CN112255573B - Single-phase earth fault processing method for neutral point ungrounded system - Google Patents
Single-phase earth fault processing method for neutral point ungrounded system Download PDFInfo
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- CN112255573B CN112255573B CN202011310475.2A CN202011310475A CN112255573B CN 112255573 B CN112255573 B CN 112255573B CN 202011310475 A CN202011310475 A CN 202011310475A CN 112255573 B CN112255573 B CN 112255573B
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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
- G01R31/52—Testing for short-circuits, leakage current or ground faults
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/26—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured
- H02H7/28—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured for meshed systems
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Abstract
The invention provides a single-phase earth fault processing method of a neutral point ungrounded system, which judges whether an earth fault occurs or not through the out-of-limit of a secondary side opening triangular voltage signal and a zero sequence current signal of a voltage transformer, further judges the specific fault type, controls a bus fault phase quick switch to execute different operation instructions according to different fault conditions, effectively transfers fault current and ensures the safety of equipment and workers.
Description
Technical Field
The invention belongs to the technical field of power fault processing, and particularly relates to a single-phase earth fault processing method of a neutral point ungrounded system.
Background
The earth fault is one of the most common faults of the power system, and the ability to quickly and accurately determine the specific fault type and fault line and further take maintenance measures is an important step for ensuring the safety and reliability of the power system.
The invention provides a single-phase earth fault processing method of a neutral point ungrounded system, which judges whether an earth fault occurs or not through the out-of-limit of a secondary side opening triangular voltage signal and a zero sequence current signal of a voltage transformer, and improves the speed of fault judgment; and then, specific fault types are further judged, the bus fault phase fast switch is controlled to execute different operation instructions according to different fault conditions, fault current is effectively transferred, and the safety of equipment and workers is guaranteed.
Disclosure of Invention
The invention provides a single-phase earth fault processing method of a neutral point ungrounded system, which can quickly and accurately determine the fault type and line and effectively transfer fault current through a quick switch.
The invention particularly relates to a single-phase earth fault processing method of a neutral point ungrounded system, which comprises the following steps:
step (1): collecting a secondary side opening triangular voltage signal, a line zero sequence current signal, a three-phase voltage signal and a three-phase current signal of a voltage transformer;
step (2): judging whether the secondary side opening triangular voltage signal of the voltage transformer is larger than a voltage reference value or not, and if so, entering the step (3); if not, returning to the step (1);
and (3): judging whether all the zero sequence current signals are suddenly changed, if yes, a single-phase earth fault occurs, and entering the step (4); if not, returning to the step (1);
and (4): judging whether one phase voltage is close to zero or not, judging whether the other two phase voltages are close to the line voltage or not, if so, judging that the metal grounding occurs and the phase voltage close to zero is a fault phase, and entering the step (6); if not, entering the step (5);
and (5): judging whether a phase voltage is smaller than the voltages of the other two phases and the previous phase voltage of the phase with small voltage is larger than the voltages of the other two phases, if so, generating a single-phase earth fault with small resistance and taking the phase with small voltage as a fault phase, and entering the step (6); if not, a large-resistance single-phase earth fault occurs, the latter phase of the phase with the largest voltage is a fault phase, and the step (6) is carried out;
and (6): controlling the bus fast switch of the fault phase to act closing;
and (7): judging whether a certain line a appears, wherein the direction of the zero sequence current signal on the line a is opposite to that of the zero sequence current signals of all other lines, the amplitude of the zero sequence current of the line a is larger than that of other lines, the direction of the zero sequence current of the line a is changed before and after the bus fast switch action, if yes, the line a is a fault line, and entering the step (8); if not, the line a is a non-fault line, and the step (9) is carried out;
and (8): controlling the bus fast switch of the fault phase not to be switched off, and entering the step (10);
and (9): controlling the bus fast switch of the fault phase not to be disconnected, and entering the step (10);
step (10): collecting a secondary side opening triangular voltage signal of the voltage transformer and a zero sequence current signal of the line;
step (11): judging whether the secondary side opening triangular voltage signal of the voltage transformer is larger than a voltage reference value or not, and if so, entering the step (12); if not, the temporary earth fault is eliminated, and the fault is eliminated, go to step (15);
step (12): judging whether all the zero sequence current signals are suddenly changed, if so, carrying out permanent ground fault, and entering the step (13); if not, the temporary earth fault is eliminated, and the step (15) is entered;
step (13): controlling the bus fast switch of the fault phase to act closing;
step (14): controlling the quick switch action of the fault line to close;
step (15): judging whether to continue detection, if so, returning to the step (1); if not, the process is finished.
And the bus fast switch of the fault phase can be rapidly closed after receiving a closing signal, and the grounding current at the fault point is transferred to the bus, so that the fault electric arc is extinguished and the electric arc reignition is inhibited.
Compared with the prior art, the beneficial effects are that: the fault processing method comprises the steps of judging whether a ground fault occurs or not through the out-of-limit of the triangular voltage signal of the secondary side opening of the voltage transformer and the zero sequence current signal, further judging a specific fault type, controlling the bus fast switch of the fault phase to execute different operation instructions according to different fault conditions, effectively transferring fault current, and guaranteeing the safety of equipment and workers.
Detailed Description
The following describes a specific embodiment of the method for processing a single-phase ground fault of a neutral ungrounded system in detail.
The fault processing method comprises the following steps:
firstly, judging whether a fault occurs: collecting a secondary side opening triangular voltage signal, a line zero sequence current signal, a three-phase voltage signal and a three-phase current signal of a voltage transformer; judging whether a secondary side opening triangular voltage signal of the voltage transformer is greater than a voltage reference value or not, and if not, continuing to collect the signal; if yes, judging whether all zero sequence current signals are suddenly changed, and if yes, generating single-phase earth fault; if not, continuing to collect signals.
Further, whether one phase voltage is close to zero or not is judged, the other two phases of voltages are close to the line voltage, if yes, metal grounding occurs, the phase voltage close to zero is a fault phase, and the bus of the fault phase is controlled to be switched on through rapid switching action; if not, judging whether a voltage of one phase is smaller than voltages of the other two phases and a voltage of the previous phase of the phase with a small voltage is larger than the voltages of the other two phases, if so, generating a single-phase earth fault with a small resistance, and if the phase with the small voltage is a fault phase, controlling a bus of the fault phase to perform fast switching action and switch on; if not, a large-resistance single-phase earth fault occurs, the latter phase of the phase with the maximum voltage is a fault phase, and the bus of the fault phase is controlled to be switched on by the quick switching action.
Judging whether a zero sequence current signal on a certain line is opposite to zero sequence current signals of all other lines in direction and has an amplitude larger than that of other lines, and the zero sequence current direction of the line is changed before and after the bus fast switch acts, if so, the line is a fault line, and controlling the bus fast switch of the fault phase not to be switched off; if not, the line is a non-fault line, and the bus fast switch for controlling the fault phase is not disconnected.
Further, collecting a secondary side opening triangular voltage signal and a line zero sequence current signal of the voltage transformer; judging whether a secondary side opening triangular voltage signal of the voltage transformer is larger than a voltage reference value or not, if not, temporarily grounding the fault, and eliminating the fault; if yes, judging whether all zero sequence current signals have sudden changes, if yes, permanently grounding the fault, controlling the bus fast switch action of the fault phase to switch on, and controlling the fast switch action of the fault line to switch on; if not, a temporary ground fault is present and the fault has been eliminated.
The method for judging the occurrence of the single-phase earth fault by using the out-of-limit judgment of the secondary side opening triangular voltage signal and the zero sequence current signal of the voltage transformer saves the processes of characteristic quantity extraction and calculation and improves the rapidity of fault judgment.
And the bus fast switch of the fault phase can be quickly closed after receiving a closing signal, and the grounding current at the fault point is transferred to the bus, so that the fault arc is extinguished and the arc reignition is inhibited.
Finally, it should be noted that the above embodiments are only used for illustrating the technical solutions of the present invention and not for limiting the same. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (2)
1. A single-phase earth fault processing method of a non-grounded neutral system is characterized by comprising the following steps:
step (1): collecting a secondary side opening triangular voltage signal, a line zero sequence current signal, a three-phase voltage signal and a three-phase current signal of a voltage transformer;
step (2): judging whether the secondary side opening triangular voltage signal of the voltage transformer is larger than a voltage reference value or not, and if so, entering the step (3); if not, returning to the step (1);
and (3): judging whether all the zero sequence current signals are suddenly changed or not, if so, generating a single-phase earth fault, and entering the step (4); if not, returning to the step (1);
and (4): judging whether a phase voltage is close to zero or not, and the other two phases of voltages are close to the line voltage, if so, the metal grounding occurs, and the phase voltage close to zero is a fault phase, and entering the step (6); if not, entering the step (5);
and (5): judging whether a phase voltage is smaller than the voltages of the other two phases and the previous phase voltage of the phase with small voltage is larger than the voltages of the other two phases, if so, generating a single-phase earth fault with small resistance and taking the phase with small voltage as a fault phase, and entering the step (6); if not, a large-resistance single-phase earth fault occurs, the latter phase of the phase with the maximum voltage is a fault phase, and the step (6) is carried out;
and (6): controlling the bus fast switch of the fault phase to act closing;
and (7): judging whether a certain line a appears, wherein the direction of the zero sequence current signal on the line a is opposite to that of the zero sequence current signals of all other lines, the amplitude of the zero sequence current of the line a is larger than that of other lines, and the direction of the zero sequence current of the line a is changed before and after the quick bus switching action, if so, the line a is a fault line, and entering the step (8); if not, the line a is a non-fault line, and the step (9) is carried out;
and (8): controlling the bus fast switch of the fault phase not to be switched off, and entering the step (10);
and (9): controlling the bus fast switch of the fault phase not to be disconnected, and entering the step (10);
step (10): collecting a triangular voltage signal of a secondary side opening of the voltage transformer and a zero sequence current signal of the line;
step (11): judging whether the secondary side opening triangular voltage signal is larger than a voltage reference value or not, and if so, entering the step (12); if not, the temporary earth fault is eliminated, and the step (15) is entered;
step (12): judging whether all the zero sequence current signals are mutated or not, if yes, carrying out permanent ground fault, and entering the step (13); if not, the temporary earth fault is eliminated, and the fault is eliminated, go to step (15);
step (13): controlling the bus fast switch of the fault phase to close;
step (14): controlling the quick switch action of the fault line to close;
step (15): judging whether to continue detection, if so, returning to the step (1); if not, the process is ended.
2. The method as claimed in claim 1, wherein the bus fast switch of the fault phase is closed rapidly after receiving a closing signal, and ground current at the fault point is transferred to the bus, so that the fault arc is extinguished and arc reignition is suppressed.
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