In this paper, a fuzzy excitation controller based on wide-are measurement system (WAMS) is built, in which the voltage deviation and its rate are introduced as the input of main-controller, while the deviation and co...
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ISBN:
(纸本)0863412467
In this paper, a fuzzy excitation controller based on wide-are measurement system (WAMS) is built, in which the voltage deviation and its rate are introduced as the input of main-controller, while the deviation and corresponding rate of local generator's frequency and center-of-inertia frequency are acted as the input of the second controller to indicate the global information. The multi-machines system model is firstly set up with MATLAB/PST. Then the digital simulation is conducted to compare the influences of PID excitation controller and fuzzy excitation controller based on WAMS on the transient stability. Results show that applying the fuzzy excitation controller proposed in this paper, the ability to endure serious disturbances can be strengthened and transient stability can be improved.
Because the compensation signals of DVR are unpredictable, this paper advanced a deadbeat control algorithm for DVR voltage waveform tracking compensation. On the basis of state equations and state variables informati...
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ISBN:
(纸本)0863412467
Because the compensation signals of DVR are unpredictable, this paper advanced a deadbeat control algorithm for DVR voltage waveform tracking compensation. On the basis of state equations and state variables information of the system, a specific scheme is produced to realize voltage waveform tracking compensation, which includes a state observer a voltage forecast and a current forecast for a random load. The switch control signals of next sampling period are calculated so that the output voltage can track the reference voltage synchronously. The simulation results show that this control algorithm is correct and feasible.
This paper analyzes characteristic harmonic currents of TCR and presents a method to reduce the harmonics by means of phase-shift transformer. It also introduces the constitution and implements methods of compensating...
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VSC-MTDC has attracted increasing attention because of its excellent characteristics. Its connection type is one of the key points in research works. Three basic connection types including Parallel, Series and Hybrid ...
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ISBN:
(纸本)0863412467
VSC-MTDC has attracted increasing attention because of its excellent characteristics. Its connection type is one of the key points in research works. Three basic connection types including Parallel, Series and Hybrid are analyzed and their characteristics are discussed in this paper. Through the analysis on VSC equations in dqO coordinate system, constant DC voltage PI controller and constant power PI controller are designed. On the basis of establishing MATLAB simulation models, the simulations of three connection types are conducted. Simulation results show that the proposed connection types of VSC-MTDC are feasible and the characteristics of them are verified.
Combining electricity market dynamic model proposed by Alvarado, this paper uses differential/algebraic equations and eigenvalue techniques to study the stability of electricity markets. The necessary and sufficient c...
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ISBN:
(纸本)0863412467
Combining electricity market dynamic model proposed by Alvarado, this paper uses differential/algebraic equations and eigenvalue techniques to study the stability of electricity markets. The necessary and sufficient conditions of judging electricity market stability and asymptotical stability are provided. As well as the sufficient conditions of judging electricity market unstable and asymptotical unstability is presented. The obtained conclusions removed the condition of Yang's with the assumption "the matrix is square and nonsingular" and other conditions. Using these stability conditions may directly judge the electricity market model stability by the initial data. In addition, the theoretical results in this paper can be used to reasonably explain the unable phenomena of electricity market proposed by Alvarado.
Asymmetric load is quite common in distribution network, the compensation of which is a serious problem under some situations. A novel integrated compensation method is put forward based on the principle of reactive p...
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Available transfer capability (ATC) determines the largest transfer that can be implemented in a certain direction across the power grid without violating security constraints. The uncertainties including load level, ...
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ISBN:
(纸本)0863412467
Available transfer capability (ATC) determines the largest transfer that can be implemented in a certain direction across the power grid without violating security constraints. The uncertainties including load level, aging and maintenance of elements and weather conditions, which have great influence on powersystem operation should be taking into account when calculating ATC. Considering time-varying nature and uncertainty of system parameters, the time-dependent model is adopted to describe the effects of weather conditions, aging and maintenance on element fault rates. Time-varying restoration time and load are modeled using random variables. The sequential simulation technique is applied to sample the system states, then based on linear programming and DC power flow ATC calculation is proposed. The algorithm based on MATLAB 6.5 is developed. IEEE 14-bus test system is used to verify the presented approach.
The power frequency over-voltage of EHV power transmission lines in three operating conditions, i.e., capacity effect of unloaded line, unsymmetrical faults and load shedding is analyzed. The shunt reactor's funct...
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ISBN:
(纸本)0863412467
The power frequency over-voltage of EHV power transmission lines in three operating conditions, i.e., capacity effect of unloaded line, unsymmetrical faults and load shedding is analyzed. The shunt reactor's function to restrain the power frequency over-voltage is analyzed theoretically. Different compensation ratios and installment positions of shunt reactors are simulated in three operating conditions of 750 kV transmission lines through the software ATP/EMTP. From the simulation results, it is found that the shunt reactors can restrain the power frequency over-voltage in three operating condition effectively and the magnitude of the power frequency over-voltage will be lower with the compensation ratio of the shunt reactor becoming larger. In addition, when the shunt reactor is switched at the terminal of the transmission line, its effect restraining the power frequency voltage is the best compared with other two modes of connection in unloaded line with single power supply, unsymmetrical faults and load shedding. The method of operation for the shunt reactor is also discussed in this paper. Along with the expansion of the system capacity and the line's transmitted power, the method of operation that the shunt reactor is switched off from the system needs to be considered according to the powersystem's operation condition.
This paper researches profoundly on the coordinated control of UPQC (Unified power Quality Conditioner). By analyzing the radical reasons of coupling effect between UPQC series unit and shunt unit, a simple and practi...
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This paper presents an approach to the detection of harmonics and reactive currents in single-phase circuit according to the orthogonal characteristic of sine function. The method is simple and practical, which cannot...
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