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.     

Analysis and Design of a Series–Parallel Uninterruptible Power Supply with an Improved Control Strategy for Seamless Transition

In this paper, a high-performance control structure is designed, implemented, and applied to a three-phase series–parallel uninterruptible power supply (UPS). This kind of UPS system provides input power factor correction, output voltage conditioning, and high efficiency. The control strategy proposed in this paper is based on voltage control of the parallel converter and current control of the series converter. It is shown that this strategy improves the system operation, specifically resulting in a smoother and more seamless transition between UPS operating modes. The controller in the proposed strategy is based on combination of two control methods with different characteristics and is therefore called a hybrid structure. To enhance the steady-state performance of the UPS and reach fast error convergence, a repetitive controller is used. In addition, to reach a fast transient response required for control of output voltage, a fast deadbeat is used. The stability of this hybrid controller is discussed, and the design procedure for a typical converter is given. For validation and verification of the theoretical analysis, both experimental and simulation results are shown.     

Optimal Nonlinear Robust Sliding Mode Control of an Excitation System Based on Mixed H2/H∞ Linear Matrix Inequalities

In this paper, an optimal nonlinear robust sliding mode control (ONRSMC) based on mixed H2/H∞ linear matrix inequalities (LMIs) is designed for the excitation system in a “one machine-infinite bus system” (OMIBS) to enhance system stability. Initially, the direct feedback linearization method is used to establish a mathematical model of the OMIBS incorporating uncertainties. ONRSMC is then designed for this model, employing the mixed H2/H∞ LMIs. The chaos mapping-based adaptive salp swarm algorithm (CASSA) is introduced to fully optimize the parameters of the sliding mode control, ensuring optimal performance under a specified condition. CASSA demonstrates rapid convergence and reduced likelihood of falling into local optima during optimization. Finally, ONRSMC is obtained through inverse transformation, exhibiting the advantages of simple structure, high reliability, and independence from the accuracy of system models. Four simulation scenarios are employed to validate the effectiveness and robustness of ONRSMC, including mechanical power variation, generator three-phase short circuit, transmission line short circuit, and generator parameter uncertainty. The results indicate that ONRSMC achieves optimal dynamic performance in various operating conditions, facilitating the stable operation of power systems following faults.     

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.     

Conference on Developing Stability Control Apparatus for Power Systems in China

A conference on developing stability control apparatus for power systemsecurity, sponsored by Ministry of Water Resources and Electtric Power,P. R. C., ended in Nanjing on January 19, 1985. The conference, composed     

Stability Analysis of Cascaded DC–DC Power Electronic System

Stability analysis of the cascaded dc-dc power electronic system is analyzed in this paper. For demonstration boost converter supplying, the hybrid switched capacitor converter considered as an example. The boost converter is acting as the bus converter, 42 V bus, while the switched capacitor converter is serving as the point of load converter. The two converters are provided with voltage-mode and peak current-mode controllers, respectively. Converter state-space, two-port network models are developed and then stability of the cascaded system has been analyzed. Cascaded system interaction effects, (i) source converter power handling capability with switching load and (ii) load converter interfacing capability with bus converter, are analyzed. Simulation and experimental results are provided for verification purpose. Copyright © 2009 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Frequency Regulation in Hybrid Power System Using Iterative Proportional-Integral-Derivative H ∞ Controller

This study considers frequency regulation in a hybrid power system consisting of conventional and distributed generation resources. The performance of two controllers—an H _∞ design via linear matrix inequalities and an iterative proportional-integral-derivative H _∞ via linear matrix inequalities—is assessed to maintain frequency deviation profile in acceptable limits. In the latter control design, the iterative linear matrix inequality approach is used to tune proportional-integral-derivative controller parameters subjected to H_∞ constraints in terms of the iterative linear matrix inequality. The efficacy of the control law and disturbance accommodation properties is shown. The robustness of these controllers is demonstrated in the hybrid power system with different load disturbance conditions, wind power, and parameter variations. Controller performance is compared with a suboptimal controller to demonstrate its superiority. It is found that the second controller design has satisfactory disturbance rejection properties and robustness against parameter variations over a wide range of conditions.     

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.     

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%.     

Design and Implementation of Adaptive Neuro–Fuzzy Inference System Based Control Algorithm for Distribution Static Compensator

This article focuses on the design and implementation of a distribution static compensator using an adaptive neuro–fuzzy inference system based controller. The distribution static compensator is controlled to provide power quality improvement, such as power factor correction, harmonics compensation, load balancing, and voltage regulation. Active and reactive power fundamental components of load currents are extracted using d-q theory. A distribution static compensator is realized using a voltage source converter. Both simulation and experimental results prove the effectiveness of the control algorithm under non-linear loads. The adaptive neuro–fuzzy inference system based controller works satisfactorily for power factor correction and harmonics reduction under balanced as well as unbalanced load conditions. Test results clearly depict the dynamics of the performance of the system under steady state as well as dynamics under load change and load unbalancing.     

Parallel Simulation of Power Systems Transient Stability Based on Implicit Runge–Kutta Methods and W-transformation

This paper presents a novel parallel algorithm for power systems transient stability simulation based on fully implicit Runge–Kutta (IRK) method. The s-stage IRK method is used to convert the differential-algebraic system simultaneously at s different time points into a set of non-linear algebraic equations, and the algebraic system is then solved by Newton's method. By the use of the matrix factorization technique, the solution of the linear equations involved in Newton's process is divided into two parts: the first part is decoupled at s different time points, thus it is fully parallelizable in time, and the second part is solved by preconditioned generalized minimal residual method (GMRES) method, while a new preconditioning method has been proposed by using the W-transformation and double-parameters method. For test, the proposed algorithm is implemented on multiple-graphics processing units (GPUs) computing platform. The results show that the proposed algorithm is accurate and has good convergence. Moreover, the parallel algorithm implemented on multiple-GPUs computing platform achieves high parallel efficiency.     

Development of Design for Circulating Water Intake Structure in Thermal Power Plant

SummaryThispaperintroducesthedesigndevelopmentinthefields0fcirculatingwater(C.W.)intakestructuredesignedbyEastChinaElectricPowerDesignInstitute(ECEPDI).Therearemanymethodssuchascaissonmeth0d,sinkingwellmethod,floatingcaiss0nmeth0d,andexterior-protectedconstructionfoundationmethodetc.f0rC.W.pumph0usedesign.Therearejackingsteelpipetunnel,jackingR.C.pipetunnel,shieIdtunnelandfl0atingpipetunneletc.f0rdesignofdiversionpipe.Thefl0atingcaiss0nc0nstructionofC.W.pumphouseisfirstusedinChina.1.…     

Research on Safety and Stability of Regional Power Grids to the Year 2020

The safety and stability study on Northeast, North, East, Northwest and Central China power grids had been carried out, which provided technical supports to planning design of regional power grids. By analyzing safety and stability under severe faults in regional power grids, revealed weaknesses on power grid configurations and measures for preventing from loss of stability were presented. In comparison of various schemes of power system safety and stability among parts of power grids, more than two recommended schemes can be chosen as reference in planning design for regional power grids. Considering the safety and stability control measures necessary for each power grids, it is believed the trunk networks of all power grids can fulfill the third criteria of Guideline for Power System Safety and Stability, while the weakness and predominated hydropower may deteriorate safety and stability of power grids. The power grid shall be regulated in line with the variation of boundary conditions.     

On the Application of Chinese Characters in Computerized Control Centres for Electric Power Systems

In modern power system opera-tion it is necessary to apply proce-ss computers for the management of the large information volume required as well as for the system cont rol.The question is studied, whether Chinese characters canbe directly used in man/machine intercommuni-cation under system operation conditions.This paper states the dif-ferent in-and output possibilities and examines their suitability and their advantages for this special problem.It proposes a control desk-scheme using a digitizing tablet. Some operation examples are de-monstrated.The paper shows that computer management of electric power systems using Chinese char-acters is feasible.     

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.     

The Contract for Entrusting Planning and Design of Jinshajiang First Phase Transmission System Project Signed

The Contract of Entrusting Planning and Design of JinshajiangFirst Phase Transmission System Project was signed in Beijingon 14th December 1999. The representative from ChinaYangtze River Three Gorges Development GeneralCorporation as the project owner and the representative fromthe State Power Corporation of China as the trustee havesigned the Contract.The middle and lower reaches of Jinshajiang is the largesthydropower base with favorable economic and technicalparameters in China. …     

New Stage of the Northwest China 330 kV Power System Development - A Brief Introduction of System Planning in Northwest China to the Year 2000

The system planning of the Northwest China 330 kV Power System from present to the year 2000 is introduced in this paper. Some technical problems arising from the system planning, such as network configuration, system stability and reactive power compensation etc. are also briefly summarized.     

Design of a 2-DOF-PID controller using an improved sine–cosine algorithm for load frequency control of a three-area system with nonlinearities

This paper proposes an improved sine–cosine algorithm (ISCA) based 2-DOF-PID controller for load frequency control. A three-area test system is built for study, while some physical constraints (nonlinearities) are considered for the investigation of a realistic power system. The proposed method is used as the parameter optimizer of the LFC controller in different scenarios. The 2-DOF-PID controllers are used because of their capability of fast disturbance rejection without significant increase of overshoot in set-point tracking. The 2-DOF-PID controllers’ efficacy is observed by examining the responses with the outcomes obtained with PID and FOPID controllers. The simulation results with the suggested scheme are correlated with some of the existing algorithms, such as SCA, SSA, ALO, and PSO in three different scenarios, i.e., a disturbance in two areas, in three areas, and in the presence of physical constraints. In addition, the study is extended to a four-area power system. Statistical analysis is performed using the Wilcoxon Sign Rank Test (WSRT) on 20 independent runs. This confirms the supremacy of the proposed method.