CN113219366A - Method for monitoring leakage of related alternating current secondary circuit of synchronous phase modulator - Google Patents
Method for monitoring leakage of related alternating current secondary circuit of synchronous phase modulator Download PDFInfo
- Publication number
- CN113219366A CN113219366A CN202110417680.7A CN202110417680A CN113219366A CN 113219366 A CN113219366 A CN 113219366A CN 202110417680 A CN202110417680 A CN 202110417680A CN 113219366 A CN113219366 A CN 113219366A
- Authority
- CN
- China
- Prior art keywords
- residual current
- load
- phase modulator
- branch
- phase
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 230000001360 synchronised effect Effects 0.000 title claims abstract description 73
- 238000012544 monitoring process Methods 0.000 title claims abstract description 44
- 238000000034 method Methods 0.000 title claims abstract description 39
- 238000001514 detection method Methods 0.000 claims abstract description 11
- 238000000926 separation method Methods 0.000 claims description 6
- JEYCTXHKTXCGPB-UHFFFAOYSA-N Methaqualone Chemical compound CC1=CC=CC=C1N1C(=O)C2=CC=CC=C2N=C1C JEYCTXHKTXCGPB-UHFFFAOYSA-N 0.000 claims description 3
- 230000002159 abnormal effect Effects 0.000 abstract description 6
- 238000010586 diagram Methods 0.000 description 19
- 238000009413 insulation Methods 0.000 description 11
- 230000035945 sensitivity Effects 0.000 description 7
- 206010000369 Accident Diseases 0.000 description 5
- 230000009471 action Effects 0.000 description 3
- 238000012806 monitoring device Methods 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 2
- 238000012423 maintenance Methods 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 239000003607 modifier Substances 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 238000003786 synthesis reaction Methods 0.000 description 2
- 230000002411 adverse Effects 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 235000008216 herbs Nutrition 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 230000016507 interphase Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000007935 neutral effect Effects 0.000 description 1
- 238000003672 processing method Methods 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
Images
Classifications
-
- 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
-
- 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
- G01R19/16533—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values characterised by the application
- G01R19/16538—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values characterised by the application in AC or DC supplies
- G01R19/16547—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values characterised by the application in AC or DC supplies voltage or current in AC supplies
Abstract
A method for monitoring leakage of a related alternating current secondary circuit of a synchronous phase modulator is characterized by comprising the following steps: step 1, measuring inherent residual current of a four-wire at the head end of an alternating current secondary branch of a synchronous phase modulator in advance; step 2, comparing the residual current and the inherent residual current of the head end with alarm constant values under different load input states based on the related load state criterion of the synchronous phase modulator; step 3, comparing the residual current dynamic compensation quantity, the head end residual current and the residual current increment fixed value of the branch at the time t and the time t + delta t based on the residual current increment detection criterion; and 4, judging whether the branch circuit has the electric leakage fault or not based on the judgment of the steady-state residual current and the residual current increment. Based on the method, the smaller abnormal current can be accurately judged, the occurrence of electrical accidents such as fire, electric shock and the like can be effectively prevented, and the safe and reliable state of the secondary circuit related to the phase modulator can be guaranteed.
Description
Technical Field
The invention relates to the field of electric leakage monitoring, in particular to a method for monitoring electric leakage of a related alternating-current secondary circuit of a synchronous phase modulator.
Background
At present, synchronous phase modulators are important devices in high voltage power grids. With the gradual development trend of unattended transformer substations in power grids above 500KV, higher requirements are put forward for the daily operation and maintenance of the transformer substations. Generally, an electrical fire accident of a substation is a focus of attention for operation and maintenance work of the substation. Electrical fire accidents in substations are generally caused by short-circuiting of cables or loads, damage to insulation devices. When a fire accident is caused by a cable or a load break, the short-circuit current is generally large, and at this time, the fault current can be cut off by the action of an air switch, a fuse, a protection device, and the like. When a fire accident is caused by damage to the insulation device, the damage is usually not severe and therefore the short circuit current is relatively small and often not easy to be detected, thus the electric shock accident or the fire is more likely to be caused. This places great fire fighting pressure on the exchange circuit of the camera.
In the prior art, an air switch is generally used as a fault clearing element. However, when the leakage current is too small, it is difficult to remove the failure. In addition, in recent years, due to the emphasis on fire problems caused by insulation damage, some important substations are equipped with residual current monitoring devices, such as RCT (residual current transformer) devices, for monitoring the insulation level of the ac feeder branches. However, it is difficult to overcome the problem of the protection dead zone of the residual current with this technique. When the alarm fixed value of the residual current is smaller than the inherent residual current value, the abnormal residual current cannot be monitored.
Therefore, a new method for monitoring leakage of ac secondary circuit is needed.
Disclosure of Invention
In order to solve the defects in the prior art, the invention aims to provide a method for monitoring leakage of a related alternating current secondary circuit of a synchronous phase modulator.
The invention adopts the following technical scheme. The invention relates to a method for monitoring leakage of a related alternating current secondary circuit of a synchronous phase modulator, which comprises the following steps: step 1, measuring inherent residual current on a head end A, B, C, N four wires of an alternating current secondary branch of a synchronous phase modulator in advance; step 2, comparing the residual current and the inherent residual current of the head end with alarm fixed values under different load input states based on the related load state criterion of the synchronous phase modulator to judge whether the steady-state residual current in the branch exceeds a limit value or not; step 3, comparing the residual current dynamic compensation quantity, the head end residual current and the residual current increment fixed value of the branch at the time t and the time t + delta t based on the residual current increment detection criterion to judge whether the residual current increment in the branch exceeds the limit value or not; and 4, judging whether the branch circuit has the electric leakage fault or not based on the judgment of the steady-state residual current and the residual current increment.
Preferably, the step 1 of pre-measuring the residual current inherent in the four lines at the branch head end A, B, C, N includes: in the initial stage of operation of synchronous phase modulator, the above-mentioned materials are fed into branch circuit in turnEntering single-phase load, three-phase load, single-phase load and three-phase load, setting the branch in an idle state, and respectively measuring inherent residual current I 'in four states'M，1、I′M，2、I′M，3And l'M，4。
Preferably, the relevant load condition criterion of the synchronous phase modulator is as follows:
wherein, IMIs the head end residual current, I 'of the branch'M，1，I′M，2，I′M，3And l'M，4The method comprises the following steps of respectively carrying out single-phase load input, three-phase load input, single-phase and three-phase load input simultaneously and inherent residual current at the head end in an idle load state; i isw1，Iw2，Iw3And Iw4The alarm fixed values of the steady-state residual current under the four states are respectively.
Preferably, if the absolute value of the difference value between the residual current at the head end and the inherent residual current is greater than the alarm fixed value of the steady-state residual current overcurrent, the steady-state residual current in the branch circuit is judged to exceed the limit value; and if the absolute value of the difference value between the residual current at the head end and the inherent residual current is less than or equal to the alarm fixed value of the steady-state residual current, judging that the steady-state residual current in the branch does not exceed the limit value.
Preferably, the residual current alarm setting is 1 to 2 times the intrinsic residual current.
Preferably, step 2 further comprises: judging the load input state of the relevant load of the phase modulator based on the voltage of the head end of the branch of the phase modulator, the single-phase load open position and the three-phase load open position; and judging whether the steady-state residual current in the branches in different load input states exceeds a limit value or not based on the load state criterion of the synchronous phase modulator.
Preferably, if the head end of a phase modulator branch is provided with a voltage, a single-phase load space open-close bit and a three-phase load space open-close bit, the relevant load of the phase modulator is judged to work in a single-phase load input state; if the head end of a phase modulator branch is provided with a voltage, a single-phase load air separation position and a three-phase load air separation position, judging that the related load of the phase modulator works in a three-phase load input state; if the head end of a phase modulator branch is provided with a voltage, a single-phase load open-close position and a three-phase load open-close position, judging that the related load of the phase modulator works in a single-phase and three-phase load input state; and if the head end of the phase modulator branch has voltage, a single-phase load space division bit and a three-phase load space division bit, judging that the related load of the phase modulator works in a no-load state.
Preferably, the residual current increment detection criterion is: iM(t)-IM(t+Δt)-ΔI′M|＞ΔIz(ii) a Wherein, IM(t) head end residual current at time t, IM(t + Δ t) is the head end residual current at time t + Δ t, Δ I'MFor dynamic compensation of residual current, Δ IzRepresenting a constant value of the residual current increment.
Preferably, the residual current dynamic compensation amount Δ IzIs the difference in residual current obtained based on the load input condition.
Preferably, if no load-in or load-out event occurs between time t and time t + Δ t, Δ I 'is present'M＝0。
Preferably, Δ I 'is given when a load-on or load-off event occurs between time t and time t + Δ t'MNot equal to 0, and,. DELTA.I'MEqual to the difference between the residual currents of the front and the rear load states.
Preferably, if the absolute value of the difference between the head-end residual current at the time t and the head-end residual current and the residual current dynamic compensation amount at the time t + Δ t is greater than the fixed value of the residual current increment, determining that the residual current increment exceeds the limit value; and if the absolute value of the difference between the head-end residual current at the time t and the head-end residual current and the residual current dynamic compensation amount at the time t + delta t is less than or equal to the fixed value of the residual current increment, judging that the residual current increment does not exceed the limit value.
Preferably, if one of the steady-state residual current and the residual current increment in the branch circuit is judged to exceed the limit value, the branch circuit is judged to have the electric leakage fault, and an alarm signal is sent out based on the judgment.
A second aspect of the present invention relates to a leakage monitoring system for a secondary ac circuit associated with a synchronous phase modulator according to the first aspect of the present invention, wherein the synchronous phase modulator is connected to a transformer and located at the head end of a secondary ac branch, and includes A, B, C, N four wires; the residual current transformers are respectively connected with A, B, C, N four wires in an alternating current secondary branch of the synchronous phase modulator and used for acquiring residual currents at the head ends of the branches and respectively measuring inherent residual currents on A, B, C, N four wires at the head ends of the branches in advance; and the electric leakage judging unit is respectively connected with A, B, C, N four wires in the AC secondary branch of the synchronous phase modulator, the residual current transformer and each phase air switch in the AC secondary branch of the synchronous phase modulator and is used for judging the working state of related loads of the synchronous phase modulator and judging whether the branch has an electric leakage fault.
Preferably, each phase air switch in the ac secondary branch of the synchronous phase modulator comprises: single-phase load air switch, three-phase load air switch.
Preferably, the three-phase load in the branch is an oil pump motor power supply, and the single-phase load in the branch is a power supply of the intelligent electronic device for online monitoring.
Compared with the prior art, the method for monitoring the leakage of the alternating current secondary circuit related to the synchronous phase modulator has the advantages that the working state of the synchronous phase modulator is changed through the action criterion of the synchronous phase modulator, the abnormal condition of the branch circuit is judged according to the residual current at the head end and the dynamic compensation quantity of the residual current at different moments, the smaller abnormal current can be accurately judged, meanwhile, the occurrence of electrical accidents such as fire, electric shock and the like is effectively prevented, and the safe and reliable state of the secondary circuit of a power grid is guaranteed.
Drawings
FIG. 1 is a schematic diagram of an air switch protection method in the prior art;
FIG. 2 is a schematic diagram of leakage monitoring by a residual current method according to the prior art;
FIG. 3 is a schematic diagram illustrating a principle of residual current vector synthesis according to the prior art;
FIG. 4 is a schematic diagram of dead zone of a residual current method in the prior art;
FIG. 5 is a schematic diagram of a method for monitoring leakage of AC secondary circuit related to synchronous phase modulator according to the present invention;
FIG. 6 is a logic diagram illustrating the load state identification decision according to the present invention;
FIG. 7 is a logic diagram for judging the leakage of the secondary AC feeder branch of the AC system of the transformer substation according to the present invention;
FIG. 8 is a diagram illustrating the sensitivity of the criterion after adding the compensation of the intrinsic residual current according to the present invention;
fig. 9 is a schematic diagram of a phase modulator related alternating current branch secondary circuit monitoring system in the invention.
Detailed Description
The present application is further described below with reference to the accompanying drawings. The following examples are only for illustrating the technical solutions of the present invention more clearly, and the protection scope of the present application is not limited thereby.
In the prior art, an air switch can be used as a protection mode for an alternating current branch. Fig. 1 is a schematic diagram of an air switch protection method in the prior art. As shown in fig. 1, the phase modulator related ac branch has no special monitoring means, and is only provided with an air switch, and when a fault such as an inter-phase short circuit occurs, the air switch can remove the fault.
Next, fig. 2 is a schematic diagram of leakage monitoring by a residual current method in the prior art. As shown in fig. 2, in recent years, due to the emphasis on fire problems caused by insulation damage, some important substations are equipped with a phase-modulator-related ac branch residual current monitoring device, and the insulation level of an ac feeder branch can be monitored by means of a residual current transformer RCT.
In general, leakage current due to insulation breakdown generally occurs between A, B, C, N (neutral line) and PE (protection line). Therefore, the insulation condition of the secondary circuit of the phase modulator of the transformer substation can be evaluated by monitoring, calculating and analyzing the comparative leakage current of the feeder cable and the load of the alternating current system, and the hidden trouble can be found in time.
Therefore, the temperature of the molten metal is controlled,the residual current inherent in the A, B, C, N four wires at the head end of the branch may be measured. In the prior art, a Residual Current Transformer (RCT) can be generally used for current measurement, and I can be takenA、IB、IC、INThe sum current of (c) is used as the head end residual current of the branch. However, when the current transformer is used for measuring the residual current, the problem of dead zone protection is easy to occur.
Fig. 3 is a schematic diagram illustrating a principle of residual current vector synthesis in the prior art. As shown in fig. 3, the Residual Current (Residual Current), i.e. the vector sum of all live body Current values at a given point of the electrical circuit in the electrical device, is a vector composition of the intrinsic Residual Current and the additional Residual Current. In FIG. 3, the first electrifier has a current value of I1The current value of the second charged body is I2The current synthesized by the first charged body and the second charged body is residual current ICombination of Chinese herbs. When a ground fault occurs in the circuit, the residual current is a vector composition of the intrinsic residual current and the additional residual current. Inherent residual currents, due to their discrete distribution, are difficult to create fire hazards. The additional residual current then comprises a residual current component due to the ground fault. Due to the large value of the additional residual current, a local arc may be initiated, thereby causing a hazard.
It will be appreciated that the inherent residual current is related to factors such as the manufacture of the cable, the load properties, etc., and that current values can reach tens to hundreds of milliamps. Due to the discreteness of this current, even if it reaches 300mA, there is still no excessive safety risk.
Fig. 4 is a schematic diagram of dead zones of a residual current method in the prior art. As shown in fig. 4, in general, when a current is monitored, a residual current is detected as a whole by a residual current detection device, and two kinds of currents having different properties cannot be distinguished. Therefore, the alarm value of the residual current should be equal to or higher than the intrinsic residual current, and the detection device can sense the existence of the additional residual current, and the alarm value of the residual current is equal to the intrinsic residual current as an example in fig. 4. A protection dead zone with the origin as the starting point and the residual current as the radius occurs. In the protection dead zone, the additional residual current value cannot be detected effectively and accurately.
If single-phase leakage occurs in the ac secondary circuit, many environmental factors affect the phase relationship between the additional residual current and the inherent residual current in the actual system. For example, in the case of single-phase leakage, when the additional residual current is small but the direction of the additional residual current is consistent with that of the inherent residual current, as shown in the left side of fig. 4, the residual current is easy to reach the alarm constant value of the residual current. However, despite the alarm threshold having been reached, the leakage condition of the circuit is not severe in practice.
For another example, in case of single-phase leakage, the additional residual current is larger, but the additional residual current is in the opposite direction of the inherent residual current, as shown in the right side of fig. 4, where the residual current measurement may be smaller. If the measured value is less than the current alarm fixed value, although the additional residual current is enough to cause safety hazard, the leakage phenomenon can not be represented due to the detection of the residual current. In summary, as the value of the residual current increases, the area of the dead zone increases, and the dead zone problem becomes more serious.
In the prior art, the load carried by the phase modifier-related alternating current loop can be various, so that the problem of complexity of the alternating current load state can also exist. Generally, the types of loads can be classified into single-phase loads, three-phase loads, and single-phase and three-phase loads. Meanwhile, when there is no load on the ac circuit, the ac circuit may be in an idle state. Because the inherent residual currents corresponding to different load states are different, a simple processing method is to obtain the maximum inherent residual current in the line and use the maximum inherent residual current as the basis for setting the residual current alarm value. The method is used for acquiring the alarm information, and the sensitivity of residual current alarm is reduced to a great extent.
Therefore, different load states in the line are automatically identified, differentiated inherent residual current compensation is carried out according to the different load states, and the sensitivity of residual current alarm can be remarkably improved.
Fig. 5 is a schematic flow chart of a method for monitoring leakage of an ac secondary circuit related to a synchronous phase modulator according to the present invention. As shown in fig. 5, a method for monitoring leakage of ac secondary circuit related to synchronous phase modulator includes the following steps: step 1, measuring inherent residual current on a head end A, B, C, N four wires of an alternating current secondary branch of a synchronous phase modulator in advance; step 2, comparing the residual current and the inherent residual current of the head end with alarm fixed values under different load input states based on the related load state criterion of the synchronous phase modulator to judge whether the steady-state residual current in the branch exceeds a limit value or not; step 3, comparing the residual current dynamic compensation quantity, the head end residual current and the residual current increment fixed value of the branch at the time t and the time t + delta t based on the residual current increment detection criterion to judge whether the residual current increment in the branch exceeds the limit value or not; and 4, judging whether the branch circuit has the electric leakage fault or not based on the judgment of the steady-state residual current and the residual current increment.
It is understood that the determination of whether the steady-state residual current and the residual current increment exceed the limit values is performed by two criteria in step 2 and step 3, respectively. For example, if the absolute value of the difference between the head-end residual current and the inherent residual current is greater than the alarm fixed value in the current load input state, it is determined that the steady-state residual current exceeds the limit of the current magnitude, and at this time, it may be determined that the leakage fault has occurred on the branch.
Preferably, the step 1 of pre-measuring the residual current inherent in the four lines at the branch head end A, B, C, N includes: in the initial stage of the operation of the synchronous phase modulator, a single-phase load, a three-phase load, a single-phase load and a three-phase load are sequentially input into a branch, the branch is set to be in an idle state, and inherent residual current I 'in four states is respectively measured'M，1、I′M，2、I′M，3And l'M，4。
It will be appreciated that the residual current early in the commissioning of the synchronous phase modifier may be assumed to be intrinsic. At the moment, single-phase load, three-phase load, single-phase load and three-phase load are respectively input, residual currents under three conditions are respectively measured, all the loads are deduced to measure the residual currents under the no-load state, and four groups of inherent residual currents can be obtained.
Considering that the ac feeder branch is in a good state at the initial stage of commissioning and has not been affected by adverse field environment, it is reasonable and accurate to calculate the residual current at the beginning of the cable by using the RCT residual current transformer and record the calculated residual current as the estimated value of the intrinsic residual current for different typical load conditions on one branch.
Preferably, the load state criterion related to the synchronous phase modulator can be set as follows:
wherein, IMIs the head end residual current, I 'of the branch'M，1，I′M，2，I′M，3And l'M，4The method comprises the following steps of respectively carrying out single-phase load input, three-phase load input, single-phase and three-phase load input simultaneously and inherent residual current at the head end in an idle load state; i isw1，Iw2，Iw3And Iw4The alarm fixed values of the steady-state residual current under the four states are respectively.
Preferably, if the absolute value of the difference value between the residual current at the head end and the inherent residual current is greater than the alarm fixed value of the steady-state residual current overcurrent, the steady-state residual current in the branch circuit is judged to exceed the limit value; and if the absolute value of the difference value between the residual current at the head end and the inherent residual current is less than or equal to the alarm fixed value of the steady-state residual current, judging that the steady-state residual current in the branch does not exceed the limit value.
Generally, the residual current alarm value should be equal to or greater than the intrinsic residual current. Preferably, the residual current alarm setting is 1-2 times the intrinsic residual current. In practical application, a constant value of 1.5 times or 2 times or the like can be selected as the multiple of the alarm constant value relative to the inherent residual current.
During the normal operation of the power grid, the head end A, B, C, N of the AC feeder branch is integrally provided with an RCT in four lines. In this branch, the terminal load is the relevant load of the synchronous phase modulator. Meanwhile, an independent CT current transformer can be arranged on the phase with the single-phase load. When data are collected on the two CT current transformers on the same side, the asymmetric electric leakage of the AC feeder branch circuits, namely the judgment of single-phase electric leakage or two-phase electric leakage, or the effective judgment of three-phase electric leakage can be carried out. Meanwhile, the monitoring of the cable insulation condition can be realized according to the data collected by the RCT at the two sides.
Preferably, in step 2, the load input state of the relevant load of the phase modulator is judged based on the voltage at the head end of the branch of the phase modulator, the single-phase load open position and the three-phase load open position; and judging whether the steady-state residual current in the branches in different load input states exceeds a limit value or not based on the load state criterion of the synchronous phase modulator.
Preferably, fig. 6 is a logic diagram of the load status identification and determination in the present invention. As shown in fig. 6, if the phase modulator branch head end has a voltage, a single-phase load space open/close bit, and a three-phase load space open/close bit, it is determined that the relevant load of the phase modulator is in a single-phase load input state; if the head end of a phase modulator branch is provided with a voltage, a single-phase load air separation position and a three-phase load air separation position, judging that the related load of the phase modulator works in a three-phase load input state; if the head end of a phase modulator branch is provided with a voltage, a single-phase load open-close position and a three-phase load open-close position, judging that the related load of the phase modulator works in a single-phase and three-phase load input state; and if the head end of the phase modulator branch has voltage, a single-phase load space division bit and a three-phase load space division bit, judging that the related load of the phase modulator works in a no-load state.
Preferably, the residual current increment detection criterion is: iM(t)-IM(t+Δt)-ΔI′M|＞ΔIz(ii) a Wherein, IM(t) head end residual current at time t, IM(t + Δ t) is the head end residual current at time t + Δ t, Δ I'MFor dynamic compensation of residual current, Δ IzRepresenting a constant value of the residual current increment.
Preferably, the residual current dynamic compensation amount Δ IzIs the difference in residual current obtained based on the load input condition.
Preferably, if no load-in or load-out event occurs between time t and time t + Δ t, Δ I 'is present'M0. If a load input or load exit event occurs between time t and time t + Δ t, Δ I 'is present'MNot equal to 0, and,. DELTA.I'MEqual to the difference between the residual currents of the front and the rear load states.
Preferably, if the absolute value of the difference between the head-end residual current at the time t and the head-end residual current and the residual current dynamic compensation amount at the time t + Δ t is greater than the fixed value of the residual current increment, determining that the residual current increment exceeds the limit value; and if the absolute value of the difference between the head-end residual current at the time t and the head-end residual current and the residual current dynamic compensation amount at the time t + delta t is less than or equal to the fixed value of the residual current increment, judging that the residual current increment does not exceed the limit value.
Fig. 7 is a logic diagram for judging the leakage of the secondary ac feeder branch of the ac system of the substation according to the present invention. As shown in fig. 7, based on the two criteria, i.e., the load condition related criterion of the synchronous phase modulator and the residual current increment detection criterion, it is determined whether the steady-state residual current and the residual current increment in the branch exceed the limit values, respectively. And if one of the steady-state residual current and the residual current increment in the branch circuit is judged to exceed the limit value, judging that the branch circuit has an electric leakage fault, and sending out an alarm signal based on the judgment. In addition, because the inherent residual current and the residual current dynamic compensation amount are added in the criterion, the problem of overlarge protection dead zone in the prior art is solved in the process of comparing the residual current at the head end with the alarm fixed value or the increment fixed value.
Fig. 8 is a diagram illustrating the sensitivity of the criterion after the compensation of the inherent residual current is added. Wherein FIG. 8(a) is a schematic diagram of theoretical limits of residual current alarm set values; fig. 8(b) is a diagram illustrating the sensitivity of the criterion after being increased.
According to the difference condition of the related AC load input conditions of the synchronous phase modulator, the inherent residual current under various conditions can be respectively measured. In order to ensure that false alarm does not occur in a normal state, theoretically, the alarm limit value of the residual current is equal to or greater than the maximum inherent residual current in various conditions. As shown in fig. 8(a), taking the residual current alarm limit equal to the maximum inherent residual current as an example, the inherent residual current values 1-4 are the inherent residual currents in the four wires of the ac secondary branch head A, B, C, N of the synchronous phase modulator, respectively. The inherent residual current value 3, namely the maximum inherent residual current when the oil pump motor power supply and the phase modulator online monitoring device IED are simultaneously switched in, is very large, so that the alarm sensitivity is limited. In this case, the conventional method can overcome the problem of the protection dead zone and provide an alarm signal only when the additional residual current reaches approximately twice the inherent residual current value 3.
In the present invention, after the intrinsic residual current compensation, as shown in fig. 8(b), a compensation amount may be superimposed on the intrinsic residual current value. After the compensation quantity is superposed, the alarm limit value of the theoretical residual current is greatly reduced, and the range of the theoretical limit value, namely the dead zone, is greatly reduced, so that the alarm sensitivity is improved. The second aspect of the present invention relates to a leakage monitoring system for a secondary ac circuit related to a synchronous phase modulator, which is characterized in that: the synchronous phase modulator is connected with the transformer, is positioned at the head end of the alternating current secondary branch and comprises A, B, C, N four wires; the residual current transformers are respectively connected with A, B, C, N four wires in an alternating current secondary branch of the synchronous phase modulator and used for acquiring residual currents at the head ends of the branches and respectively measuring inherent residual currents on A, B, C, N four wires at the head ends of the branches in advance; and the electric leakage judging unit is respectively connected with A, B, C, N four wires in the AC secondary branch of the synchronous phase modulator, the residual current transformer and each phase air switch in the AC secondary branch of the synchronous phase modulator and is used for judging the working state of related loads of the synchronous phase modulator and judging whether the branch has an electric leakage fault.
In an embodiment of the invention, a synchronous phase modulator alternating current branch of a 500KV transformer substation alternating current system can be applied to build a residual current monitoring system. Fig. 9 is a schematic diagram of a phase modulator related alternating current branch secondary circuit monitoring system in the invention. The connection mode of the leakage determination unit and the branch four lines is shown in fig. 9.
Preferably, each phase air switch in the ac secondary branch of the synchronous phase modulator comprises: single-phase load air switch, three-phase load air switch.
Preferably, the three-phase load in the branch is an oil pump motor power supply, and the single-phase load in the branch is a power supply of the intelligent electronic device for online monitoring. At the moment, the oil pump motor power supply is used as a three-phase load in a related alternating current branch of the phase modulator, and the online monitoring intelligent electronic equipment power supply is used as a single-phase load. And testing the inherent residual current in the commissioning period, and installing an RCT on the side of the branch M and installing an independent CT on the phase A of the single-phase load end in the running process.
Particularly, based on the judgment, the insulation condition of the AC feeder branch can be monitored on line, so that whether hidden dangers exist in an AC system is judged, an alarm signal is sent out, the fire-fighting hidden dangers caused by insulation abnormity can be found in time, and the occurrence of fire accidents is effectively avoided.
Compared with the prior art, the method for monitoring the leakage of the alternating current secondary circuit related to the synchronous phase modulator has the advantages that the working state of the synchronous phase modulator is changed through the action criterion of the synchronous phase modulator, the abnormal condition of the branch circuit is judged according to the residual current at the head end and the dynamic compensation quantity of the residual current at different moments, the smaller abnormal current can be accurately judged, meanwhile, the occurrence of electrical accidents such as fire, electric shock and the like is effectively prevented, and the safe and reliable state of the secondary circuit of a power grid is guaranteed.
The present applicant has described and illustrated embodiments of the present invention in detail with reference to the accompanying drawings, but it should be understood by those skilled in the art that the above embodiments are merely preferred embodiments of the present invention, and the detailed description is only for the purpose of helping the reader to better understand the spirit of the present invention, and not for limiting the scope of the present invention, and on the contrary, any improvement or modification made based on the spirit of the present invention should fall within the scope of the present invention.
Claims (16)
1. A method for monitoring leakage of a related alternating current secondary circuit of a synchronous phase modulator is characterized by comprising the following steps:
step 1, measuring inherent residual current on a head end A, B, C, N four wires of an alternating current secondary branch of a synchronous phase modulator in advance;
step 2, comparing the residual current and the inherent residual current of the head end with alarm fixed values under different load input states based on the related load state criterion of the synchronous phase modulator to judge whether the steady-state residual current in the branch exceeds a limit value;
step 3, comparing the dynamic compensation quantity of the residual current of the branch at the time t and the time t + delta t, the residual current of the head end and the constant value of the residual current increment based on the residual current increment detection criterion to judge whether the residual current increment in the branch exceeds a limit value or not;
and 4, judging whether the branch circuit has the electric leakage fault or not based on the judgment of the steady-state residual current and the residual current increment.
2. The method for monitoring leakage of ac secondary circuit related to synchronous phase modulator as claimed in claim 1, wherein:
in step 1, the pre-measuring the inherent residual current at the four lines of the branch head end A, B, C, N includes:
in the initial stage of the operation of the synchronous phase modulator, a single-phase load, a three-phase load, a single-phase load and a three-phase load are sequentially input into the branch, the branch is set to be in an idle state, and inherent residual current I 'in four states is measured respectively'M，1、I′M，2、I′M，3And l'M，4。
3. The method for monitoring leakage of ac secondary circuit related to synchronous phase modulator as claimed in claim 2, wherein:
the related load state criterion of the synchronous phase modulator is as follows:
wherein, IMIs a head end residual current, I 'of the branch'M，1，I′M，2，I′M，3And l'M，4The method comprises the following steps of respectively carrying out single-phase load input, three-phase load input, single-phase and three-phase load input simultaneously and inherent residual current at the head end in an idle load state; i isw1，Iw2，Iw3And Iw4The alarm fixed values of the steady-state residual current under the four states are respectively.
4. The method for monitoring leakage of AC secondary circuit related to synchronous phase modulator as claimed in claim 3, wherein:
if the absolute value of the difference value between the head-end residual current and the inherent residual current is greater than the alarm fixed value of the steady-state residual current, judging that the steady-state residual current in the branch exceeds the limit value;
and if the absolute value of the difference value between the head-end residual current and the inherent residual current is less than or equal to the alarm fixed value of the steady-state residual current, judging that the steady-state residual current in the branch does not exceed the limit value.
5. The method for monitoring leakage of AC secondary circuit related to synchronous phase modulator as claimed in claim 4, wherein:
the residual current alarm setting value is 1 to 2 times of the inherent residual current.
6. The method for monitoring leakage of ac secondary circuit related to synchronous phase modulator according to claim 5, wherein step 2 further comprises:
judging the load input state of the relevant load of the phase modulator based on the voltage of the head end of the branch of the phase modulator, the single-phase load open position and the three-phase load open position;
and judging whether the steady-state residual current in the branch under different load input states exceeds a limit value or not based on the load state criterion of the synchronous phase modulator.
7. The method for monitoring leakage of AC secondary circuit related to synchronous phase modulator as claimed in claim 6, wherein:
if the head end of the phase modulator branch is provided with a voltage, a single-phase load air-break-open position and a three-phase load air-break-open position, judging that the related load of the phase modulator works in a single-phase load input state;
if the head end of the phase modulator branch has pressure, a single-phase load air separation position and a three-phase load air separation position, judging that the related load of the phase modulator works in a three-phase load input state;
if the head end of the phase modulator branch has pressure, a single-phase load open-close position and a three-phase load open-close position, judging that the related load of the phase modulator works in a single-phase and three-phase load input state;
and if the head end of the phase modulator branch is provided with a voltage, a single-phase load space division bit and a three-phase load space division bit, judging that the related load of the phase modulator works in a no-load state.
8. The method for monitoring leakage of ac secondary circuit related to synchronous phase modulator as claimed in claim 7, wherein:
the residual current increment detection criterion is as follows: iM(t)-IM(t+Δt)-ΔI′M|>ΔIZ；
Wherein, IM(t) head end residual current at time t, IM(t + Δ t) is the head end residual current at time t + Δ t, Δ I'MFor dynamic compensation of residual current, Δ IZRepresenting a constant value of the residual current increment.
9. The method for monitoring leakage of ac secondary circuit related to synchronous phase modulator as claimed in claim 8, wherein:
the residual current dynamic compensation quantity delta IZIs the difference in residual current obtained based on the load input condition.
10. The method for monitoring leakage of ac secondary circuit related to synchronous phase modulator as claimed in claim 9, wherein:
if no load input or load exit event occurs between time t and time t + delta t, delta I 'exists'M＝0。
11. The method for monitoring leakage of ac secondary circuit related to synchronous phase modulator as claimed in claim 9, wherein:
if a load input or load exit event occurs between time t and time t + Δ t, Δ I 'is present'MNot equal to 0, and,. DELTA.I'MEqual to the difference between the residual currents of the front and the rear load states.
12. The method for monitoring leakage of ac secondary circuit related to synchronous phase modulator as claimed in claim 9, wherein:
if the absolute value of the difference between the head-end residual current at the time t and the head-end residual current and the residual current dynamic compensation amount at the time t + delta t is greater than the fixed value of the residual current increment, judging that the residual current increment exceeds the limit value;
and if the absolute value of the difference between the head-end residual current at the time t and the head-end residual current and the residual current dynamic compensation amount at the time t + delta t is less than or equal to the fixed value of the residual current increment, judging that the residual current increment does not exceed the limit value.
13. The method for monitoring leakage of ac secondary circuit related to synchronous phase modulator as claimed in claim 12, wherein:
and if one of the steady-state residual current and the residual current increment in the branch circuit is judged to exceed the limit value, judging that the branch circuit has the electric leakage fault, and sending out an alarm signal based on the judgment.
14. A system for monitoring leakage in a secondary ac circuit associated with a synchronous phase modulator according to any one of claims 1-13, wherein:
the synchronous phase modulator is connected with the transformer, is positioned at the head end of the alternating current secondary branch and comprises A, B, C, N four wires;
the residual current transformers are respectively connected with A, B, C, N four wires in an alternating current secondary branch of the synchronous phase modulator and used for acquiring residual currents at the head ends of the branches and respectively measuring inherent residual currents on A, B, C, N four wires at the head ends of the branches in advance;
the electric leakage judging unit is respectively connected with A, B, C, N four wires in the synchronous phase modulator alternating current secondary branch, the residual current transformer and each phase air switch in the synchronous phase modulator alternating current secondary branch, and is used for judging the working state of the related load of the synchronous phase modulator and judging whether the branch has an electric leakage fault.
15. The system according to claim 14, wherein the leakage monitoring system comprises:
each phase air switch in the synchronous phase modulator AC secondary branch respectively includes: single-phase load air switch, three-phase load air switch.
16. The system according to claim 15, wherein the leakage monitoring system comprises:
the three-phase load in the branch is an oil pump motor power supply, and the single-phase load in the branch is a power supply of intelligent electronic equipment for online monitoring.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110417680.7A CN113219366B (en) | 2021-04-19 | 2021-04-19 | Method for monitoring leakage of related alternating current secondary circuit of synchronous phase-change modulator |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110417680.7A CN113219366B (en) | 2021-04-19 | 2021-04-19 | Method for monitoring leakage of related alternating current secondary circuit of synchronous phase-change modulator |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN113219366A true CN113219366A (en) | 2021-08-06 |
| CN113219366B CN113219366B (en) | 2024-05-03 |
Family
ID=77087924
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202110417680.7A Active CN113219366B (en) | 2021-04-19 | 2021-04-19 | Method for monitoring leakage of related alternating current secondary circuit of synchronous phase-change modulator |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN113219366B (en) |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN201515183U (en) * | 2009-10-22 | 2010-06-23 | 泉州科力电气有限公司 | Intelligent integrated distribution box with leakage protection remote monitoring function |
| JP2012215423A (en) * | 2011-03-31 | 2012-11-08 | Patokkusu Japan Kk | Leak current measuring device and leak current measuring method in power supply system |
| CN203929951U (en) * | 2014-01-25 | 2014-11-05 | 泉州天梭电气有限公司 | Intelligent alarm is surveyed in integral type electric leakage |
| CN106560718A (en) * | 2016-05-06 | 2017-04-12 | 艾思玛新能源技术（上海）有限公司 | Grounding fault current detection protection method and device |
| EP3514905A1 (en) * | 2018-01-18 | 2019-07-24 | EURODIMA GmbH & Co KG | Construction site power distributor with residual current protection, protective earth monitoring and leakage current compensation |
| CN112147403A (en) * | 2020-09-16 | 2020-12-29 | 国创新能源汽车智慧能源装备创新中心(江苏)有限公司 | Method and system for improving temperature adaptability of residual current detection device |
-
2021
- 2021-04-19 CN CN202110417680.7A patent/CN113219366B/en active Active
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN201515183U (en) * | 2009-10-22 | 2010-06-23 | 泉州科力电气有限公司 | Intelligent integrated distribution box with leakage protection remote monitoring function |
| JP2012215423A (en) * | 2011-03-31 | 2012-11-08 | Patokkusu Japan Kk | Leak current measuring device and leak current measuring method in power supply system |
| CN203929951U (en) * | 2014-01-25 | 2014-11-05 | 泉州天梭电气有限公司 | Intelligent alarm is surveyed in integral type electric leakage |
| CN106560718A (en) * | 2016-05-06 | 2017-04-12 | 艾思玛新能源技术（上海）有限公司 | Grounding fault current detection protection method and device |
| EP3514905A1 (en) * | 2018-01-18 | 2019-07-24 | EURODIMA GmbH & Co KG | Construction site power distributor with residual current protection, protective earth monitoring and leakage current compensation |
| CN112147403A (en) * | 2020-09-16 | 2020-12-29 | 国创新能源汽车智慧能源装备创新中心(江苏)有限公司 | Method and system for improving temperature adaptability of residual current detection device |
Non-Patent Citations (1)
| Title |
|---|
| 陈昊 等: "变电站站用电系统混合型负荷支路的漏电监测方法", 消防科学与技术, vol. 41, no. 06, 30 June 2022 (2022-06-30), pages 739 - 743 * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN113219366B (en) | 2024-05-03 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| KR101003814B1 (en) | Switchgear for diagnosing electrical network disorder and method therefor | |
| CN110554234B (en) | Zero-sequence current loop inspection method for in-service switch cabinet | |
| CN103618377B (en) | For being connected to backup auto-activating device system and the spare power automatic switching method of small power supply | |
| CN104836330B (en) | Backup auto-activating device bus PT three-phases broken string quick determination method and faulty action preventing method | |
| CN104599901B (en) | Detection circuit used for contactor | |
| KR20180066732A (en) | MICROGRID SYSTEM and TROUBLE PROCESSING METHOD thereof | |
| Mahapatra et al. | Analysis of symmetrical fault in IEEE 14 bus system for enhancing over current protection scheme | |
| CN110320432B (en) | Single-phase line-breaking fault detection and protection method and system | |
| KR100920946B1 (en) | Apparatus and method for fault detection and fault location decision on a distribution line using load current | |
| CN111579934A (en) | Method and device for realizing electric safety monitoring of external power network of base station and base station | |
| JP4924199B2 (en) | Three-phase circuit breaker characteristic measurement device, three-phase circuit breaker irregularity abnormality detection method, and program for causing a computer to execute three-phase circuit breaker irregularity abnormality detection | |
| KR20180081478A (en) | Electric failure master detector | |
| Boljevic et al. | Fault current level issues for urban distribution network with high penetration of distributed generation | |
| CN113219366A (en) | Method for monitoring leakage of related alternating current secondary circuit of synchronous phase modulator | |
| KR20170051984A (en) | Before using electrical short circuit resistance measuring device for applying distribution board | |
| CN110970877B (en) | Safety protection method and device for live working of power distribution network | |
| CN115166596A (en) | Yd11 wiring transformer single-phase wire break on-line monitoring method | |
| Comech et al. | Protection in distributed generation | |
| KR101473224B1 (en) | Power distribution board for preventing of black out and arc fault | |
| CN112710931B (en) | Method and system for detecting earth leakage current of secondary side long-distance cable pair of alternating current system | |
| CN107204609B (en) | A kind of the power distribution network busbar protective device and method of earthing mode self-identifying | |
| Austin et al. | Fault Diagnosis Algorithm and Protection of Electric Power Systems in an Alternative Distribution System | |
| CN214409251U (en) | Grounding fault alarm device for low-voltage side of transformer for high-temperature gas cooled reactor high-voltage station | |
| KR102616906B1 (en) | System for Controlling the Distribution System by Detecting Phase Loss | |
| CN219224959U (en) | Anti-electricity-stealing detection mechanism |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant |