CN-122026278-A - Generator rotor grounding protection circuit, device and method

CN122026278ACN 122026278 ACN122026278 ACN 122026278ACN-122026278-A

Abstract

The invention relates to the technical field of generators, in particular to a generator rotor grounding protection circuit, a device and a method, which comprises a rotor winding, an injection loop and a measurement loop, wherein the rotor winding is provided with a positive end, a negative end and an insulation resistor corresponding to a grounding fault point, one end of the injection loop is electrically connected with the positive end or the negative end, the other end of the injection loop is electrically connected with the insulation resistor, the injection loop comprises an injection module and a sampling module, the injection module and the sampling module are both connected in series on the injection loop, or the two ends of the measurement loop are respectively electrically connected with the positive end and the negative end, the measurement loop comprises a measurement module and a switch module, the measurement module is connected in series on the measurement loop, and the switch module is connected in parallel on the measurement module. According to the invention, through the sampling resistor connected in series in the injection loop, fault current signals can be extracted, the detection sensitivity and the signal-to-noise ratio of weak fault current are effectively improved, and the problems of low sampling precision and easiness in interference in the traditional scheme are solved.

Inventors

YANG ZHANGBIN
SUN LIGUO
QIANG LINLIN
WU JUNCHAO
LI JIACHENG
SU LE
WANG ZHAOHENG
ZHANG BING
YANG CHENCHEN

Assignees

中国三峡建工(集团)有限公司
南京南瑞继保工程技术有限公司

Dates

Publication Date: 20260512
Application Date: 20260211

Claims (10)

1. A generator rotor grounding protection circuit is characterized by comprising, A rotor winding (100) having a positive end (Ur+), a negative end (Ur-) and an insulation resistance (Rg) corresponding to the ground fault point (N), and An injection circuit (101) with one end electrically connected to the positive (Ur+) or negative (Ur-) end and the other end electrically connected to an insulation resistor (Rg), the injection circuit (101) comprising an injection module (101 a) and a sampling module (101 b), the injection module (101 a) and the sampling module (101 b) being connected in series with the injection circuit (101), or, The measuring circuit (102) is electrically connected to the positive end (Ur+) and the negative end (Ur-) respectively at two ends, the measuring circuit (102) comprises a measuring module (102 a) and a switching module (102 b), the measuring module (102 a) is connected to the measuring circuit (102) in series, and the switching module (102 b) is connected to the measuring module (102 a) in parallel.
2. The generator rotor ground protection circuit of claim 1, wherein the injection module (101 a) comprises an injection power supply (Us), one end of the injection power supply (Us) is electrically connected with the large rotor shaft (103), one end of the insulation resistor (Rg) is electrically connected with the large rotor shaft (103), and the other end of the injection power supply (Us) is electrically connected with the positive end (Ur+) or the negative end (Ur-).
3. The generator rotor ground protection circuit of claim 2, wherein the sampling module (101 b) comprises a sampling resistor (Rx) and a high power resistor (Ry), the sampling resistor (Rx) is connected in series with the high power resistor (Ry), the sampling resistor (Rx) is connected in series with an injection power supply (Us), and the high power resistor (Ry) is electrically connected to a positive terminal (Ur+) or a negative terminal (Ur-).
4. The generator rotor ground protection circuit of claim 3, wherein two of said high power resistors (Ry) are provided, one of said high power resistors (Ry) being electrically connected to the positive terminal (Ur+), and the other of said high power resistors (Ry) being electrically connected to the negative terminal (Ur-).
5. The generator rotor grounding protection circuit according to any one of claims 1-4, wherein the measuring module (102 a) comprises measuring resistors (R), two measuring resistors (R) are connected in series and then connected between a positive end (Ur+) of the rotor winding (100) and a rotor large shaft (103), two measuring resistors (R) are connected in series and then connected between a negative end (Ur-) of the rotor winding (100) and the rotor large shaft (103), and the rotor large shaft (103) is grounded.
6. The generator rotor ground protection circuit of claim 5, wherein said switch module (102 b) comprises a first electronic switch (S1) and a second electronic switch (S2), said first electronic switch (S1) being connected in parallel across one of said measurement resistors (R) on the positive side (Ur+) and said second electronic switch (S2) being connected in parallel across one of said measurement resistors (R) on the negative side (Ur-).
7. A generator rotor grounding protection device is characterized by comprising, The analog input plug-in (200), the analog input plug-in (200) is used for being connected with a positive end (Ur+), a negative end (Ur-) and a rotor large shaft (103) of the rotor winding (100), and the analog input plug-in (200) comprises a generator rotor grounding protection circuit; A signal plug-in (300) which is in communication connection with the analog input plug-in (200), wherein the signal plug-in (300) is provided with an alarm signal output contact, a tripping signal output contact and an abnormal output contact; A trip outlet plug-in (400) in communication with the signal plug-in (300), the trip outlet plug-in (400) being configured with a plurality of outlet relays (401); And the digital signal processor DSP plug-in (500) is respectively in communication connection with the analog quantity input plug-in (200), the signal plug-in (300) and the trip outlet plug-in (400).
8. The generator rotor ground protection device as recited in claim 7, wherein said digital signal processor DSP package (500) comprises, The protection DSP board (501), the input end of the protection DSP board (501) is connected with the output end of the analog input plug-in unit (200), and the output end of the protection DSP board (501) is connected with the input end of the outlet relay (401); The start DSP board (502), the input of start DSP board (502) is connected with the output of analog input plug-in components (200), the output of start DSP board (502) is connected with positive power (+E) of export relay (401).
9. A method for protecting the grounding of the rotor of electric generator is characterized by comprising, The system automatically switches modes according to the insulation damage degree, when the resistance is reduced to a sensitive section and an alarm mode is activated, early warning is sent out through delay, if the resistance is further reduced to a common section and a tripping mode is activated, a tripping judgment program is entered, on the basis that one-point grounding has already occurred, the system automatically checks whether the two-point grounding tripping function is ready or not, and carries out logic operation by combining a fault starting signal monitored in real time, and only after the logic confirms that the fault is deteriorating and reaches a set time, a tripping instruction is issued.
10. The method for protecting a rotor of an electrical generator according to claim 9, comprising, By collecting the current of the injection loop (101), comparing the measured value of the rotor voltage with the change of the current amplitude, and when the voltage is higher than the threshold value and the current is lower than the threshold value, determining that the loop is broken and outputting an alarm signal.

Description

Generator rotor grounding protection circuit, device and method Technical Field The invention relates to the technical field of generators, in particular to a generator rotor grounding protection circuit, a generator rotor grounding protection device and a generator rotor grounding protection method. Background The rotor winding main insulation gradually deteriorates due to mechanical stress, moisture intrusion or carbon dust contamination, possibly causing a single point ground fault. If the faults can not be found and processed in time, the faults are very easy to develop into the problems of second point grounding, burning loss of the rotor core and the guard ring and the like. At present, the grounding protection of the generator rotor mainly adopts two principles of injection type and ping-pong type. Injection protection determines the location of a ground fault and insulation conditions by injecting a voltage signal of a specific frequency into the rotor circuit, detecting current or voltage changes in the circuit. However, the conventional injection type protection circuit has the problems of poor stability of an injection power supply, low sampling precision, weak anti-interference capability and the like, and is particularly easy to malfunction or reject under the high-temperature and high-electromagnetic interference environment. The ping-pong protection calculates the grounding resistance and the grounding position by alternately switching the measuring loops and utilizing the principle of measuring the voltage division of the resistance. However, the circuit structure is complex, the electronic switch is frequently operated, the service life is easily shortened, and the judgment accuracy is reduced under the condition of multiple grounding faults. In addition, the existing rotor grounding protection device is single in function, lacks a perfect signal processing and multistage protection mechanism, and is difficult to adapt to the requirements of a large-sized generator set on high-reliability and high-precision protection. Therefore, there is a need for a generator rotor ground protection circuit and device that is rational in infrastructure, accurate in measurement, highly reliable, and easy to integrate. Disclosure of Invention Some simplifications or omissions may be made in this section as well as in the description of the application and in the title of the application, which may not be used to limit the scope of the application. In order to solve the defects in the prior art, one of the purposes of the invention is to provide a generator rotor grounding protection circuit. In order to achieve the above-mentioned objective, the invention adopts the following technical scheme that the generator rotor grounding protection circuit comprises a rotor winding, an injection loop and a measurement loop, wherein the rotor winding is provided with a positive end, a negative end and an insulation resistor corresponding to a grounding fault point, one end of the injection loop is electrically connected with the positive end or the negative end, the other end of the injection loop is electrically connected with the insulation resistor, the injection loop comprises an injection module and a sampling module, the injection module and the sampling module are both connected in series with the injection loop, or the measurement loop is respectively connected with the positive end and the negative end at two ends of the measurement loop, the measurement loop comprises a measurement module and a switch module, the measurement module is connected in series with the measurement loop, and the switch module is connected in parallel with the measurement module. As an optimized scheme of the generator rotor grounding protection circuit, the injection module comprises an injection power supply, one end of the injection power supply is electrically connected with the rotor large shaft, one end of the insulation resistor is electrically connected with the rotor large shaft, and the other end of the injection power supply is electrically connected with the positive end or the negative end. The invention relates to a generator rotor grounding protection circuit, which is characterized in that the sampling module comprises a sampling resistor and a high-power resistor, wherein the sampling resistor is connected with the high-power resistor in series, the sampling resistor is connected with an injection power supply in series, and the high-power resistor is electrically connected with a positive end or a negative end. As an optimized scheme of the generator rotor grounding protection circuit, two high-power resistors are arranged, one high-power resistor is electrically connected to the positive end, and the other high-power resistor is electrically connected to the negative end. As an optimized scheme of the generator rotor grounding protection circuit, the measuring module comprises measuring resistors, wherein the two m