CN109387723B - Resonant grounding system grounding line selection method based on instantaneous impedance grounding method - Google Patents
Resonant grounding system grounding line selection method based on instantaneous impedance grounding method Download PDFInfo
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- CN109387723B CN109387723B CN201810964721.2A CN201810964721A CN109387723B CN 109387723 B CN109387723 B CN 109387723B CN 201810964721 A CN201810964721 A CN 201810964721A CN 109387723 B CN109387723 B CN 109387723B
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- 238000000034 method Methods 0.000 title claims abstract description 15
- 238000010187 selection method Methods 0.000 title claims abstract description 13
- 230000001052 transient effect Effects 0.000 claims abstract description 35
- 230000005350 ferromagnetic resonance Effects 0.000 claims abstract description 7
- 238000004458 analytical method Methods 0.000 claims description 2
- 230000001629 suppression Effects 0.000 description 4
- 238000010586 diagram Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/08—Locating faults in cables, transmission lines, or networks
- G01R31/081—Locating faults in cables, transmission lines, or networks according to type of conductors
- G01R31/086—Locating faults in cables, transmission lines, or networks according to type of conductors in power transmission or distribution networks, i.e. with interconnected conductors
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/08—Locating faults in cables, transmission lines, or networks
- G01R31/088—Aspects of digital computing
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Abstract
The invention relates to a grounding line selection method of a resonance grounding system based on an instantaneous impedance grounding method, which is mainly technically characterized by comprising the following steps: when the zero sequence voltage of the system is greater than the protection fixed value, judging whether the influence is ferromagnetic resonance influence, and if so, recording a grounding event; otherwise, continuously recording grounding data, starting a transient algorithm, judging a fault line, and outputting three lines with the maximum probability to perform auxiliary decision; if the grounding is the steady grounding, comprehensively outputting a final line selection result; judging whether the fault is intermittent continuous earth fault, if so, starting a transient algorithm, analyzing a transient waveform, and outputting a primary fault judgment result; if the fault is not an intermittent continuous earth fault, an earth event is recorded. The invention can effectively meet the requirements of fault line selection under various fault states, has high line selection accuracy and high reliability, can effectively shorten the fault processing time, reduces the labor cost of fault processing, and improves the power supply reliability and the power quality of the system.
Description
Technical Field
The invention belongs to the technical field of relay protection, and particularly relates to a resonant grounding system grounding line selection method based on an instantaneous impedance grounding method.
Background
In an electric power system, a resonance grounding system is generally formed by a system with less than 35 kilovolts by adopting an arc suppression coil grounding mode. In the operation mode, when a single-phase earth fault occurs to a line in the system, the arc suppression coil can compensate the capacitive current generated by the fault, and the current passing through a fault point is controlled at a low level, so that the system can operate for 1-2 hours with the fault. However, due to the compensation effect of the arc suppression coil, the current change after the fault is small, and the fault line selection is difficult.
Currently, for a resonant grounding system, there are two common fault line selection methods: one is a medium impedance line selection method, namely after a fault, a resistor connected in parallel on an arc suppression coil is put into operation, power frequency current is injected into a fault line within 2-3 seconds, the phase current of the fault is suddenly changed, and the other lines are not changed, so that the judgment is finished; the other method is a transient line selection method, and fault line selection is completed by collecting high-frequency components of zero-sequence current. The above methods all have limitations: the medium impedance method needs stable grounding of fault points, and is not suitable for single-point grounding which frequently occurs in a short time; the transient state line selection method has high requirement on acquisition of current break variable, is easily influenced by environmental factors, and has obviously lower reliability than the medium impedance line selection method for stable single-phase fault grounding.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide the grounding and line selecting method of the resonance grounding system based on the instantaneous impedance grounding method, which has high line selecting accuracy and high reliability and can effectively meet the requirements of fault line selection under various fault states.
The technical problem to be solved by the invention is realized by adopting the following technical scheme:
a resonant grounding system grounding line selection method based on an instantaneous impedance grounding method comprises the following steps:
step 1, when the zero sequence voltage of the system is greater than a protection fixed value, starting a grounding line selection protection device; judging whether the influence is ferromagnetic resonance influence, if so, recording a grounding event; otherwise, continuously recording grounding data, and entering the step 2;
step 2, starting a transient algorithm, analyzing a transient waveform according to instantaneous abrupt current and voltage information, judging a fault line, outputting three lines with the maximum probability for auxiliary decision making, and entering step 3;
step 3, if the system is in steady-state grounding, the grounding impedance of the system is controlled by the grounding line selection protection device, the steady-state current and voltage information of the system is analyzed, a grounding line is judged, the grounding impedance device is controlled to quit operation, a line selection judgment result is output, a transient state criterion result when the protection is started is comprehensively compared, and a final line selection result is comprehensively output; otherwise, entering step 4;
step 4, judging whether the intermittent continuous ground fault occurs or not, if so, starting a transient algorithm, analyzing a transient waveform when each intermittent fault occurs, and outputting a primary fault judgment result;
and 5, if the fault is not an intermittent continuous grounding fault, indicating that the fault is transient grounding, and recording a grounding event.
The basis for judging the grounding circuit in the step 3 is as follows: after impedance of one line is put into use, the zero sequence current amplitude is obviously increased, and currents of other synchronous lines are kept unchanged or reduced, and the line is judged to be a grounding line.
The transient waveform analysis method in the step 4 comprises the following steps: comprehensively comparing the transient state discrimination results for more than 10 times for comprehensive judgment; if the comprehensive probability is more than 60%, the result is considered to be reliable, and a judgment result is output; if the probability is lower than 60%, outputting a circuit with the maximum probability of three days as an auxiliary decision; and comparing the results synchronously with the initial transient algorithm discrimination result, and finally outputting a line selection result.
The invention has the advantages and positive effects that:
the invention has reasonable design, can effectively meet the fault line selection requirements under various fault states, and has high line selection accuracy and high reliability; the passive switching-off line selection caused by low reliability of the line selection device is avoided, the fault processing time can be effectively shortened, the labor cost for fault processing is reduced, and the power supply reliability and the power quality of the system are improved.
Drawings
FIG. 1 is a schematic diagram of an application system of the present invention;
FIG. 2 is a process flow diagram of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings.
A resonance grounding system grounding line selection method based on an instantaneous impedance grounding method is realized on a system shown in a figure 1, in the figure, zero sequence voltage in the system can be obtained through a bus PT, when the voltage is larger than a set value and larger than a starting fixed value and ferromagnetic resonance influence is eliminated, grounding exists in the system, after the system is judged to be in steady grounding through short-time monitoring (about 1 min), a grounding impedance switch K in the system is controlled to be closed through a grounding line selection protection device, an impedance device is put into the system, obvious active components are injected into a grounding line, and the judgment of a fault line is completed through a medium impedance algorithm. When a single-phase earth fault occurs, the zero sequence voltage of a bus in the transformer substation rises, and when a protection action value is reached, the earth line selection protection device is started to judge whether ferromagnetic resonance exists. After the interference of ferromagnetic resonance is eliminated, transient algorithm is put into use.
The invention divides the fault into three types, one is a single instantaneous grounding event, and because the fault has little damage effect on the system, the grounding line selection protection device records the grounding event and does not output the line selection result. Secondly, instantaneous earth faults are continuously and repeatedly determined, the result of each earth line selection is independently determined through a transient algorithm, the determination results are counted for 10 times, when the probability that a certain line is diagnosed as a fault line is about 60%, the line is determined as the fault line, the transient algorithm introduces a statistical concept, the influence of random factors of the instantaneous earth faults on the result of the transient criterion line selection is weakened to a great extent, and the reliability of line selection is high. And thirdly, when the system has a steady-state earth fault, controlling the impedance device connected in parallel on the arc eliminating coil to be instantly put into use according to the actual operation condition of the system and the operation condition of the equipment.
The grounding and line selection method of the resonance grounding system based on the instantaneous impedance grounding method, as shown in fig. 2, comprises the following steps:
step 1, when the zero sequence voltage of the system is greater than a protection fixed value, starting a grounding line selection protection device; judging whether the influence is ferromagnetic resonance influence, if so, recording a grounding event; if not, the grounding data is continuously recorded and step 2 is entered.
Step 2, starting a transient algorithm, analyzing a transient waveform according to instantaneous abrupt current and voltage information, judging a fault line, and outputting three lines with the highest probability for auxiliary decision making; a steady-state grounding decision is synchronously initiated (step 3).
Step 3, if the line is stably grounded, controlling the grounding impedance of the input system through the grounding line selection protection device, analyzing the information of the stable current and voltage of the system (power frequency current and voltage), judging that a certain line is a grounding line according to the condition that the zero sequence current amplitude value of the line is obviously increased after the impedance is input and the current of other synchronous lines is kept unchanged or reduced, controlling the grounding impedance device to quit the operation (opening a switch K in the figure 1), outputting a line selection judgment result, comprehensively comparing the transient judgment result when the protection is started, and comprehensively outputting a final line selection result; if not, go to step 4.
Step 4, judging whether the intermittent continuous ground fault exists, if so, starting a transient algorithm, analyzing a transient waveform when each intermittent fault occurs, and outputting a primary fault judgment result; comprehensively comparing the transient state discrimination results for more than 10 times for comprehensive judgment; if the comprehensive probability is more than 60%, the result is considered to be reliable, and a judgment result is output; if the probability is lower than 60%, outputting a circuit with the maximum probability of three days as an auxiliary decision; and comparing the results synchronously with the initial transient algorithm discrimination result, and finally outputting a line selection result.
And 5, if the fault is not intermittent continuous grounding fault, the fault is indicated to be transient grounding, the influence on the system is small, line selection is not carried out, and the flow is ended after a grounding event is recorded.
It should be emphasized that the embodiments described herein are illustrative rather than restrictive, and thus the present invention is not limited to the embodiments described in the detailed description, but also includes other embodiments that can be derived from the technical solutions of the present invention by those skilled in the art.
Claims (1)
1. A resonant grounding system grounding line selection method based on an instantaneous impedance grounding method is characterized by comprising the following steps:
step 1, when the zero sequence voltage of the system is greater than a protection fixed value, starting a grounding line selection protection device; judging whether the influence is ferromagnetic resonance influence, if so, recording a grounding event; otherwise, continuously recording grounding data, and entering the step 2;
step 2, starting a transient algorithm, analyzing a transient waveform according to instantaneous abrupt current and voltage information, judging a fault line, outputting three lines with the maximum probability for auxiliary decision making, and entering step 3;
step 3, if the system is in steady-state grounding, the grounding line selection protection device controls the instantaneous impedance grounding device to be put into the system, the steady-state current and voltage information of the system is analyzed, a grounding line is judged, the instantaneous impedance grounding device is controlled to quit operation, a line selection judgment result is output, a transient algorithm judgment result during protection starting is comprehensively compared, and a final line selection result is comprehensively output; otherwise, entering step 4;
step 4, judging whether the intermittent continuous ground fault occurs or not, if so, starting a transient algorithm, analyzing a transient waveform when each intermittent fault occurs, and outputting a primary fault judgment result;
step 5, if the fault is not intermittent continuous grounding fault, indicating that the fault is transient grounding, and recording a grounding event;
the basis for judging the grounding circuit in the step 3 is as follows: after impedance of one line is put into use, the zero sequence current amplitude is obviously increased, and meanwhile, the current of other lines is kept unchanged or reduced, and the line is judged to be a grounding line;
the transient waveform analysis method in the step 4 comprises the following steps: comparing the transient state discrimination results for more than 10 times for comprehensive judgment; if the comprehensive probability is more than 60%, the result is considered to be reliable, and a judgment result is output; if the comprehensive probability is lower than 60%, outputting three lines with the maximum probability for auxiliary decision making; meanwhile, the method is compared with a transient algorithm judgment result during protection starting, and a line selection result is finally output; the integrated probability refers to the probability that a line is diagnosed as a faulty line.
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