基于状态转移矩阵的小水电机组发电系统可靠性评估

作为我国重要的电力资源,小水电机组大规模并网运行给发电系统乃至整个电网可靠性与安全运行带来新的挑战。由于小水电数量众多,容量不等,采用现有递推公式建立停运容量模型来进行小水电机组发电系统可靠性评估时步骤繁琐,中间数据多,工作量大,对此提出了一种基于状态转移矩阵的小水电发电系统可靠性算法,用状态空间图表示小水电机组停运容量模型,基于状态空间算法直接计算小水电机组各个停运容量状态的确切概率,由转移率矩阵适当变换求取增量频率,用分块矩阵组合表示小水电机组停运容量模型和负荷容量模型的组合,合并相同容量状态,增加等步长而未出现的容量状态,即得小水电发电系统的裕度容量模型,进而计算累积概率、累积频率等可靠性指标。算例分析验证了此算法的可行性,可在实际操作中推广应用。     

多区域综合能源系统互联下的共享储能容量优化配置

为有效提高多个区域综合能源系统(regional integrated energy system,RIES)的能源利用率,同时合理配置储能系统的容量,提出一种多RIES互联下的共享储能系统容量优化配置模型.首先,介绍了共享储能背景下多RIES运行框架,分析了共享储能系统的运行模式.其次,针对一类包含热电联产机组与热泵...     

区域电网互联下的省间联络线功率控制评价标准研究

针对华中电网存在的两层联络线功率控制模式,分析了特高压交流跨区联络线功率控制评价标准（T标准）与区域电网内省间联络线功率控制评价标准（CPS标准）特点,并结合特高压交流跨区联络线运行要求,分析了CPS标准下的省间联络线功率控制对跨区联络线功率波动的影响。通过对现有T标准与CPS标准中部分指标的改进,提出了一套新的区域电网互联下的省间联络线功率控制评价标准,使区域电网省间联络线功率控制与跨区联络线功率控制相互协调。     

风光水互补发电系统的优化配置

为提高风光水互补发电系统的供电可靠性,降低经济成本,研究了电源容量的优化配置。首先提出独立和并网运行调度策略,然后考虑供电可靠性和蓄水库水量平衡等约束,建立了以全寿命周期成本最小为目标的优化配置模型,采用改进遗传算法进行求解。算例探讨了供电可靠性和联络线传输容量对优化配置的影响,验证了所提方法的有效性。由仿真结果可知,独立运行时,利用风光水互补发电即可保证较高的供电可靠性;并网运行时,采用联络线的双向交互电能能力,可进一步提高系统供电可靠性,有效降低经济成本。     

中国区域低温天气及其对风力发电影响的统计

罕见低温天气可能导致大规模风电机组非计划停运,威胁电力系统的可靠安全运行.研究低温天气对风力发电停运容量影响的时空规律,对于未来高比例甚至100％可再生能源电力系统的发展,具有重要意义.以风力发电机组的设计运行温度下限为阈值,关注低于阈值的低温天气.结合全国2481个地面气象站点历史48年(1970—2017年)的日气温观测数据及国家电网有限公司经营区的实际风电场分布数据,从发生频率、持续时间、反复穿越阈值次数、影响国土面积、风电停运容量等指标,对中国区域低温天气及其对风力发电的影响进行了统计分析,并总结了低温天气对风力发电的影响规律,可为未来高比例可再生能源电力系统的规划和运行提供基础.     

新疆与西北联网750 kV交流联络线功率波动峰值计算分析研究

2010年,新疆电网通过750 kV哈密—安西(哈敦)双回线与西北主网联网运行.为保障联网后电网的安全运行,分析了哈敦联络线在各种方式下的功率波动情况.联网后的电网通过等值和简化,在扰动后的特定时间段内,联络线功率波动曲线为二阶系统阶跃响应曲线;功率波动峰值大小,取决于功率缺额的数值、两大区交流电网的惯性常数比和区域振荡模式的阻尼比.最后,对新疆送西北1 000 MW、新疆受西北500 MW 2种极限方式下的功率波动幅值进行了估算,并通过哈敦线的PMU实测数据、以及中国电科院PSASP程序仿真结果验证了等值、估算的正确性和有效性;同时,该结果表明,在目前的方式下,对设定的扰动仍留有较大的功角稳定裕度.该研究方法有助于掌握两大区互联系统联络线功率波动的动态特性,并提供了扰动校验的简便方法,有利于运行方式的安排和控制措施的制定.     

区域互联模式下的电力市场AGC调频方式研究

限于我国能源与需求不平衡的现状,大规模区域电网互联的输电网络格局已经初步形成.首先以三区域互联系统为例,推导三区域互联系统下两区域发生相同或不同扰动的频率偏差、联络线功率偏差和区域控制偏差表达式,将系统各区域的相互关系用数学模型直观的呈现.考虑到电力市场环境因素,对自动发电控制(Automatic Generation Control,AGC)模型进行改进使各个发电单元输出电力满足市场合同要求,对负荷违约时机组调节动作特性进行仿真并进一步分析了各参数响应指标.针对区域调频机组发生拒动或者延迟动作的情况,未经修正的三种调频方式使系统仍然存在一定频率偏差、联络线功率偏差.对AGC模型状态方程进行修正,通过对未修正和修正的三种调频方式进行仿真对比分析,仿真结果证明修正之后的调频达到无差调节的良好效果.     

基于非合作博弈的微网混合储能容量配置方法

并网型微电网的混合储能容量配置方法一般仅考虑其经济性,难以解决微电网联络线功率波动问题,会对电网产生不利影响.为了权衡混合储能的经济性与联络线功率波动平抑效果,提出了基于非合作博弈的混合储能容量优化配置方法.首先,以混合储能和联络线作为参与者,建立非合作博弈模型;其次,引入入侵杂草算法中繁殖机制和变异算子改进遗传算法,...     

基于集合经验模态分解的微电网混合储能优化配置

为了平抑微电网联络线功率,该文采用磷酸铁锂电池与超级电容组合的方式进行微电网混合储能优化配置。首先,根据电网调度安排,将微电网净负荷分解为联络线功率与混合储能系统总功率。其次,通过集合经验模态分解将混合储能总功率分解为锂电池平抑的低频分量与超级电容平抑的高频分量,并建立混合储能的等年值成本、平抑联络线功率、能量供需平衡目标函数,采用自适应粒子群算法求解混合储能容量。根据储能的荷电状态,采用模糊控制算法对锂电池、超级电容的充放电功率进行二次修正,保证储能系统的长期运行。基于某并网型微电网进行算例分析,仿真验证该方法的经济性与有效性。     

计及风电和小水电的发电系统可靠性评估研究

根据分布式电源随机输出功率的特点,利用集群技术,将较多的机组出力状态集合成较少的组群,建立了风电多容量机组可靠性模型和小水电机组改进的双状态模型。针对现有发电系统停运容量模型存在计算繁琐的问题,运用停运容量预备表优化排序,减省计算步骤和时间。将容量模型和日尖峰负荷模型结合,形成新型发电系统的裕度评估体系,采用某含多风电场和遍布小水电的地区的发电系统作为算例,编制MATLAB程序计算了一系列可靠性指标,定量分析了分布式电源对发电系统可靠性的影响。     

An Interactive Package for Risk Evaluation and Maintenance Scheduling

The calculation of the Loss of Load Probability (LOLP) is an important element in generation planning studies. LOLP is calculated either independently to evaluate the risk of a certain generation system or in conjunction with several planning application programs such as, generator maintenance scheduling, probabilistic production costing, hydrothermal scheduling, generation expansion, etc. Exact calculation of the LOLP requires the calculation of the Capacity Outage Probability Table (COPT). This table takes into consideration the capacity rating the the forced outage rates of the generating units of the system and it provides the probability values associated with various amounts of system capacity on outage. The capacity outage table is calculated by utilizing the well known recursive convolution formula. Usually the table is simplified by rounding the capacity outage table to selected discrete capacity levels. The size of the round off increment depends on the desired accuracy. The classic approach is time consuming and requires a considerable amount of computer memory. In order to reduce the computational time and computer storage several methods have been proposed, in which the capacity outage probabilities are approximated with analytic continuous probability distributions. Most of these methods utilize the Central Limit Theorem, Fourier techniques and the Gram Charlier's expansion. Closely related to the LOLP is the maintenance scheduling problem. Preventive maintenance is required for all generating units in order to reduce the probability of capacity shortage and improve the overall reliability of the power system.     

Load‐frequency control of an interconnected hydro‐thermal power system with new area control error considering battery energy storage facility

This paper deals with load‐frequency control of an interconnected hydro‐thermal system considering battery energy storage (BES) system. A new area control error (ACEN) based on tie‐power deviation, frequency deviation, time error and inadvertent interchange (unscheduled energy transfer) is used for the control of the BES system. Time domain simulations are used to study the performance of the power system and the BES system. Results reveal that BES meets sudden requirements of real power load and is very effective in reducing the peak deviations of frequencies, tie‐power, time errors and inadvertent interchange accumulations. Copyright © 2000 John Wiley & Sons, Ltd.     

基于热泵群灵活控制的电热微网联络线功率分层协同平抑策略

为有效平抑电热微网的联络线功率波动,提出一种基于热泵群灵活控制的电热微网联络线功率分层协同平抑策略,即根据热泵启停控制与功率调节控制的特点,灵活运用两种控制方式使热泵群有效参与微网联络线中低频波动功率的平抑。建立含蓄热水箱的热泵群模型,并将波动功率协调分配层分频后的波动功率平抑目标在热泵与超级电容间分配;由热泵群优化控制层分析热泵群优先度序列,通过模拟退火算法优化启停方案,同时调节热泵动态运行功率;最后调节超级电容出力平抑剩余波动。算例结果表明,该策略能有效优化微网电热能流,平抑联络线波动功率,提升微网运行可靠性。     

A line outage study for prediction of static voltage collapse

A simple but useful technique is proposed to study steady-state line outage and hence voltage collapse of the system. Voltage collapse prediction can be performed through the study of line outages, though techniques for nodal-based prediction or critical-node identification are frequently proposed. Experimentally, it was proven that both line outage and system voltage collapse take place simultaneously. In fact, line outages can be treated as the secondary cause of voltage collapse. A scalar index called line-stability index for each line is calculated based on the power flow through the line. The line-stability index may have a value that varies from zero (no power flows through the line) to one (maximum power flows through the line). Any line exceeding the maximum limit of stability index (1.00) can cause system-wide voltage collapse. The proposed technique is tested on a six-bus standard test system, and encouraging results are observed. The results obtained indicate that the technique has the potential to be used as a tool for system monitoring and future load planning     

A stochastic method for battery sizing with uninterruptible-power and demand shift capabilities in PV (photovoltaic) systems

This paper presents a stochastic simulation using Monte Carlo technique to size a battery to meet dual objectives of demand shift at peak electricity cost times and outage protection in BIPV (building integrated photovoltaic) systems. Both functions require battery storage and the sizing of battery using numerical optimization is popularly used. However, the weather conditions, outage events and demand peaks are not deterministic in nature. Therefore, the sizing of battery storage capacity should also be based on a probabilistic approach. The Monte Carlo simulation is a rigorous method to sizing BIPV system as it takes into account a real building load profiles, the weather information and the local historical outage distribution. The simulation is split into seasonal basis for the analysis of demand shifting and outage events in order to match the seasonal weather conditions and load profiles. Five configurations of PV (photovoltaic) are assessed that cover different areas and orientations. The simulation output includes the predicted PV energy yield, the amount of energy required for demand management and outage event. Therefore, consumers can base sizing decisions on the historical data and local risk of outage statistics and the success rate of meeting the demand shift required. Finally, the economic evaluations together with the sensitivity analysis and the assessment of customers’ outage cost are discussed.     

A firm-level analysis of outage loss differentials and self-generation: Evidence from African business enterprises

This study examines the outage loss differential between firms that engage in backup generation and those that do not. Unmitigated outage losses were estimated to be US$2.01–23.92 per kWh for firms engaging in self-generation, and range from US$1.54 to 32.46 per kWh for firms without self-generation. We also find that firms engaging in self-generation would have suffered additional 1–183% outage losses had they not invested in self-generation. On the other hand, firms without self-generation would have reduced their outage losses by around 6–46% if they had engaged in self-generation. Further analyses, however, reveal that, although engagement in self-generation reduced outage losses, a firm engaging in self-generation may still suffer a greater unmitigated outage loss relative to a firm without a backup generator. The relative outage losses depend on the relative vulnerability of the operations of the two sets of firms to power interruption, and the relative generating capacity of a self-generating firm to its own required electricity loads. Policy reforms that allow firms, whose operations are highly vulnerable to outages, to make a binding contract with utilities in order to get preferential supply are recommended.