KR-102964084-B1 - Detection Logic System for the Short Circuit of Generator Stator Winding

KR102964084B1KR 102964084 B1KR102964084 B1KR 102964084B1KR-102964084-B1

Abstract

The present invention relates to a generator stator winding short-circuit fault detection logic system for determining a winding short-circuit fault phase. According to the present invention, the system includes a negative sequence current detection unit that detects a negative sequence current and voltage fluctuation relative to a positive sequence; a voltage fluctuation detection unit that generates a signal when a certain ratio of phase voltage is maintained and transmits an operation signal to the negative sequence current detection unit; and a fault phase determination unit that detects a phenomenon in which the current of the winding short-circuit phase decreases and determines the winding short-circuit fault phase. By detecting the negative sequence current and voltage fluctuation relative to a positive sequence, the system has the effect of determining a winding short-circuit fault phase in which the current decreases significantly compared to the winding short-circuit fault phase when the conditions of phases A, B, and C are satisfied according to the voltage fluctuation.

Inventors

정필범
김순용
차지현
김태석
서동관

Assignees

한국수력원자력 주식회사

Dates

Publication Date: 20260511
Application Date: 20231215

Claims (5)

In a logic system for detecting a stator winding short-circuit fault of a generator, The above logic system is, A negative sequence current detection unit that calculates positive sequence current and negative sequence current by symmetrical component analysis of the input three-phase current, detects the negative sequence current and voltage fluctuation relative to the positive sequence current, and outputs an abnormal signal by determining it as a sign of fault when the negative sequence current relative to the positive sequence current exceeds 5%; A voltage fluctuation detection unit that generates an operation signal when at least one of the line voltages between each phase of a generator is maintained at a ratio greater than or equal to the phase voltage, and When the judgment conditions of the above-mentioned reverse sequence current detection unit and voltage fluctuation detection unit are satisfied, A generator stator winding short-circuit fault detection logic system characterized by including a fault phase determination unit that determines a fault phase by detecting a phenomenon in which the real-time phase current value of a phase leading in phase to the fault occurrence phase decreases based on the rated current.
In paragraph 1, A generator stator winding short-circuit fault detection logic system characterized by the above-mentioned reverse-sequence current detection unit transmitting the above-mentioned abnormal signal to the above-mentioned fault phase determination unit.
In paragraph 1, The above voltage fluctuation detection unit generates a signal when at least one of the line voltages between each phase of the generator is maintained at 90% or more of the phase voltage, and A generator stator winding short-circuit fault detection logic system characterized by transmitting the signal as a '1' signal to a negative sequence current detection unit when, with respect to the above signal generation, at least one of the line voltages between phase A-B, phase B-C, and phase C-A satisfies the condition that the signal is maintained at a certain ratio or higher than the rated voltage.
In paragraph 1, A generator stator winding short-circuit fault detection logic system characterized by the above fault phase determination unit determining the winding short-circuit fault phase by the phenomenon in which the phase current of the phase 120 degrees ahead of the winding short-circuit fault phase decreases.
In paragraph 1, The above fault determination unit compares the real-time phase current values of each of the A, B, and C phases, and A generator stator winding short-circuit fault detection logic system characterized by determining a phase 120 degrees ahead of the phase with the smallest current value as the fault phase when the phase with the smallest current value exists.

Description

Detection Logic System for the Short Circuit of Generator Stator Winding The present invention relates to a generator stator winding short-circuit fault detection logic system, and more specifically, to a generator stator winding short-circuit fault detection logic system for determining a winding short-circuit fault phase. Generators are critical equipment for supplying power by converting mechanical input energy into electrical energy. Among the electrical faults that can occur in a generator, a short circuit in the stator winding of a single phase is a phenomenon caused by the breakdown of insulation between windings wound on the same phase. When a short circuit occurs in the windings, the winding ratio changes and an imbalance occurs in the three phases of the generator. At the point of the short circuit, a large circulating current flows between the shorted windings, which can damage the windings due to overheating. In the event of a winding short circuit, the fault current circulates only within the short-circuited section of the winding, so the fault is not detected in the current transformers (CTs) located on the generator's neutral side and terminal side. In other words, although the fault originates within the generator winding, the fault current input to the relay is measured as current flowing out like an external fault, making protection impossible by the primary differential protection relay. Current imbalance caused by a winding short circuit occurs, and as a result, the reverse phase current protection element can operate. However, since negative sequence current occurs during two-line ground faults on the generator terminal side and one-line ground faults in the transmission system, it is difficult to distinguish between electrical faults in the internal and external systems of the power plant and generator winding short-circuit faults when the negative sequence current protection element operates, and as a result, a lot of time is spent on identifying the cause and restoring normal operation. FIG. 1 is a configuration diagram of a generator stator winding short-circuit fault detection logic system according to one embodiment of the present invention. Figure 2 shows the voltage before the fault and the voltage at the time of the fault of a generator stator winding short-circuit fault detection logic system according to one embodiment of the present invention. Figure 3 shows the magnitude of the symmetrical component voltage at the time of a fault in a generator stator winding short-circuit fault detection logic system according to one embodiment of the present invention. Figure 4 shows the current signal at the generator terminal side during the same fault of a generator stator winding short-circuit fault detection logic system according to one embodiment of the present invention. Figure 5 shows the magnitude of the symmetrical terminal-side current at the same fault in a generator stator winding short-circuit fault detection logic system according to one embodiment of the present invention. FIG. 6 shows the logic configuration of a generator stator winding short-circuit fault detection logic system according to one embodiment of the present invention. A generator stator winding short-circuit fault detection logic system according to one embodiment of the present invention relates to a generator stator winding short-circuit fault detection logic, and relates to a technology for detecting negative sequence current and voltage fluctuations relative to the normal sequence and determining a winding short-circuit fault phase in which the current decreases significantly compared to the winding short-circuit fault phase when the conditions of phases A, B, and C according to the voltage fluctuation are satisfied. Hereinafter, a generator stator winding short-circuit fault detection logic system according to one embodiment of the present invention will be described with reference to the attached drawings. FIG. 1 is a configuration diagram of a generator stator winding short-circuit fault detection logic system according to one embodiment of the present invention. As illustrated in FIG. 1, the generator stator winding short-circuit fault detection logic system (10) includes a reverse phase current detection unit (100), a voltage fluctuation detection unit (200), and a fault phase determination unit (300). The negative sequence current detection unit (100) is configured to detect the negative sequence current and voltage fluctuation relative to the normal sequence. This negative sequence current detection unit detects the negative sequence current and voltage fluctuation relative to the positive sequence, and performs a detection operation when the negative sequence current relative to the positive sequence current is 5% or more. The voltage fluctuation detection unit (200) generates a signal when the phase voltage is maintained above a certain ratio and transmits an operation signal to the reverse ph