Neuro-Fuzzy Based Interline Power Flow Controller for Real Time Power Flow Control in Multiline Power System

This article investigates the power quality enhancement in power system using one of the most famous series converter based FACTS controller like IPFC (Interline Power Flow Controller) in Power Injection Model (PIM). The parameters of PIM are derived with help of the Newton-Raphson power flow algorithm. In general, a sample test power system without FACTs devices has generated more reactive power, decreased real power, more harmonics, small power factor and poor dynamic performance under line and load variations. In order to improve the real power, compensating the reactive power, proficient power factor and excellent load voltage regulation in the sample test power system, an IPFC is designed. The D-Q technique is utilized here to derive the reference current of the converter and its D.C link capacitor voltage is regulated. Also, the reference voltage of the inverter is arrived by park transformation technique and its load voltage is controlled. Here, a sample 230 KV test power system is taken for study. Further as the conventional PI controllers are designed at one nominal operating point they are not competent to respond satisfactorily in dynamic operating conditions. This can be circumvented by a Fuzzy and Neural network based IPFC and its detailed Simulink model is developed using MATLAB and the overall performance analysis is carried out under different operating state of affairs.

Small Signal Stability Analysis of DFIG Fed Wind Power System Using a Robust Fuzzy Logic Controller

This paper focuses on the small signal stability analysis of Doubly-Fed Induction Generator (DFIG) fed wind power system under three modes of operation. The system stability is affected by the influence of electromechanical oscillations, which can be damped using Power System Stabilizer (PSS). A detailed modeling of DFIG fed wind system including controller has been carried out. The damping controller is designed using fuzzy logic to damp the oscillatory modes for stability. The robust performance of the system with controllers has been evaluated using eigen value analysis and time domain simulations under various disturbances and wind speeds. The effectiveness of the proposed fuzzy based PSS is compared with the performance of conventional PSS implemented in the wind system.

A New Coordinated Fuzzy-PID Controller for Power System Considering Electric Vehicles

With penetration growing of renewable energy sources which integrated into power system have caused problems on grid stability. Electric Vehicles (EV) are one of the renewable energy sources that can bring significant impacts to power system during their charging and discharging operations. This article established a model of single machine infinite bus (SMIB) power system considering EV as a case study of load disturbance for power system oscillation. The objective of this research is to enhance stability and overcome the drawbacks of traditional control algorithms such as power system stabilizer (PSS), PID controller and fuzzy logic controller (FLC). The implementation’s effect of FLC parallel with PID controller (Fuzzy-PID) has been shown in this paper. The speed deviation (?ω) and electrical power (Pe) are the important factors to be taken into consideration without EV (only change in mechanical torque), EV with change in the mechanical torque and sudden plug-in EV. The obtained result by nonlinear simulation using Matlab/Simulink of a SMIB power system with EV has shown the effectiveness of using (Fuzzy-PID) against all disturbances.

STABILIZATION EFFECT OF MULTI-MACHINE POWER SYSTEM BY USING ADJUSTA BLE SPEED GENERATOR

This paper describes a stabilization effect after installating an adjustable speed generator (ASG) in a multi machine power system. A personal computer based ASG module has been de veloped for the simulations in parallel with the analog power system simulator i n the Research Laboratory of the Kyushu Electric Power Co. The three phase ins t antaneous value based ASG model has been developed in the Matlab/Simulink envir onment for its detailed and real time simulations, which have been performed on a digital signal processor (DSP) board with AD and DA conversion interfaces inst alled in a personal computer (PC). Simulational results indicate the hig hly improved overall stability of the multi machine power system after installa ting the ASG.

Fuzzy Logic Controller-based Synchronverter in Grid-connected Solar Power System with Adaptive Damping Factor

In recent years,renewable energy sources,specifically solar power systems,have developed rapidly owing to their technological maturity and cost effectiveness.However,its grid integration deteriorates frequency stability because of insufficient rotating masses and inertial response.Hence,a synchronverter,which is an inverter that mimics the operation of a synchronous generator,is crucial to interface solar power in a power grid.It stabilizes the power grid by emulating a virtual inertia.However,a conventional proportional-integral(PI)-based synchronverter is not equipped with an adaptive damping factor(Dp)or a digitalized smart controller to manage fast-responding solar inputs.Hence,a novel fuzzy logic controller(FLC)framework is proposed such that the synchronverter can operate in a grid-connected solar power system.In this study,Dp is controlled in real time using an FLC to achieve balance between speed and stability for frequency error correction based on frequency difference.Results of four case studies performed in Matlab/Simulink show that the proposed FLC-based synchronverter can stabilize the grid frequency by reducing the frequency deviation by at least 0.2 Hz(0.4%),as compared with the conventional PI-based synchronverter.

基于T-S模糊逻辑的混合储能孤岛直流微电网功率分配控制

在含混合储能的直流微电网中,传统阻容下垂控制无法解决由线路电阻和负荷功率波动导致的系统功率分配失衡问题。为此,提出一种基于Takagi-Sugeno(T-S)模糊逻辑的自适应阻容下垂控制方法以实现混合储能的分频分配。根据蓄电池和超级电容的物理特性,建立单个蓄电池支路输出电压、蓄电池组间输出功率差额和阻性下垂系数之间的T-S模糊逻辑关系,以及单个超级电容支路输出功率及其变化率、超级电容组间功率差额和容性下垂系数之间的T-S模糊逻辑关系,并由此构建基于T-S模糊逻辑的阻容下垂控制器。推导含混合储能的直流微电网中各部分的平均阻抗模型,并采用阻抗比分析法对微电网的小信号稳定性进行研究。MATLAB/Simulink仿真结果表明,基于T-S模糊逻辑的阻容下垂控制可保证在线路电阻和负荷功率波动情况下系统功率的合理分配。

Chaos control of the power system via sliding mode based on fuzzy supervisor

Purpose-The purpose of this paper is to address the problem of control in a typical chaotic power system.Chaotic oscillations cannot only extremely endanger the stabilization of the power system but they can also not be controlled by adding the traditional controllers.So,the sliding mode control based on a fuzzy supervisor can sufficiently ensure perfect tracking and controlling in the presence of uncertainties.Closed-loop stability is proved using the Lyapunov stability theory.The simulation results show the effectiveness of the proposed method in damping chaotic oscillations of the power system,eliminating control signal chattering and also show less control effort in comparison with the methods considered in previous literatures.Design/methodology/approach-The sliding mode control based on a fuzzy supervisor can sufficiently ensure perfect tracking and controlling in the presence of uncertainties.Closed-loop stability is proved using the Lyapunov stability theory.Findings-Closed-loop stability is proved using the Lyapunov stability theory.The simulation results show the effectiveness of the proposed method in damping chaotic oscillations of power system,eliminating control signal chattering and also less control effort in comparison with the methods considered in previous literatures.Originality/value-Main contributions of the paper are as follows:the chaotic behavior of power systems with two uncertainty parameters and tracking reference signal for the control of generator angle and the controller signal are discussed;designing sliding mode control based on a fuzzy supervisor in order to practically implement for the first time;while the generator speed is constant,the proposed controller will enable the power system to go in any desired trajectory for generator angle at first time;stability of the closed-loop sliding mode control based on the fuzzy supervisor system is proved using the Lyapunov stability theory;simulation of the proposed controller shows that the chattering is low control signal.

Optimal Design of Fuzzy-AGC Based on PSO&RCGA to Improve Dynamic Stability of Interconnected Multi-area Power Systems

Quickly getting back the synchronism of a disturbed interconnected multi-area power system due to variations in loading condition is recognized as prominent issue related to automatic generation control(AGC).In this regard,AGC system based on fuzzy logic,i.e.,so-called FLAGC can introduce an effectual performance to suppress the dynamic oscillations of tie-line power exchanges and frequency in multi-area interconnected power system.Apart from that,simultaneous coordination scheme based on particle swarm optimization(PSO)along with real coded genetic algorithm(RCGA)is suggested to coordinate FLAGCs of the all areas.To clarify the high efficiency of aforementioned strategy,two different interconnected multi-area power systems,i.e.,three-area hydro-thermal power system and five-area thermal power system have been taken into account for relevant studies.The potency of this strategy has been thoroughly dealt with by considering the step load perturbation(SLP)in both the under study power systems.To sum up,the simulation results have plainly revealed dynamic performance of FLAGC as compared with conventional AGC(CAGC)in each power system in order to damp out the power system oscillations.

Stabilization of Wind Farm by Using PMSG Based Wind Generator Taking Grid Codes into Consideration

This paper presents a new operational strategy for a large-scale wind farm (WF) which is composed of both fixed speed wind turbines with squirrel cage induction generators (FSWT-SCIGs) and variable speed wind turbines with permanent magnet synchronous generators (VSWT-PMSGs). FSWT-SCIGs suffer greatly from meeting the requirements of fault ride through (FRT), because they are largely dependent on reactive power. Integration of flexible ac transmission system (FACTS) devices is a solution to overcome that problem, though it definitely increases the overall cost. Therefore, in this paper, a new method is proposed to stabilize FSWT-SCIGs by using VSWT-PMSGs in a WF. This is achieved by injecting the reactive power to the grid during fault condition by controlling the grid side converter (GSC) of PMSG. The conventional proportional-integral (PI)-based cascaded controller is usually used for GSC which can inject small amount of reactive power during fault period. Thus, it cannot stabilize larger rating of SCIG. In this paper, a suitable fuzzy logic controller (FLC) is proposed in the cascaded controller of GSC of PMSG in order to increase reactive power injection and thus improve the FRT capability of WF during voltage dip situation due to severe network fault. To evaluate the proposed controller performance, simulation analyses are performed on a modified IEEE nine-bus system. Simulation results clearly show that the proposed method can be a cost-effective solution which can effectively stabilize the larger rating of SCIG compared to conventional PI based control strategy.

模糊电力系统稳定器的混沌优化方法

将混沌优化方法应用于模糊电力系统稳定器的参数设计 ,从而避免了设计过程中大量的参数调试工作 ,同时也使模糊电力系统稳定器获得最佳的控制性能。仿真结果表明 ,混沌优化方法结构简单、寻优速度快 。

基于神经网络逆系统的电力系统稳定器的研究

首先分析了具有PSS辅助励磁控制的单机无穷大系统的可逆性,在此基础上,以发电机功角为控制输出量,提出了一种基于神经网络a阶逆系统的电力系统稳定器(NNIPSS)的设计方案,为了增强伪线性系统的动态品质特性和鲁棒性,闭环辅助控制器采用Fuzzy-PID开关切换控制方式。将所设计的NNIPSS用于单机无穷大电力系统,并同常规PSS(CPSS)相比,仿真结果表明了其对于改善电力系统动态水平和暂态稳定的优越性和有效性。

电力系统强稳模糊稳定器

本文提出一种强稳模糊稳定器。它以发电机的转速偏移△ω、转速偏移一阶导数△ω以及二阶导数△ω作为输入信号，通过直接映射算法求出控制信号。仿真试验表明：它比只考虑△ω、△ω作为输入信号的模糊稳定器性能优越。

多机电力系统间接自适应模糊分散H_∞控制研究

针对多机电力系统励磁控制模型,考虑到系统的多变量、强耦合非线性等特性,提出了基于模糊逼近的间接自适应模糊分散H∞跟踪控制方案。该方案通过构建模糊自适应系统来逼近未知函数,然后设计H∞补偿器来抵消外部扰动和模糊逼近误差,从而实现了对多机电力系统的稳定性控制并且具有H∞性能。仿真结果表明,当多机电力系统发生三相可恢复故障和三相不可恢复故障时,发电机的转子运行角趋于某一固定值,相对转速和跟踪误差都趋于零。所提方案与电力系统稳定器(PSS)方案对比可知,PSS方案虽然能使系统稳定,但是其超调量大、过渡时间长,而所提方案不仅可以使系统在故障之后迅速稳定,而且超调量更小。

发电机变结构模糊逻辑稳定器

本文基于发电机速度和加速度相平面上的正态型模糊隶属函数以及控制和机端电压平面上的戒上型模糊隶属函数，提出了电力系统发电机的变结构模糊逻辑励磁稳定器．稳定信号不仅依赖于发电机运行的速度和加速度的状态，而且依赖于发电机端电压的实际状态。仿真分析表明，这种变结构模精逻辑稳定器不仅可以改善电力系统的稳定性，而且可以改善发电机端电压的调节精度。

基于模糊比例?微分控制的永磁直驱风电机组频率调节

在分析系统不同等效惯量和阻尼对电网频率影响的基础上,提出了基于模糊比例-微分(proportional differential,PD)控制的含飞轮储能单元的永磁直驱风电机组频率调节控制策略,以动态调节电网等效惯量和阻尼。建立了系统小信号稳定性模型,以确定模糊PD控制器的输出论域,并通过相应仿真验证了理论分析的正确性。通过对1台含飞轮储能单元的2MW永磁直驱风电系统进行仿真研究表明,所提控制策略能辅助电网频率调节,减小电网受扰动后的频率波动,有助于增强电网的频率稳定性。

启发式电力系统暂态稳定裕度在线评估方法研究

本文定义了一个能综合反映电力系统特定结构和运行方式下整体暂态稳定水平的连续指标：综合临界切除时间（ＧＣＣＴ）。结合知识库、模糊逻辑推理和综合技术，本文提出了一种能以较高精度在线估计ＧＣＣＴ值的暂态稳定估计（ＴＳＡ）方法。利用该方法推理过程的中间结果还能帮助确定系统中稳定裕度较低的部分机群。文章以一个７机电力系统为例，集中探讨了知识库和模糊推理模型的构造、ＧＣＣＴ的估计方法以及推理结果的综合分析等问题。

基于模糊逻辑的鲁棒电力系统稳定器设计

提出了一种基于模糊逻辑的鲁棒电力系统稳定器 (RPSS)的设计方法。将同步发电机的速度偏差及其变化率作为RPSS的输入信号 ,采用常规完全平方差(NSSD)指数来设计RPSS ,分析了将其应用于多机电力系统时的鲁棒性。在不同干扰下进行了非线性仿真实验 。

基于遗传算法的窄间距隶属函数在模糊逻辑电力系统稳定器设计中的应用

提出了一种简单、高效的模糊逻辑电力系统稳定器的设计方案,其特点是采用了窄间距隶属函数(SSMFs)。SSMFs是设计模糊逻辑控制器隶属函数的一种新方法。采用遗传算法选择SSMFs模糊逻辑控制器的最佳参数值,包括间距系数、重叠系数和增益系数等。通过单机无穷大系统验证所提方案的正确性。结果表明,所提出的SSMFs模糊逻辑电力系统稳定器在发电机负载和励磁增益大范围变化情况下,改善了电力系统的稳定性。

兼顾功角稳定的水电机组调节系统模糊滑模控制器的设计

水电机组调节系统对水电站的安全稳定运行起着关键的作用,不当的调节参数会弱化系统的阻尼,诱发水电机组功角振荡行为。为保证水电机组稳定运行,提出了一种兼顾功角稳定的模糊滑模控制策略。首先,考虑水力与机电系统暂态特性之间的相互影响,建立了包含弹性水击的水轮机内特性模型和三阶发电机模型的水电机组调节系统模型,并分析不同工况下系统的振荡特性。其次,通过将Δδ及ΔV_(t)引入滑模面函数,改善控制器输出对系统阻尼的影响,提升系统功角输出的稳定性。在此基础上,以系统机械功率为参考指标,设计了一种基于指数规律调整的变速趋近律,使收敛速度能够随工况变化及时调整。不同工况下的仿真结果表明,提出的控制律在系统受到功率扰动时,能够有效改善水电机组功角振荡行为,抑制系统低频振荡的发生,提高了系统的稳定性和控制器的鲁棒性。

舰载机动力补偿系统模糊逻辑设计技术

在舰载机迎角恒定动力补偿系统(Approach power compensator sysytem,APCS)研究的基础上,提出了一种采用模糊自适应PID控制参数整定方法,将模糊控制思想和PID控制技术有机地结合起来,实现了舰载飞机进场动力补偿系统智能化设计和PID参数在线自整定。该算法的另一个重要特点是省略了常规控制算法中法向加速度Δaz及舵偏Δδe两路信号反馈,仅利用迎角误差Δα及其变化率Δ.α进行反馈控制,简化了工程实现。最后,以国外某舰载飞机为研究对象,对它的动力补偿系统进行了设计和数字仿真。结果表明,该方法提高了舰载机的着舰精度,改善了系统的抗阵风干扰能力,提高了系统的鲁棒性。