Power Quality Improvement in Grid-connected Photovoltaic–Fuel Cell Based Hybrid System Using Robust Maximum Power Point Tracking Controller

This article addresses power quality improvement in a 3-Φ grid-connected photovoltaic–fuel cell based hybrid system using hybrid filter topology. In the context of the extraction of maximum power due to the uncertainty of solar insolation and temperature in the hybrid system, backstepping control is addressed for the DC-DC boost converter. A space vector pulse-width modulation control technique is implemented for the voltage source inverter for the grid integration objective. Compensation of the distorted waveform at the point of common coupling is accomplished by a suitable controller design using the hybrid filter. The series of simulation results in MATLAB environment (The MathWorks, Natick, Massachusetts, USA) followed by prototype experimental validation reflects the superiority of the proposed controllers to achieve power quality improvements.     

Frequency Stabilization for Multi-area Thermal–Hydro Power System Using Genetic Algorithm-optimized Fuzzy Logic Controller in Deregulated Environment

Abstract—This article develops a model of load frequency control for an interconnected two-area thermal–hydro power system under a deregulated environment. In this article, a fuzzy logic controller is optimized by a genetic algorithm in two steps. The first step of fuzzy logic controller optimization is for variable range optimization, and the second step is for the optimization of scaling and gain parameters. Further, the genetic algorithm-optimized fuzzy logic controller is compared against a conventional proportional-integral-derivative controller and a simple fuzzy logic controller. The proposed genetic algorithm-optimized fuzzy logic controller shows better dynamic response following a step-load change with combination of poolco and bilateral contracts in a deregulated environment. In this article, the effect of the governor dead band is also considered. In addition, performance of genetic algorithm-optimized fuzzy logic controller also has been examined for various step-load changes in different distribution unit demands and compared with the proportional-integral-derivative controller and simple fuzzy logic controller.     

A Robust H∞ Controller Based Gain-scheduled Approach for the Power Smoothing of Wind Turbine Generator with a Battery Energy Storage System

Output power fluctuation of the wind turbine generator is a serious issue for power systems. The battery energy storage system is installed to the power system to solve this problem. However, the large battery energy storage system can increase the capital cost of the wind turbine generator system. Hence, the capacity of the battery should be reduced as much as possible. This article presents an H_∞ based control method for the output power smoothing method of the wind turbine generator by using a battery energy storage system. The output power fluctuation of the wind turbine generator is considered in the frequency domain. Low-frequency fluctuations are smoothed by pitch angle control of the wind turbine generator, while high-frequency variations are smoothed by charge or discharge of the battery energy storage system, respectively. The battery energy storage system’s capacity and mechanical stress of wind turbine blades can be reduced by the proposed method. In addition, the gain-scheduled control theory is applied to the pitch angle control system of the wind turbine generator. Therefore, the robust control performance for high non-linearities of the wind turbine generator model can be achieved. The effectiveness of the proposed method is validated by numerical simulations.     

Application of Hybrid Differential Evolution–Grey Wolf Optimization Algorithm for Automatic Generation Control of a Multi-Source Interconnected Power System Using Optimal Fuzzy–PID Controller

This paper deals with an optimal hybrid fuzzy-Proportional Integral Derivative (fuzzy-PID) controller optimized by hybrid differential evolution–Grey Wolf optimization algorithm for automatic generation control of an interconnected multi-source power system. Here a two area system is considered; each area is provided with three types of sources namely a thermal unit with reheat turbine, a hydro unit and a gas unit. The dynamic performance of the system is analyzed under two cases: with AC tie-line and with AC-DC tie-line. The efficiency and effectiveness of the proposed controller is substantiated equally in the two cases. The sturdiness of the system is proved by varying the values of the system parameters. The supremacy of the recommended work is additionally ascertained by comparison with the recently published results like differential evolution optimized PID Controller and hybrid Local Unimodal Sampling-Teaching Learning based Optimization (LUS-TLBO) optimized fuzzy-PID controller. The dynamic performance of the system is observed in terms of settling time, peak overshoot and peak undershoot. Finally the analysis is extended by applying the proposed control technique in two different models namely (i) A three area unequal thermal system considering proper generation rate constraints (GRC) and (ii) A three area hydro-thermal system with mechanical hydro governor. These test results reveal the adaptability of the proposed method in multi-area interconnected power system.     

Design of an Improved Nonlinear H∞ Control for UPFC to Enhance Transient Stability of Power System

An improved nonlinear (IN) H_∞ control of unified power flow controller (UPFC) is investigated and designed in the power system by using the Hamiltonian function method. First, the dissipative Hamiltonian structure of the UPFC system is established by means of variable transformation. Then, based on the obtained dissipative Hamiltonian structure, an IN H_∞ control is put forward. Simulation results on the two-area four-machine power system demonstrate the effectiveness and robustness of the IN H_∞ control in comparison with that of feedback linearization control (FLC) and add-on self-tuning (ST) control. The research results show that the IN H_∞ control has better performance than the two other controls.     

Power System Operation and Control in Restructured Era

Mohammad Shahidehpour (F'01) is Bodine Professor and Chairman in the Electrical and Computer Engineering Department at Illinois Institute of Technology (IIT). He is the author of 300 technical papers and four books on electric power systems planning, operation, and control. His books include Maintenance Scheduling in Restructured Power Systems, Kluwer, May 2000; Restructured Electrical Power Systems, Marcel Dekker, June 2001; Market Operations in Electric Power Systems, John Wile…     

Fixed-boundary-layer Sliding-mode and Variable Switching Frequency Control for a Bidirectional DC–DC Converter in Hybrid Energy Storage System

In this paper, a soft switching DC–DC converter is presented for a hybrid energy storage system (HESS) in an electric vehicle (EV), using fixed boundary layer sliding mode control (FBLSMC) and variable switching frequency modulation. This strategy is aimed at improvement of the transient performance, energy transfer efficiency and system robustness for the HESS which is composed of a battery, an ultracapacitor (UC) and a bidirectional DC–DC converter. The state-space model of such DC–DC converter is firstly established involving all operating modes and system uncertainties. The FBLSMC scheme is proposed for the satisfactory voltage/current tracking despite system uncertainties. It can guarantee the system robustness and avoid the chattering existing in conventional sliding mode control (CSMC). In order to ensure the soft switching under transient load variations, a variable switching frequency modulation method is introduced into the controller. Finally, experimental results confirm that (1) within the full-load range the efficiency of the DC–DC converter with variable switching frequency is ～96% in contrast to 90% efficiency at hard switching, and (2) the energy delivered by the UC follows the reference closely for EVs.     

Reduced-order design of Robust H∞ Controller for an Inertial Stabilized Aerial Platform

The uncertainty disturbance is one of the main disturbances that seriously influences the stabilization precision of an aerial inertially stabilized platform (ISP) system. In this paper, to improve the stabilization precision of the ISP under disturbance uncertainty, a robust H∞ controller is designed in this paper. Then, the reduction order is carried out for high-order controllers generated by the robust H∞ loop shaping control method. The application of the minimum implementation and balanced truncation algorithm in controller reduction is discussed. First, the principle of reduced order of minimum implementation and balanced truncation are analyzed. Then, the method is used to reduce the order of the high-order robust H∞ loop shaping controller. Finally, the method is analyzed and verified by the simulations and experiments. The results show that by the reduced-order method of minimum implementation and balanced truncation, the stabilization precision of the robust H∞ loop shaping controller is increased by about 10%.     

Functional Predictive Control for Voltage Stability Improvements of Autonomous Hybrid Wind–Diesel Power System

This study investigates the application of the model predictive control technique for voltage stability of an isolated hybrid wind–diesel power system based on reactive power control. The proposed generation system mainly consists of a synchronous generator for a diesel-generator system and an induction generator for a wind energy conversion system. A static VAR compensator is used to stabilize load voltage through compensating reactive power. Two control paths are used to stabilize load bus voltage based on model predictive control. The first control path is used to adjust the total reactive power of the system by controlling the static VAR compensator firing angle. The second is proposed to control the excitation voltage of the synchronous generator. Model predictive control is used to determine t optimal control actions, including system constraints. To mitigate calculation effort and reduce numerical problems, especially in a large prediction horizon, an exponentially weighted functional model predictive control (F-model predictive control) is applied. The proposed controller was tested through step change in load reactive power plus step increase in input wind power. The performance of the proposed system with the proposed controller was compared with classical model predictive control; moreover, this scheme is tested against parameter variations.     

Booming up of the Electric Power System in Central China

Ⅰ.The situation of geography and economy in Central ChinaregionThe Central China region covers Henan,Hubei,Hunan andJiangxi four provinces.Its total area amounts to 730,000 squarekilometers with a population of about 238 million and possess culti-vable land of 16.82 million hectares.This region is one of the im-portant productive bases of grains,cotton and edible oil.     

Investigation on Development of Condition-Based Maintenance in Power Supply System

Introduction The trend of equipment maintenance from emergency repair and periodic maintenance to condition-based maintenance is in- evitable. Only alongside the rise of understanding level and the development of science and technology, can it be possible…     

EMS Supporting System for Dispatching Automation in Northeast Power Network

1.DistributedRunTimeEnvir0nmentDistributedruntimeenvir0nmentaimsatprovidingthedistributedruntimeenvironmentofthehighefficiency.reliability.locationtransparencyfortheusers.Onthebasisofabidingbyopensystemstandard.accordingtotheobjectorientedidea-theenvironmentisdesignedanddonebymeansofevent-drive,whichprovidesamechanismfordevelopment.maintenanceandoperationwithaclearinterface,aflexib1econstruction,freearrangementandreliableoperationfortheapplicati0nsystem,ultimateusers.developingstaffandotherse…     

Unbalanced Load Simulation of Electronic Power Transformer in Distribution System

Introduction Electronic Power Transformer (EPT) is also called as power electronic transformer , solid-state transformer or electronictransformer.Itisakindofstate-of-the-arttransformer emerging from the development of high-power electronic technology.This…     

Design and Implementation of a Class of Robust H ∞ Control for Stability Enhancement in Power Systems

The paper presents a method of designing a class of robust H X generator excitation controller in a power system. The proposed controller is utilized to damp inter-area oscillations and enhance power system stability. The robust controller design procedure for a linear composite system is presented in terms of positive definite solutions to modified algebraic inequalities. The resulting controller guarantees closed-loop stability and an H X -norm bound on disturbance attenuation. The effectiveness of the H X controller is demonstrated through digital simulation studies on a two-machine system. The digital simulation studies are conducted using a PSCAD/EMTDC software package. The simulation results show that the controller contributes significantly to the damping of inter-area oscillations and the enhancement of power system stability during disturbances.     

Analytical Comparison of Static and Dynamic Reactive Power Compensation in Isolated Wind–Diesel System Using Dynamic Load Interaction Model

This article presents static and dynamic reactive power compensators together for a self-excited induction generator and synchronous generator based isolated hybrid power system. Reactive power is required for excitation of the induction machine and for load under steady-state and transient state operations in an isolated hybrid power system. For small perturbation of load reactive power and input wind power, the use of a dynamic compensator alone may give better voltage stability but at a high cost; in contrast, the static compensator reduces the cost on compromising with the voltage stability. The proper rating selection of both compensators used may give the optimum solution between the voltage stability as system performance and cost of compensation. The fixed costs and voltage profiles are compared for the different participations of the fixed capacitor bank and STATCOM. The interaction of the dynamic load model is also introduced to make the system more reliable and hence a new power balance equation is derived. A 10% step disturbance in the dynamic load model as well as wind power input is considered for the system study. Four different cases designed for unique participation of static and dynamic reactive power compensators are presented. The analytical comparison is based on cost, rating selection, and voltage stability under transient condition.     

2.85 billion yuan gross profit realized in East China Power System

In2000, the East China Power Corporation under the auspicesof the State Power Corporation together with Shanghai, Jiangsu,Zhejiang and Anhui three provincial and one municipal powercompanies have completed electricity sales of 200 TWh andrealized a gross profit of 2.85 billion yuan in 2000, in which 780million yuan realized by Shanghai, 810 million yuan by JiangsuProvince, 510 million yuan by Zhejiang Province, 210 millionyuan by Anhui Province and 540 million by East China powerCorpor…     

Practice and Prospect of AC/DC Hybrid Power Grid in Southern China

China Southern Power Grid is a unique EHV AC/DC hybrid transmission network that operates in China. In its service area, the distribution of energy resources and the development of economy are extremely unbalanced, so long-distance and bulk power transmission are needed; besides, the geography and climate conditions are serious, rains, fogs, lightning and typhoon as well as high temperature are common all the year round. Facing these challenges, the power grid enhanced stability control, improved the equipment and strengthen the network structure. In the future, the power grid plans to optimize the disposition of power sources and build digitalized power system.     

Realization of UPQC H∞ coordinated control in Microgrid

Aiming at the complicated power quality problems with the coexistence of voltage quality and current quality in Microgrid, a comprehensive regulation technology of power quality is urgently needed, which makes unified power quality conditioner (UPQC) have widespread application fields. As a multiple power quality conditioner, UPQC gathers the functions of voltage quality compensator, current quality compensator and energy storage device in the integrated manner, meeting the needs of comprehensive power quality control for the Microgrid. In this paper, the advanced H_∞ control theory is adopted for further development on the UPQC generalized controlled system, and the Riccati solution method of the H_∞ controller is presented. Through analyzing the coupling effect between UPQC series unit and shunt unit, a design method of UPQC coordinated controller based on H_∞ control theory is proposed. The simulation and experimental results show that the proposed method can realize UPQC series unit voltage tracking compensation and shunt unit current tracking compensation simultaneously without steady-state phase shift and amplitude degradation. Moreover, the proposed method radically eliminates the coupling effect between UPQC series unit and shunt unit, and realizes the multiple power quality coordinated control functions of UPQC.     

Review of relaying protection sessions in International Conference on Power System Technology in China 1991

There were two sessions and onepanel discussion on relaying pro-tection at the conference,with participantsfrom Australia,Canada,Japan,Korea,arepresentative of the well known relaymanufacturer ABB and from the host coun-try China.The papers presented at thesessions covered a large variety of subjectsrelated to protection,including novel pro-tection principles and schemes,computer     

Review of some of the papers in 1991 International Conference on Power System Technology

Introduction The 1991 International Conference on Power System Tech-nology was held on September 13-17 in Beijing. About 200 technicalpapers were presented in 36 sessions in the conference and bunchedinto the conference publication. The paper covered wide variety ofmodern power system techniques and categorised into the followingmajor subjects: