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Inrush current during the charging of coupling transformer in ±800kV UHV(Ultra high voltage) DC(Direct-Current) converter station, will make the converter AC(Altenative-Current) bus voltage distortion and trigger harmonics in DC system. The harmonics are dominated by the second and the third harmonic. Harmonic will lead to DC voltage, current and power fluctuations, especially DC voltage fluctuation...
Traditional methods usually use the quasi-steady state model with simplified assumptions for HVDC system analysis, which cannot take voltage distortion into account. The impact of occurrence instant of AC fault on critical commutation voltage is analytically derived and the possibility of commutation failure (CF) is analyzed. However, the complexity and nonlinearity of the single- and multi-infeed...
Electromagnetic transient (EMT) simulation is one of the routine tasks being executed in modern power systems. Typically, the most common EMT simulation method is the trapezoidal integration method, however, sustained numerical oscillations are possible to appear using this method, for instance, getting the voltage waveform across an inductance during a sudden current interruption. Two-stage diagonally...
Traditional transformer models assume that the tap positions only influence the turns ratio when studying power system load flow, electromagnetic and electromechanical simulations. It is found that the original parameters of transformers, such as the winding resistances and inductances, also vary with different tap positions. An inductance matrix model for transformers is proposed in this paper, based...
To solve the contradiction between UHV transmission line's over-voltage limitation strategy and its reactive power compensation strategy, China plans to apply controllable shunt reactors in its UHV system. The paper briefly introduces the UHV power transmission system using controllable shunt reactors. The structure and basic operating principle of the controllable shunt reactors is described. Through...
AC Half-Wavelength transmission in UHV stage is an alternate for the long distance and large capacity power transmission. The transient working condition of UHV circuit breakers for UHV Half-Wavelength transmission lines is different with that for normal AC transmission lines. In this paper, a study model of Half-Wavelength line transmission system was established based on China's present UHV lines...
A conventional four-legged shunt reactor serving untransposed extra-high voltage or ultra-high voltage transmission lines may cause the secondary arc difficult to extinguish and result in single-phase autoreclosing (SPAR) failure. This paper proposed an unbalanced shunt reactor (USR) scheme and focuses on the secondary current analysis with respect to untransposed extra high-voltage/ultra-high voltage...
An aggregation method of wind farm considering electromagnetic transient process is given and verified. It includes doubly-fed (wind turbine generators)WTGs, converter-driven WTGs and squirrel cage WTGs with same and different parameters. Simplifications are analyzied. For the aggregation WTG, main parameters of its control and protection system need to be amended besides the main circuit values....
In this paper, the transmission-line theory based fast algorithm for voltage distribution along the UHV transmission line with series capacitors is proposed. Firstly, the two-port transmission parameter matrix of UHV transmission lines is transformed to the two-port node admittance matrix, therefore, the lumped parameters of strict equivalent π model for UHV transmission line is obtained. Secondly,...
In order to study the working condition of UHV circuit breakers and determine the parameters of the transient recovery voltage (TRV) for the test of UHV circuit breakers, this paper investigated the prospect transient recovery voltages (TRV) of UHV circuit breakers in the Huainan-Wannan-Zhebei-Huxi UHV double circuit transmission system. The TRVs of UHV circuit breaker after interrupting breaker terminal...
State Grid Corporation of China plans to build the Huainan-Wannan-Zhebei-Huxi UHV double-circuit transmission project and install series capacitors (SCs) in Huainan-Wannan transmission lines. During the circuit breakers clearing system faults on series compensated transmission line, the transient recovery voltage (TRV) of circuit breaker may be increased due to the impact of series capacitor. If there...
By using EMTP, this paper analyzes effect of various factors on power frequency overvoltage during rejecting load in UHV double-circuit transmission system with serious compensation. They include system structure, source capability, scale of power flow, line's operation mode (double-circuit and single-circuit), and compensation degree of series compensation device and its bypassing situation. Based...
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