![<?echo $_SERVER['SERVER_NAME'];?>](/template/twentyseventeen/skin/images/header.jpg)
The voltage dip refers to the sudden drop of the voltage amplitude of the AC power system to an unacceptable level, which leads to the disconnection and collapse of the interconnected system. Voltage dips are an unstable condition that occurs when the system is overloaded. Because the load increases, the system voltage first changes slightly, then suddenly accelerates and decreases, eventually leading to system collapse. In the case of voltage dips, voltage control appliances, such as switching transformers, may be less voltage before the voltage drops suddenly. The change is within the allowable range and does not move. The slowing down may cause the undervoltage relay to operate before the transformer switches. In this way, the operator of the control center will not observe the alarm sound because the phase angle, frequency and voltage amplitude of the power system may remain within the normal range. Then the sudden drop of voltage caused the system protection device to act immediately, the interconnection system was dismissed, and the system immediately smashed.
In this paper, by introducing the perturbation of the load characteristic parameters, the voltage sags of the power system can be suppressed. The simulation shows that the perturbation suppression method is feasible.
1 System Model The power system model discussed in this paper is shown in the figure, which is based on the model studied by Dobson and Chiang. Dobson and Chiang applied this power system model to describe some of the dynamic characteristics of voltage dips. It can be regarded as the equivalent circuit of the local power system connected to the external large power system; the external large power system can be regarded as a bus with unlimited capacity, that is, a power source whose voltage amplitude and phase angle do not change regardless of the load size. In the figure, the terminal voltage amplitude and phase angle of the infinite bus are %° and 0.°, respectively, and 匕>0; the terminal voltage of the generator in the local system is 匕 can also be described as the guide of the transmission line. A generator, an infinite power bus, a load and a capacitor are connected. The terminal voltage of the load is used to maintain the voltage amplitude close to 1 unit. (The unitized model of Dobson and CWang is large. In the power system model, saddle branches occur when approaching 11.41 units.
The three-bus power system model 2 introduces the perturbation voltage dip characteristic suppression to introduce the perturbation in the load characteristic parameter r, and the simulation is obtained by the formula (1), which is obtained by using the initial value (0.350, 0.151, 0.150, 0.980). The load voltage of the system is related to time as shown in b. No voltage sags occurred when the time was 〖=5 000s. Near the point of collapse, by introducing perturbation, the system can operate stably, delaying or avoiding the occurrence of voltage dips.
=l, when no perturbation is introduced (b). 98, the time behavior of the load voltage at 0.980). This paper introduces the perturbation of the load characteristic parameter, which effectively suppresses the occurrence of voltage dip in the power system. The simulation results show the feasibility of the perturbation suppression method, which is effective for delaying or suppressing the voltage dip and system collapse of the power system. How to implement more effective control of chaotic phenomena in the power system, completely avoiding voltage dips and systems. The collapse has yet to be studied.
Formal Dresses,Cocktail Dresses,Semi Formal Gown,Corset Evening Gown
SHAOXING LIDONG TRADING CO.,LTD , https://www.lidonggarments.com