A New Technology Applied to Power System Stability Control: Phase Sequence Exchange Technology

Abstract

AC transmission systems are often affected by stability issues. During the design phase of such systems, their ability to cope with the various kinds of disturbance is taken into consideration, however, sudden large disturbances may still result in power angle instability, which can greatly increase the risk of an overarching power system break down. Therefore, the development of a safety protection system is a priority in the field of power system construction. In response to this problem, we propose a new exploratory solution strategy -Phase Sequence Exchange Technology (PSET). The PSET can be summarized as follows: when the power angle of an equivalent dual power supply system swings to a suitable angle between 90 • and 180 • , disconnect the primary side phase of the communication line by power electronic equipment and causing the swift misalignment of the connection. The A, B, C three-phase sequence then, connects to the three-phase C, A, B sequence. The PSET instantaneously realizes this change and reduces the power angle by 120 • , pulling the formerly increasing power angle back to a smaller angle and preventing the system from becoming imbalanced. In this paper, the mechanism which improves the stability of the PSET is explained by using the equal area rule. The threshold of the PSET work angle is determined by the energy function and the unbalanced potential energy in the system that can be effectively reduced by the PSET. Based on these findings, the phase trajectory method is used to determine the evaluation criteria for the PSET. This allows us to establish whether the PSET is effective by examining the state of the system after the fault is removed. Finally, an example is given in order to verify the effectiveness of the PSET and to prove that PSET is able to prevent the system from becoming imbalanced while still maintaining its structural integrity.INDEX TERMS Transient stability emergency control, phase sequence exchange technology, power electronic equipment, effective criterion.

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

“…Phase sequence exchange (PSE) is a recently developed emergency control technology in which a PSE device is utilized to disconnect the primary-side phase of the communication line, causing a swift misalignment of the connection [10] . The three-phase A, B, C sequence then connects to the three-phase C, A, B sequence and reduces the power angle by 120°, thereby changing the power angle back to a smaller angle and preventing the system from falling out-of-step while maintaining the structural integrity of the power grid.…”

“…The three-phase A, B, C sequence then connects to the three-phase C, A, B sequence and reduces the power angle by 120°, thereby changing the power angle back to a smaller angle and preventing the system from falling out-of-step while maintaining the structural integrity of the power grid. 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.…”

A simultaneous phase sequence exchange control method based on transient energy function

“…Phase sequence exchange (PSE) is a recently developed emergency control method. 17 The technique utilizes controllable power electronic components to create a PSE device in which the primary side phase of the communication line is disconnected by power electronic equipment, causing a swift misalignment of the connection. The A, B, C three-phase sequence then connects to the three-phase C, A, B sequence and reduces the power angle by 120 , thereby returning the power angle back to a smaller angle and preventing the system from becoming out of step.…”

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

“…Reference [1] presented a recently developed emergency control method, phase sequence exchange technology (PSET). This technique utilizes controllable power electronic components to form a phase sequence exchanging device, taking the system power angle as a control variable to realize a series of functions including fast interruption, phase sequence adjusting, and fast closing at the appropriate time.…”

“…Phase sequence exchange technology can prevent a system from becoming out-of-step, while still maintaining the structural integrity of the power grid. As detailed in [1], the PSET process begins when the power electronic device, consisting of solid state circuit breakers, disconnects the line. The phase sequence is then exchanged in turn, and the solid state circuit breaker is activated.…”