Environmental/economic power dispatch with wind power

Economic environmental dispatch (EED) is a significant optimization problem in electric power system. With more wide spread use of wind power, it is necessary to include wind energy conversion system (WECS) in the EED problem. This paper presents a model to solve the EED problem incorporating wind power. In addition to the classic EED factors, the factors accounting for overestimation and underestimation of available wind power in both economic and environmental aspects are also considered. In order to obtain some quantitative results, the uncertain characteristic of available wind power and the performance of WECS are determined on the basis of the statistical characteristic of wind speed. The optimization problem is numerically solved by a scenario involving two conventional generators and two wind-powered generators. The results demonstrate that the allocation of system generation capacity may be influenced by multipliers related to the cost for overestimation and underestimation of available wind power, and by the multiplier related to the emissions for underestimation of available wind power. Nevertheless, the multiplier related to the emissions for overestimation of available wind power has little impact on the allocation. Taking account of economic factors, environmental factors and impacts of wind power penetration, the proposed EED model is beneficial to finding the right balance between radical and conservative strategy for wind power development.     

基于风光互补电力入网的电力系统动态经济调度

为解决风光互补电力入网的不确定性给电网调度带来的影响,文章对其的经济调度问题进行研究。针对火电机组的排污特性引入了环境污染惩罚成本,针对风光电力输出功率的间歇波动性引入了备用容量惩罚成本,在考虑系统供需平衡与机组爬坡率等约束条件的基础上,给出了风光电力互补入网的调度策略,建立了含有风光互补电力的动态经济调度模型;应用一种改进的粒子群算法对所提模型进行求解。最后以IEEE-30节点测试系统为例进行仿真分析,仿真结果验证了所提模型的合理性及算法的有效性,同时也说明了风光互补电力入网能够平抑风电的出力波动,可以在保证系统可靠性的基础上,提高风光电力的并网率。     

含分布式发电并网虚拟发电厂鲁棒优化经济调度方法

文章基于鲁棒优化理论建立了虚拟发电厂最优经济调度模型。首先以虚拟发电厂发电净收益最大为目标函数,计及出力计划约束、机组运行约束、机组启停约束、储能运行约束等必要约束条件建立系统优化运行模型;然后考虑风光出力区间不确定性,以风光出力为自然决策者,以虚拟发电厂为系统决策者,分别制定博弈策略和支付,建立虚拟发电厂最优经济调度鲁棒优化模型,并对其Nash均衡点进行分析;基于两阶段松弛法将所建立的鲁棒优化模型转化为有限可解的步骤;最后通过一个算例验证了所建立的模型在制定虚拟发电厂运行计划方面的经济优势。     

Investigation of the relationship between ill-conditioned powerflow and voltage collapse

Ill-conditioned power flow problems have been widely investigated and discussed in the literature. Typical approaches are to develop enhanced solution algorithms when a power flow case is found to diverge using the conventional Newton method. It is known that a genuine ill-conditioned problem is caused by the presence of a large condition number in the power flow Jacobian matrix. Since a large condition number is associated with small singular values and the voltage collapse is related to small eigenvalues, we therefore speculate that an ill-conditioned power flow problem is actually a voltage collapse problem. The objective of this letter is to demonstrate the relationship between power flow ill conditioning and voltage instability. Case studies of five classical ill-conditioned cases have confirmed that the ill conditioning of power flow indeed occurs-and only occurs-at the voltage collapse point     

Application of the invasive weed optimization algorithm to economic dispatch problems

In this paper the invasive weed optimization algorithm has been applied to a variety of economic dispatch (ED) problems. The ED problem is concerned with minimizing the fuel cost by optimally loading the electrical generators which are committed to supply a given demand. Some involve prohibited operating zones, transmission losses and valve point loading. In general, they are non-linear non-convex optimization problems which cannot be directly solved by conventional methods. In this work the invasive weed algorithm, a meta-heuristic method inspired by the proliferation of weeds, has been applied to four numerical examples and has resulted in promising solutions compared to published results.     

考虑柔性负荷的综合能源系统低碳经济优化调度

随着低碳发展进程的不断推进,综合能源系统(IES)逐渐成为实现减排目标的重要支撑技术。基于能源集线器概念,结合需求侧柔性负荷的可平移、可转移、可削减特性,构建了含风光储、燃气轮机、柔性负荷等在内的IES模型。综合考虑了系统运行成本和碳交易成本,建立了以总成本最低为优化目标的IES低碳经济调度模型,采用鲸鱼优化算法对算例进行求解。通过场景对比,分析了碳交易因素对能源调度的影响,以及在碳交易体系之下,柔性负荷的合理调度对IES进一步减少碳排放、降低系统成本可发挥的作用。研究结果表明,在碳交易体系下,柔性负荷参与调度能有效地提高系统的经济环境综合效益。     

An effortless hybrid method to solve economic load dispatch problem in power systems

This paper proposes a new approach and coding scheme for solving economic dispatch problems (ED) in power systems through an effortless hybrid method (EHM). This novel coding scheme can effectively prevent futile searching and also prevents obtaining infeasible solutions through the application of stochastic search methods, consequently dramatically improves search efficiency and solution quality. The dominant constraint of an economic dispatch problem is power balance. The operational constraints, such as generation limitations, ramp rate limits, prohibited operating zones (POZ), network loss are considered for practical operation. Firstly, in the EHM procedure, the output of generator is obtained with a lambda iteration method and without considering POZ and later in a genetic based algorithm this constraint is satisfied. To demonstrate its efficiency, feasibility and fastness, the EHM algorithm was applied to solve constrained ED problems of power systems with 6 and 15 units. The simulation results obtained from the EHM were compared to those achieved from previous literature in terms of solution quality and computational efficiency. Results reveal that the superiority of this method in both aspects of financial and CPU time.     

A review on the economic dispatch and risk management considering wind power in the power market

With the rapid development of world economy, wind power has been given more and more consideration owing to its energy saving and environmental protection. But due to intermittency and unpredictability nature of wind power generation, many new problems come into being when infusing wind power into power network with conventional generators. Aiming at these difficulties, this paper presents a review on the historical research production of this theme. The models of economic dispatch schedule of wind power considering dissimilar actual condition, different optimized algorithms and risk management in the electric market are discussed and the future trend is prospected in this paper.     

Combined heat and power economic dispatch problem using the invasive weed optimization algorithm

Cogeneration units which produce both heat and electric power are found in many process industries. These industries also consume heat directly in addition to electricity. The cogeneration units operate only within a feasible zone. Each point within the feasible zone consists of a specific value of heat and electric power. These units are used along with other units which produce either heat or power exclusively. Hence the economic dispatch problem for these plants optimizing the fuel cost is quite complex and several classical and meta-heuristic algorithms have been proposed earlier. This paper applies the invasive weed optimization algorithm which is inspired by the ecological process of weed colonization and distribution. The results obtained have been compared with those obtained by other methods earlier and showed a marked improvement over earlier ones.     

Applying a non-intrusive energy-management system to economic dispatch for a cogeneration system and power utility

Non-intrusive energy-management (NIEM) techniques are based on energy signatures. While such approaches lack transient energy signatures, the reliability and accuracy of recognition results cannot be determined. By using neural networks (NNs) in combination with turn-on transient energy analysis, this study attempts to identify load demands and improve recognition accuracy of NIEM results. Case studies are presented that apply various methods to compare training algorithms and classifiers in terms of artificial neural networks (ANN) due to various factors that determine whether a network is being used for pattern recognition. Additionally, in combination with electromagnetic transient program (EMTP) simulations, calculating the turn-on transient energy facilitate load can lead to identification and a significant improvement in the accuracy of NIEM results. Analysis results indicate that an NIEM system can effectively manage energy demands within economic dispatch for a cogeneration system and power utility. Additionally, a new method based on genetic algorithms (GAs) is used to develop a novel operational strategy of economic dispatch for a cogeneration system in a regulated market and approach the global optimum with typical environmental constraints for a cogeneration plant. Economic dispatch results indicate that the NIEM system based on energy demands can estimate accurately the energy contribution from the cogeneration system and power utility, and further reduce air pollution. Moreover, applying the NIEM system for economic dispatch can markedly reduce computational time and power costs.     

计及光伏出力模糊性和旋转备用的电力系统环境经济调度

光伏发电的出力和负荷的不确定性给电力系统经济调度提出了新要求。针对光伏出力和负荷难以准确预测的特性,基于可信性理论引入模糊变量,并将光伏出力和负荷用模糊参数表示;用模糊约束取代传统确定性约束,建立含梯形模糊变量的功率平衡和正负旋转备用容量的模糊机会约束模型。采用清晰等价类的方法将模糊约束转换为确定性约束,提出用简化的粒子群优化算法求解模型。算例分析验证了所提模型和算法的有效性。     

区域电压无功控制系统在地区电网中的应用

区域电压无功控制系统以电压无功的分级控制思想为指导，在调度自动化主站实现集中的、以保证负荷母线电压质量为首要目标的变电站一级控制；以220kV变电站的供电范围进行动态分区，实现区域内的二级协调控制；以基子全网实时潮流的网损灵敏度对可控设备进行在线寻优，实现准三级控制。二三级拉制中充分地考虑了电网运行的经济性要求。实践表明应用该系统是即时控制电压在合格范围、供应优质电能、降低电力服务成本度降损节能的有效措施。     

含电动汽车的气电互联虚拟电厂区间多目标优化调度策略

气电互联虚拟电厂能够推动分布式能源的高效利用,考虑诸多不确定因素的有效调度策略是保证其运行品质的关键.本文在构建含电动汽车的气电互联虚拟电厂风电、光伏、燃气轮机、电转气设备、电动汽车各单元模型的基础上,采用区间优化理论描述了该虚拟电厂中风电、光伏出力及电负荷、气负荷的不确定性;以运行经济效益、用户舒适度、二氧化碳排放作...     

Evolution of China’s power dispatch principle and the new energy saving power dispatch policy

With social economic reform in the past decades, the power industry of China is gradually evolving from a highly integrated one toward an electricity market, which can be characterized based on the transition of the power dispatch principle. To attract investment in the power generating industry, China introduced non-state-owned power plants to the original system of a highly vertically integrated power industry with annual power generation quota guarantees, which makes the traditional economic dispatch principle not applicable. The newly debuted energy saving power dispatch (ESPD) is an attempt to fully exploit the maximum energy savings and was implemented by an administrative code. Starting in August 2007, the pilot operation of the ESPD was implemented in five provinces, but after two years, it is still not widely applied all over the country. This paper details the transition of China’s power dispatch principle with particular attention to its origin and content. Moreover, the factors that influence the ESPD’s actual energy saving effect are discussed, as well as the sustainability of the policy.     

计及电压稳定的含高比例光伏电源电网FACTS优化配置

高比例光伏电源接入电网后,输电电网的电压和潮流均会发生剧烈波动,从而增加了无功功率的优化难度。文章提出了一种基于自适应粒子群算法的柔性交流输电设备优化配置方法。该优化配置方法以电压稳定性最优、可用输电能力最大、综合费用最小为目标,建立优化模型,并采用基于分布熵改进的自适应粒子群算法确定最佳配置方案。此外,文章还把IEEE-30节点模型的模拟结果和某地区电网的实际光伏出力测量结果进行对比。分析结果表明,文章所提出的优化配置方法能够实现典型柔性交流输电设备的优化配置,该优化配置方法的寻优精度、速度均显著优于传统粒子群算法和遗传算法;利用该优化配置方法确定的最佳配置方案可显著提高电网电压的稳定性和输电能力,降低综合费用,具有工程实用价值。     

机组经济运行的负荷优化分配方法研究

并列运行的火电机组负荷优化分配是火电厂乃至电力系统优化运行的重要部分。在分析燃耗特性的基础上，建立了负荷优化分配的等微增率模型、线性规划模型和二次规划模型．并对某电力系统十台并列运行的单元机组进行求解计算，得到三种方法不同的负荷分配优化值和系统燃耗量。结果表明：二次规划分配方法节能效果最明显，线性规划分配方法的节能效果介于二次规划分配方法和等微增率分配方法之间。     

Solution to economic dispatch problem with valve-point loading effect by using catfish PSO algorithm

This paper proposes application of a catfish particle swarm optimization (PSO) algorithm to economic dispatch (ED) problems. The ED problems considered in this paper include valve-point loading effect, power balance constraints, and generator limits. The conventional PSO and catfish PSO algorithms are applied to three different test systems and the solutions obtained are compared with each other and with those reported in literature. The comparison of solutions shows that catfish PSO outperforms the conventional PSO and other methods in terms of solution quality though there is a slight increase in computational time.     

A cost-effective approach for fast voltage recovery of power distribution networks with renewable energy

This paper presents a cost-effective reactive power planning for active distribution networks based on a new index called reactive power loadability (Q-loadability). The impact of high renewable energy penetration on the static voltage stability of the system is analysed. The effect of load models in distributed generation planning is also demonstrated through nonlinear simulations. In order to ensure fast voltage recovery after a sudden disturbance, compensating devices are located using Q-loadability to increase the system voltage stability limit. Both static and dynamic analyses are carried out to determine the size of distribution static synchronous compensator (D-STATCOM). The parameters of the controller are also tuned to reduce the rating of D-STATCOM. Simulation results show that the proposed approach can reduce the sizes of compensating devices required which, in turn, reduces costs. The effectiveness of the proposed algorithm is verified through several case studies.     

基于微网内节点功率优化配置的频率-电压调节方法

分布式电源出力以及节点负荷的不确定性,严重影响了孤网模式下微网系统的频率和电压。文章首先考虑发电机有功-频率特性,无功-电压特性以及负荷的频率电压特性,定义微网系统频率和节点电压对有功功率和无功功率的灵敏度;其次,将系统频率偏差和节点电压偏差进行归一化加权处理,得到优化目标函数;然后,以灵敏度较大节点为功率调节节点,采用粒子群优化算法对这些节点的有功功率和无功功率进行优化。在14节点的微网系统中对算法的验证结果表明,当孤网运行的微网系统频率和电压偏差需要调节时,文章所提出的算法通过优化微网节点的功率,能够使系统频率偏差和节点电压偏差减小,实现频率和节点电压的调节。     

考虑可再生能源利用率的风-光-气-储微能源网经济调度研究

文章对风、光、气、储微能源网的多目标优化问题进行研究,建立了经济调度模型和整体满意度模型,综合计算了微能源网区域用电总费用,考虑了相关各类约束条件,并计及政策补贴,以区域内负荷平均用电费用最小且可再生能源利用率最高为目标优化,采用基于实数编码的加速遗传算法(Real coding based Accelerating Genetic Algorithm, RAGA)对优化目标进行求解。通过算例对上述模型进行仿真计算,验证了上述模型实现快速优化的有效性。