一种集中协调-实时分布控制的低频低压减载方法

低频低压减载是一种能有效防止电网电压崩溃的紧急措施。提出一种预先集中协调,实时分布控制的低频低压减载方案。基于独立低频低压减载装置构建分布式低频低压减载方案架构;采用负荷分层分区控制决定负荷切除量,实现站间、站内负荷的协调控制。通过仿真将低频低压减载方案与传统减载方案进行对比。结果表明,该方法能够提高切负荷精度,实现精准的负荷控制,降低稳控措施代价影响,加强电网的稳定性。     

考虑风火协同的电网低频减载在线整定策略

随着越来越多的新能源接入电网,电网的频率特性发生了显著变化,现有的低频减载整定策略难以适应现代高比例新能源电网安全稳定运行的要求。文章提出了一种考虑风火协同的电网低频减载在线整定策略。在考虑风电参与电网调频的条件下,分析了不同风火占比以及不同负荷水平下的系统频率动态特性,基于系统多运行方式下的离线低频减载优化计算,采用深度长短时记忆网络算法进行在线低频减载参数整定,并以区域电网为实际算例进行了计算分析。结果表明,在线电网低频减载参数整定策略对于多源联合调频的高比例新能源电网具有较好的适用性。     

计及负荷响应的电力系统低频低压联合减载方案

传统的逐轮次低压减载和低频减载相互独立,减载时未计及负荷的频率电压特性以及频率电压之间的相互影响,在严重扰动下可能因为欠切或者过切负荷而导致系统失稳。提出了一种基于响应的电力系统低压、低频联合减载方案,该方案将负荷有功的动态响应解耦为负荷母线频率和负荷电压的动态响应,依据实测得到的负荷电压响应与频率响应来计算低压减载量,再计及离线计算的低频减载量从而构成综合减载量。IEEE 39节点系统的仿真结果说明,该方法与传统逐轮次减载方法相比,能使受扰系统的频率和电压恢复得更好,有效地保障了电力系统的电压和频率稳定性。     

智能变电站站域低频减载

针对传统低频低压减载装置无法获取负荷的实时状态信息,不能实现精确切负荷,不能充分利用负荷自身调节作用的不足,提出了智能变电站站域低频减载的框架和实现方案。通过站域信息共享,准确获取负荷的实时信息;综合负荷的重要性、实际功率、单位停电损失和频率调节系数将低频减载问题转化为一个多目标优化问题,通过线性加权法将多目标优化问题转化为单目标优化问题。实例仿真验证了文中所提出的站域低频减载策略正确性和优越性。     

发电机模型的选取对低频减载分析计算的影响

针对频率变化的不同处理方式,分析了发电机模型的选取对低频减载分析计算结果的影响,表明发电机转子运动方程和定子绕组电压平衡方程都不及计频率变化的影响使低频减载分析计算结果偏于保守,发电机转子运动方程和定子绕组电压平衡方程都及计频率变化的影响使低频减载分析计算结果偏于乐观。通过在实际电网中比较不同发电机模型下的频率安全裕度和低频减载动作情况,证实了分析结论的正确性。     

750kV同塔双回交流输变电工程防雷保护研究

针对频率变化的不同处理方式,分析了发电机模型的选取对低频减载分析计算结果的影响,表明发电机转子运动方程和定子绕组电压平衡方程都不及计频率变化的影响使低频减载分析计算结果偏于保守,发电机转子运动方程和定子绕组电压平衡方程都及计频率变化的影响使低频减载分析计算结果偏于乐观.通过在实际电网中比较不同发电机模型下的频率安全裕度和低频减载动作情况,证实了分析结论的正确性.     

考虑风电频率响应的电力系统低频减载控制策略研究北大核心CSCD

大规模风电机组参与调频会对电力系统的频率稳定产生较大影响。传统低频减载控制策略的研究尚未考虑风电机组频率响应的影响,可能导致低频减载控制策略与传统火电、风电调频资源配置不合理。为此,文章提出一种考虑风电频率响应的电力系统低频减载控制策略。首先,基于风电虚拟惯性和一次调频控制模型,建立考虑风电参与调频的电力系统频率响应简化模型;其次,分析风电参与频率响应的有功响应特性对系统不平衡功率量的影响,进而精细化估算用于指导低频减载的不平衡功率量;最后,利用MATLAB/Simulink仿真平台对所提电力系统低频减载控制策略进行了仿真验证。     

当代变电站综合自动化发展趋向

随着当代计算机技术的广泛运用,电力系统也进入了微机控制时代,原老式常规变电站控制系统已远远不能适应当代电力系统的发展,综合自动化系统已逐渐取代传统的变电站二次系统,成为当前电力系统发展的趋势。变电站综合自动化系统,是变电站(所)自动化监控管理的重要设备,是集计算机技术、自动控制技术和通讯技术为一体的综合性电力装置,具有微机监测、监控、保护、小电流接地选线,故障录波、低频减载等功能,它改变了传统变电站(所)主控室、保护室的主体结构和值守方式,减少投资和减轻劳动强度,以便实现变电站(所)的自动监控、保护和提高供电质…     

适应新能源高占比系统的低频减载优化方法

该文介绍考虑低频减载反馈环节的改进频率响应模型,分析了传统低频减载方案在新能源高占比电力系统中的不足,提出一种基于频率变化率的多次加速减载的优化方法.在Matlab/Simulink中进行仿真,结果证明了优化方法的有效性.与传统低频减载方案相比,优化方案减载量更少,系统频率恢复更加快速稳定,在新能源高占比系统中具有更强...     

高新能源占比系统的低频减载优化方法

电网系统中大规模新能源的并网对电网的安全稳定提出新的挑战,在高新能源占比电网中,系统的第三道防线的适应能力对于系统的安全稳定尤为重要,低频减载是第三道防线中频率紧急控制的主要手段。该文介绍适用于低频减载整定计算的频率响应模型,在此模型的基础上分析得出传统低频减载方案对高新能源占比系统的适应性较差的结论,提出基于df/dt的低频减载闭锁优化策略。通过仿真对比验证所提方案的可行性与适应性。此种方案也可为低惯性的受端网络系统的频率稳定第三道防线的协调配置提供借鉴。     

Optimal dynamic load shedding policy for generation load imbalances including characteristics of loads

Modern electrical power systems are highly interconnected and heavily loaded. An emergency may occur as a result of a sudden increase in system load or unexpected partial or total outage of a generator. This paper presents an optimal dynamic load shedding policy for generation load imbalances. The effects of voltage and frequency characteristics of system loads, transmission lines, transformers and reactive power compensator are reported. Equality and inequality system constraints are also considered in the formulation of this nonlinear programming problem. The further effects of system average time constant, speed drop factor, load reduction ratio (load frequency sensitivity factor), system inertia, load shedding and spinning reserve are included. Furthermore a simple load distribution factor is considered in this algorithm. Results of the unified power system of lower Egypt have been presented to validate the algorithm and show its effectiveness. Copyright © 1999 John Wiley & Sons, Ltd.     

An automatic load shedding scheme including pumped-storage units

An automatic load shedding scheme considering the pumped-storage units at Taiwan Power Company (Taipower) is proposed in this paper. Taipower owns ten pumped-storage units which can be shed with higher priority when operated in pumping mode in order to restore the system frequency. In this way, the amount of customer load required to be shed can be significantly decreased. The system reliability and stability can also be enhanced. In the paper, a load frequency control model is developed. An automatic load shedding scheme that is adaptable to Taipower operation is thus developed. The proposed method has been validated through the utility data and compared with the utility shedding scheme. Test results solidify the feasibility and effectiveness of the proposed method for the applications     

计及风电功率误差的短期风电消纳评估

风电功率的短时大幅变化会对电网的可靠性与经济性产生影响,为更加准确地量化评估电力系统在较短时间内的风电消纳状况,需要考虑风电功率预测的误差。为此,基于风电预测误差的分布与自相关函数,生成风电预测误差时间序列,通过模拟实际系统的发电计划制定、自动发电控制、弃风、切负荷,计算可靠性指标与经济性指标,以此评估短期风电消纳状况。在IEEE 30节点系统上进行了不同预测误差分布参数以及AGC机组占比的仿真,从而验证了所提方法的有效性。     

Terminal voltage build-up and control of a DFIG based stand-alone wind energy conversion system

The paper presents the voltage build-up process and the terminal voltage control of a doubly-fed induction generator (DFIG) driven by a pitch controlled wind turbine for the supply of autonomous system without any auxiliary source. A control strategy for the complete system including voltage build-up phase is developed with a view to provide as well as possible the required power for load. Indirect stator flux-oriented vector control is proposed to keep the stator voltage constant by means of a back-to-back converter connected to the rotor side, while the management system is supported by the pitch angle and the load shedding controllers. A novel scheme for voltage build-up is presented, which requires no additional hardware support, and physical interpretation of how self-excitation can occur from residual magnetism in the machine core is examined. A reliable start-up process is accomplished by using an appropriate voltage reference ramp which enables minimizing energy loss during the starting. The proposed system is modeled and simulated using Matlab/Simulink software program to examine the dynamic characteristics of the system with proposed control strategy. Dynamic simulation results for different transient conditions demonstrate the effectiveness of the proposed control strategy.     

Optimization of load shedding system

An optimization algorithm is presented for an underfrequency load shedding system which is composed of several stages that are tripped at preset frequencies. The optimization of this system is considered with respect to a cost function that includes a dynamic part, which is the integral of the deviation from nominal frequency, and a static part which is the total load shedding. The optimization is constrained by the requirement of minimum allowed frequency and limitation on the total load of the shedding system. A projected gradient method is used for the solution, and analytic expressions for the partial derivatives are used to simplify the computation. Results of applying the optimization to a model of the Israeli power system are given together with a study of the cost parameters     

500 kV输电钢管塔的风雨激励分析

利用ANSYS软件建立了500 kV狮洋至五邑送电线路DZV674直线塔的有限元模型,研究了其动力特性,获得了前10阶自振频率,基于Kaimal脉动风速谱及线性自回归滤波器法（AR）模拟脉动风速时程原理,利用Matlab软件得到模拟脉动风速谱,在此基础上完成对雨荷载的模拟。并采用时程分析法分析了风单独作用与风雨共同作用下的动力响应,计算了输电塔的位移、轴力和弯矩。结果表明,在对输电塔的风雨激励分析中风荷载为主要设计荷载,但雨荷载对其影响也不可忽略。     

Load shedding scheme for an interconnected hydro-thermal hybrid system with SMES

The frequency of the power system varies based on the load pattern of the consumers. With continuous increase in the load, the frequency of the system keeps decreasing and may reach its minimum allowable limits. Further increase in the load will result in more frequency drop leading to the need of load shedding, if excess generation is not available to cater the need. This paper proposed a methodology in a hybrid thermal-hydro system for finding the required amount of load to be shed for setting the frequency of the system within its minimum allowable limits. The load shedding steps were obtained based on the rate of change of frequency with the increase in the load in both areas. The impact of superconducting magnetic energy storage (SMES) was obtained on load shedding scheme. The comparison of the results was presented on the two-area system.     

运用虚拟同步机技术的新型兆瓦级光-储并网结构

提出一种新型的VSG光-储分布式发电系统结构,该方案在传统光-储并网发电系统的逆变器后端另外添置了一套储能电池。这样不但可提高光伏组件的工作效率,避免光伏出力变化对系统频率造成影响,而且还可根据电网负荷的异常波动情况及时有效地输出有功及无功功率,达到稳定电网频率、电压的作用。系统的动态分析及仿真结果证明了该新型光-储并网发电系统结构能够实现新能源并网的目标与要求。