电力市场中发电机组发电计划与最优协调策略

提出了连续发电与间断发电策略性竞标的数学模型。根据发电公司的发电特点以及市场清算价格的估计值,研究了发电公司赖以获取最大收益的两种发电形式。连续性发电和间断性发电。同时,还研究了发电公司调节发电输出量的两种方法及其对系统和用户的影响。在构建的模型中,考虑了机组的上升率、最小允许运行时间、最小允许停机时间和每天允许的最大开停机次数等约束条件,也考虑了由输出量调节所带来的增容或减容成本、给出了一个计算实例,可以证明在一定条件下间断性发电也是发电公司获得最大收益的发电形式之一。     

基于超级电容储能控制的双馈风电机组惯量与一次调频策略

双馈感应发电机在最大功率点跟踪控制下,发电机的输出功率难以响应电网频率波动,常规超速减载控制虽然可保留部分有功备用参与系统调频,但存在风电机组发电效益降低、转速调节范围减小及桨距角控制启动频繁等问题。为此,文中结合双馈感应发电机网侧变流器的控制特性,提出了基于超级电容储能控制的双馈风电机组惯量与一次调频策略。其中,虚拟惯量调节和一次频率调节都由超级电容控制实现,无须改变或增加风电机组额外附加控制,提高了单台风电机组的自稳性和抗扰性;根据实际超级电容模组的成本和充放电效率对储能单元容量进行优化配置。通过对比预留备用一次调频方案的经济性,表明所提方案具有较强的经济优势。最后,通过仿真实验表明其惯量支撑和一次频率调节能力及发电效益相较于常规一次频率控制具有明显提高。     

基于变功率点跟踪和超级电容器储能协调控制的双馈风电机组一次调频策略

通常双馈风电机组运行在最大功率点跟踪模式下,发电机功率输出难以响应电网频率波动,亦无备用有功功率支撑电网频率控制,风电渗透率的提升使得系统的等效时间常数降低,并且系统频率调节压力增大,从而弃风现象严重。传统超速减载控制通过保留部分有功备用参与系统调频,但存在风电机组发电效益降低、转速调节范围减小及桨距角控制起动频繁等问题。为此提出了基于变功率点跟踪和超级电容器储能协调控制的双馈风电机组一次调频策略,为储能装置在新能源机组渗透率逐渐加大的背景下提供了新的应用思路,同时综合考虑储能装置容量优化配置问题,设计出一套最高放电效率下成本最低的超级电容储能装置。相比传统超速减载控制预留备用容量的一次调频方式,通过经济性评估可知,具有较强的经济优势,仿真分析可得到在源荷随机波动场景下,其发电效益接近于最大功率跟踪模式,明显高于超速减载控制模式,同时还具有明显优于传统超速减载控制的一次频率调节能力,且无需进行桨距角调节。有利于延长变桨系统的寿命,提高其运行的安全性和可靠性。     

孤岛模式下的微电网低频减载策略分析

文中提出了一种微电网在孤岛模式下的低频减载策略.总结了各种分布式电源的特性,建立了由双馈风电机组、光伏发电系统、燃料电池发电系统、微型燃气轮机发电系统、蓄电池及局部控制器组成的微电网的动态仿真模型.探讨了孤岛模式下微电网的频率控制架构,以及系统频率变化率、等效转动惯量与有功缺额之间的关系,并据此提出了估算微电网扰动后有...     

大规模风电参与系统调频研究综述

目前在发电系统中风电比例越来越高,系统频率受此影响波动变大,如何利用风电调节系统频率成为亟待解决的问题。综述了各类调频控制策略与未来研究的发展方向。从影响来看,分析了风电比例与风机类型对系统频率的影响。从策略来看,总结了协调控制、桨距角控制、转子转速控制、模拟惯量控制、下垂控制等调频方法,分析比较各方法的适用范围、优缺点,着重阐述了各类协调控制策略,包括风电机组之间、风机与其他类型机组、风机与电力电子器件的协调控制,同时研究了各类储能参与风电调频的效果、成本与容量。从未来研究方向来看,分析了风电调频中的成本控制与智能算法在调频中的应用,并评估了风电在实际运行过程中的调频能力。     

电力市场环境下的发电机组检修问题

传统的发电机组检修计划安排在电力市场环境下面临着新的问题和挑战。文中对国内外此领域的研究工作进行了简要而系统的综述。重点论述了下述几个问题：机组检修计划的安排方式,即应由调度机构集中确定还是由发电公司自主确定;检修协调机制;机组检修计划对系统可靠性的影响;发电公司最优机组检修策略;机组检修安排与市场模式、输电设备检修安排和发电容量充裕性等问题的关系。     

乌沙山发电公司4×600MW机组脱硫增容改造工程可行性研究

文中对浙江大唐乌沙山发电有限责任公司一期4×600MW燃煤机组烟气脱硫系统增容改造的可行性进行了分析,希望通过改造,进一步提高600 MW燃煤机组湿法烟气脱硫系统生产运行的安全可靠性,满足环保设施投用要求.     

动态分离器在HP1003/Dyn制粉系统上的应用

某发电公司新建机组采用了HP1003/Dyn制粉系统,并配备了动态分离器以优化制粉系统的运行方式.为了掌握动态分离器在该类型制粉系统上的特性及对锅炉燃烧特性的影响,进行了动态分离器特性试验.试验结果表明,动态分离器对调节煤粉细度特性很有效,但对改善煤粉细度均匀性方面特性不显著.给出了制粉系统运行方式的意见,以提高机组的...     

考虑事故后频率约束的两阶段经济调度

为了保证事故后电力系统仍能正常运行,基于多阶段决策的思想提出了考虑事故后频率约束的两阶段随机经济调度模型。该模型中同时考虑事故前(第一阶段)和事故后(第二阶段)系统的运行成本,分别称为"当前成本"和"未来成本"。第一阶段的优化目标函数考虑在满足供电可靠性的条件下使常规机组和风电机组的发电成本最小;为了保证系统频率在事故后较短时间内恢复正常,第二阶段考虑了对低频减载的约束,目标函数为常规机组和风电机组的发电成本,风能高估低估的惩罚成本以及减负荷的惩罚成本最小。针对模型的非光滑性,采用光滑化方法对其进行处理,并以IEEE30节点系统进行仿真,仿真结果验证了新模型和算法的有效性。     

ZGM95型磨煤机增加出力改造

针对当前煤质劣化和一期机组增容需要,秦皇岛发电有限责任公司公司先后对5台ZGM95型磨煤机进行了增加出力改造,增大了磨辊和磨盘的直径,提高了磨煤机的碾磨能力.改造后实现了三台磨煤机就可以保证机组满发电的目标.此项改造不仅提高了机组满发、稳发能力和安全性,还大大减少了厂用电量的消耗,提高了运行经济性.     

An efficient approach for the siting and sizing problem of distributed generation

This paper deals with the subject of finding the site and size of distributed generation in distribution systems. This problem corresponds to a mixed-integer nonlinear problem which is difficult and hard to solve with classical optimization techniques. Many approaches and with different objective functions have been applied to solve it. In this paper, the problem to solve comprises multiple distributed generation sources and the objective of minimizing power losses and generation costs, both for the distributed and conventional generators. Since it is highly combinatorial, a search space reduction is needed. So, an approximate model is used to reduce the search space of the possible buses where the distributed generation has to be located. Then, for each combination of the reduced space search, a nonlinear equations system is solved by a numerical method to get the size of the distributed generation, checking the voltage limits and the lines’ capacities. To test the method, a comparison between the proposed algorithm and a force brute algorithm is performed on a 69 and 118 bus test systems. The obtained results indicate that this method find the optimal or near optimal solution in a reasonable computation time.     

Comment: LCOE is an undiscounted metric that distorts comparative analyses of energy costs

Loewen (2019) claims the levelized cost of energy (LCOE) metric as currently formulated in most studies relying on that metric is incorrect. The claim is that the distortion increases with both the discount rate and the lifespan of the resource. Loewen proposes an alternative present value cost of energy (PVCOE) that divides the net present value of cashflows by the undiscounted sum of energy production.This comment shows that the LCOE method is the only method conceptually and mathematically consistent with using discount rates to compare investment options over time. The PVCOE method allocates initial costs annually in a manner which does not sum to the initial investment on a net present value basis. Such a result is inconsistent with basic economic and financial principles.Instead of looking for a simple solution to comparing resources with different lifespans, the correct approach is to string together a series of investments for two options that arrive at the same total lifespan for each option. The two LCOEs will then be comparable.     

Demand and generation cost uncertainty modelling in power system optimization studies

This paper describes the formulations and the solution algorithms developed to include uncertainties in the generation cost function and in the demand on DC OPF studies. The uncertainties are modelled by trapezoidal fuzzy numbers and the solution algorithms are based on multiparametric linear programming techniques. These models are a development of an initial formulation detailed in several publications co-authored by the second author of this paper. Now, we developed a more complete model and a more accurate solution algorithm in the sense that it is now possible to capture the widest possible range of values of the output variables reflecting both demand and generation cost uncertainties. On the other hand, when modelling simultaneously demand and generation cost uncertainties, we are representing in a more realistic way the volatility that is currently inherent to power systems. Finally, the paper includes a case study to illustrate the application of these models based on the IEEE 24 bus test system.     

Optimal Power Flow using Glowworm Swarm Optimization

An important objective of the Optimal Power Flow (OPF) problem is to minimize the generation cost and keep the power outputs of generators, bus voltages, bus shunt reactors/capacitors and transformer tap settings in their secure limits. Solving this OPF problem using classical methods suffer from the disadvantages of highly limited capability to solve the practical large scale power system problems. To overcome the inherent limitations of conventional optimization techniques, Swarm Intelligence (SI) methods have been developed. However, the environmental concern, dictate the minimization of emissions of the thermal plants. Individually, if one objective is optimized, other objective is compromised. Hence, Multi-Objective Optimal Power Flow (MO-OPF) problem has been formulated in this paper. Swarm Intelligence methods, such as Particle Swarm Optimization (PSO) and Glowworm Swarm Optimization (GSO) have been used to solve the OPF problem with generation cost and emission minimizations as objective functions. The effectiveness of the proposed algorithms are tested on IEEE 30 bus and practical Indian 75 bus systems for cost minimization as objective function, and IEEE 30 bus test system for minimization of cost and emission as objectives. The results obtained from both the networks, the PSO and GSO are compared with each other based on different parameters.     

Multi-period multi-objective electricity generation expansion planning problem with Monte-Carlo simulation

A new approach to the electricity generation expansion problem is proposed to minimize simultaneously multiple objectives, such as cost and air emissions, including CO₂ and NO_x, over a long term planning horizon. In this problem, system expansion decisions are made to select the type of power generation, such as coal, nuclear, wind, etc., where the new generation asset should be located, and at which time period expansion should take place. We are able to find a Pareto front for the multi-objective generation expansion planning problem that explicitly considers availability of the system components over the planning horizon and operational dispatching decisions. Monte-Carlo simulation is used to generate numerous scenarios based on the component availabilities and anticipated demand for energy. The problem is then formulated as a mixed integer linear program, and optimal solutions are found based on the simulated scenarios with a combined objective function considering the multiple problem objectives. The different objectives are combined using dimensionless weights and a Pareto front can be determined by varying these weights. The mathematical model is demonstrated on an example problem with interesting results indicating how expansion decisions vary depending on whether minimizing cost or minimizing greenhouse gas emissions or pollutants is given higher priority.     

Arbitration of day-ahead real power market clearing under the influence of voltage dependent load models

Social welfare maximization is used as an objective function to clear day-ahead real power electricity markets with elastic loads. The conventional way is to model loads as voltage independent. This paper investigates behaviour of day-ahead market clearing in the presence of voltage dependent load models at different loading conditions. In a multi-objective framework, different objective functions (load served, generation cost, emission and voltage stability enhancement index) are combined with social welfare so as to examine each function’s behaviour. However, it is observed and demonstrated that the objective functions are either in accord or discord with social welfare at different loading conditions. Therefore, Pareto fronts are obtained to decide the most optimal functioning condition subject to all operating and technical constraints for the judgement making authority. The differential evolution algorithm is applied for single and multi-objective optimization purposes. The model is implemented on IEEE 30 bus system for testing and verification.     

在多种交易模式共存的电力市场中确定输电系统使用费的一种实用方法

在多种交易模式(联营体交易,双边交易,多边交易)共存的电力市场中,如何公平合理地分摊对输电网的使用费是一个尚未很好解决的困难问题,作者提出了一种实用的方法.以直流潮流模型为基础,首先根据发电转移分配因子(GSDF)计算各个合同交易应该承担的输电网的使用费,然后分别用顺流跟踪法和逆流跟踪法将由此确定的每个交易应该承担的总的使用费分摊到参与该交易的各个发电公司和负荷.这就综合了GSDF方法和潮流跟踪方法的优点,概念清晰,计算速度快,并且可以应用于存在多种电力交易的电力市场,以及互联的多区域与分层电力市场.     

燃料电池发电技术综述

简要介绍燃料电池的工作原理、特点,以及国内外燃料电池的发展情况。     

电力市场中发电项目投资风险研究

电力市场环境下发电公司面临着更多的风险,发电项目的投资决策需对其面临的风险进行详细分析。介绍了电力市场环境下发电项目投资决策中存在的风险,并进行了定性分析;同时提出电力市场环境下发电项目投资评价方法———发电项目收益成本对比法。在此基础上,通过不同的融资假设和敏感性分析考察不同发电项目的风险。通过算例验证煤电厂在各项风险的排序中都居于中间位置,而天然气电厂和核电厂各有所长,在抵御上网电价变动风险和燃料成本风险能力方面天然气电厂最弱;在抵御静态投资成本风险权益回报率风险能力方面核电厂最弱。     

MULTIOBJECTIVE DECISION MAKING IN STOCHASTIC ECONOMIC DISPATCH

ABSTRACT

Recently, multiple objective decision making has been well established as a practical approach to seek satisfactory solutions to decision making problems in limited resources, information and cognitive ability of the Decision Maker (DM). In the past, it was normal to assume well behaved and deterministic system data. Now the trend is to assume them variable and uncertain for more realistic approach. This paper deals with decision making methodology based on fuzzy set theory in order to determine the optimal generation dispatch with due consideration of uncertainties in system production cost and randomness of load demand. The classical economic dispatch problem is formulated as stochastic multiobjective optimisation problem where operating cost and variance of generation mismatch are two non-commensurable objectives. Such problems are solved to generate non-inferior solutions. Weighted sum technique is used to simulate trade_off relation among the conflicting objectives in the non-inferior domain, once the trade-off has been obtained, fuzzy set theory helps the power system operator (DM) to choose the optimal operating point over the trade-off curve and adjust the generation levels in the most economic manner. Validity and effectiveness of the proposed method has been demonstrated by analysing a sample power system comprising three generators.