A New Phase Sequence Exchanging Control Method for Reducing Impulse Current and Voltage

Abstract

Phase sequence exchanging technology (PSET) is a recently developed emergency control technology for out-of-step power systems. The PSET system does not satisfy the condition of synchronization however, and will produce impulse current and impact torque. In this paper, the impulse current and impact torque produced by PSET are calculated. Taking the three-phase short circuit at the generator outlet as a reference, the impulse current generated by PSET is determined to be less than half of the threephase short circuit at the generator outlet, which is within the system's endurable range. When the system connection reactance is 0.543 times larger than generator direct axis sub-transient reactance, it can endure the impact torque produced by PSET. To reduce the impact and improve the practicability of PSET, a splitphase switching control method is proposed in this paper. The characteristics of fast breaking are utilized to turn off the solid-state circuit breaker separately when the three-phase current is at zero-crossing, and after exchanging the phase sequence, it is turned-on separately when two sides of the three-phase voltage are equal. An example is provided to verify that the impact of PSET can be dramatically reduced by using the proposed control method instead of the traditional simultaneous switching control method. INDEX TERMS Phase sequence exchange technology, impulse current, impact torque, split-phase switching control method.

An optimal phase control method for the suppression of phase sequence exchange impulse current and voltage

“…Taking phase A as an example, Figure 13 exhibits the waveforms of the measured and calculated values of the phase-A and phase-C voltages and the closing pulses when the number of FIGURE 12 The current waveforms and opening pulses of Exp. II FIGURE 13 The voltage waveforms and closing pulses of Exp. II The same principle can be applied for phases B and C, and will therefore not be repeated here.…”

“…Ref. [13] calculated the impulse current and torque generated by PSE, and defined the conditions under which the system can sustain the PSE impulse, and proposed split-phase control can suppress the impulse to a certain extent. At present, there are many different phase control methods have been proposed to suppress the impulse current caused by component access or removal, such as that for the reduction of the impulse current of a three-phase transformer [14][15][16][17][18].…”

The impact of phase sequence exchange on relay protection and its resolution schemes

“…Ref. [7] analyzed the influence of the installation position of the PSE device on the stability control effect. At present, the relay protection system covers the entire line.…”

Design and test of a novel power electronic device for phase sequence exchange technology

“…In previous research [10] , the mechanism of improving system stability via PSE was described, and the PSE technology was verified by using the one-machine infinite bus (OMIB) system as an example. In another previous work [11] , the conditions under which the system can endure PSE were determined; a PSE control mode of split-phase switching control, which greatly reduces the impact of PSE, was also proposed. In yet another existing study [12] , the installation position of a PSE device in a multi-machine system was proposed and its application was discussed.…”