考虑源荷不确定性的配电网风光储综合规划

针对考虑分布式电源和负荷不确定性的配电网风光储综合规划问题,首先以概率模型表征分布式电源和负荷不确定性,并基于改进半不变量法求解概率潮流;然后考虑投资成本、碳成本、经济收益和电压改善等,以综合效益最大为目标,建立考虑无功补偿装置的风光储综合规划模型,并提出基于食肉植物算法（carnivorous plant algorithm,CPA）和协同进化算法（coevolutionary algorithm,CA）进行求解。该算法将待求解的多主体综合规划问题分解为分布式电源、储能和无功补偿装置3个子规划问题,并基于CPA对每个子问题进行求解,然后通过生态系统协调各种群进化,获取最优规划方案;最后在IEEE33节点和IEEE69节点算例中验证了模型的合理性和求解算法的高效性、普适性。     

A hybrid genetic algorithm for optimal reactive power planningbased upon successive linear programming

A hybrid methodology is presented for the solution of the problem of the optimal allocation of reactive power sources. The technique is based upon a modified genetic algorithm, which is applied at an upper level stage, and a successive linear program at a lower level stage. The objective is the minimization of the total cost associated to the installation of the new sources. The genetic algorithm is devoted to defining the location of the new reactive power sources, and therefore to handle the combinatorial nature of the fixed costs problem. At the lower level, the variable cost problem is solved by calculating the magnitude of the sources to be installed at the previously determined locations by means of a linear program iterated successively with a fast decoupled load flow. Results are presented for the application of the proposed methodology when applied to the Venezuelan electric network     

用于地区电网无功配置的极限潮流方法

指出现有的无功优化算法并不能较好地解决省地协调下的地区电网无功配置问题,提出了基于电压贡献度和无功贡献度的极限潮流方法。为满足省地协调下的电压和关口功率因数要求,该方法选择对系统电压水平和关口功率因数改善最有效的电容器进行松弛优化,并提出电压贡献度和无功贡献度的指标进行相应的量化。极限潮流方法选择合理的电容器进行松弛后,能够有效地扩大优化问题的搜索空间寻求不同负荷方式下的最优解,并根据最优解的形式给电网规划和运行部门提出相应的建议。最后在IEEE30节点系统和四川省某地区电网141节点系统中验证了该方法的灵活性与有效性。     

Optimal reactive power control via loss minimization and voltage control

This paper presents a mathematical formulation of optimal reactive power control problem via loss minimization and voltage control. The model minimizes real power losses, deviation from the optimal active power despatch policy, and the difference between percentage sharing of reactive power by controlling the generator terminal voltage magnitudes, transfer tap setting, and reactive power sources. The constraints set include power flow equations and limits on the variables. A method is developed to solve this problem using reduced gradient and Fletcher's update. Several test problems were solved using the developed technique. Correction to the groups of decision variables are applied simultaneously as well as hierarchically, and the results are compared for 6-bus, 30-bus, and 103-bus sample systems.     

基于内点法与改进遗传法的无功规划优化混合算法

建立了利用调节发电机端电压、可带载调压变压器分接头与静止电容器组的补偿容量来获得系统年综合费用最小的无功规划优化数学模型。将此问题分成连续优化和离散优化两个子问题,采用非线性内点法和改进遗传算法交替求解的混合算法。在迭代的不同阶段,分别对内点法和改进遗传算法进行收敛条件改进,使两者的优化结果互为基础、相互利用,保证了混合算法的整体寻优效率。118节点系统的无功优化计算表明,所提算法可有效提高单一算法的收敛性能和运算速度。     

Interior-point based algorithms for the solution of optimal power flow problems

Interior-point method (IPM) is a very appealing approach to the optimal power flow (OPF) problem mainly due to its speed of convergence and ease of handling inequality constraints. This paper analyzes the ability of three interior-point (IP) based algorithms, namely the pure primal-dual (PD), the predictor–corrector (PC) and the multiple centrality corrections (MCC), to solve various classical OPF problems: minimization of overall generation cost, minimization of active power losses, maximization of power system loadability and minimization of the amount of load curtailment. These OPF variants have been formulated using a rectangular model for the (complex) voltages. Numerical results on three test systems of 60, 118 and 300 buses are reported.     

Cost-based reactive power pricing with voltage security consideration in restructured power systems

In the restructuring power industry, voltage security has become a challenging problem since power systems tend to operate closer to security boundaries and as a consequence, the voltage instability, which is caused by insufficient reactive power supply, poses a serious threat to system security and reliability. Establishing an equitable and effective reactive power market with consideration of the voltage security problem is very important to provide a reliable restructured power system. Therefore, this paper proposes a cost-based reactive power pricing, which can integrate the reactive power cost minimization and the voltage security problem into the optimal power flow (OPF) problem, and the sequential quadratic programming (SQP) is employed to solve the optimization problem. The effectiveness of the proposed method is verified using a modified IEEE 14-bus system. A study on the effects of the voltage stability margin (VSM) requirement under normal condition and contingencies on the reactive power cost is also presented.     

系统分解协调算法的抽水蓄能电站优化调度

建立了包含抽水蓄能电站的电网统一调度优化模型,即以调度周期内火电燃料成本为最小目标函数,满足系统及各机组约束条件。利用系统分解协调思想,开发了一个结合拉格朗日松弛方法和粒子群优化算法的混合算法,将原优化问题分解为两层优化问题。上层拉格朗日算子优化利用次梯度算法求解,下层各子问题利用粒子群优化算法求解,经过迭代寻优得到最优对偶解后,利用一个启发式算法求得满足系统约束及各机组运行约束的原问题的可行解。最后通过算例验证了模型的合理性及算法的有效性。     

地区电网感性无功补偿优化配置方法

提出地区电网进行感性无功补偿优化规划的思路和方法,建立了兼顾电压质量、投资成本和运行费用全网优化的地区电网感性无功补偿模型,以解决由于小水电等分布式电源大量接入时在小运行方式下地区电网无功过剩电压偏高的问题。结合某地实际电网,进行了感性无功优化计算,比较了所提方法与工程估算法、平均功率因数法等方法的结果。仿真结果表明,按照优化方案进行感性无功补偿配置后,该地区的无功电压水平显著改善,取得了较好的经济效益和社会效益。     

多负荷水平下含风电接入的配电网无功优化

由于风电输出功率的随机性,风电机组的大量接入给配电网无功优化带来更多不确定性因素。为了提高配电网无功优化对风力发电并网的适应能力,建立了多负荷水平下基于场景分析的考虑风电接入的多目标无功优化模型。该模型综合考虑了节省电能损失费用和节点电压偏差2个指标,将2个指标进行模糊化,采用最大化模糊满意度指标法将多目标优化问题转换为单目标优化问题,然后采用自适应遗传算法进行求解。并以IEEE 33节点测试系统为例,计算和分析了在不同场景时最大负荷、一般负荷和最小负荷3种负荷水平下,电容器投切、系统有功损耗、节点电压以及节省电能费用情况。计算结果表明,所提出的无功模糊优化方法,在不同负荷水平、不同场景下改善电压质量和降损节能效果显著,适合多负荷水平下含风电机组的配电网无功优化需要。     

Optimal VAR control for real power loss minimization using differential evolution algorithm

Differential evolution algorithm (DEA) is an efficient and powerful population-based stochastic search technique for solving optimization problems over continuous space, which has been proved to be a promising evolutionary algorithm for solving the ORPD problem and many engineering problems. However, the success of DEA in solving a specific problem crucially depends on appropriately choosing trial vector generation strategies (mutation strategies) and their associated control parameter values. This paper presents a differential evolution technique with various trial vector generation strategies based on optimal reactive power dispatch for real power loss minimization in power system. The proposed methodology determines control variable settings such as generator terminal voltages, tap positions and the number of shunts compensator to be switched, for real power loss minimization in the transmission systems. The DE method has been examined and tested on the IEEE 14-bus, 30-bus and the equivalent Algerian electric 114-bus power system. The obtained results are compared with two other methods, namely, interior point method (IPM), Particle Swarm Optimization (PSO) and other methods in the literature. The comparison study demonstrates the potential of the proposed approach and shows its effectiveness and robustness to solve the ORPD problem.     

基于柔性互联技术的含高渗透率新能源配电网多目标优化运行

智能软开关（SOP）可控制潮流、提供无功补偿,进而改善配电网电压、降低网损。因此,针对可再生能源大规模接入配电网后电能质量下降问题,采用K-means算法构建风-光典型场景,同时建立了基于SOP、可投切电容器的含高渗透率分布式电源的主动配电网优化运行模型。该模型以电压偏差、系统网损最小以及系统运行成本最低为目标,综合考虑了能源利用率及系统运行稳定性。最后利用基于参考点的非支配排序方法的多目标优化算法（NSGA-III）进行求解,输出Pareto最优解集,并采用改进的IEEE 33节点系统对所建立模型的有效性进行了验证。     

考虑不确定性的含DG与EV配电网无功电压协调优化方法

利用双馈风电机组和光伏发电系统等能够提供无功功率的分布式电源作为一种电压调节手段与传统的电压调节方式结合,在计及电动汽车入网充电作为一种随机负荷的情况下,建立了考虑不确定性的含分布式电源与电动汽车的配电网无功电压协调优化模型。以节点电压期望值平均偏差最小为目标函数,同时加入有功网损期望值和节点电压期望值最大偏差值为罚函数,使用本文提出的一种改进果蝇优化算法对优化模型进行求解。最后利用IEEE 33节点系统进行仿真计算并与粒子群算法进行比较,证明了本文所提出的优化模型和算法的有效性。     

Distribution system planning considering integration of distributed generation and load curtailment options in a competitive electricity market

Distribution systems management is becoming an increasingly complicated issue due to the introduction of new technologies, new energy trading strategies and new deregulated environment. In the new deregulated energy market and considering the incentives coming from the technical and economical fields, it is reasonable to consider distributed generation (DG) as a viable option to solve the lacking electric power supply problem. This paper presents a mathematical distribution system planning model considering three planning options to system expansion and to meet the load growth requirements with a reasonable price as well as the system power quality problems. DG is introduced as an attractive planning option with competition of voltage regulator devices and interruptible load. In mathematical model, the object function includes investment costs, which are evaluated as annualized total cost, plus total running cost as well as cost of curtailed loads and losses. This model identifies the optimal type, size and location of the planning options. In the studies presented in this paper also the fluctuation of load and electricity market price versus time period and the effect of DG placement on system improvement are considered. To solve the proposed mathematical planning model a new software package interfacing MATLAB and GAMS is developed. This package is enabling to solve large extent distribution system planning program visually and very fast. The proposed methodology is tested in the case of the well-known IEEE 30-bus test system.     

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.     

基于灵敏度分析与最优潮流的电网无功/电压考核方法

针对电网的无功/电压水平考核问题,提出了一种综合应用灵敏度分析和最优潮流的实用化考核方法.当供电公司所辖电网内有节点电压越限时,通过计算各负荷节点的注入无功功率对节点电压变化的灵敏度,可以直接根据考核点的电压偏差求得相应的无功功率偏差;当所有节点电压都在规定范围内时,以全网有功网损最小为目标函数进行最优潮流计算,求得各节点的最优无功补偿量.该方法考虑了电网运行的安全性和经济性,考核结果可以为供电公司实施关于无功/电压水平考核的奖惩提供科学的决策依据,同时也可以对供电公司合理进行无功补偿起到指导作用.     

考虑SVC和储能接入电网的多目标协同经济调度

针对风电并网引起的电网功率波动和安全运行问题,提出一种考虑SVC和储能的多目标协同经济调度优化方法。以典型日运行为例,建立了以系统综合运行成本、电压偏差和系统网损最小为目标函数的经济调度多目标优化模型,在优化过程中对经济调度和无功优化模型的目标进行协同迭代,获取兼顾电网经济性和安全性的最优解,并将结果与利用权重系数法获得的Pareto前沿面进行对比分析,通过对IEEE RTS-24节点系统进行仿真分析,验证其算法的合理性和可行性。     

APPLICATION OF EXTENDED EVOLUTIONARY PROGRAMMING TO SVC PLACEMENT

An extended evolutionary programming (EXEP) technique is proposed for optimal solution of the SVC placement in voltage stability enhancement. Multiple genetic transformation operators are used to ensure that the global optimal solution can be obtained. The problem is posed as the minimization of the function whose objectives are to increase the reactive power margin, the reactive power spinning reserve and the system voltage profile. At the same time it is required that the transmission losses are reduced and the additional cost of new SVC devices is minimal. All the operational inequality constraints are transformed to the objective function by using quadratic and cosine penalty functions. Numerical results show that EXEP technique is superior to simulated annealing(SA) technique.     

基于GA-PSO混合算法的农网无功优化

针对农村配电网电压质量较低的问题,该文建立了完整的无功优化模型。采用前推回代法进行潮流计算,建立以网损最小、电容器投资成本最小、电压水平最好、电压最稳定为目的的无功优化目标函数,无功优化方法采用GA-PSO（遗传-粒子群）混合算法,该混合算法更有效地寻找到全局最优解,并加快了收敛速度。对典型IEEE33节点配电网系统进行了测试分析,并将优化结果与其他优化算法相比较,结果表明使用该优化算法后,配电网系统电压水平明显提高,线路损耗明显降低,电压水平和电压稳定裕度都有所提高。     

A new formulation for FACTS allocation for security enhancement against voltage collapse

This paper proposes a new formulation for reactive power (VAr) planning problem including the allocation of flexible ac transmission systems (FACTS) devices. A new feature of the formulation lies in the treatment of security issues. Different from existing formulations, we directly take into account the expected cost for voltage collapse and corrective controls, where the control effects by the devices to be installed are evaluated together with the other controls such as load shedding in contingencies to compute an optimal VAr planning. The inclusion of load shedding into the formulation guarantees the feasibility of the problem. The optimal allocation by the proposed method implies that the investment is optimized, taking into account its effects on security in terms of the cost for power system operation under possible events occurring probabilistically. The problem is formulated as a mixed integer nonlinear programming problem of a large dimension. The Benders decomposition technique is tested where the original problem is decomposed into multiple subproblems. The numerical examinations are carried out using AEP-14 bus system to demonstrate the effectiveness of the proposed method.