The major advantage of the proposed method is that the matrix theory is used to directly build the TPF model and no proportional sharing assumption on the flow distribution is needed. The method was tested using a 4-bus system, and the IEEE 30-bus and IEEE 14-bus power systems. The case studies indicate that the developed technique can be applied to any power system with or without loop flows.     

配电网功率量的逆向潮流追踪方法

为了得到以负荷为主体的配电网中各功率量的关系,提出了逆向潮流追踪方法。利用功率分布理论,得到了表示每个负荷与对应损耗之间关系的功率链和每个负荷与对应汲取功率之间关系的功率流。给出正弦稳态形式的负荷—损耗分布系数、负荷—汲取功率流分布系数。将该方法应用到一典型的14节点配电网,得到各功率量的和与网络原有功率量相等的结论。算例分析结果表明,单电源网络中正弦稳态功率按照阻抗匹配原则来分配。     

基于潮流分解的输电成本分摊的改进方法

输电服务的成本分摊及其定价是输电网开放所面临的主要问题。经济学上的纯粹的边际成本定价方法尽管可以提供有用的经济学信息,但是输电网的规模经济效益却使得依赖边际成本定价的输电收入远远不能满足输电投资成本的收支平衡。从工程角度出发,结合经济学概念,对基于潮流分解的输电成本分摊方法进行介绍,并对其进行改进,提出了改进的输电成本分摊方法以用于定价问题的研究计算,并对算例的计算结果进行分析比较。