考虑电压稳定裕度的机组组合新方法

介绍了通过采用基于时段的优化算法求解考虑电压稳定裕度约束的机组组合,校验各时段的电压稳定裕度,并根据机组耗量优先级增减机组,使其满足相应的约束,针对该算法在处理爬坡约束上的缺陷提出了一种快速简便的修正方法。最后,采用IEEE 30节点算例论证上述方法的可行性和合理性。     

Pumped-storage unit commitment with considerations for energy demand,economics, and environmental constraints

Aside from their zero fuel costs, the pumped-storage units can reduce emissions of thermal generating units. The objective of this study is to investigate (a) thermal unit commitment with considerations for environmental constraints (ECUC), and (b) pumped-storage and thermal unit commitment with considerations for environmental constraints (PSECUC) based on a new optimization methodology. The PSECUC determines the start-up and shut-down schedules of pumped-storage and thermal generating units that meet the required demand so that the costs for fuel, start-up, and emissions (TC) are minimized. For the ECUC (thermal generating units only), the results show improvements of 0.03 and 0.50% in TC and excess emissions (EXEM), respectively. For the PSECUC, it is determined that 2-pumped-storage units can simultaneously decrease the TC and EXEM by 1.20 and 60%, respectively.     

考虑多时间尺度灵活性的含大规模风电电力系统机组组合研究

考虑机组多时间尺度启停约束,建立系统多时间尺度灵活性供给模型;考虑风电预测误差分布时变性,建立多时间尺度灵活性需求分析模型;基于混合整数线性规划方法,提出考虑多时间尺度灵活性的含大规模风电电力系统机组组合模型.模型能够充分反映含大规模风电电力系统多时间尺度灵活性供需平衡关系,在保证灵活性和安全性的前提下,提高运行经济性...     

Experience with voltage control from large offshore windfarms: the Danish case

This paper gives an overview of the state of the art and lists future challenges to reactive power and voltage control in the Danish transmission system in relation to large offshore windfarms. Today, the reliable and stable operation of the Danish transmission system is based on the voltage and frequency control carried out at central, conventional power plants. Moreover, the control of some larger decentralized combined heat and power units is activated for voltage control and system balancing, which is specific for the Danish system. In the years to come, according to the government's goal of increasing the share of renewable energy sources in the Danish power system, the share of large offshore windfarms in the Danish power generation mix will increase greatly, replacing central power plants, including their control characteristics during periods of strong winds. Large offshore windfarms must therefore provide the transmission system with the necessary voltage and frequency control, e.g. ancillary services, and ensure secure operation of the power system through their contribution to system service. Danish experience, based on the operation of a system with two large offshore windfarms and several smaller ones, has shown that the efficient use of windfarms' reactive power and voltage control for the on‐land transmission system might be limited by several factors. Among such limiting factors are the reactive power and current capability limits of the electronic power converters and switchable capacitor banks of the offshore wind turbines, which are smaller than those of central power plants measured per unit of the active power rating. Combine this with the use of AC cables, tens of kilometres long, to connect the large offshore windfarms to the on‐land transmission system, the reactive power range available to the transmission system gets poor. The Transmission System Operator should already take such limiting factors and alternative solutions for efficient reactive power and voltage control, such as incorporation of a reactive power compensation unit at the on‐land point of connection or evaluation of a Voltage Sourced Converter‐High Voltage Direct Current instead of an AC connection, into consideration during the planning phase for a windfarm connection. Copyright © 2009 John Wiley & Sons, Ltd.     

宁波电网无功优化及自动电压控制研究

以宁波电网AVC系统为研究背景,对无功优化实用化的相关问题进行研究。提出了解决无功优化配置方案,并利用宁波电网的实际数据进行计算,给出分析结论。结果表明,宁波电网AVC系统采用的分支定界法能有效地解决混合整数问题,可以满足闭环控制的实时性要求,保证控制策略的完备性、可靠性、快速性以及全局最优性,在实际电网运行中能够发挥较大作用。     

多场景概率机组组合在含风电系统中的备用协调优化

备用配置是系统抵御风险、提高运行可靠性的重要手段,也是系统运行安全与经济协调决策的问题。提出了基于状态转移的概率机组组合方法,该方法将风电的运行场景离散化,通过对风电预测误差进行概率表达,并在时间尺度上考虑状态的转移矩阵组成多场景的方法,以场景发生的概率协调系统在场景下的调度决策,并以实时校正备用作为正常和误差场景之间机组的调整限制。通过安全与经济的协调,能够自动为风电出力的波动配置适宜的备用,且模型中考虑了网络安全约束对机组组合和备用决策的影响。最后对含风电系统进行了实例仿真分析,结果表明模型的有效性和可行性,对风电的调度和规划具有指导意义。     

Stochastic reactive power market with volatility of wind power considering voltage security

While wind power generation is growing rapidly around the globe; its stochastic nature affects the system operation in many different aspects. In this paper, the impact of wind power volatility on the reactive power market is taken into account. The paper presents a novel stochastic method for optimal reactive power market clearing considering voltage security and volatile nature of the wind. The proposed optimization algorithm uses a multiobjective nonlinear programming technique to minimize market payment and simultaneously maximize voltage security margin. Considering a set of probable wind speeds, in the first stage, the proposed algorithm seeks to minimize expected system payment which is summation of reactive power payment and transmission loss cost. The object of the second stage is maximization of expected voltage security margin to increase the system loadability and security. Finally, in the last stage, a multiobjective function is presented to schedule the stochastic reactive power market using results of two previous stages. The proposed algorithm is applied to IEEE 14-bus test system. As a benchmark, Monte Carlo Simulation method is utilized to simulate the actual market of given period of time to evaluate results of the proposed algorithm, and satisfactory results are achieved.     

求解计及可靠性机组启停的随机摄动蚁群算法

利用安全函数的概率性分析方法并针对机组启停问题对系统的旋转备用需求进行评估。针对该评估模型，在基本蚁群优化算法的基础上，提出了一种新的随机摄动蚁群优化算法来进行求解。对模型的转化、可靠性约束及其他运行约束的处理等进行了较深入的研究。试验系统的计算结果表明：一方面该算法可以有效地克服基本蚁群算法容易出现停滞现象的缺陷，具有更好的全局优化能力；另一方面所做的期望安全水平对优化解的影响的敏感度分析，对实际工程决策具有一定的指导意义。     

考虑风电消纳能力单目标及多目标模糊机组组合模型及应用

从机组经济调度优化的角度入手,研究了风电消纳的合理应对方式。为使机组组合安排能在消纳更多风电的同时兼顾电力系统运行的安全、可靠性准则,并满足一定的经济性,分别以弃风电量、机组运行费用和机组运行风险度三方面为优化目标建立了机组组合的优化模型及这三者共同的多目标优化模型。利用粒子群算法及模糊多目标优化方法对模型进行求解,并将上述模型和算法应用于某10机算例的计算中。分析结果表明,该建模思路能为风电的有效接纳提供有益的指导。     

供热机组间热电负荷最佳分配的研究

以供热机组热力试验数据及修正曲线为依据,较准确地建立了表达供热式汽轮机机组热力特性的数学解析式。给出了多台供热机组并列运行的目标函数和约束条件的数学模型。用单纯形法和改进的综合约束函数双下降法进行优化,实现了供热机组间的热电负荷最佳分配,达到了节能的目的。     

Contribution to the improvement of voltage profile in electrical network with wind generator using SVC device

Wind energy is a growing renewable energy because of its several advantages; this has changed dramatically with more wind energy penetrating the conventional power network. The influence of wind generators on the power quality is becoming an important issue; non-uniform power production causes variations in system voltage and frequency, therefore, a wind farm requires high reactive power compensation. The advances in high power semiconductor devices have led to the development of Flexible AC Transmission System (FACTS). This paper presents the impact of wind energy integration on voltage stability and the goal of FACTS devices such as Static Var Compensator (SVC), which is a power electronic switch, to control the reactive power injection according to the thyristor firing angle, introduced as a state variable in power flow and combined with the nodal voltage magnitudes and angles of the power network for iterative solutions, thereby regulating the bus voltages.     

基于线性化潮流的配电网无功优化

运用一种线性化法计算配电网潮流,构建了一种计及电压稳定性系数和网损的综合因子最小化的无功优化模型,并采用含衰老与竞争机制的粒子群算法(ACM-PSO)进行求解。IEEE33和PGE69节点测试系统的应用结果表明,线性化法无功优化在10-4的数量级误差下,其计算速度与前推回代法和牛顿拉夫逊法下的无功优化相比具有明显的优势。     

Viscous Potential Flow Analysis of Kelvin–Helmholtz Instability of a Cylindrical Flow with Heat and Mass Transfer

A linear analysis of Kelvin–Helmholtz instability of a cylindrical interface has been carried out when there is heat and mass transfer across the interface, using viscous potential flow theory. Both fluids are considered as incompressible, viscous, and thermally conducting with different kinematic viscosities. Both axisymmetric as well as asymmetric disturbances are considered. Stability criterion is given by a critical value of relative velocity and stability is discussed theoretically as well as numerically. Various graphs with respect to physical parameters such as wave number, viscosity ratio, heat transfer coefficients, Reynolds number, etc., have been drawn and the effect of various parameters have been described. A comparison with the linear stability analysis of inviscid fluids (Lee [10]) has been made and it is observed that viscosity has a stabilizing effect on the stability of the system. © 2013 Wiley Periodicals, Inc. Heat Trans Asian Res, 43(6): 489–503, 2014; Published online 3 October 2013 in Wiley Online Library ( wileyonlinelibrary.com/journal/htj ). DOI 10.1002/htj.21092     

Electrical and electrical–thermal power plants with molten carbonate fuel cell/gas turbine‐integrated systems

In this article the calculation tool further developed and implemented in Matlab language by the authors was used to determine some optimal operating conditions in electrical and thermal or electrical terms for two different types of hybrid systems: molten carbonate fuel cells (MCFC)/gas turbine with their heat recovery system and the hybrid systems operating in these optimal conditions were analyzed. In the heat recovery system, in both cases, a part of the thermal energy of these gases is used to produce the steam necessary for the MCFC system. The remaining thermal energy is used, in one case, for the production of steam at various levels of pressure and temperature, which feeds a steam bottom plant to produce additional electric energy; in the other case, the same thermal energy is used to produce steam for cogenerative use. The heat recovery system was suitably designed according to the circumstances and the performances and the specific CO₂ emissions of the hybrid systems were evaluated. Copyright © 2010 John Wiley & Sons, Ltd.