Resilient Fixed-Order Distributed Dynamic Output Feedback Load Frequency Control Design for Interconnected Multi-Area Power Systems

The paper proposes a novel H∞ load frequency control(LFC) design method for multi-area power systems based on an integral-based non-fragile distributed fixed-order dynamic output feedback(DOF) tracking-regulator control scheme. To this end, we consider a nonlinear interconnected model for multiarea power systems which also include uncertainties and timevarying communication delays. The design procedure is formulated using semi-definite programming and linear matrix inequality(LMI) method. The solution of the proposed LMIs returns necessary parameters for the tracking controllers such that the impact of model uncertainty and load disturbances are minimized. The proposed controllers are capable of receiving all or part of subsystems information, whereas the outputs of each controller are local. These controllers are designed such that the resilient stability of the overall closed-loop system is guaranteed. Simulation results are provided to verify the effectiveness of the proposed scheme. Simulation results quantify that the distributed(and decentralized) controlled system behaves well in presence of large parameter perturbations and random disturbances on the power system.

Robust H_∞ Load Frequency Control of Multi-area Power System With Time Delay:A Sliding Mode Control Approach

This paper is devoted to investigate the robust H∞sliding mode load frequency control(SMLFC) of multi-area power system with time delay. By taking into account stochastic disturbances induced by the integration of renewable energies,a new sliding surface function is constructed to guarantee the fast response and robust performance, then the sliding mode control law is designed to guarantee the reach ability of the sliding surface in a finite-time interval. The sufficient robust frequency stabilization result for multi-area power system with time delay is presented in terms of linear matrix inequalities(LMIs). Finally,a two-area power system is provided to illustrate the usefulness and effectiveness of the obtained results.

Ant Lion Optimization Approach for Load Frequency Control of Multi-Area Interconnected Power Systems

This work proposes a novel nature-inspired algorithm called Ant Lion Optimizer (ALO). The ALO algorithm mimics the search mechanism of antlions in nature. A time domain based objective function is established to tune the parameters of the PI controller based LFC, which is solved by the proposed ALO algorithm to reach the most convenient solutions. A three-area interconnected power system is investigated as a test system under various loading conditions to confirm the effectiveness of the suggested algorithm. Simulation results are given to show the enhanced performance of the developed ALO algorithm based controllers in comparison with Genetic Algorithm (GA), Particle Swarm Optimization (PSO), Bat Algorithm (BAT) and conventional PI controller. These results represent that the proposed BAT algorithm tuned PI controller offers better performance over other soft computing algorithms in conditions of settling times and several performance indices.

Load Frequency Control of Multi-interconnected Renewable Energy Plants Using Multi-Verse Optimizer

A reliable approach based on a multi-verse optimization algorithm(MVO)for designing load frequency control incorporated in multi-interconnected power system comprising wind power and photovoltaic(PV)plants is presented in this paper.It has been applied for optimizing the control parameters of the load frequency controller(LFC)of the multi-source power system(MSPS).The MSPS includes thermal,gas,and hydro power plants for energy generation.Moreover,the MSPS is integrated with renewable energy sources(RES).The MVO algorithm is applied to acquire the ideal parameters of the controller for controlling a single area and a multi-area MSPS integrated with RES.HVDC link is utilized in shunt with AC multi-areas interconnection tie line.The proposed scheme has achieved robust performance against the disturbance in loading conditions,variation of system parameters,and size of step load perturbation(SLP).Meanwhile,the simulation outcomes showed a good dynamic performance of the proposed controller.

Regional Coordination for under Frequency Load Shedding

Frequency deviation can be used as an indicator of imbalance between supply and demand. When generation is insufficient, it can cause frequency decline in a power system operation. Implementing under frequency load shedding (UFLS) is one of the common methods to overcome this problem. This paper proposes a novel approach for adaptive load shedding. The concept is an extension of shared and targeted load shedding using reserve margin. The optimal system configuration is then selected from those candidates to fulfill operational objectives. Operational constraints related to system parameters, threshold frequency, total of load shed and control area including line capacity are considered. An example using four sub-areas connected to an external system shows that the proposed regional coordination as an adaptive UFLS is feasible.

风电场参与电网调频的多机协同控制策略

【目的】考虑风电场中不同风况下风电机组参与一次调频能力的差异,在下垂控制和惯量控制策略的基础上,对机组的调频能力评估方法进行优化。【方法】提出了一种改进的多机组调频参考功率协同控制策略。【结果】引入多机组协同控制方法能够有效改善机组之间调频参考功率的分配,从而有效调节各机组参与系统一次调频的程度。在惯量控制和下垂控制的基础上引入改进的协同控制策略,依据机组在实际风况下运行的状态,评估机组能够有效参与一次调频的参考功率。引入调频能力系数能够实现调频功率参考值在各机组之间按能分配。【结论】协同控制策略能够有效保护风电机组转速,同时能够有效改善电网频率响应。

多风电场支撑电网频率稳定的动态差异化时序协同控制策略

针对大规模风电接入带来的系统调频能力不足和调频能量透支引发的频率二次跌落问题,提出一种多风电场动态差异化时序协同的频率支撑控制策略。首先,阐述综合惯量控制下的风电调频原理,基于能量守恒理论分析频率响应阶段风电场群的动能变化过程,揭示多风电场调频时序对调频效果的影响机理。然后,考虑多风电场群同时调频引发的频率二次跌落风险,从场站交互视角逆向设计风电场群调频时序和任务分工,并依据风电实时调频能力动态调整投入顺序,以保证初期过程惯量安全需求,并提升频率最低点、抑制风电场群退出调频导致的系统频率严重二次跌落。最后,通过3机9节点测试系统和某实际电网算例对所提控制策略进行仿真分析,结果验证了所提策略的有效性和实用性。

考虑火电运行平稳性的飞轮储能辅助二次调频控制策略

为解决电网波动剧烈导致的火电机组运行平稳性问题,提出一种考虑火电运行平稳性的飞轮储能辅助二次调频控制策略。首先,建立了超超临界火电机组联合飞轮储能的二次调频控制模型;其次,提出了一种基于多层变增益速率限制的AGC指令非线性分解方法;最后,综合机组平稳性和系统AGC性能设计了适应度函数,借助鲸鱼优化算法(WOA)实现了最优化的速率限制算法参数获取。基于上述方法设计了火储协同二次调频控制策略。以某1000 MW火电机组-飞轮储能联合系统为例进行了仿真验证。结果表明:所提控制策略在不影响系统调频性能的前提下可以使联合系统有效响应系统高频指令,减小了火电机组的动作幅度,提升了机组运行的平稳性。

风电场与多分布式变速抽水蓄能协同调频控制

针对单个变速抽蓄调频容量不足和风电场调频后转子转速恢复容易引发频率二次跌落的问题,提出一种风电场与多分布式变速抽水蓄能协同调频控制策略。首先,当电网发生频率事件时,该策略根据风电场风速和区域内多分布式变速抽水蓄能可调节容量对电网频率提供支撑。然后,针对风电调频后转子转速恢复过程容易引发系统频率二次跌落的问题,在风电转子转速恢复时通过多分布式变速抽蓄提供功率支撑来缓解系统频率二次跌落。最后,以含风电场与分布式变速抽蓄的四机两区域系统为例,通过Matlab/Simulink仿真验证了所提控制策略相比风电场和多分布式变速抽水蓄能独立调频对于系统具有更好的调频效果。

Frequency Regulation of VSC-MTDC System with Offshore Wind Farms

Frequency regulation of voltage source converter-based multi-terminal high-voltage direct current(VSC-MTDC)system with offshore wind farms enhances the frequency stability by compensating the power for a disturbed AC system.However,it is difficult to reasonably allocate frequency-regulation resources due to a lack of coordination mechanisms between wind farms and the MTDC system.Moreover,it is difficult for the frequency control of the wind farms to manage changes in wind speed;and the risk of wind-turbine stalls is high.Thus,based on the kinetic energy of wind turbines and the power margin of the converters,the frequency-regulation capability of wind turbines is evaluated,and a dynamic frequency-support scheme considering the real-time frequency-support capability of the wind turbines and system frequency evolution is proposed to improve the frequency-support performance.A power adaptation technique at variable wind speeds is developed;the active power in the frequency-support stage and restoration stage is switched according to the wind speed.A hierarchical zoning frequency-regulation scheme is designed to use the frequency-regulation resources of different links in the MTDC system with wind farms.The simulation results show that the novel frequency-regulation strategy maintains frequency stability with wind-speed changes and avoids multiple frequency dips.

考虑频率死区的储能单元协同控制策略

新能源并网比例的不断攀升降低了电力系统惯量,导致系统调频能力下降。为此,开展了储能参与调频的研究。储能参与调频受到单元数量、荷电状态(state of charge,SOC)、充放电策略等因素影响,提出一种考虑频率死区的储能单元协同控制策略,根据SOC一致性对储能单元进行分组,不同组别单独执行下垂控制或虚拟惯量控制,简化出力控制指令。依据系统频率偏差或频率变化率进行控制指令切换,并分别设置频率偏差和频率变化率死区,以减少小扰动干扰导致储能系统频率充放电。基于Matlab/Simulink进行仿真验证,结果表明:所提控制策略简单便于执行,能够快速响应调频需求,并且能保证储能电池使用寿命。

储能用户多市场协同响应服务优化模型

储能是推动能源向绿色低碳转型和提高电力系统安全运行的重要支撑。文章利用电力物联网平台对储能的数据和信息进行实时监控和分析,为储能用户提供更智能、高效的管理方式。针对储能用户在电力市场环境下如何参与多样化交易的问题,在研究弃风弃光量调控的同时,将储能用户参与的交易范围扩展至新能源消纳方面,建立了储能用户同时参与能量市场、调频辅助服务市场和备用辅助服务市场的协同响应服务优化模型,并以用户的最大收益为目标进行了优化。通过对算例中3个方案的仿真分析,验证了该模型及方法的可行性和经济性。

Demand response for frequency control of multi-area power system

Over the last few years, lots of attentions have been given to the demand response(DR) for the frequency control. DR can be incorporated with traditional frequency control method and enhance the stability of the system. In this paper, the frequency control strategy of DR for a multiarea power system is specially designed. In order to quickly stabilize the frequency of different areas, the tie-line power is adopted as the additional input signal of DR. To get the optimal parameters of the control system, the frequency control problem is formulated as a multi-objective optimization problem, and the parameters such as the integral gains of secondary frequency control, the frequency bias parameters, and coefficients of DR are optimized. Numerical results verify the effectiveness of the proposed method.

大规模风电经LCC-HVDC送出的送端电网频率协同控制策略

针对大规模风电经电网换相型高压直流(LCC-HVDC)送出的送端电网所面临的严峻高频问题,充分挖掘风电潜在调频能力,提出一种风电与直流频率限制器(FLC)参与送端电网调频的协同控制策略.分析直流FLC参与送端电网调频的响应特性,刻画送端电网频率与风电机组功率的下垂关系,设计风电机组变转速与变桨距角相结合的一次调频控制方法.建立包括常规机组一次调频、风电机组下垂控制和直流FLC的频率响应综合模型,结合电网的频率稳定要求,采用灵敏度方法整定风电机组与直流FLC的调频参数,设计风电与直流FLC共同参与的频率协同控制策略.算例仿真结果表明:所提频率协同控制策略可有效降低高频切机、直流过载运行风险,提高送端电网的频率稳定性.

基于频率偏差的VSG变惯量阻尼协同控制策略

虚拟同步发电机(virtual synchronous generator,简称VSG)能提高电力系统稳定性.传统同步发电机机械参数固定,而VSG的转动惯量和阻尼系数可根据不同应用场景选择合适的值,因而改善系统稳定性.为了避免因引入与频率微分成正比的函数而产生的高频噪声,提出一种基于频率偏差的VSG变惯量阻尼协同控制策略.仿真分析结果表明:相对于固定参数控制策略、Bang-bang控制策略,该文控制策略当输入功率突变时,在调节时间少量增加的情况下能更有效地减小有功功率超调量,有更小频率偏差,能更好地抑制频率变化率.

面向灾后电力应急通信系统的多AP协作功率控制技术

为解决重大自然灾害发生后灾区电力系统的应急通信问题,近年来出现了利用Wi-Fi结合北斗技术的解决方案.如何增大系统覆盖能力、数据传输能力、用户承载能力,增强系统部署便宜性、灵活性是该应急通信系统面临的核心挑战.针对灾后电力应急通信系统上述核心需求,本研究基于第7代Wi-Fi多接入点(access point, AP)协作通信技术,提出一种协作式功率控制技术:增加无线接入过程中用户类型,并调整部分协议帧结构,具化相关字段用于指示新增用户类型;结合软频率复用技术设计了频谱资源分配算法和AP中心功率控制算法.仿真结果表明,与现有Wi-Fi系统多AP协作技术和软频率复用技术相比,所提算法有效提高了数据传输能力;与现有多AP协作技术相比,在用户承载能力相近条件下,可提高信号覆盖范围.

基于改进灰狼优化算法的多区域频率协同控制

微分博弈理论可以解决多区域互联电力系统中频率的协调问题,但对于带非线性约束的微分博弈问题,传统算法难以求解。针对该问题,基于微分博弈理论,建立了多区域频率协同控制模型,考虑了电力系统中常见的非线性约束,并提出了一种基于改进灰狼优化算法的协同进化算法,用于求解该模型的反馈纳什均衡解,从而得到各区域二次调频的协同控制策略。通过仿真验证了所提方法的可行性,并与协同进化遗传算法和协同进化灰狼优化算法进行了对比,结果表明该方法的控制效果更佳。同时,所提方法对系统的功率扰动变化具有稳定的动态响应性能,对机组参数变化具有良好的鲁棒性。

基于PCS变主从协同控制的微电网平滑离网技术

当微电网由并网模式进入离网模式时,储能变流器和光伏逆变器采用传统控制方式可能会造成微电网系统振荡、储能系统过充和过放的问题。采用储能变流器和光伏逆变器并联运行的微电网结构,通过分析微电网各电源出力情况,提出一种在微电网离网时刻,考虑储能系统荷电状态(State of charge,SOC)的变主从协同控制策略,即将主从控制、对等控制、分层控制的优势结合起来,实现储能变流器在二次调压调频的下垂控制和PQ控制间灵活切换,实现微电网的平滑离网,防止储能系统过充和过放。最后搭建仿真模型,对所提方法的有效性进行验证。

Sliding mode controller design for frequency regulation in an interconnected power system

In this paper, a Sliding mode controller design method for frequency regulation in an interconnected power system is presented. A sliding surface having four parameters has been selected for the load frequency control (LFC) system model. In order to achieve an optimal result, the parameter of the controller is obtained by grey wolf optimization (GWO) and particle swarm optimization (PSO) techniques. The objective function for optimization has been considered as the integral of square of error of deviation in frequency and tie-line power exchange. The method has been validated through simulation of a single area as well as a multi-area power system. The performance of the Sliding mode controller has also been analyzed for parametric variation and random loading patterns. The performance of the proposed method is better than recently reported methods. The performance of the proposed Sliding mode controller via GWO has 88.91% improvement in peak value of frequency deviation over the method of Anwar and Pan in case study 1 and similar improvement has been observed over different case studies taken from the literature.

电解铝负荷响应下的源网荷协同频率二次控制

针对新能源大量接入背景下电力系统频率调节能力紧张、旋转备用不足的问题,提出一种“源网荷”协同的二次调频策略。通过柔性直流输电(voltage source converter-high voltage direct current,VSC-HVDC)系统将拥有丰富可控资源的电解铝工业电网与传统电力系统互联,建立考虑VSC-HVDC功率支援的两端互联系统二次调频模型。基于互联系统频率控制模型构建分布式架构,在两端设计模型预测控制器,控制器在本区域内进行优化控制,定期进行信息交互,主动调节电解铝负荷功耗进行需求响应,减轻由功率支援引起的送端系统功率不平衡。最后以我国西部地区某工业电网的实际数据进行仿真验证了所提出策略的有效性。结果表明,在大扰动场景下,所提出的策略可以将受端系统频率恢复时间缩短约30%,同时在调控过程中,送端系统频率偏差始终保持在0.05 Hz以内,且电解铝负荷与VSC-HVDC系统参数始终处于安全范围内。