Interval type-2 fuzzy modeling of wind power generation in Genco's generation scheduling

Wind power is a promising source of electric power generation since it has tremendous environmental and social benefits. The generation scheduling (GS) problem encounters several uncertainties in terms of the system's parameters such as load, reserve and available wind power generation. The modeling of those uncertainties is an important issue in power system scheduling. A fuzzy based modeling approach can be used to develop the generation schedule under an uncertain environment.In this paper, the type-2 fuzzy membership function (MF) is implemented to model the linguistic uncertainty of type-1 MF of available wind power generation which stems from opinions of different experts. The proposed approach is applied to two test systems (six and twenty-six conventional generating units both with two wind farms) and the results of generation scheduling using both fuzzy modeling type-1, and type-2 are presented. These results demonstrate that the advantage of using the type-2 fuzzy to model the linguistic uncertainty of the type-1 MF. This paper demonstrates how unit scheduling in an uncertain environment of type-1 fuzzy MF modeling can be performed just by using a single type-2 fuzzy MF when all type-1 MF were in the footprint of uncertainty (FOU) of type-2 MF.     

Electricity generation scheduling with large-scale wind farms using particle swarm optimization

Large-scale integration of wind power in the electricity system presents some planning and operational difficulties, which are mainly due to the intermittent and difficult nature of wind prediction process. Therefore it is considered as an unreliable energy source.     

水火电力系统短期发电计划优化方法综述

水火电力系统的短期发电计划问题在电力系统的安全可靠和经济运行中发挥着越来越重要的作用，由于其本身的复杂性，很难从理论上找到全局最优解。深入探讨各种优化算法，并加以分类，详细综述各种优化方法在水火电力系统短期发电计划问题中所取得的研究成果和存在的不足之处。     

A novel differential evolution application to short-term electrical power generation scheduling

This paper proposes a new way of applying a differential evolution algorithm to short-term electrical power generation scheduling. Traditionally, the problem is divided into two subproblems. An evolutionary algorithm, which works with binary decision variables, is applied to the first subproblem to find a low cost scheduling of power generators, satisfying some operational constraints. Then, the lambda-iteration method, is used to calculate the power generated by the online generators. In this study, the problem is treated as a whole for the first time in literature and an application of a real-valued differential evolution algorithm is proposed. This approach eliminates the use of an iterative local search technique such as lambda-iteration in all solution evaluations. Through comparisons with results from literature, it is shown that the proposed method achieves a similar solution quality to existing methods, without needing the time consuming lambda-iteration step. Finally, the new approach is applied to real-world data from the Turkish interconnected power network.     

Reliability centered planning for distributed generation considering wind power volatility

This paper investigates a stochastic planning model to minimize the lifecycle cost of distributed generation (DG) systems under the energy reliability criterion, namely the loss-of-load probability. In particular, our study focuses on the DG system penetrated by renewable wind technology. The optimization is formulated to determine the wind turbine capacity and their placement in the DG system with the intent to minimize the capital, operational and environmental costs. Statistical moments including mean and variance are utilized to characterize the wind power volatility and the load uncertainty. Genetic algorithm combined with heuristic search is used to find the best sitting and sizing of the distributed energy recourses. Our study is among the first attempts in the literature to model and optimize DG system based on continuous probabilistic theory. The moment methods are shown to be effective in characterizing the stochastic behavior of wind power and load dynamics. Case studies are provided to demonstrate the application and performance of the planning method.     

Probabilistic three-phase load flow for unbalanced electrical systems with wind farms

In this paper, a three phase probabilistic load flow for transmission system based on point estimation method along with three phase unbalanced induction generator model for the wind farm has been proposed. The proposed method is tested on a IEEE-118 bus three phase system and accuracy of the results have been validated by comparing the results with those obtained by Monte Carlo simulation studies. The effect of variation of standard deviation of the connected loads on the system and effect on the voltage profile has also been studied.     

计及风电置信风险的源网协调多目标优化调度

为了更为合理灵活地评估风电高估/低估给电力系统优化调度带来的风险性以及降低调度决策的保守性,基于风电机会约束提出风电高估/低估置信风险功率偏差量化计算方法,并在决策变量中引入变压器变比调节和无功补偿容量优化,构建计及风电置信风险和源网协调运行的经济/风险多目标优化调度模型。提出一种基于可行性和非劣性综合排序回溯搜索算法,从而实现对调度模型的高效准确求解。IEEE 30节点系统算例结果验证了所提方法的有效性和优越性。     

基于公平发电的新能源电站协调调度方法研究

我国新能源电站普遍存在限电现象,限电条件下多个新能源电站如何公平的参与调度成为关键问题。文中提出一种考虑新能源发电公平性的新能源电站协调调度方法。考虑技术性、运营特性、经济性和可靠性等多维度提出新能源电站评价指标体系;提出基于灰色关联度和熵权法的新能源电站评价指标体系综合分析方法,以综合评价新能源电站先进性。基于新能源电站先进性综合排名,提出了包含电网对新能源发电的可消纳空间计算和调度计划公平性分配的新能源电站协调调度方法。通过算例结果表明,所提出的评价指标体系及其分析方法可以正确评价新能源电站先进性,所提出的新能源协调调度方法可以有效保障综合排名高的电站优先发电,提升新能源电站参与调度的公平性。     

Effects of wind power intermittency on generation and emissions

Wind power depends on environmental conditions that vary and are imperfectly forecastable. This intermittency could increase the desired flexibility of fossil fuel generation, impacting emissions. This paper finds that various types of wind generation intermittency are associated with a shift towards natural gas generation and decreasing CO₂ emissions. The environmental effects of wind intermittency should be considered when determining the overall impact of intermittency-related activities such as expanded grid storage or turbine siting decisions.     

Large penetration of wind and dispersed generation into Danish power grid

The present Danish power grid is characterised by large penetration of wind power and local combined heat and power (CHP) units. Today, there are two large offshore wind farms commissioned in the Danish power grid. Construction of two more offshore wind farms (430 MW) with grid connection to the Danish transmission power grid will be by the year 2009. The Danish power grid is undergoing a change from a classical power network with few centralised large power plants into a power network with a significant amount of wind power and dispersed generation. Presently, there must be at least three large power plant units in operation in Western Denmark to control voltage and frequency and maintain security of the power system operation. The technology change to wind power and dispersed generation implies that power supply and control from the large power plants – and, consequently, also ancillary services such as, e.g. voltage and frequency control capability – have to be reduced in favour of dispersed generation and wind. Such a change constitutes a challenge with respect to maintaining security of the power system operation in different operational situations, and creates a need for new solutions with voltage and frequency control and compliance with planned power balance between the Danish power system and the neighbouring areas. This article focuses mainly on issues with regard to short-term voltage stability of the power grid.     

基于免疫遗传算法的超短期发电计划优化

超短期发电计划优化在电力系统调度运行中发挥着越来越重要的作用,但由于其是一个非线性整数约束优化问题,数学模型复杂,很难从理论上找到全局最优解。针对电力系统发电计划优化问题,引入免疫遗传算法,很好地解决了遗传算法局部收敛的问题,实现了群体收敛性和个体多样性间的动态平衡调整,能快速准确求解,及时调整超短期发电计划方案,从而达到安全经济环保调度,优化资源配置的效果。     

Residue Theorem based soft sliding modecontrol for wind power generation systems

This paper proposes a residue theorem based soft sliding mode control strategy for a permanent magnet synchronous generator (PMSG) based wind power generation system (WPGS), to achieve the maximum energy conversion and improved in the system dynamic performance. The main idea is to set a soft dynamic boundary for the controlled variables around a reference point. Thus the controlled variables would lie on a point inside the boundary. The convergence of the operating point is ensured by following the Forward Euler method. The proposed control has been verified via simulation and experiments, compared with conventional sliding mode control (SMC) and proportional integral (PI) control.     

故障时双馈风力发电系统的控制策略研究

基于变速恒频双馈风力发电系统的有功、无功的解耦控制,提出了电网故障时双馈电机的紧急控制策略,在Mtalab/Simulink里建立了模型,并验证了故障控制策略的正确性。在常规情况下,双馈电机转子侧的有功采用最大功率点跟踪控制,无功采用额定功率因数控制,可以获得最大的风能利用效率和较好的功率因数;但若电网故障时仍采用此常规控制策略,电网不但获取不到最大的风能利用效率和较好的功率因数,而且电网的频率和电压波动影响较大。所以在故障期间把最大功率点追踪控制和额定功率因数控制切换到频率控制和电压控制策略,通过控制有功电流分量和无功电流分量来减小或者增加有功和无功的输出,减小电网频率和电压的波动。建立了故障控制的模型,针对系统单相接地故障和两相短路故障这两种短路故障类型进行了仿真,仿真结果验证了故障控制策略的正确性,提高了风力发电系统在故障时的稳定性。     

Hybrid wind power balance control strategy using thermal power,hydro power and flow batteries

The increased number of renewable power plants pose threat to power system balance. Their intermittent nature makes it very difficult to predict power output, thus either additional reserve power plants or new storage and control technologies are required. Traditional spinning reserve cannot fully compensate sudden changes in renewable energy power generation. Using new storage technologies such as flow batteries, it is feasible to balance the variations in power and voltage within very short period of time. This paper summarises the controlled use of hybrid flow battery, thermal and hydro power plant system, to support wind power plants to reach near perfect balance, i.e. make the total power output as close as possible to the predicted value. It also investigates the possibility of such technology to take part in the balance of the Lithuanian power system. A dynamic model of flow battery is demonstrated where it evaluates the main parameters such as power, energy, reaction time and efficiency. The required battery size is tested based on range of thermal and hydro power plant reaction times. This work suggests that power and energy of a reasonable size flow battery is sufficient to correct the load and wind power imbalance.     

广东风电 大有作为

广东省的一次能源缺乏,能源自给率低,而丰富的风力资源尚未得到很好的开发和利用。针对上述情况,从引入市场机制、合理配置资源、政策引导扶持等方面对加快广东风电建设进行初步探讨。     

Stochastic optimal power flow incorporating offshore wind farm and electric vehicles

In this paper, an optimal power flow model of a power system, which includes an offshore wind farm and plug-in electric vehicles (PEVs) connected to grid, is presented. The stochastic nature of wind power and the uncertainties in the EV owner’s behavior are suitably modelled by statistical models available in recent literatures. The offshore wind farms are assumed to be composed of doubly fed induction generators (DFIGs) having reactive power control capability and are connected to offshore grid by HVDC link. In order to obtain the optimal active power schedules of different energy sources, an optimization problem is solved by applying recently introduced Gbest guided artificial bee colony algorithm (GABC). The accuracy of proposed approach has been tested by implementing AC–DC optimal power flow on modified IEEE 5-bus, IEEE 9-bus, and IEEE 39-bus systems. The results obtained by GABC algorithm are compared with the results available in literatures. This paper also includes AC–DC optimal power flow model, implemented on modified IEEE-30 bus test system by including wind farm power and V2G source. It has been shown that the uncertainty associated with availability of power from wind farm and PEVs affects the overall cost of operation of system.     

针对风电引起闪变的数字化测试系统仿真

IEC闪变测试模拟系统在低频段存在误差,将模拟系统转换成数字系统后误差依然存在,而风力发电引起的闪变频率约为1～3 Hz,正好位于闪变测试系统的低频段。在Matlab/Simulink仿真平台上用双线性变换法将模拟系统变换成数字系统,建立了IEC闪变仪的数字化模型,对闪变仪在低频段产生误差的原因进行了分析,然后通过修正加权滤波器的参数,使瞬时闪变视感度S(t)的误差在允许的±5%的范围内,提高了闪变仪在低频段的精度,同时又不影响高频段的精度,从而满足了风力发电引起的闪变测试要求。所提出的方法可用于测试风电引起闪变的闪变仪设计中。     

消纳风电预测偏差功率的电采暖负荷群运行调度策略

构建以新能源为主体的新型电力系统将面临尖锐的调节资源供需矛盾,电采暖负荷具有可时移特性,是优质的存量可调节资源。拟挖掘电采暖负荷调节功率作为电网辅助备用,针对风电功率预测偏差消纳问题,设计了负荷聚合商响应风电预测偏差功率的调度架构,构建了电采暖负荷群响应风电预测偏差功率的轮流调控响应策略以最大化消纳偏差功率,设计了电采暖负荷群-风电场算例系统,基于此对所提出的电采暖负荷群响应风电预测偏差调控方法的有效性进行了仿真验证,并分析了负荷群参与响应后的经济性。     

四川电网节能发电调度的措施及节能效果

四川省电力公司作为国家首批节能发电调度试点单位,充分利用试点契机,在实际调度工作中,摸索出一系列节能发电调度的有效实施措施。通过分析节能发电调度实施过程中出现的问题,深入研究节能发电调度规则。从节能减排角度出发,完善节能发电调度的实施措施,并通过试运行期间的实际运行结果,验证了这些措施的有效性、正确性。     

风电自动发电控制策略可行性分析

为应对大规模风电并网运行带来的诸多不利因素,在传统水、火电机组有功控制技术的基础上,综合风电运行特点,研究分析了计划曲线跟踪、限时段控制等多种风电有功控制策略,并且成功实现了宁夏首次风电联网有功闭环控制。研究结果表明：风电有功控制策略有较强的可行性,能够为电网接纳大规模风电运行提供关键技术支撑。