This paper proposes a high-powercontrollable voltage quality disturbance generator, which is composed of multiplex cascade H bridge modules, and simulates many types of voltage quality problems, such as voltage swell...
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This paper proposes a high-powercontrollable voltage quality disturbance generator, which is composed of multiplex cascade H bridge modules, and simulates many types of voltage quality problems, such as voltage swell and sag, fluctuation and flicker and so on. One side of the device connects the powersystem with cascade H bridge to improve voltage level. The other side connects the system directly to aviod the problems caused by series transformer, such as additional phase shifting and voltage drop. Cascade inverter H bridge modules and PWM rectifier H bridge modules are all controlled by triangular carrier phase shifting to increase the equivalent switching frequency of inverter to simplify the control. Finally, a 10 k V/2MVA controllable voltage quality disturbance generator has been created. The experiment result proves that the proposed main circuit topology, control strategy and Ether Cat-based controller are feasible and efficient.
The estimation of operating reserve to guarantee the systemsecurity and economic operation is an important task in powersystem operation. With the rapid increase of wind power installation and its large scale integr...
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The estimation of operating reserve to guarantee the systemsecurity and economic operation is an important task in powersystem operation. With the rapid increase of wind power installation and its large scale integration into powersystems, the uncertainty of wind power should be considered in operating reserve estimation. This paper discusses the risk from wind power forecast error and introduces the idea of wind power at risk. The total risk due to wind power forecast error is studied from two different aspects, and two sets of indices are proposed. Credibility theory is applied to get the comprehensive index which is used to estimate operating reserve. Numerical tests are done to compare the proposed approach with others. The results show that the proposed approach can give more economic operating reserve estimation without loss of systemsecurity, which may be a reference for the powersystems with large scale intermittent generation to estimate operating reserve.
dynamic economic dispatch (DED) is a high-dimensional, non-convex, multi-constrained optimization problem. With the increase of wind power penetration into powersystems, the DED problem becomes more difficult. In the...
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dynamic economic dispatch (DED) is a high-dimensional, non-convex, multi-constrained optimization problem. With the increase of wind power penetration into powersystems, the DED problem becomes more difficult. In the mathematical model, the constraints of wind farm output and spinning reserve are proposed to deal with the random and unpredictable nature of wind power. In the powersystem with large-scale wind farm, wind power should be adjusted according to available spinning reserve capacity. To improve the searching capability of binary differential evolution (BDE) algorithm, an adaptive adjusting strategy for control parameters is adopted. At the same time, the constraints are solved by some new strategies, which can make all the particles feasible, then searching efficiency is greatly improved. The presented method is proved effective by some numerical examples.
Studying the HVDC typical fault-the commutation failure and its protection measures will give some guidance for HVDC engineering,also,it will improve the AC-DC powersystem safety and reliability with great *** on the...
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Studying the HVDC typical fault-the commutation failure and its protection measures will give some guidance for HVDC engineering,also,it will improve the AC-DC powersystem safety and reliability with great *** on the analysis of commutation failure of HVDC,the article studies the effect of the commutation failure when the commutation buses have different kinds of AC faults on the base of CIGRE HVDC benchmark model,with the simulation of PSCAD/*** in-depth analysis of the causes of commutation failure,the type and characteristics of the fault will be done in this *** for the characteristics of HVDC system,combined with AC transmission relay protection tuning principle,conservation and protection action principle approach,are given to promoting HVDC transmission should take measures to return to *** simulation results show that the HVDC transmission recovers from commutation failure effectively after the fault is cleared due to the high controllability of the system and the reasonable protection strategies.
Loss of field protection is of great importance for the security of large-scale generators. With the development of large-scale generators and corresponding loss of field protection, the complicated structure leads to...
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ISBN:
(纸本)9781457710001
Loss of field protection is of great importance for the security of large-scale generators. With the development of large-scale generators and corresponding loss of field protection, the complicated structure leads to the high possibility of loss of field faults. According to the statistical data, more than sixty percentages of the synchronous generator faults are the excitation system faults, which might cause loss of load, tie-line tripping, instability, collapse and etc. Therefore, it is crucial to identify loss of field as early as possible and take countermeasures. In loss of field protection, the impedance boundary criterion of steady state stability limit is widely used to distinguish loss of field and normal condition. However, the steady state stability limit circle is affected by the system operating modes, which might result in mis-operation of the relay. In this paper, an approach for on-line identifying system equivalent impedance is presented based on PMU measurements. The steady state stability limit circle can be adaptively fit for operating modes. The computer simulation results demonstrate that the proposed method works well.
Real-time digital simulation has been widely used in powersystem analysis, which is becoming a very important tool to system planning, feasibility studies, and new equipment design, and the accuracy of real-time digi...
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Real-time digital simulation has been widely used in powersystem analysis, which is becoming a very important tool to system planning, feasibility studies, and new equipment design, and the accuracy of real-time digital simulation has great effects on the security and economic efficiency of powersystem operation. In this paper, residual similarity is calculated by average percentage error, and shape similarity is calculated by coefficient method. Accuracy assessment method of real-time digital powersystem simulation is proposed concerning the two similarity indexes from the static and dynamic perspective. During the assessment of similarity of two curves, both the residual error between the two curves and the similar extent of variation trend of the curves are considered, and the assessment result is helpful to model modification. Analysis based on measurement data of test occurring in a certain ultra HVDC transmission powersystem of China and the simulation results on RTDS is presented, which proves the validity of this method.
The fault in any complex systems is inevitable. Fault detection is an important area in systems engineering. Different solution techniques using qualitative, semi-quantitative and quantitative methods have been propos...
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dynamicsecurity region (DSR), which describing the transient stability of powersystem from the parameter space, has attracted a lot of attentions. However, there are few literatures concerning the impact of generati...
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dynamicsecurity region (DSR), which describing the transient stability of powersystem from the parameter space, has attracted a lot of attentions. However, there are few literatures concerning the impact of generation system model on the DSR. This paper focuses on the impact of generation system model including high order model of generator, excitation system, speed governor, on DSR, based on the extension of DSR theory from the powersystem with ordinary differential structure to the powersystem with differential-algebraic equation(DAE). The simulation results investigate impact of generation system, especially exciter magnitude and the governor system to DSR, i.e. DSR with different generation system model.
A novel scheme based on generalized leakage inductance (GLI) to distinguish the inrush current from the internal fault current in the power transformer is proposed. By eliminating the mutual flux linkage in the transf...
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ISBN:
(纸本)9781457710001
A novel scheme based on generalized leakage inductance (GLI) to distinguish the inrush current from the internal fault current in the power transformer is proposed. By eliminating the mutual flux linkage in the transformer loop equation and adopting the trapezoid principle, the GLI is calculated in the real time. According to the difference between the GLI and the leakage inductance obtained from transformer manufacturer, the criterion to identify the internal fault is developed. A total of 162 experimental cases have been tested and the proposed method is able to reliably and accurately discriminate internal faults from inrush currents with easy implementation. Also, the method is suitable if it is not possible to measure the currents in the delta winding. Furthermore, the method is independent of the B-H curve and iron losses.
This paper develops a systematic procedure of designing global powersystem stabilizers (GPSSs) based on collocated control to enhance the damping during interarea oscillations. The availability of remote signals from...
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ISBN:
(纸本)9781457710001
This paper develops a systematic procedure of designing global powersystem stabilizers (GPSSs) based on collocated control to enhance the damping during interarea oscillations. The availability of remote signals from phasor measurement units (PMUs) enables the wide-area control in large scale systems. The closed loop eigenvalues are excluded from a region of the complex plane by the collocated control algorithm guaranteeing that low frequency modes must be damped. The optimum locations for GPSSs were selected using controllability. The damping performance of a 16-machine, 68-bus study system reinforced with GPSSs is examined in the frequency and time domains. The simulation results show that the control scheme is able to damp out interarea oscillations following possible disturbances.
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