CN111211545B - Method and system for protecting single-phase broken line at high-voltage side of transformer with balance winding - Google Patents
Method and system for protecting single-phase broken line at high-voltage side of transformer with balance winding Download PDFInfo
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- CN111211545B CN111211545B CN202010163747.4A CN202010163747A CN111211545B CN 111211545 B CN111211545 B CN 111211545B CN 202010163747 A CN202010163747 A CN 202010163747A CN 111211545 B CN111211545 B CN 111211545B
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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
- H02H7/261—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 involving signal transmission between at least two stations
- H02H7/262—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 involving signal transmission between at least two stations involving transmissions of switching or blocking orders
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/165—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values
- G01R19/16566—Circuits and arrangements for comparing voltage or current with one or several thresholds and for indicating the result not covered by subgroups G01R19/16504, G01R19/16528, G01R19/16533
- G01R19/16571—Circuits and arrangements for comparing voltage or current with one or several thresholds and for indicating the result not covered by subgroups G01R19/16504, G01R19/16528, G01R19/16533 comparing AC or DC current with one threshold, e.g. load current, over-current, surge current or fault current
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/165—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values
- G01R19/16566—Circuits and arrangements for comparing voltage or current with one or several thresholds and for indicating the result not covered by subgroups G01R19/16504, G01R19/16528, G01R19/16533
- G01R19/16576—Circuits and arrangements for comparing voltage or current with one or several thresholds and for indicating the result not covered by subgroups G01R19/16504, G01R19/16528, G01R19/16533 comparing DC or AC voltage with one threshold
- G01R19/1658—AC voltage or recurrent signals
-
- 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
- H02H7/261—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 involving signal transmission between at least two stations
- H02H7/263—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 involving signal transmission between at least two stations involving transmissions of measured values
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Testing Of Short-Circuits, Discontinuities, Leakage, Or Incorrect Line Connections (AREA)
Abstract
The invention relates to a method and a system for protecting a single-phase broken line at the high-voltage side of a transformer with a balance winding, wherein the balance winding of the transformer is periodically in a short-time disconnection state; and calculating the change of the electrical quantity of the transformer in the opening-closing state process of the balance winding, and generating an alarm signal or sending an instruction of a jump transformer breaker when the electrical quantity meets the criterion of single-phase disconnection at the high-voltage side. The invention can overcome the problems of low sensitivity and difficult engineering realization in the prior art and improve the reliability of the high-voltage side single-phase wire break detection of the transformer with the balance winding.
Description
Technical Field
The invention relates to the technical field of relay protection of power systems, in particular to a method and a system for protecting a single-phase broken line at a high-voltage side of a transformer with a balance winding.
Background
Double-sided or three-sided all-star-connected transformers require the provision of balanced windings, and such transformers are commonly used as step-down transformers in large power plants. Under no-load or light-load working conditions, if single-phase wire breakage occurs on the high-voltage side of the transformer, voltage change on the low-voltage side is not obvious, and service voltage protection cannot be performed frequently. At this time, if the transformer is loaded with a small amount of load or switched to the transformer loaded with the load, the motor will generate a large negative sequence current and generate an overcurrent phenomenon, which causes tripping or serious damage, and finally forces the unit to stop running, thus posing a great threat to the safe and stable operation of the power plant.
In the prior art, a method for detecting the exciting current of a transformer by using an optical current transformer and judging whether the line is broken or not by using the fault sequence component is proposed. This method has the following disadvantages: firstly, an optical current transformer is used, and the measurement precision is greatly influenced by temperature; secondly, because the value of the exciting current is very small, the method has very high precision requirement on a sampling system, the protection sensitivity is difficult to ensure, and the engineering realization is difficult; and thirdly, electronic equipment such as an optical fiber current transformer, a merging unit and the like needs to be added, and the interface is difficult to protect with the existing large number of analog microcomputers.
Disclosure of Invention
In view of this, the present invention provides a method and a system for protecting a high-voltage side single-phase disconnection of a transformer with a balanced winding, which can overcome the problems of low sensitivity and difficult engineering implementation in the prior art, and improve the reliability of the high-voltage side single-phase disconnection detection of the transformer with the balanced winding.
The invention is realized by adopting the following scheme: a single-phase wire-break protection method for a high-voltage side of a transformer with a balance winding comprises the following steps:
periodically making a balance winding of the transformer in an open-close state;
and calculating the change of the electrical quantity of the transformer in the process of the open-close state of the balance winding, and generating an alarm signal or sending an instruction of a jump transformer breaker when the electrical quantity meets the criterion of single-phase disconnection at the high-voltage side.
Further, the periodically opening and closing the balance winding of the transformer specifically includes:
a balanced winding circuit breaker is configured to be connected between external wiring terminals of the balanced winding of the transformer in series and form a complete loop with the balanced winding;
and periodically switching on and off the balance winding circuit breaker to enable the balance winding to be correspondingly in an open-close state, and monitoring the voltage at the low-voltage side and the current at the low-voltage side in real time.
Further, the real-time regular opening and closing operation of the balanced winding circuit breaker is performed, so that the balanced winding is correspondingly in an open-close state, and the real-time monitoring of the voltage at the low-voltage side and the current at the low-voltage side specifically comprises:
step S11: judging whether the low-voltage side current of the transformer is larger than a preset setting value or not according to a certain time interval, if not, indicating that the transformer is in a light load or no load state, and entering the step S12 to perform the operation of switching on and off the balance winding circuit breaker; if so, not operating the switching balance winding circuit breaker;
step S12: sending a duration of T to a balanced winding circuit breaker0The switching-off pulse of the balance winding circuit breaker is used for switching off the balance winding circuit breaker and then is separated by TdThe time is enough to remove the free air gap of the switch, and then the time is T durationcThe closing pulse of (a) causes the balanced winding circuit breaker to close.
Further, the calculating the change of the electrical quantity of the transformer in the process of the open-close state of the balanced winding, and when the electrical quantity meets the criterion of the single-phase disconnection at the high-voltage side, generating an alarm signal or sending a command of a jump transformer breaker specifically comprises:
and under the condition that the balance winding circuit breaker is disconnected and the PT is not disconnected, detecting the negative sequence component or the zero sequence component of the voltage at the low-voltage side of the transformer, if one of the negative sequence component and the zero sequence component exceeds a preset setting value or both the negative sequence component and the zero sequence component exceed the preset setting value, judging that a single-phase disconnection fault occurs at the high-voltage side of the transformer, and generating an alarm signal or sending a command of jumping the transformer circuit breaker.
Further, whether the balanced winding circuit breaker is disconnected or not is judged by adopting the following method: and when the position of the balanced winding circuit breaker is detected to be in the sub-position and the third harmonic of the voltage at the low-voltage side of the transformer is measured to exceed a preset setting value, judging that the balanced winding circuit breaker is in the off state.
The invention also provides a high-voltage side single-phase wire break protection system of the transformer with the balance winding, which comprises the transformer with the balance winding and a high-voltage side circuit breaker CB of the transformer1And a low-voltage side circuit breaker CB of the transformer2Comprises a single-phase wire-break protection device and a balanced winding circuit breaker CB which is connected between external wiring terminals of the balanced winding in series and forms a complete loop with the balanced winding0；
Single-phase broken string protection device and transformer high-voltage side circuit breaker CB1And a circuit breaker CB at the low-voltage side of the transformer2Balanced winding circuit breaker CB0Electrically connected; the single-phase wire-break protection device collects current and voltage information of the low-voltage side of the transformer in real time and periodically enables the balance winding circuit breaker CB0Performing a dividing-combining operation to enable the balance winding to be correspondingly in an open-closed state; and calculating the change of the electrical quantity of the transformer in the process of the open-close state of the balance winding, and generating an alarm signal or sending an instruction of a jump transformer breaker when the electrical quantity meets the criterion of single-phase disconnection at the high-voltage side.
Further, the balanced winding circuit breaker CB0Including but not limited to vacuum interrupters.
Furthermore, the single-phase disconnection protection device is a microcomputer processing system, can collect voltage and current analog quantities, has the functions of opening and closing, and can perform logic judgment.
Compared with the prior art, the invention has the following beneficial effects: by disconnecting the balance winding loop for a short time, the invention has the advantages that the low-voltage side of the transformer has obvious negative sequence and zero sequence fault components, the microcomputer protection can accurately identify, and the sensitivity of fault detection is very high. The invention only needs to add a breaker and a set of microcomputer protection, and has less added equipment and easy realization in engineering.
Drawings
FIG. 1 is a schematic diagram of a system according to an embodiment of the present invention.
Fig. 2 is a schematic control flow diagram of a balanced winding circuit breaker according to an embodiment of the present invention.
Fig. 3 is a logic diagram of the single-phase disconnection judgment on the high-voltage side of the transformer according to the embodiment of the invention.
Detailed Description
The invention is further explained below with reference to the drawings and the embodiments.
It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.
The embodiment provides a method for protecting a single-phase broken line at a high-voltage side of a transformer with a balance winding, which comprises the following steps:
periodically making a balance winding of the transformer in an open-close state;
and calculating the change of the electrical quantity of the transformer in the process of the open-close state of the balance winding, and generating an alarm signal or sending an instruction of a jump transformer breaker when the electrical quantity meets the criterion of single-phase disconnection at the high-voltage side.
In this embodiment, the periodically opening and closing the balance winding of the transformer specifically includes:
a balanced winding circuit breaker is configured to be connected between external wiring terminals of the balanced winding of the transformer in series and form a complete loop with the balanced winding;
and periodically switching on and off the balance winding circuit breaker to enable the balance winding to be correspondingly in an open-close state, and monitoring the voltage at the low-voltage side and the current at the low-voltage side in real time.
In this embodiment, the regular opening and closing operation of the balanced winding circuit breaker is performed, so that the balanced winding is correspondingly in an open state and a closed state, and the real-time monitoring of the voltage at the low-voltage side and the current at the low-voltage side specifically includes:
step S11: judging whether the low-voltage side current of the transformer is larger than a preset setting value or not according to a certain time interval, if not, indicating that the transformer is in a light load or no load state, and entering the step S12 to perform the operation of switching on and off the balance winding circuit breaker; if so, not operating the switching balance winding circuit breaker;
step S12: sending a duration of T to a balanced winding circuit breaker0The opening pulse of the circuit breaker with the flat winding is used for opening the circuit breaker with the flat winding, and the circuit breaker is separated by TdThe time is enough to remove the free air gap of the switch, and then the time is T durationcThe closing pulse of (a) causes the balanced winding circuit breaker to close. Specifically, as shown in fig. 2, the period of detection may be set to 24 hours, and the operation is started when the counter reaches the set period. Firstly, judging the current at the low-voltage side, if the current is not greater than a setting value (such as 0.1 time of rated load, the current can be adjusted after theoretical calculation according to field parameters), indicating that the transformer is in light load or no load, and performing disconnection detection, otherwise, stopping. Then, in the detecting step, the emitting duration is T0(e.g. 0.1 second) opening pulse, further interval Td(e.g., 0.3 s) for a period of time sufficient to free the switching air gap, followed by a reissue duration of Tc(e.g., 0.1 second) closing the pulse. And finally, resetting the counter to complete the detection.
In this embodiment, the calculating the change of the electrical quantity of the transformer in the process of the open-close state of the balanced winding, and when the electrical quantity meets the criterion of the single-phase disconnection at the high-voltage side, generating the alarm signal or sending the instruction of the jump-type transformer breaker specifically includes:
and under the condition that the balance winding circuit breaker is disconnected and the PT is not disconnected, detecting the negative sequence component or the zero sequence component of the voltage at the low-voltage side of the transformer, if one of the negative sequence component and the zero sequence component exceeds a preset setting value or both the negative sequence component and the zero sequence component exceed the preset setting value, judging that a single-phase disconnection fault occurs at the high-voltage side of the transformer, and generating an alarm signal or sending a command of jumping the transformer circuit breaker.
In this embodiment, whether the balanced winding circuit breaker is disconnected or not is determined by the following method: and when the position of the balanced winding circuit breaker is detected to be in the split position and the third harmonic of the voltage at the low-voltage side of the transformer is measured to exceed the preset setting value, judging that the balanced winding circuit breaker is in a disconnected state.
The logic for determining the high-voltage single-phase disconnection is specifically shown in fig. 3. When the breaker is at the opening position and the third harmonic of the low-voltage side voltage is detected to exceed a setting value (for example, 5 percent, the third harmonic can be adjusted according to an actual measurement value), the position condition of the breaker is met. The voltage criterion is provided with a negative sequence voltage criterion and a zero sequence voltage criterion, and setting values can be respectively set to be 0.04 times and 0.06 times of rated voltage. And opening the voltage criterion when the position condition of the balanced winding breaker is met and the PT does not have the condition of wire breakage. If the negative sequence voltage criterion or the zero sequence voltage criterion meets the conditions, the single-phase line break fault occurs on the high-voltage side, and the single-phase line break protection device sends out an alarm signal or an instruction of a jump transformer breaker.
The embodiment also provides a high-voltage side single-phase wire-break protection system of the transformer with the balance winding based on the method, as shown in fig. 1, the high-voltage side single-phase wire-break protection system comprises the transformer with the balance winding and a CB (circuit breaker) of the high-voltage side of the transformer1And a circuit breaker CB at the low-voltage side of the transformer2Comprises a single-phase wire-break protection device and a balanced winding circuit breaker CB which is connected between external wiring terminals 1 and 2 of the balanced winding in series and forms a complete loop with the balanced winding0(ii) a By controlling the circuit breaker CB0The short-time separation is carried out to change the zero sequence impedance of the transformerTherefore, the voltage on the low-voltage side of the transformer can generate fault components during the open circuit of the balance winding.
Single-phase broken wire protection device and transformer high-voltage side circuit breaker CB1And a circuit breaker CB at the low-voltage side of the transformer2Balanced winding circuit breaker CB0Electrically connected; the single-phase wire-break protection device collects current and voltage information of a low-voltage side of a transformer in real time, and periodically enables the balance winding circuit breaker to perform opening and closing operations, so that the balance winding is correspondingly in an open state and a closed state; and calculating the change of the electrical quantity of the transformer in the switching-on and switching-off state process of the balance winding, and generating an alarm signal or sending an instruction of a jump transformer breaker when the electrical quantity meets the high-voltage side single-phase disconnection criterion. The specific determination method and control method are as described in the above method provided in this embodiment, wherein the transformer breaker comprises a transformer high-voltage side breaker CB1And a high-voltage side circuit breaker CB of the transformer2。
In the embodiment, the balanced winding circuit breaker CB0Including but not limited to vacuum interrupters.
In this embodiment, the single-phase disconnection protection device is a microcomputer processing system, can collect voltage and current analog quantities, has an input and output function, and can perform logic judgment.
The foregoing is directed to preferred embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow. However, any simple modification, equivalent change and modification of the above embodiments according to the technical essence of the present invention are within the protection scope of the technical solution of the present invention.
Claims (7)
1. A single-phase wire-break protection method for a high-voltage side of a transformer with a balance winding is characterized by comprising the following steps:
periodically making a balance winding of the transformer in an open-close state;
calculating the change of the electrical quantity of the transformer in the process of an open-close state of the balance winding, and generating an alarm signal or sending an instruction of a jump transformer breaker when the electrical quantity meets the criterion of single-phase disconnection at the high-voltage side;
the high-voltage side single-phase disconnection criterion is specifically as follows: and under the condition that the balance winding circuit breaker is disconnected and the PT is not disconnected, detecting the negative sequence component or the zero sequence component of the voltage at the low-voltage side of the transformer, if one of the negative sequence component and the zero sequence component exceeds a preset setting value or both the negative sequence component and the zero sequence component exceed the preset setting value, judging that a single-phase disconnection fault occurs at the high-voltage side of the transformer, and generating an alarm signal or sending a command of jumping the transformer circuit breaker.
2. The method for protecting the high-voltage side single-phase wire break of the transformer with the balance winding according to claim 1, wherein the periodically opening and closing the balance winding of the transformer specifically comprises:
a balanced winding circuit breaker is configured to be connected between external wiring terminals of the balanced winding of the transformer in series and form a complete loop with the balanced winding;
and periodically carrying out opening-closing operation on the balance winding circuit breaker, so that the balance winding is correspondingly in an opening-closing state, and monitoring the voltage at the low-voltage side and the current at the low-voltage side in real time.
3. The method for protecting the single-phase disconnection at the high-voltage side of the transformer with the balanced winding according to claim 2, wherein the breaker with the balanced winding is periodically switched on and off, so that the balanced winding is correspondingly in an open-closed state, and the real-time monitoring of the voltage at the low-voltage side and the current at the low-voltage side specifically comprises the following steps:
step S11: judging whether the low-voltage side current of the transformer is larger than a preset setting value or not according to a certain time interval, if not, indicating that the transformer is in a light load or no load state, and entering the step S12 to perform the operation of switching on and off the balance winding circuit breaker; if so, not performing the operation of the switching balance winding circuit breaker;
step S12: sending a duration of T to a balanced winding circuit breaker0Is controlled by the switching-off pulseObtain the opening of the balanced winding breaker and then space TdThe time is enough to remove the free air gap of the switch, and then the time is T durationcThe closing pulse of (a) causes the balanced winding circuit breaker to close.
4. The method for protecting the high-voltage side single-phase wire break of the transformer with the balance winding according to claim 1, wherein whether the circuit breaker with the balance winding is disconnected or not is judged by adopting the following method: and when the position of the balanced winding circuit breaker is detected to be in the sub-position and the third harmonic of the voltage at the low-voltage side of the transformer is measured to exceed a preset setting value, judging that the balanced winding circuit breaker is in the off state.
5. A high-voltage side single-phase wire break protection system of a transformer with a balance winding comprises the transformer with the balance winding and a transformer high-voltage side circuit breaker CB1And a circuit breaker CB at the low-voltage side of the transformer2The circuit breaker is characterized by comprising a single-phase wire-breaking protection device and a balanced winding circuit breaker CB which is connected between external wiring terminals of the balanced winding in series and forms a complete loop with the balanced winding0；
Single-phase broken wire protection device and transformer high-voltage side circuit breaker CB1And a circuit breaker CB at the low-voltage side of the transformer2Balanced winding circuit breaker CB0Electrically connected; the single-phase wire-break protection device collects current and voltage information of the low-voltage side of the transformer in real time and periodically enables the balance winding circuit breaker CB0Performing a dividing-combining operation to enable the balance winding to be correspondingly in an open-closed state; calculating the change of the electrical quantity of the transformer in the process of an open-close state of the balance winding, and generating an alarm signal or sending an instruction of a jump transformer breaker when the electrical quantity meets the single-phase disconnection criterion of the high-voltage side;
the high-voltage side single-phase disconnection criterion is specifically as follows: and under the condition that the balance winding circuit breaker is disconnected and the PT is not disconnected, detecting the negative sequence component or the zero sequence component of the voltage at the low-voltage side of the transformer, if one of the negative sequence component and the zero sequence component exceeds a preset setting value or both the negative sequence component and the zero sequence component exceed the preset setting value, judging that a single-phase disconnection fault occurs at the high-voltage side of the transformer, and generating an alarm signal or sending a command of jumping the transformer circuit breaker.
6. The high-voltage side single-phase wire break protection system of the transformer with the balanced winding as claimed in claim 5, wherein the CB is0Including but not limited to vacuum interrupters.
7. The high-voltage side single-phase disconnection protection system of the transformer with the balance winding according to claim 5, wherein the single-phase disconnection protection device is a microcomputer processing system, can collect voltage and current analog quantities, has a switch-in and switch-out function, and can perform logic judgment.
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| CN202010163747.4A CN111211545B (en) | 2020-03-10 | 2020-03-10 | Method and system for protecting single-phase broken line at high-voltage side of transformer with balance winding |
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| CN202010163747.4A CN111211545B (en) | 2020-03-10 | 2020-03-10 | Method and system for protecting single-phase broken line at high-voltage side of transformer with balance winding |
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| CN110320432A (en) * | 2019-06-04 | 2019-10-11 | 国网江苏省电力有限公司无锡供电分公司 | Single-phase wire break fault detection and guard method and system |
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| CN110320432A (en) * | 2019-06-04 | 2019-10-11 | 国网江苏省电力有限公司无锡供电分公司 | Single-phase wire break fault detection and guard method and system |
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