CN113219366B - Method for monitoring leakage of related alternating current secondary circuit of synchronous phase-change modulator - Google Patents
Method for monitoring leakage of related alternating current secondary circuit of synchronous phase-change modulator Download PDFInfo
- Publication number
- CN113219366B CN113219366B CN202110417680.7A CN202110417680A CN113219366B CN 113219366 B CN113219366 B CN 113219366B CN 202110417680 A CN202110417680 A CN 202110417680A CN 113219366 B CN113219366 B CN 113219366B
- Authority
- CN
- China
- Prior art keywords
- residual current
- branch
- load
- synchronous
- 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.)
- Active
Links
- 230000001360 synchronised effect Effects 0.000 title claims abstract description 83
- 238000012544 monitoring process Methods 0.000 title claims abstract description 38
- 238000000034 method Methods 0.000 title claims abstract description 36
- 238000001514 detection method Methods 0.000 claims abstract description 8
- 230000002159 abnormal effect Effects 0.000 abstract description 8
- 238000010586 diagram Methods 0.000 description 19
- 238000009413 insulation Methods 0.000 description 10
- 230000035945 sensitivity Effects 0.000 description 7
- 206010000369 Accident Diseases 0.000 description 5
- 230000009471 action Effects 0.000 description 4
- 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
- 230000008569 process Effects 0.000 description 2
- 238000003786 synthesis reaction Methods 0.000 description 2
- 230000002411 adverse 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
- 239000006185 dispersion Substances 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 230000016507 interphase Effects 0.000 description 1
- 238000004519 manufacturing process Methods 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
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
The method for monitoring the leakage of the related alternating current secondary circuit of the synchronous camera is characterized by comprising the following steps of: step 1, measuring the inherent residual current of four wires at the head end of an alternating current secondary branch of a synchronous regulator in advance; step 2, comparing the head-end residual current and the inherent residual current with alarm fixed values in different load input states based on related load state criteria of the synchronous camera; step 3, comparing the residual current dynamic compensation quantity, the head end residual current and the residual current increment constant value of the branch circuit at the time t and the time t+delta t based on the residual current increment detection criterion; and step 4, judging whether the branch circuit has leakage faults or not based on judgment on the steady-state residual current and the residual current increment respectively. Based on the method provided by the invention, small abnormal current can be accurately judged, the occurrence of electrical accidents such as fire disaster, electric shock and the like can be effectively prevented, and the safe and reliable state of a secondary circuit related to the camera can be ensured.
Description
Technical Field
The invention relates to the field of leakage monitoring, in particular to a method for monitoring leakage of an alternating current secondary circuit related to a synchronous regulator.
Background
Currently, synchronous modems are important devices in high voltage power networks. With the gradual development trend of unattended substations in power grids above 500KV, higher requirements are put forward for daily operation and maintenance of the substations. Generally, an electrical fire accident of a transformer substation is an important point of operation and maintenance work of the transformer substation. Electrical fire accidents in substations are generally caused by cable or load short circuits and insulation damage. When a fire accident is caused by a cable or a load break, a short-circuit current is generally large, and at this time, the fault current can be cut off by the actions of an air switch, a fuse, a protection device, and the like. When a fire accident is caused by the damage of the insulating device, the damage is usually not serious by short circuit, so that the short circuit current is relatively small, and the short circuit current is not easy to find, so that the electric shock accident or the fire is more easy to cause. This is a significant fire pressure for the ac circuit of the camera.
In the prior art, air switches are commonly used as fault-removal elements. However, when the leakage current flows through an hour, it is difficult to cut off the fault. In addition, in recent years, attention has been paid to fire problems caused by insulation damage, and some of the important substations are equipped with residual current monitoring devices, such as RCT (residual current transformer) devices, for monitoring the insulation level of ac feeder branches. However, the protection dead zone problem of the residual current is also difficult to overcome with this technique. When the alarm constant value of the residual current is smaller than the inherent residual current value, 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 synchronous camera related alternating current secondary circuit leakage monitoring method, which is used for changing the working state of a synchronous camera through the action criterion of the synchronous camera and judging the abnormal condition of a branch according to the head end residual current and the residual current dynamic compensation quantity at different moments.
The invention adopts the following technical scheme. The invention relates to a method for monitoring leakage of an alternating current secondary circuit related to a synchronous camera, which comprises the following steps: step 1, measuring inherent residual current on four lines of a head end A, B, C, N of an alternating current secondary branch of a synchronous regulator in advance; step 2, comparing the head end residual current, the inherent residual current and the alarm fixed value under different load input states based on the related load state criteria of the synchronous camera to judge whether the steady state residual current in the branch circuit 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 constant value of the branch circuit at the time t and the time t+delta t based on the residual current increment detection criterion so as to judge whether the residual current increment in the branch circuit exceeds the limit value; and step 4, judging whether the branch circuit has leakage faults or not based on judgment on the steady-state residual current and the residual current increment respectively.
Preferably, in step 1, pre-measuring the intrinsic residual current on the four lines of the branch head end A, B, C, N includes: and in the initial stage of operation of the synchronous camera, 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 intrinsic residual currents I 'M,1、I′M,2、I′M,3 and I' M,4 in the four states are respectively measured.
Preferably, the load state criteria related to the synchronous camera are as follows:
Wherein, I M is the head end residual current of the branch, and I 'M,1,I′M,2,I′M,3 and I' M,4 are the single-phase load input, the three-phase load input, the single-phase and three-phase load input simultaneously and the head end of the idle load state respectively; i w1,Iw2,Iw3 and I w4 are alarm fixed values of steady state residual current overcurrent in four states respectively.
Preferably, 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 of the steady-state residual current flowing through, judging that the steady-state residual current in the branch circuit exceeds the limit value; if the absolute value of the difference value between the head-end residual current and the inherent residual current is smaller than or equal to the alarm fixed value of the steady-state residual current flowing through, judging that the steady-state residual current in the branch circuit does not exceed the limit value.
Preferably, the residual current warning value is 1 to 2 times the intrinsic residual current.
Preferably, step 2 further includes: judging the load input state of the related load of the phase regulator based on the voltage of the head end of the branch of the phase regulator, the idle position of the single-phase load and the idle position of the three-phase load; and judging whether the steady-state residual current in the branch circuits in different load input states exceeds a limit value or not based on the synchronous camera load state criterion.
Preferably, if the head end of the branch of the camera has pressure and single-phase load on-off position and three-phase load on-off position, judging that the related load of the camera works in a single-phase load input state; if the head end of the branch of the phase-adjusting camera has pressure, single-phase load open-close position and three-phase load open-close position, judging that the related load of the phase-adjusting camera works in a three-phase load input state; if the head end of the branch of the phase-adjusting camera has a voltage, single-phase load open-close position and three-phase load open-close position, judging that the related load of the phase-adjusting camera works in a single-phase load input state and a three-phase load input state; if the head end of the branch of the camera has pressure, single-phase load space division and three-phase load space division, the relevant load of the camera is judged to work in an idle state.
Preferably, the residual current increment detection criterion is: i M(t)-IM(t+Δt)-ΔI′M|>ΔIz; wherein, I M (t) is the head-end residual current at time t, I M (t+Δt) is the head-end residual current at time t+Δt, Δi' M is the residual current dynamic compensation amount, and Δi z represents the constant value of the residual current increment.
Preferably, the residual current dynamic compensation amount Δi z is a difference in residual current obtained based on the load input condition.
Preferably, if no load input or load exit event occurs between time t and t+Δt, there is Δi' M =0.
Preferably, if a load input or load exit event occurs between time t and t+Δt, Δi 'M +.0, and Δi' M is equal to the difference between the residual currents of the two 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 quantity 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; 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 quantity at the time t+delta t is smaller than or equal to the constant value of the residual current increment, judging that the residual current increment does not exceed the limit value.
Preferably, if the steady state residual current and the residual current increment in the branch circuit are 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 synchronous rectifier related to an ac secondary circuit leakage monitoring system according to the first aspect of the present invention, wherein the synchronous rectifier is connected to a transformer used and is located at a head end of an ac secondary branch, and includes A, B, C, N four wires; the residual current transformers are respectively connected with A, B, C, N four wires in the alternating current secondary branch of the synchronous rectifier and are used for obtaining the residual current at the head end of the branch and respectively measuring the inherent residual current on the four wires at the head end A, B, C, N of the branch in advance; the leakage judging unit is respectively connected with A, B, C, N four wires in the synchronous rectifier AC secondary branch, the residual current transformer and each phase of air switch in the synchronous rectifier AC secondary branch and is used for judging the working state of the load related to the synchronous rectifier and judging whether the branch has leakage faults or not.
Preferably, each phase of air switch in the alternating current secondary branch of the synchronous camera 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 intelligent electronic equipment for on-line monitoring.
Compared with the prior art, the synchronous camera-related alternating current secondary circuit leakage monitoring method has the advantages that the working state of the synchronous camera is changed through the action criteria of the synchronous camera, abnormal conditions of the branch are judged according to the head-end residual current and the residual current dynamic compensation quantity at different moments, small abnormal currents can be accurately judged, meanwhile, electrical accidents such as fire and electric shock are effectively prevented, and the safe and reliable state of the secondary circuit of the power grid is guaranteed.
Drawings
FIG. 1 is a schematic diagram of an air switch protection scheme in the prior art;
FIG. 2 is a schematic diagram of residual current method leakage monitoring in the prior art;
FIG. 3 is a schematic diagram of a residual current vector synthesis principle in the prior art;
FIG. 4 is a schematic diagram of a dead zone of a residual current method according to the prior art;
FIG. 5 is a schematic diagram of a method flow chart of a leakage monitoring method for an AC secondary circuit related to a synchronous regulator according to the present invention;
FIG. 6 is a logic diagram of the load status recognition and discrimination according to the present invention;
FIG. 7 is a logic schematic diagram for discriminating leakage of a secondary AC feeder branch of a transformer substation AC system according to the present invention;
FIG. 8 is a schematic diagram of the sensitivity of the criteria after adding intrinsic residual current compensation according to the present invention;
Fig. 9 is a schematic diagram of a secondary loop monitoring system for an ac branch related to a camera of the present invention.
Detailed Description
The application is further described below with reference to the accompanying drawings. The following examples are only for more clearly illustrating the technical aspects of the present application, and are not intended to limit the scope of the present application.
In the prior art, an air switch can be used as a protection mode for the alternating current branch circuit. Fig. 1 is a schematic diagram of an air switch protection mode in the prior art of the present invention. As shown in fig. 1, the related ac branch of the phase regulator has no special monitoring means, and is only provided with an air switch, so that the air switch can cut off faults when faults such as interphase short circuit and the like occur.
Next, fig. 2 is a schematic diagram of leakage monitoring by a residual current method according to the prior art. As shown in fig. 2, in recent years, attention has been paid to the problem of fire caused by insulation damage, and a part of important substations are equipped with a residual current monitoring device for an ac branch related to a phase adjuster, by which the insulation level of an ac feeder branch can be monitored by means of a residual current transformer RCT.
In general, leakage caused by insulation damage usually occurs between A, B, C, N (neutral line) and PE (protection line). Therefore, the secondary circuit insulation condition of the substation shunting device can be evaluated by monitoring, calculating and analyzing the comparison leakage current of the feeder cable and the load of the alternating current system, and fault hidden danger can be found timely.
Therefore, the intrinsic residual current on the A, B, C, N four lines at the head end of the branch can be measured. In the prior art, a Residual Current Transformer (RCT) can be generally used for current measurement, and the sum current of I A、IB、IC、IN can be taken as the head-end residual current of the branch. However, when the residual current is measured using a current transformer, a problem of dead zone protection is liable to occur.
Fig. 3 is a schematic diagram of a residual current vector synthesis principle in the prior art of the present invention. As shown in fig. 3, the Residual Current (Residual Current), i.e. the vector sum of all charged body Current values at a given point of an electrical circuit in an electrical device, is synthesized with a vector of the intrinsic Residual Current and the additional Residual Current. In fig. 3, the current value of the first charged body is I 1, the current value of the second charged body is I 2, and the combined current of the first charged body and the second charged body is I Closing device . When a ground fault occurs in the circuit, the residual current is a vector combination of the intrinsic residual current and the additional residual current. Inherent residual current, due to the dispersion of its distribution, is difficult to form a fire hazard. The additional residual current then comprises a residual current component due to the ground fault. Because of the large value of the additional residual current, a local arc may be initiated, thus creating a hazard.
It will be appreciated that the intrinsic residual current is related to factors such as the manufacture of the cable, the load properties, etc., and that the current value may be tens to hundreds of milliamps. Because of the discreteness of this current, even if it reaches 300mA, there is still no excessive safety risk.
Fig. 4 is a schematic diagram of a dead zone of a residual current method according to the prior art. As shown in fig. 4, in general, when monitoring a current, a residual current is detected by a residual current detecting device, and two 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, at which point the detecting device can sense the existence of the additional residual current, and the alarm value of the residual current is illustrated as being equal to the intrinsic residual current in fig. 4. A guard dead zone with the origin as the starting point and the residual current as the radius appears. Within the protection dead zone, the additional residual current value cannot be effectively and accurately detected.
If a 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 additional residual current and the inherent residual current are in the same direction, as shown in the left side of fig. 4, the residual current is easier to reach the alarm value of the residual current. However, although the alarm set value has been reached, the leakage condition of the circuit is not serious in practice.
For another example, in case of single-phase leakage, the additional residual current is larger, but the direction of the additional residual current is completely opposite to that of the inherent residual current, as shown on the right side of fig. 4, and the residual current measurement value may be smaller. If the measured value is less than the current warning value, although the additional residual current is sufficient to cause a safety hazard, the leakage phenomenon cannot be characterized by detecting 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, since the load carried by the ac loop related to the camera may be various, there may be a problem of complexity of the ac load state. Generally, the types of loads can be classified into single-phase loads, three-phase loads, single-phase and three-phase loads. Meanwhile, when no load is applied to the alternating current loop, the alternating current loop can be in an idle state. Because of the difference of the intrinsic residual currents corresponding to different load states, a simple processing method is to acquire the maximum intrinsic residual current in the line and take the maximum intrinsic residual current as a residual current alarm value setting basis. The method is used for acquiring the alarm information, so that the sensitivity of the residual current alarm is greatly reduced.
Therefore, the sensitivity of residual current warning can be remarkably improved by automatically identifying different load states in the circuit and carrying out differential inherent residual current compensation aiming at the different load states.
Fig. 5 is a schematic flow chart of a method for monitoring leakage of an ac secondary circuit related to a synchronous regulator according to the present invention. As shown in fig. 5, a method for monitoring leakage of an ac secondary circuit related to a synchronous regulator includes the following steps: step 1, measuring inherent residual current on four lines of a head end A, B, C, N of an alternating current secondary branch of a synchronous regulator in advance; step 2, comparing the head end residual current, the inherent residual current and the alarm fixed value under different load input states based on the related load state criteria of the synchronous camera to judge whether the steady state residual current in the branch circuit 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 constant value of the branch circuit at the time t and the time t+delta t based on the residual current increment detection criterion so as to judge whether the residual current increment in the branch circuit exceeds the limit value; and step 4, judging whether the branch circuit has leakage faults or not based on judgment on the steady-state residual current and the residual current increment respectively.
It will be appreciated that the determination as to whether the steady state residual current and the residual current increase exceed the limit values is made 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 intrinsic residual current is greater than the alarm fixed value in the current load input state, it is determined that the steady-state residual current has exceeded the limit of the current magnitude, and at this time, it can be considered that the leakage fault has occurred on the branch.
Preferably, in step 1, pre-measuring the intrinsic residual current on the four lines of the branch head end A, B, C, N includes: and in the initial stage of operation of the synchronous camera, 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 intrinsic residual currents I 'M,1、I′M,2、I′M,3 and I' M,4 in the four states are respectively measured.
It will be appreciated that the residual current at the beginning of the operation of the synchronous rectification device can be assumed to be the intrinsic residual current. At this time, single-phase load, three-phase load, single-phase load and three-phase load are respectively input, and residual currents of three conditions are respectively measured, so that residual currents of all the loads in a no-load state are measured, and four groups of inherent residual currents can be obtained.
Considering that the state of the alternating current feeder line branch is good in the initial stage of operation and is not influenced by adverse field environment, the residual current at the beginning of a cable is calculated by using RCT residual current transformers according to different typical load conditions on one branch, and the residual current is recorded as an estimated value of inherent residual current reasonably and accurately.
Preferably, the load state criteria related to the synchronous camera may be set as follows:
Wherein, I M is the head end residual current of the branch, and I 'M,1,I′M,2,I′M,3 and I' M,4 are the single-phase load input, the three-phase load input, the single-phase and three-phase load input simultaneously and the head end of the idle load state respectively; i w1,Iw2,Iw3 and I w4 are alarm fixed values of steady state residual current overcurrent in four states respectively.
Preferably, 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 of the steady-state residual current flowing through, judging that the steady-state residual current in the branch circuit exceeds the limit value; if the absolute value of the difference value between the head-end residual current and the inherent residual current is smaller than or equal to the alarm fixed value of the steady-state residual current flowing through, judging that the steady-state residual current in the branch circuit does not exceed the limit value.
In general, the residual current warning constant should be equal to or greater than the intrinsic residual current. Preferably, the residual current warning value is 1-2 times of 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.
In the normal operation process of the power grid, the four wires at the head end A, B, C, N of the alternating current feeder line branch are integrally provided with an RCT. In the branch, the terminal load is the relevant load of the synchronous camera. At the same time, an independent CT current transformer can be installed on the phase with single-phase load. When data are collected on two CT current transformers on the same side, asymmetric leakage of an alternating current feeder branch, namely discrimination during single-phase leakage or two-phase leakage, or effective discrimination of three-phase leakage can be performed. Meanwhile, the cable insulation condition can be monitored according to data acquired by RCTs on two sides.
Preferably, in the step 2, the load input state of the load related to the camera is determined based on the voltage of the head end of the branch of the camera, the idle position of the single-phase load and the idle position of the three-phase load; and judging whether the steady-state residual current in the branch circuits in different load input states exceeds a limit value or not based on the synchronous camera load state criterion.
Preferably, fig. 6 is a logic diagram of load status identification and discrimination in the present invention. As shown in fig. 6, if the head end of the branch of the phase-adjusting camera has 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-adjusting camera works in a single-phase load input state; if the head end of the branch of the phase-adjusting camera has pressure, single-phase load open-close position and three-phase load open-close position, judging that the related load of the phase-adjusting camera works in a three-phase load input state; if the head end of the branch of the phase-adjusting camera has a voltage, single-phase load open-close position and three-phase load open-close position, judging that the related load of the phase-adjusting camera works in a single-phase and three-phase load input state; if the head end of the branch of the camera has pressure, single-phase load space division and three-phase load space division, the relevant load of the camera is judged to work in an idle state.
Preferably, the residual current increment detection criterion is: i M(t)-IM(t+Δt)-ΔI′M|>ΔIz; wherein, I M (t) is the head-end residual current at time t, I M (t+Δt) is the head-end residual current at time t+Δt, Δi' M is the residual current dynamic compensation amount, and Δi z represents the constant value of the residual current increment.
Preferably, the residual current dynamic compensation amount Δi z is a difference in residual current obtained based on the load input condition.
Preferably, if no load input or load exit event occurs between time t and t+Δt, there is Δi' M =0. If a load input or load exit event occurs between time t and t+Δt, Δi 'M +.0 is present and Δi' M is equal to the difference between the residual currents of the front and 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 quantity 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; 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 quantity at the time t+delta t is smaller than or equal to the constant value of the residual current increment, judging that the residual current increment does not exceed the limit value.
Fig. 7 is a logic schematic diagram for discriminating the leakage of a secondary ac feeder branch of the ac system of the transformer substation according to the present invention. As shown in fig. 7, based on two criteria, namely the synchronous regulator related load state criterion and the residual current increment detection criterion, whether the steady state residual current and the residual current increment in the branch circuit exceed the limit values or not is respectively judged. If the steady state residual current and the residual current increment in the branch circuit are 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. In addition, the inherent residual current and the residual current dynamic compensation quantity are added in the criterion in the method, so that the problem of overlarge protection dead zone in the prior art is solved in the process of comparing the head-end residual current with the alarm fixed value or the increment fixed value.
FIG. 8 is a schematic diagram of the sensitivity of the criteria after adding intrinsic residual current compensation in the present invention. FIG. 8 (a) is a schematic diagram of theoretical limits for the residual current warning values; fig. 8 (b) is a schematic diagram after the criterion sensitivity is improved.
According to the difference of the input conditions of the alternating current loads related to the synchronous phase-adjusting machine, the inherent residual currents under various conditions can be measured respectively. In order to ensure that no false alarms occur in normal conditions, the residual current warning limit should ideally be equal to or greater than the maximum intrinsic residual current in each case. As shown in fig. 8 (a), taking an example that the residual current alarm limit value is equal to the maximum intrinsic residual current, the intrinsic residual current values 1 to 4 are respectively the intrinsic residual currents on four lines of the head end A, B, C, N of the ac secondary branch of the synchronous regulator. The inherent residual current value 3, namely the maximum inherent residual current when the oil pump motor power supply and the on-line monitoring device IED of the camera are simultaneously input, is very large, so that the sensitivity of alarming is limited. In this case, the conventional method can overcome the problem of the protection dead zone and provide the alarm signal only when the additional residual current reaches approximately twice the intrinsic residual current value 3.
In the present invention, after the intrinsic residual current is compensated, as shown in fig. 8 (b), the compensation amount may be superimposed on the intrinsic residual current value. After the compensation amount is overlapped, the theoretical residual current warning limit value is greatly reduced, and the range of the theoretical limit value, namely the dead zone, is greatly reduced, so that the warning sensitivity is improved. The second aspect of the invention relates to a synchronous camera related alternating current secondary circuit leakage monitoring system, which is characterized in that: the synchronous phase regulator is connected with the transformer and 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 the alternating current secondary branch of the synchronous rectifier and are used for obtaining the residual current at the head end of the branch and respectively measuring the inherent residual current on the four wires at the head end A, B, C, N of the branch in advance; the leakage judging unit is respectively connected with A, B, C, N four wires in the synchronous rectifier AC secondary branch, the residual current transformer and each phase of air switch in the synchronous rectifier AC secondary branch and is used for judging the working state of the load related to the synchronous rectifier and judging whether the branch has leakage faults or not.
In an embodiment of the invention, a synchronous camera alternating current branch of a certain 500KV transformer substation alternating current system can be applied to construct a residual current monitoring system. Fig. 9 is a schematic diagram of a secondary loop monitoring system for an ac branch related to a camera of the present invention. The connection mode of the leakage discriminating unit and the branch four-wire is shown in fig. 9.
Preferably, each phase of air switch in the alternating current secondary branch of the synchronous camera 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 intelligent electronic equipment for on-line monitoring. At this time, the oil pump motor power supply is used as a three-phase load in the related alternating current branch of the camera, and the intelligent electronic equipment power supply is monitored on line to be used as a single-phase load. The intrinsic residual current is tested in the operation period, and an RCT is installed on the side of a branch circuit M, and an independent CT is installed on the phase A of a single-phase load end.
Specifically, based on the discrimination, the insulation condition of the alternating current feeder line branch circuit can be monitored on line, so that whether the hidden danger exists in an alternating current system or not is judged, and an alarm signal is sent out, so that the hidden danger of fire fighting caused by abnormal insulation can be found in time, and the occurrence of fire accidents can be effectively avoided.
Compared with the prior art, the synchronous camera-related alternating current secondary circuit leakage monitoring method has the advantages that the working state of the synchronous camera is changed through the action criteria of the synchronous camera, abnormal conditions of the branch are judged according to the head-end residual current and the residual current dynamic compensation quantity at different moments, small abnormal currents can be accurately judged, meanwhile, electrical accidents such as fire and electric shock are effectively prevented, and the safe and reliable state of the secondary circuit of the power grid is guaranteed.
While the applicant has described and illustrated the embodiments of the present invention in detail with reference to the drawings, it should be understood by those skilled in the art that the above embodiments are only 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 to limit the scope of the present invention, but any improvements or modifications based on the spirit of the present invention should fall within the scope of the present invention.
Claims (11)
1. The method for monitoring the leakage of the related alternating current secondary circuit of the synchronous camera is characterized by comprising the following steps of:
Step 1, measuring inherent residual current on four lines of a head end A, B, C, N of an alternating current secondary branch of a synchronous regulator in advance;
step 2, comparing the head end residual current, the inherent residual current and the alarm fixed value under different load input states based on the related load state criteria of the synchronous camera to judge whether the steady state residual current in the branch circuit exceeds a limit value or not;
The related load state criteria of the synchronous camera are as follows:
Wherein, I M is the head end residual current of the branch, and I 'M,1,I'M,2,I'M,3 and I' M,4 are the head ends of the single-phase load input, the three-phase load input, the single-phase load input and the three-phase load input simultaneously and the idle load state respectively, and the residual current is fixed; i w1,Iw2,Iw3 and I w4 are alarm fixed values of steady-state residual current overcurrent in four states respectively;
Step 3, comparing the residual current dynamic compensation quantity, the head end residual current and the residual current increment constant value of the branch circuit at the time t and the time t+delta t based on residual current increment detection criteria so as to judge whether the residual current increment in the branch circuit exceeds a limit value;
The residual current increment detection criterion is as follows: i M(t)-IM(t+Δt)-ΔI'M|>ΔIz;
Wherein, I M (t) is the head-end residual current at time t, I M (t+Δt) is the head-end residual current at time t+Δt, Δi' M is the residual current dynamic compensation amount, and Δi z represents the constant value of the residual current increment;
If no load input or load exit event occurs between time t and time t+Δt, Δi' M =0;
If a load input or load exit event occurs between the time t and the time t+delta t, delta I 'M is not equal to 0, and delta I' M is equal to the difference value of residual currents of the front load state and the rear load state;
And step 4, judging whether the branch circuit has leakage faults or not based on the judgment of the steady-state residual current and the residual current increment respectively.
2. The method for monitoring leakage of an ac secondary circuit related to a synchronous rectifier according to claim 1, wherein the method comprises the steps of:
In the step 1, pre-measuring the intrinsic residual current on the four lines of the branch head end A, B, C, N includes:
And in the initial stage of operation of the synchronous camera, sequentially inputting a single-phase load, a three-phase load, a single-phase load and a three-phase load into the branch, setting the branch to be in an idle state, and respectively measuring intrinsic residual currents I 'M,1、I'M,2、I'M,3 and I' M,4 in four states.
3. The method for monitoring leakage of an ac secondary circuit related to a synchronous rectifier according to claim 2, wherein the method comprises the steps of:
if the absolute value of the difference value between the head-end residual current and the inherent residual current is larger than the alarm constant value of the steady-state residual current, judging that the steady-state residual current in the branch circuit exceeds a limit value;
And if the absolute value of the difference value between the head-end residual current and the inherent residual current is smaller than or equal to the alarm constant value of the steady-state residual current flowing through, judging that the steady-state residual current in the branch circuit does not exceed the limit value.
4. A synchronous rectifier related ac secondary circuit leakage monitoring method according to claim 3, wherein:
the alarm value of the steady state residual current overcurrent is 1 to 2 times of the inherent residual current.
5. The method for monitoring leakage of an ac secondary circuit associated with a synchronous rectifier according to claim 4, wherein step 2 further comprises:
Judging a load input state of a related load of the synchronous regulation camera based on the voltage of the head end of the synchronous regulation camera branch, the single-phase load idle position and the three-phase load idle position;
And judging whether the steady-state residual current in the branch circuits under different load input states exceeds a limit value or not based on the load state criterion of the synchronous camera.
6. The method for monitoring leakage of the ac secondary circuit related to the synchronous rectifier as set forth in claim 5, wherein the method comprises the following steps:
If the head end of the synchronous phase-adjusting machine branch circuit has a voltage and single-phase load open-close position and a three-phase load open-close position, judging that the related load of the synchronous phase-adjusting machine works in a single-phase load input state;
If the head end of the synchronous phase-adjusting machine branch circuit has a voltage, single-phase load open-close position and three-phase load open-close position, judging that the related load of the synchronous phase-adjusting machine works in a three-phase load input state;
if the head end of the synchronous phase-adjusting machine branch circuit has a voltage and single-phase load open-close position and a three-phase load open-close position, judging that the related load of the synchronous phase-adjusting machine works in a single-phase load input state and a three-phase load input state;
and if the head end of the synchronous phase-adjusting machine branch circuit has a voltage, single-phase load space-division position and three-phase load space-division position, judging that the related load of the synchronous phase-adjusting machine works in an idle state.
7. The method for monitoring leakage of an ac secondary circuit associated with a synchronous rectifier according to claim 6, wherein the method comprises the steps of:
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 quantity at the time t+delta t is larger than the fixed value of the residual current increment, judging that the residual current increment exceeds a 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 residual current dynamic compensation quantity at the time t+delta t is smaller than or equal to the constant value of the residual current increment, judging that the residual current increment does not exceed the limit value.
8. The method for monitoring leakage of an ac secondary circuit associated with a synchronous rectifier according to claim 7, wherein the method comprises the steps of:
If the steady state residual current and the residual current increment in the branch circuit are 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.
9. A synchronous rectifier related ac secondary circuit leakage monitoring system according to any one of claims 1-8, characterized in that:
The system comprises a synchronous regulator, a residual current transformer and a leakage judging unit;
the synchronous phase regulator is connected with the transformer and 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 regulator and are used for obtaining the head end residual current of the branch and respectively measuring the inherent residual current on the four wires of the head end A, B, C, N of the branch in advance;
The electric leakage judging unit is respectively connected with A, B, C, N four wires in the synchronous rectifier alternating current secondary branch, the residual current transformer and each phase of air switch in the synchronous rectifier alternating current secondary branch and is used for judging the working state of the synchronous rectifier related load and judging whether the branch has electric leakage faults or not.
10. The synchronous rectifier related ac secondary loop leakage monitoring system according to claim 9, wherein:
each phase of air switch in the synchronous camera alternating current secondary branch circuit comprises: single-phase load air switch, three-phase load air switch.
11. The synchronous rectifier related ac secondary loop leakage monitoring system according to claim 10, wherein:
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 on-line 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 CN113219366A (en) | 2021-08-06 |
| CN113219366B true 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 |
|---|
| 变电站站用电系统混合型负荷支路的漏电监测方法;陈昊 等;消防科学与技术;20220630;第41卷(第06期);739-743 * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN113219366A (en) | 2021-08-06 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US8837097B2 (en) | Protection, monitoring or indication apparatus for a direct current electrical generating apparatus or a plurality of strings | |
| CN108169615B (en) | Optical CT-based phase failure detection method for starting standby transformer | |
| CN103618377B (en) | For being connected to backup auto-activating device system and the spare power automatic switching method of small power supply | |
| US8102634B2 (en) | Differential protection method, system and device | |
| CN104836330B (en) | Backup auto-activating device bus PT three-phases broken string quick determination method and faulty action preventing method | |
| CN110912114A (en) | High-safety low-voltage direct current system | |
| CN110554234A (en) | Zero-sequence current loop inspection method for in-service switch cabinet | |
| CN1323476C (en) | DC system short circuit protection device | |
| CN111579934A (en) | Method and device for realizing electric safety monitoring of external power network of base station and base station | |
| CN110320432A (en) | Single-phase wire break fault detection and guard method and system | |
| KR20180081478A (en) | Electric failure master detector | |
| CN113219366B (en) | Method for monitoring leakage of related alternating current secondary circuit of synchronous phase-change modulator | |
| KR20150134563A (en) | Power system in the event of power failure recovery device | |
| CN104009453B (en) | A kind of fault detection method for micro-capacitance sensor off-grid operation situation | |
| KR20190049662A (en) | Electric fault master recovery device(breaker) | |
| CN115166596A (en) | Yd11 wiring transformer single-phase wire break on-line monitoring method | |
| 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 | |
| KR102616906B1 (en) | System for Controlling the Distribution System by Detecting Phase Loss | |
| CN219224959U (en) | Anti-electricity-stealing detection mechanism | |
| US11852692B1 (en) | Electric distribution line ground fault prevention systems using dual parameter monitoring with high sensitivity relay devices | |
| Theron et al. | Case study: Transformer Differential Incorrect Operation due to System Grounding | |
| JP7181760B2 (en) | Protection control device for AC/DC converter station, protection control system for DC power transmission system, and protection control method for AC/DC converter station | |
| CN216486718U (en) | Fire monitoring system |
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 |