A Current Control Scheme for a Bi-Directional AC-DC Power Converter with Power Factor Correction by Using FLC for DC Micro Grid
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Secondary controllers for hydrothermal multisource hydraulic systems (MSHS) have been built in this chapter using PDICs and FLCs. Two control areas are linked by a tie line, and each control area includes both hydroelectric and thermoelectric energy systems. Conventional controllers are unable to manage the frequency and power oscillations caused by a load that changes with time and load. A proportionally dual integral controller and a fuzzy logic controller have been designed to stabilize the switching frequency and enhance the dynamic characteristics of a multi-area, multi-source hydro thermal system.In this paper, use of the additional supplementary damping controller for unified power flow controller (UPFC) to damp out low frequency oscillations in a heavily loaded power system is investigated. Normal damping controllers are inferior when the power system is subjected to large and fast changing loads. In order to handle the situation, an additional supplementary damping controller for UPFC is designed using Fuzzy logic technique. The effectiveness of the proposed controller on damping low frequency oscillations is tested and demonstrated through simulation studies for single machine connected to infinite bus power system (SMIB). In addition power system response with UPFC damping controller & Fuzzy logic based supplementary damping controller (FLSDC) are compared at various loading conditions. It can be concluded that Fuzzy logic based supplementary damping controller improves greatly the system stability under heavily loaded conditions.
Open-loop controller
Damping torque
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This paper proposes an explicit adaptive controller to damp oscillations and to enhance the single machine infinite bus SMIB stability. Owing to the increasing requests for renewable energy and operating conditions, the identification for power systems has been increased recently. Changes in the power system parameters cause to use an explicit self-tuning control. The controller structure consists of combined on-line identifier and a feedback controller as PID and a radial basis function neural network (RBFNN) which acts as an adaptive power system stabilizer for SMIB. An adaptive linear neural network (ADALINE) depending on the input and output of open loop system is employed as on-line model identification to mimic on-line the SMIB output. The difference between SMIB and the identified model responses is used to adjust the ADALANN model weights on-line depending on a recursive least squares principle RLS and a recursive least square with adaptive directional forgetting RLSMadf. The particles swarm optimization (PSO) beside RLS and RLSMadf assess the weights of (RBFNN) and coefficients of PID controllers depending on the on-line ADALINE model weights. The proposed controller is validated with several operating conditions under various disturbances. The simulation results show the proposed controller whose parameters depend on on-line tuning techniques provides better performance than a conventional PID controller.
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Line (geometry)
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A new decentralized nonlinear voltage controller for multimachine power systems is proposed in this paper. The nonlinear n-machine power system model is first linearized and decoupled over the whole operating region by using the direct feedback linearization (DFL) technique. Then a decentralized nonlinear voltage controller is developed by use of the robust control theory. Performance of the proposed controller in a three-machine example system is simulated. The simulation results show that both voltage regulation and system stability enhancement can be achieved with this proposed controller regardless of the system operating conditions.
Feedback linearization
Linearization
Decentralised system
Voltage controller
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This paper proposes an effective stalbe interconnected system model to maintain stable frequency into an interconnected power system combining three areas through automatic generation control (AGC). The proposed system is formulated by two different controllers, such as, Integral controller based AGC model (ICAGC) and PID controller based AGC model (PIDAGC) that are individually applied to a common interconnected system model. The major technique is to incorporate three different PID controllers in this system. The aim of the consideration is to be achieved an effective stable interconnected power system. According to our knowledge, no one has considered before such PIDAGC model for an interconnected system combining three areas. For evaluations of the proposed models, an interconnected power system is simulated by MATLAB Simulink. The simulation results are compared with that of existing model and found that our results are better in terms of frequency deviation and settling time.
Automatic Generation Control
Settling time
System model
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A model of two-area interconnected power system is established to analyse the theory of static synchronous series compensator(SSSC) in load frequency control.The SSSC frequency controller uses a first-order controller,which is equipped with a lead-lag compensator.The state equation of system is derived based on the linear processing of the two-area system.By using overlapping decomposition to decouple the control system to obtain the damping ratio of the control system,the objective function of the SSSC frequency controller can be designed.Then the controller parameters are optimized by using the improved genetic algorithm.The good performance of the system obtained from simulation demonstrates that the SSSC frequency controller can not only reduce the peak of frequency fluctuation,but also can damp out inter-area low-frequency oscillation efficiently.
Lead–lag compensator
Low-frequency oscillation
Automatic Generation Control
Oscillation (cell signaling)
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In this paper, an H/sub /spl infin// controller, based on the standard H/sub /spl infin// control design approach, is proposed for power system load-frequency control with system parametric uncertainties. The variation bounds of power system parameters are obtained by changing parameters by 30% to 50% simultaneously from their typical values. The proposed H/sub /spl infin// controller is effective and can ensure that the overall system is asymptotically stable for all admissible uncertainties. The simulation results show that for the example system the proposed H/sub /spl infin// load-frequency controller can achieve good performance even in the presence of generation rate constraint.< >
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Power System Stabilizer controller (PSS) and Static Var Compensator (SVC) with damping controller can effectively damp power system oscillations. In order to eliminate the adverse effects between controllers caused by improper setting of parameters, coordination control of PSS and SVC is studied in this paper using bacterial colony chemotaxis (BCC) optimization algorithm, to improve dampings of electromechanical oscillation modes. Case study based on Two-Area with Four-Machine System, in both eigenvalue analysis and time domain simulation, confirms that the method is valid, and the simulation result shows that the optimal scheme obtained by method proposed in this paper can effectively damp low frequency oscillation and enhance the system small signal stability.
Static VAR compensator
Low-frequency oscillation
Oscillation (cell signaling)
Stabilizer (aeronautics)
Damp
SIGNAL (programming language)
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In an interconnected multi-area power system, as a power load demand varies randomly, which results in the variation of frequency, thus leading to load frequency control problem (LFC). The main goals of Load Frequency Control (LFC) are, to hold the frequency and the desired power output in the interconnected power system at the scheduled values and to control the change in the tie-line power flow between control areas. This research involves the load frequency control is done by PI and PID controller, which is a conventional controller. In order to overcome drawbacks, a new Genetic Algorithm-based controller is presented to quench the deviations in the frequency and the tie-line power due to different load disturbances. The proposed controller guarantees the stability of the overall closed-loop system. Simulation results for a real three-area power system prove the effectiveness of the proposed LFC and show its superiority over a classical PID controller and a PI controller.
Frequency deviation
Tie line
Open-loop controller
Load regulation
Automatic Generation Control
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This paper deals with load frequency control of interconnected power system before and after the deregulation. In this work single area and two area concepts is considered. The major intention of Load Frequency Control is to sustain the power performance of electric generator within a specified area, due to which alters in frequency of the system and tie-line loading. Thus, Load Flow Controller assists in sustaining the frequency of the system and tie-line power performance with other areas within their specified limits. Mostly LFCs are initially comprises of an integral and PID controller. The gain of the controller is building put to a value that gives better response among fast transient recovery and low overshoot in the performance of the entire power system. The major focus of this dissertation work is on the controller to achieve good output frequency performances. LFC's for every area are mostly designed based on accessibility of frequency fluctuation of every area and tie line power fluctuation between areas. The proposed controller guarantees the stability of the overall closed loop system. Simulation responses for a real two-area power system confirm the usefulness of the proposed LFC and proved its superiority without using controller. So by using MATLAB simulation tools a method is proposed for fine tuning of integral controller.
Overshoot (microwave communication)
Automatic Generation Control
Open-loop controller
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This paper presents a mathematical formulation of a centralised controller for damping the unwanted oscillations in power systems. The proposed approach assumes a linearised model of the power system around an operating point and makes intensive use of the eigenstructure of the state matrix. The proposed algorithm accurately computes the unstable and poorly damped modes and determines the system components most involved in these critical modes, and damps all undamped modes simultaneously in an acceptable time. Simulation results in a two-area power system indicate that all unwanted oscillations due to a 1% step load change are damped when the controller is used. Validity and effectiveness of the proposed controller are demonstrated by comparing the obtained results with results of previously reported approaches
Operating point
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