CN110957706A - Method for judging switching operation of distribution system without power outage - Google Patents
Method for judging switching operation of distribution system without power outage Download PDFInfo
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- CN110957706A CN110957706A CN201911170572.3A CN201911170572A CN110957706A CN 110957706 A CN110957706 A CN 110957706A CN 201911170572 A CN201911170572 A CN 201911170572A CN 110957706 A CN110957706 A CN 110957706A
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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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Abstract
The invention discloses a method for judging the switching operation of a power distribution system without power outage. According to the invention, by utilizing the matching of the switching instant closing point impact current and the switching line current protection setting value, when switching operation occurs, whether the switching operation can be carried out without power failure is judged by comparing the switching instant closing point impact current with the relay protection setting value; when the impact current is smaller than the relay protection setting value, the switching operation is judged to be possible, and when the impact current is larger than the relay protection setting value, the uninterrupted switching operation is judged to be impossible. The method provides a judgment basis for judging whether the power distribution network can be switched off or not without power outage, avoids unreliable switching operation and improves the power supply reliability of a power distribution network system.
Description
Technical Field
The invention relates to a method for judging whether a power distribution network system can perform uninterrupted switching operation, in particular to a method for judging whether the power distribution network system can perform uninterrupted switching operation.
Background
The urban medium-voltage distribution network in China adopts a ring network power supply mode of closed-loop design and open-loop operation, and load areas of different buses are connected through interconnection switches. The ring network power supply mode adopts a double power supply loop or a double-side power supply, and in the operation process, the ring network power supply system not only adopts a normal power supply or a power supply loop, but also adopts a standby power supply or a standby power supply loop, so that the standby power supply can be switched to supply power at any time through simply switching a control switch. Under the power supply mode, when power failure maintenance, sudden events or load transfer, the loads are transferred without power failure through the power distribution network without power failure switching operation, the reliable power supply of the power distribution network to users can be guaranteed, and the running stability of the power distribution network is improved.
Because the current protection action can be caused when the distribution network is switched off without power failure, before switching off, whether the distribution network system can be switched off without power failure or not must be strictly judged, and accidents such as large-scale power failure and the like caused by the current protection action are avoided. In the operation of switching, because of the difference of amplitude, phase and the like of bus voltages at two sides of a loop closing point, too large difference of short-circuit impedance and the like, a large circulating current is often caused after switching, so that overcurrent protection or quick-break protection action is caused, and serious overcurrent can even burn power supply equipment, thereby influencing the reliability of power supply and the safe operation of a system. Before switching, whether switching can be carried out is determined through simulation research, a strategy for reducing the circulation current is provided when the circulation current exceeds an allowable value, accidents caused by the circulation current are reduced, and the safety and the reliability of the operation of a power grid are improved.
Disclosure of Invention
In order to effectively judge whether the uninterrupted switching operation of the power distribution network system can be carried out, the invention provides a method for judging whether the uninterrupted switching operation of the power distribution network system can be carried out, which takes the problem of uninterrupted switching of the power distribution network system as a research object and analyzes and compares loop closing current and current setting values of a relay protection device under different conditions through simulation so as to provide a judgment basis for judging whether the uninterrupted switching operation can be carried out.
Therefore, the technical scheme adopted by the invention is as follows: a method for judging the uninterrupted switching operation of a power distribution system judges whether the uninterrupted switching can be carried out or not by comparing the magnitude of a loop closing current in the uninterrupted switching process with a current setting value of a loop closing point relay protection device;
the selected judgment conditions comprise the amplitude difference and the phase difference of the transformer substation bus voltage on two sides of the closed loop point, the total length of a 10kV circuit of the closed loop and the load of the circuit on two sides of the closed loop point, and switching operation cannot be carried out if the judgment basis is not met; the criterion is specifically set as follows:
when the loop length of the closed loop is more than 2km,
under the condition of satisfying A<10％，B<5°，C<1.3ImSwitching operation is carried out without power failure;
when the loop length of the closed loop is less than 2km,
under the condition of satisfying A<5％，B<3°，C<ImSwitching operation is carried out without power failure;
the switching operation can not be carried out under other conditions;
the loop length of the closed loop is the sum of the outgoing line lengths of 10kV substations on two sides of the closed loop point,
in the formula, A is the amplitude difference of the bus voltage of the transformer substation on two sides of the closed loop point,
b is the phase difference of the substation bus voltage on two sides of the loop closing point,
c is the line load on two sides of the loop closing point,
Imthe line is rated for current.
The invention takes the problem of uninterrupted switching of a 10kV power distribution network system as a research object, and provides a judgment basis for judging whether uninterrupted switching can be carried out or not by analyzing influence factors of loop closing current in switching operation in different grounding modes. The invention relates to a method for judging whether a 10kV power distribution system running in an open loop mode can carry out uninterrupted switching operation or not by aiming at' closed loop design.
As a supplement to the above judgment method, the loop length of the loop is determined to be 2km by considering the total impedance of the 10kV cable loop in the ATP-EMTP software simulation; wherein the line is a crosslinked polyethylene cable with a cross section of 3 × 300mm2(ii) a Positive or negative sequence parameter r 1: 0.0601 Ω/km, X1: 0.061 omega/km，C1: 0.37 muF/km; zero sequence parameter r0:0.601 Ω/km, X0: 0.2135 Ω/km, C0: 0.37. mu.F/km.
As a supplement to the above determination method, the voltage amplitude difference parameter a is determined by simulation, and specifically includes: setting one of the bus voltages of the transformer substation
And regulating the bus voltage of the other transformer substation as a reference, and then respectively measuring the closed loop current under the corresponding voltage amplitude difference to determine the amplitude difference condition required to be met by uninterrupted switching.
As a supplement to the above determination method, the voltage-phase difference B parameter is determined by simulation, and specifically: setting the voltage phase of the bus of one transformer substation as 0 as a reference, adjusting the voltage phase of the bus of the other transformer substation, and then respectively measuring loop closing currents under corresponding voltage phase differences to determine phase difference conditions required to be met by uninterrupted switching.
As a supplement to the above determination method, the load parameter C of the circuit on both sides of the loop closing point is determined by simulation, and specifically includes: the load currents of lines on two sides of a loop closing point are respectively adjusted to be 0A, 50A, 100A, 150A, 200A, 250A, 300A, 350A, 400A, 450A and 500A, and the magnitude of the loop closing current is measured under different combinations of the load currents on the two sides of the loop closing point to judge whether the non-power-cut switching operation can be carried out or not.
According to the method, the loop closing time states under different conditions are analyzed in detail through simulation, a set of method suitable for a power grid technician to judge whether the non-power-outage switching operation can be carried out is summarized quantitatively, and the purpose of accurately and quickly judging whether the non-power-outage switching operation can be carried out is achieved. The method provides a judgment basis for judging whether the power distribution network can be switched off or not without power outage, avoids unreliable switching operation and improves the power supply reliability of a power distribution network system.
Drawings
Fig. 1 is a schematic block diagram of a method for determining a non-power-outage switching operation of a power distribution system according to the present invention.
Detailed Description
The invention is further described in the following with reference to the figures and examples of the specification.
Example 1
As shown in fig. 1, the present invention is a method for determining whether a no-power-off switching operation of a 10kV power distribution network system can be performed, and the specific implementation manner is: firstly, data such as the voltage amplitude and the phase of a substation bus at two sides of a switching point, the total length of a loop closing loop of the switching point, the load current of the switching point and the like are collected, and then whether the total length of the loop closing loop is greater than 2km or not is judged. If the voltage amplitude difference is larger than 2km, whether the voltage amplitude difference of the transformer substation buses on the two sides of the loop closing point is smaller than 10%, the voltage phase difference of the transformer substation buses on the two sides of the loop closing point is smaller than 5 degrees and the load of the circuit on the two sides of the loop closing point does not exceed 150% of the rated current of the circuit needs to be continuously judged, the uninterrupted switching can be carried out if the voltage amplitude difference is smaller than 10%, and the uninterrupted switching cannot. If the voltage amplitude difference is less than 2km, whether the voltage amplitude difference of the transformer substation buses on the two sides of the loop closing point is less than 5%, the voltage phase difference of the transformer substation buses on the two sides of the loop closing point is less than 3 degrees and the line load on the two sides of the loop closing point does not exceed the rated current of the line needs to be continuously judged, and the uninterrupted switching can be carried out only if the voltage amplitude difference is less than 3 degrees, or else the uninterrupted switching cannot.
The above description is only for the preferred embodiment of the present invention, and is not intended to limit the structure of the present invention in any way. Any simple modification, equivalent change and modification of the above embodiments according to the technical spirit of the present invention fall within the scope of the present invention.
Claims (5)
1. A method for judging the uninterrupted switching operation of a power distribution system is characterized in that whether the uninterrupted switching can be carried out or not is judged by comparing the magnitude of a loop closing current in the uninterrupted switching process with a current setting value of a loop closing point relay protection device;
the selected judgment conditions comprise the amplitude difference and the phase difference of the transformer substation bus voltage on two sides of the closed loop point, the total length of a 10kV circuit of the closed loop and the load of the circuit on two sides of the closed loop point, and switching operation cannot be carried out if the judgment basis is not met; the criterion is specifically set as follows:
when the loop length of the closed loop is more than 2km,
under the condition of satisfying A<10％，B<5°，C<1.3ImSwitching operation is carried out without power failure;
when the loop length of the closed loop is less than 2km,
under the condition of satisfying A<5％，B<3°，C<ImSwitching operation is carried out without power failure;
the switching operation can not be carried out under other conditions;
the loop length of the closed loop is the sum of the outgoing line lengths of 10kV substations on two sides of the closed loop point,
in the formula, A is the amplitude difference of the bus voltage of the transformer substation on two sides of the closed loop point,
b is the phase difference of the substation bus voltage on two sides of the loop closing point,
c is the line load on two sides of the loop closing point,
Imthe line is rated for current.
2. The method for determining the uninterrupted switching operation of the power distribution system according to claim 1, wherein the loop length of the closed loop is 2km, which is determined by considering the total loop impedance of the 10kV cable in ATP-EMTP software simulation; wherein the line is a crosslinked polyethylene cable with a cross section of 3 × 300mm2(ii) a Positive or negative sequence parameter r 1: 0.0601 Ω/km, X1:0.061 Ω/km, C1: 0.37 muF/km; zero sequence parameter r0:0.601 Ω/km, X0: 0.2135 Ω/km, C0: 0.37. mu.F/km.
3. The method for determining uninterruptible switching operation of a power distribution system according to claim 1, wherein the voltage amplitude difference parameter a is determined by simulation, and specifically includes: setting one of the bus voltages of the transformer substation
And regulating the bus voltage of the other transformer substation as a reference, and then respectively measuring the closed loop current under the corresponding voltage amplitude difference to determine the amplitude difference condition required to be met by uninterrupted switching.
4. The method for determining uninterruptible switching operation of a power distribution system according to claim 1, wherein the voltage phase difference B parameter is determined by simulation, and specifically includes: setting the voltage phase of the bus of one transformer substation as 0 as a reference, adjusting the voltage phase of the bus of the other transformer substation, and then respectively measuring loop closing currents under corresponding voltage phase differences to determine phase difference conditions required to be met by uninterrupted switching.
5. The method for judging uninterrupted switching operation of the power distribution system according to claim 1, wherein the load parameter C of the lines on both sides of the loop closing point is determined by simulation, and specifically comprises: the load currents of lines on two sides of a loop closing point are respectively adjusted to be 0A, 50A, 100A, 150A, 200A, 250A, 300A, 350A, 400A, 450A and 500A, and the magnitude of the loop closing current is measured under different combinations of the load currents on the two sides of the loop closing point to judge whether the non-power-cut switching operation can be carried out or not.
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| CN201911170572.3A CN110957706B (en) | 2019-11-26 | 2019-11-26 | Method for judging switching operation of distribution system without power outage |
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| CN201911170572.3A CN110957706B (en) | 2019-11-26 | 2019-11-26 | Method for judging switching operation of distribution system without power outage |
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| CN110957706B CN110957706B (en) | 2021-10-01 |
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0795725A (en) * | 1993-09-21 | 1995-04-07 | Hitachi Ltd | Device and method for protecting distribution line |
| CN102638103A (en) * | 2012-04-11 | 2012-08-15 | 国电南瑞科技股份有限公司 | Switching operation on-line early warning analysis method suitable for distributed molding system |
| US20140070613A1 (en) * | 2008-04-22 | 2014-03-13 | Belkin International, Inc. | Electric power supply and related methods |
| CN206481111U (en) * | 2016-12-30 | 2017-09-08 | 国网浙江省电力公司绍兴供电公司 | 30 degree of phase angle difference distribution lines, which do not have a power failure, to be turned to close solution loop device for system |
| CN110061501A (en) * | 2019-06-11 | 2019-07-26 | 云南涞浦电气科技有限公司 | A kind of power distribution network intelligence cyclization switch |
-
2019
- 2019-11-26 CN CN201911170572.3A patent/CN110957706B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0795725A (en) * | 1993-09-21 | 1995-04-07 | Hitachi Ltd | Device and method for protecting distribution line |
| US20140070613A1 (en) * | 2008-04-22 | 2014-03-13 | Belkin International, Inc. | Electric power supply and related methods |
| CN102638103A (en) * | 2012-04-11 | 2012-08-15 | 国电南瑞科技股份有限公司 | Switching operation on-line early warning analysis method suitable for distributed molding system |
| CN206481111U (en) * | 2016-12-30 | 2017-09-08 | 国网浙江省电力公司绍兴供电公司 | 30 degree of phase angle difference distribution lines, which do not have a power failure, to be turned to close solution loop device for system |
| CN110061501A (en) * | 2019-06-11 | 2019-07-26 | 云南涞浦电气科技有限公司 | A kind of power distribution network intelligence cyclization switch |
Non-Patent Citations (1)
| Title |
|---|
| 黄彪: "10kV配电网中合环倒电技术的运用分析", 《中国高新技术企业》 * |
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