Active Distribution Network Expansion Planning Integrating Practical Operation Constraints

This paper proposes a mathematics model of active distribution network expansion planning (DNEP) integrating the practical operation constraints, which are the OLTC (On-Load Tap Changer) tap adjusting frequency and substation voltage variation. Distributed Generation (DG) curtailment, load curtailment, OLTC tap adjustment, and reactive power compensation are considered as the active management schemes. The expansion model allows alternatives to be considered for new wiring, DG installation, new substation, and substation expansion. The DNEP problem is a mixed integer non-linear programming problem, active management, and uncertainties, especially with the DG integration make the DNEP problem much complex. In order to find the suitable algorithm, this paper converts the DNEP problem to a Second-Order Cone Programming (SOCP) model through distflow equations and constraints relaxation. A modified 33-bus application example is used to verify the proposed model with different active management scenarios.     

变电站扩容和电池储能系统容量配置的协调规划方法

充分考虑电池储能系统（BESS）的充放电效益对变电站扩容建设的推迟作用,建立了变电站扩容建设和BESS容量配置的协调规划模型。新模型基于一个含风电场的典型地区配电网络及其日负荷曲线,考虑了购电费用和BESS与变电站扩容的综合投资运行费用目标,同时还考虑了BESS的充放电特点和网络的安全约束。其中对于变电站扩容容量包含给定待选与连续可调两种情况。该模型是一个多时段非线性规划问题,在变电站扩容容量为给定待选的情况下还包含整数变量,需将其转换为含互补约束条件的连续优化问题,再采用原对偶解耦内点法将其解耦为单时段优化问题进行协调迭代求解。算例结果表明该方法可以有效减小电网的扩容投资,并实现储能系统容量的优化配置。     

A multistage multiobjective substation siting and sizing model based on operator–repair genetic algorithm

The establishment of a multistage multiobjective substation siting and sizing planning model, taking into account various constraints such as load flow constraint, maximum capacity constraint, and maximum power supply radius constraint makes possible substation planning between multiple years to be adjusted to achieve an optimal overall plan. Through multiple optimization objectives, it is possible to prevent the plan from becoming useless because of excessive changes in power supply affiliation during the multistage optimization process. To find the optimal solution for the model, a repair operator is proposed and used with an improved multiobjective genetic algorithm to repair the decision variables for each chromosome corresponding to one stage so as to satisfy the constraints while ensuring that population diversity evolves heuristically to the optimal solution. Moreover, a tournament selection operator based on crowding distance is adopted, which can prevent the algorithm from premature convergence and make populations trend to the Pareto frontier. Experimental results show that the proposed model and algorithm can efficiently solve the issue of rolling planning between multiple target years and achieve a joint optimal planning. © 2014 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

A new algorithm for power distribution system planning

In this paper, an attempt has been made to develop a new algorithm for distribution system planning. The proposed algorithm does not require prior knowledge of candidate substation location and can automatically select location of a substation, the optimal feeder configuration and the optimal sizes of branch conductors while satisfying constraints such as current capacity, voltage drop and heuristic rules. Several algorithms are proposed for distribution systems planning. A generalized algorithm is developed for obtaining the optimal feeder path and the optimal location of substation on minimum loss criterion. Heuristic rules are incorporated in the above algorithm. Another algorithm is for branch conductor optimizations. Modified load flow method is also presented in the paper, which can handle composite load models. The load flow algorithm is used for solving radial distribution networks (RDN) and branch conductor optimization algorithm. The load flow algorithm and branch conductor optimization techniques are used as subroutine in the generalized distribution systems planning algorithm. Through numerical example the validity of proposed method is verified.     

A planning model for siting,sizing and timing of distribution substations and defining the associated service area

A new planning model is developed for solving sizing, sitting and timing of distribution substation and defining the associated service area. The model incorporates a non-discrete function that accurately simulates the different cost components of distribution substations. Voltage, capacity, power conservation and radial-flow constraints are included into the developed model. The efficiency of the developed model is illustrated using a detailed numerical example.     

基于网络流的含分布式电源配电网两阶段规划

针对含分布式电源（DG）的配电网规划问题,利用图论的思想,建立以规划年费用最小为目标的含分布式电源配电网规划图模型,提出两阶段的启发式算法,实现优化分布式电源的接入位置、接入容量、实际接入量及变电站和配电线路的新建或者升级改造等综合优化。第一阶段,对所建的图模型应用多重局部搜索算法确定分布式电源的接入位置、接入容量及变电站和配电线路的新建或者升级改造决策;第二阶段,利用第一阶段优化得到的线路、电源参数,建立精确的数学模型,并运用遗传算法确定分布式电源的实际接入量。33节点典型系统算例证明了该算法在含分布式电源配电网规划中应用的可行性和有效性。     

考虑多种主动管理策略的配电网扩展规划

提出了主动配电网扩展规划的混合整数二阶锥规划模型,该模型以总的投资与运行费用最小为目标函数。文中考虑了4种主动管理措施降低规划方案成本及未来的运行风险,包括有载调压变压器调节、切机、切负荷及无功补偿。规划措施包括主动管理、新建线路、新建变电站、扩建变电站、新建分布式电源。配电网规划是一个混合整数非线性规划问题,再加对各种主动管理措施及未来不确定性的考虑,配电网规划问题求解变得相当复杂。基于配电网潮流方程及约束松弛技术,建立了配电网规划的二阶锥规划模型,并利用改进的IEEE 33节点系统及Miranda 54节点系统进行了算例验证。     

基于地理信息系统的农村电网规划方法的研究

本文针对目前农村电网（以下间称农网）难以满足规划人员实用要求的现状，提出应用地理信息系统（Geographical Information System，简称GIS）技术改进农网规划的设想。基于中心地理论的应用模型，提出基于GIS的子系统模型及算法，将配网规划这一NP－hard问题转化为无约束的线性凸规划问题，并使问题规模大为减小。研究结果表明借助GIS无需复杂的算法便可实现规划过程更具交互性、规划结果更具直观性、方案调整更具灵活性。基于GIS的农网规划可作为农网规划人员的得力工具。     

考虑峰谷分时电价影响的变电站容量规划方法

针对峰谷分时电价的实施会调整电力负荷进而影响电网规划的问题,提出了考虑峰谷分时电价影响的电网规划方案制定方法,并且建立了基于需求侧管理各参与方成本效益分析的峰谷分时电价模型及变电站容量规划模型。在峰谷电价比恒定的情况下,根据峰谷分时电价模型的计算结果选取算例地区峰谷分时电价的最优拉开比。在此基础上,对传统变电站容量规划方案和考虑峰谷分时电价影响的修正方案进行对比,最终得出:考虑峰谷分时电价影响的变电站容量规划方案在新建变电站容量减少的条件下,仍能满足地区电力平衡。并且该方案还能保证需求侧管理的各参与方均能获得更多利润,在有效节省建设投资的同时降低电力用户用电成本,明显提升电网规划的经济性和合理性。     

变电站规划模型改进研究

在现有变电站规划模型的基础上,结合城市电网规划技术导则,将供电容量约束、容载比要求、最大供电线路距离等约束条件转化为罚函数,与变电站建设总投资费用组成规划模型目标函数。根据改进后的变电站规划模型特点,选择适于求解大型复杂优化问题的自适应粒子群优化算法对目标函数进行求解。通过实际算例验证改进模型的有效与实用性。     

Integrated distribution network expansion planning incorporating distributed generation considering uncertainties,reliability, and operational conditions

In this paper, an integrated methodology is proposed for distribution network expansion planning which considers most of the planning alternatives. The planning aims to determine the optimal reinforcement of existing medium voltage lines and high voltage/medium voltage substations, or installation of new ones to meet the load growth in the planning horizon subject to the technical and operational constraints. Also, to take the advantages of new technologies, the renewable and non-renewable distributed generations have been included in the problem as another alternative. The uncertainties related to renewable DGs, load demand, and energy price have been considered in the calculation of cost components. The load duration curve has been utilized for loads such that the results be more precise. The possibility of islanding and load transferring through the reserve feeders have been regarded in the problem to improve the reliability of the network. Also, the required condition for successful and safe operation of island considering all of uncertainty states have been checked out to accurately calculate the reliability. The genetic algorithm is employed to solve this integrated problem. Finally, the proposed method is applied to the 54-bus system and also a real large-scale distribution network, and the results are discussed. The results verify the effectiveness of the presented method.     

A procedure for distribution system planning of a large-scale agricultural project

Different mathematical techniques adapting linear, nonlinear, mixed-integer, and network flow programming have been developed over the past decades to solve the distribution planning optimization problem. The high dimensionality of the problem made it in some of practical cases unmanageable by such classical optimization techniques. This gave rise to the application of knowledge based, heuristics, artificial intelligence, and approximate iterative techniques to search for the optimal solution. The problem also was typically perceived from the distribution companies’ perspectives with the objective being to supply sustainable yet cost effective power to multi-objective multi-interest consumers with different damage functions and relatively uncertain data. This paper presents a value-based distribution system planning procedure for large-scale agricultural real life project. This type of distribution planning is characterized not only by high load demand but also with a huge distribution network covering the vast agricultural area. Yet it is a planning for single type of customers who has a consistent developing policy, interest, cost damage function, together with a realistic and less uncertain data. The planning is also perceived from the consumer perspective who may even question the connection to the power utility unless it is proved as cost effective way of power supply. Macro and micro-levels planning is suggested for both overall project and farm modules, respectively. The proposed planning procedure evaluates different feasible alternatives based on life cycle cost while reliability indices and cost of interruption are taken into consideration. The procedure is illustrated on the micro-level for a real life agricultural problem.     

Flexible generation mix under multi objectives and uncertainties

Criteria for evaluating flexibility of a generation mix are presented, and an efficient computational algorithm for determining a flexible generation mix considering uncertainties in the power system expansion planning is developed. The flexible generation mix problem is formulated as a multiobjective optimization problem and solved by the dynamic programming technique in which type of generation plant is selected as a stage and generation capacity is selected as a state. The proposed method can treat easily not only the uncertainties but also many constraints of generation planning such as integer solutions of generation capacities, reliability constraints, and so on. The effectiveness and feasibility of the proposed method are demonstrated on a typical power system model     

电气主接线可靠性评估的区间方法

提出了发电厂／变电站电气主接线可靠性评估的区间分析方法,同时提出了主接线方案经济分析的区间模型。该方法能够较为合理地将可靠性参数处理为区间数,在计算过程中全程考虑参数的不确定性。经1次计算即可得到反映所有(或任意)参数不确知风险影响的各个可靠性指标和经济性计算结果。由于区间值结果涵盖了已知风险因素,因此为决策者提供了更为科学和符合工程实际的定量评估数据。电气主接线可靠性评估的区间分析方法同时也是一种更新的、更为灵活和强大的多因素灵敏度分析手段。     

计及分布式电源渗透率变化的变电站动态扩展规划

针对规划区域在不同发展阶段分布式电源(DG)渗透率由低到高变化场景下的源网荷协调匹配问题,提出了一种有源配电网变电站动态扩展规划方法。首先,考虑变电站滚动投入效应及规划期内剩余价值差异,建立了一种计及DG渗透率的变电站动态扩展规划模型。其次,考虑负载均衡度和DG置信容量对变电站供电范围划分的影响,提出了加权Voronoi图算法的罚函数、凹凸性和方向性改进方法。然后,提出了基于遗传算法和启发式算法的有源配电网变电站动态扩展规划求解方法,得到有源配电网变电站建设顺序。最后,通过实例说明了所述方法的科学性和实用性。     

基于GM(1,1)负荷预测的500kV变电站经济运行规划

提出了基于灰色GM(1,1)模型负荷预测的500 kV变电站经济运行规划方法.首先介绍了变电站常用的经济运行措施,针对500 kV变电站的特点,从理论角度分析了三绕组主变压器的运行损耗、经济运行区间,制定了基于临界负载功率的多主变经济运行方式;而后提出了基于GM(1,1)模型的变电站负载滚动预测方法;最后制定了基于负荷预测的500kV变电站经济运行规划方法.算例分析表明本经济运行规划方法具有有效性和实用性.     

An approach for simultaneous distribution,sub-transmission,and transmission networks expansion planning

Sub-transmission network, as an intermediate grid between the distribution and transmission systems, receives the electric energy from the transmission network at extra high voltage levels, and delivers it to the distribution network at medium or low voltage levels. The adequate design and operation of sub-transmission system will lead to an efficient design of transmission network from the technical and economic viewpoints on one hand and the adequacy of power delivery to the distribution loads on the other hand. Therefore, the design optimality of these three networks is highly dependent on each other. However, as the simultaneous design of distribution, sub-transmission, and transmission systems is highly complicated, very few researches have tried to model and solve such a difficult problem. In this paper, a new approach has been developed for simultaneous distribution, sub-transmission, and transmission networks expansion planning. The proposed approach has been formulated as an optimization problem where an efficient and improved genetic algorithm (GA) is employed to solve such a complex problem. The utilized GA has been equipped with different modifying operators in order to make sure of its appropriate performance in obtaining useful and optimal solutions for the coordinated planning problem. The conducted approach has been implemented on a real network of Zanjan Regional Electrical Company (ZREC), and the results are compared with those of conventional method, i.e. separate expansion planning of these networks. The simulation results demonstrate the effectiveness of the conducted approach.     

基于噪声控制的变电站平面布置优化设计

目前变电站噪声对周边环境的影响愈发明显,并已成为亟待解决的环境问题。基于上述原因,针对变电站规划设计阶段,提出一种变电站噪声控制的技术方法,通过优化变电站平面布置来降低噪声排放。该方法首先依据变电站的规划设计方案,建立变电站噪声预估数值模型,并对站界噪声进行预测,结合预测结果及噪声排放标准,整体分析变电站布置形式,对变电站平面布置进行优化设计,通过调整变电站平面布局降低站界噪声。通过对优化结果进行分析,总结得到变电站合理布置形式。仿真分析表明,该方法对变电站站界噪声具有明显的抑制作用,具有一定的推广应用价值。     

考虑风电机组无功特性的安全约束机组组合方法

随着风能的广泛使用,安排发电计划时更多的风电机组将会被引入,这对传统的机组组合提出了新要求。风电出力具有很强的波动性,将风电出力按一个区间放入原模型中更显合理。另外,异步风电机组的结构与普通火电机组不同,异步电机发电的同时要吸收一定的无功功率,因此模型用交流潮流约束更合理。由此建立的是一个非线性混合整数问题模型,为了提高计算效率,将问题分解为2层优化子问题,第1层为无网络约束的机组组合问题,第2层为以网损最小为目标函数的交流网络约束最优潮流问题,对于最优潮流算完后仍有电压或线路潮流越限的,将形成一些新的约束返回原问题。考虑到普通异步风电机组的大量使用,在处理约束问题时对风电机组采用无功功率—电压模型,避免出现无功不足而导致电压越限。以添加了风电机组的IEEE 57节点测试系统为算例,验证了该方法的可行性。     

Distribution network expansion considering distributed generation and storage units using modified PSO algorithm

Multistage distribution network expansion because of load growth is a complex problem in distribution planning. The problem includes minimizing cost of objective function subject to technical constraints. The objective function consists of investment, operation and reliability costs. In this paper, HV/MV substations, main and reserve MV feeders, dispatchable DG sources and storage units are considered as possible solutions for multistage distribution expansion planning. A three-load level is used for variable load and some strategies are proposed for DG and storage units operation. A modified PSO algorithm is applied to solve the complex optimization problem. Numerical results of the case studies show the ability of the modification. Moreover, the proposed strategies improve the distribution network from both economical and reliability points of view compared with the other methods.