CN118962516A - Single-phase ground fault monitoring and fault section isolation method for DC power supply system of electrified highway - Google Patents
Single-phase ground fault monitoring and fault section isolation method for DC power supply system of electrified highway Download PDFInfo
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/40—Testing power supplies
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
- G01R31/52—Testing for short-circuits, leakage current or ground faults
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- H—ELECTRICITY
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- H02H7/26—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured
- H02H7/268—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured for DC systems
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- Y04S—SYSTEMS INTEGRATING TECHNOLOGIES RELATED TO POWER NETWORK OPERATION, COMMUNICATION OR INFORMATION TECHNOLOGIES FOR IMPROVING THE ELECTRICAL POWER GENERATION, TRANSMISSION, DISTRIBUTION, MANAGEMENT OR USAGE, i.e. SMART GRIDS
- Y04S10/00—Systems supporting electrical power generation, transmission or distribution
- Y04S10/50—Systems or methods supporting the power network operation or management, involving a certain degree of interaction with the load-side end user applications
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Abstract
本发明公开了一种电气化公路直流供电系统单相接地故障监测及故障区段隔离方法，步骤如下：根据变电所输入电压Um、并联电阻R0、绝缘电阻门槛下降系数L，计算压差比设定值A、差电流设定值B；采集各变电所分区内的正、负极对地电压和上、下行差电流的实时数据，若差电流≥B，则判定对应的上行或下行接地故障，计算压差比k，若k≥A则负极接地故障，若k≤‑A则正极接地故障；通过“逐一顺序”法或“二分选择”法来判定故障小分区位置；打开故障小分区两端的隔离开关对故障小分区进行隔离，变电所对故障小分区与电源之间的各小分区进行供电，闭合供电分区间的联络开关，由相邻变电所对故障小分区与相邻供电分区之间的各小分区进行供电。
The invention discloses a method for monitoring single-phase grounding faults and isolating fault sections of a DC power supply system for an electrified highway, and the steps are as follows: according to a substation input voltage U m , a parallel resistance R 0 , and an insulation resistance threshold drop coefficient L, a voltage difference ratio setting value A and a differential current setting value B are calculated; real-time data of positive and negative pole-to-ground voltages and uplink and downlink differential currents in each substation partition are collected, if the differential current is ≥ B, a corresponding uplink or downlink grounding fault is determined, and a voltage difference ratio k is calculated, if k ≥ A, a negative pole grounding fault occurs, and if k ≤ ‑A, a positive pole grounding fault occurs; the position of a faulty sub-partition is determined by a "one-by-one sequence" method or a "binary selection"method; disconnectors at both ends of the faulty sub-partition are opened to isolate the faulty sub-partition, the substation supplies power to each sub-partition between the faulty sub-partition and a power supply, the connecting switch between the power supply partitions is closed, and the adjacent substation supplies power to each sub-partition between the faulty sub-partition and the adjacent power supply partition.
Description
Technical Field
The invention relates to the field of protection of electrified highway direct current power supply systems, in particular to a single-phase grounding fault monitoring and fault section isolation method of an electrified highway direct current power supply system.
Background
The electrified highway is characterized in that an electric traction power supply system is arranged along the highway, and the electric traction power supply system is provided with a road for enabling motor vehicles to obtain continuous driving electric energy from a traction network in the driving process, and is characterized in that uninterrupted electric energy is provided for the driving vehicles. The current electrified highway direct current power supply system adopts a direct current 1500V positive and negative pole suspension system, and a positive pole contact net supplies power and a negative pole contact net returns.
The positive and negative poles of the contact net have insulating resistances to ground of tens of megaohms, and the positive and negative poles have the same or little difference in insulating resistances to ground and the voltages to ground are relatively balanced during normal operation. When single-phase single-point ground fault occurs, the positive electrode or the negative electrode of the single-phase single-point ground fault changes, the ground voltage of the grounding electrode is reduced, the ground voltage of the non-grounding electrode is increased, the power supply reliability is greatly reduced, the secondary fault of the system is not caused at the moment, and the personnel is not injured. However, if the system is not timely processed, when the system is developed to a two-point or multi-point ground fault or a non-ground electrode is in ground fault, the motor vehicle can not normally run, and serious consequences of short circuit fault and casualties are caused.
In the current single-phase grounding fault monitoring of a direct current power supply system, there are a mode of directly measuring insulation resistance and a mode of adopting a balanced bridge type monitoring circuit, wherein the mode of adopting the balanced bridge type monitoring circuit is more common. However, no matter what method is adopted, the single-phase grounding monitoring of the direct current system can only judge the single-pole (positive electrode or negative electrode) and the specific feed-out loop which have faults, but can not judge more specific grounding points, so that effective fault isolation can not be realized.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a single-phase grounding fault monitoring and fault section isolation method for an electrified highway direct current power supply system, which realizes effective monitoring of single-phase grounding faults of the direct current power supply system, minimized isolation of fault sections and finally quick recovery of power supply of other non-fault sections.
The invention realizes the aim through the following technical scheme:
The method is suitable for the sectional insulation of a plurality of normally closed electric isolating switches in parallel in a power substation power supply partition, and the electrified highway direct current power supply system which divides each power supply partition into a plurality of small electric communication partitions, and comprises the following steps:
monitoring real-time data of the ground voltage and the uplink and downlink differential current of the positive electrode and the negative electrode in each substation partition;
Calculating a differential pressure ratio set value A and a differential current set value B according to the input voltage U m of the substation, the parallel resistor R 0 and an insulation resistance threshold falling coefficient L (L represents the multiple of the reduction of the insulation resistance of the anode or the cathode to the ground to the parallel resistor R 0), wherein U m＝|U+|+|U- I, U+ is the anode voltage of a power supply, U-is the cathode voltage of the power supply, L is (0, 1);
calculating a differential pressure ratio k according to the positive and negative voltages to the ground in each substation partition, If k is more than or equal to A, the negative electrode is grounded, and if k is less than or equal to-A, the positive electrode is grounded;
if the uplink differential current is more than or equal to B, an uplink ground fault is generated, and if the downlink differential current is more than or equal to B, a downlink ground fault is generated;
After judging that the fault partition is located in the uplink and the downlink and the positive and negative electrodes, selecting a corresponding isolating switch to conduct closing and opening operation by using a one-by-one sequence method or a binary selection method, and gradually judging the final fault small partition;
The method of sequential is specifically as follows: according to the arrangement sequence of the electric isolating switch in the power supply subarea, according to the distance from the power substation, sequentially switching off from far to near one by one, isolating the small subareas from the power supply subarea one by one, and correspondingly, the fault sections are as follows: if the grounding fault disappears after the feeder circuit breaker is switched on, the small partition behind the last opened electric isolating switch is the fault small partition; if the grounding faults still do not disappear after all the electric isolating switches are turned on one by one, the first small partition is a fault section;
The "binary selection" method is specifically: when the feeder circuit breaker is operated, according to the arrangement sequence of the electric isolating switches in the power supply subareas, the electric isolating switches positioned in the middle position are opened, the whole power supply subareas are divided into two groups, namely a front group and a rear group, if the grounding fault disappears after the feeder circuit breaker is closed, the small fault subarea is positioned behind the opening electric isolating switches; otherwise, the switch is positioned in front of the opening electric isolating switch; after judging a half fault range through one round of half operation of the electric isolating switch, selecting the operation range of the next round, and repeating the operation until the half fault range corresponds to a small fault partition; in each cycle of judgment, when the fault small section is positioned in a half fault range after the breakpoint, the electric disconnecting switch which is disconnected is switched on, so that the original power supply partition is recovered; the fault section corresponds to: if the grounding fault disappears after the feeder circuit breaker is switched on under the condition that the half fault range corresponds to the small partition, the small partition after the last opened electric isolating switch is the fault section; if the grounding fault does not disappear after the feeder circuit breaker is switched on, the small partition before the last opened electric isolating switch is a fault section;
And opening isolating switches at two ends of the fault small partition to isolate the fault small partition, supplying power to each small partition between the fault small partition and a power supply by a partition substation, closing a contact switch between the power supply and an adjacent substation partition, and supplying power to each small partition between the fault small partition and an adjacent power supply partition by the adjacent substation.
Further, the electric isolating switch operated each time in the "binary selection" method is related to the small partition number N, and when the small partition number N satisfies 2 C-1<N≤2C, the maximum operation times are C times, c=round dup (log 2 N, 0), and round dup is an EXCEL rounding-up function; when the number of small partitions N meets 2 C-1<N<2C, setting virtual small partitions from (n+1) to (2) C, and processing operation steps and corresponding electric isolating switches according to the number of small partitions n=2 C in the judging process.
Further, the "binary selection" method comprises the following steps:
S1, calculating the maximum operation times C according to the power supply small partition number N, wherein C=Roundup (log 2 N, 0);
s2, selecting the position of the electric isolating switch which is pre-operated in the 1 st round, namely considering all the electric isolating switches in the virtual electric isolating switch and the electric isolating switch which is positioned in the middle position;
s3, opening a corresponding feeder circuit breaker;
S4, opening an mth electric isolating switch, and performing 1 st-round operation on the middle electric isolating switch;
s5, closing the corresponding feeder circuit breaker;
S6, judging whether the fault disappears, and if not, going to S7; when the judgment is yes, the step S12 is carried out;
S7, concluding that the fault small partition is before the mth electric isolating switch;
S8, judging whether the operation times C is smaller than 2, namely, judging whether the operation times are over; if not, go to S9; when the judgment is yes, the step S11 is carried out;
s9, selecting the position of an electric isolating switch pre-operated in the next round;
s10, resetting the operation times C, wherein the operation times are reduced by 1 time;
S11, the conclusion of 'the fault in the mth fault small partition' is obtained;
s12, concluding that the fault small partition is behind the mth electric isolating switch;
S13, judging whether the number N of the small partitions is equal to the number m of the electric isolating switch operated by the current wheel plus 1, namely whether the electric isolating switch operated by the current wheel is the electric isolating switch at the last position; if no, go to S14; when the judgment is yes, the step goes to S20;
s14, judging whether the operation times C are smaller than 2, namely, judging whether the operation times are over; if not, go to S15; when the judgment is yes, the step goes to S20;
S15, closing an mth electric isolating switch; after judging that the fault small partition is positioned on the opened electric isolating switch, closing the electric isolating switch before the next operation of the incoming line;
S16, selecting the position of an electric isolating switch pre-operated in the next round;
s17, resetting the operation times C, wherein the operation times are reduced by 1 time;
S18, selecting whether the position of the pre-operated electric isolating switch is within the small partition number N, namely whether the position is a virtual position, and the position is more than or equal to the small partition number N; if no, go to S19; when the judgment is yes, the step S4 is carried out;
S19, the position of the pre-operated electric isolating switch is selected as a virtual position by the wheel, and the position of the electric isolating switch operated by the previous wheel is returned;
S20, the conclusion of 'the m+1th fault intra-small-area fault' is drawn.
The invention also provides a computer program product, which comprises a computer program/instruction, wherein the computer program/instruction realizes the steps of the single-phase grounding fault monitoring and fault section isolation method of the electrified highway direct current power supply system when being executed by a processor.
The invention also provides a computer readable storage medium, wherein the computer readable storage medium is stored with a computer program, and the computer program realizes the steps of the single-phase grounding fault monitoring and fault section isolation method of the electrified highway direct current power supply system when being executed by a processor.
The invention also provides an electronic device, which comprises a processor, a memory and a computer program stored on the memory and capable of running on the processor, wherein the computer program realizes the steps of the single-phase grounding fault monitoring and fault section isolation method of the electrified highway direct current power supply system when being executed by the processor.
The invention also provides a single-phase earth fault monitoring and fault section isolation device of the electrified highway direct current power supply system, which is used for implementing the single-phase earth fault monitoring and fault section isolation method of the electrified highway direct current power supply system, and comprises the following steps:
The input module is used for collecting the positive and negative electrode voltages to the ground and the uplink and downlink differential currents in each substation area and carrying out real-time data monitoring;
The A/D conversion module converts the data signals acquired by the input module and inputs the data signals into the CPU processor module;
the CPU processor module judges whether a ground fault occurs according to the positive and negative electrode ground voltage and the uplink and downlink difference current values acquired by the input module, if the ground fault occurs, the position of the small fault partition is further judged according to a judging program, and isolation processing is carried out on the small fault partition;
the output module is used for outputting instructions sent by the CPU processor module to corresponding switch loops and controlling the opening and closing of the electric isolating switch and the feeder circuit breaker;
The data storage module is used for storing the collected and processed data information;
the communication module is used for being connected PSCADA and transmitting data;
The display module is used for displaying real-time operation data, checking event records and data information and the opening and closing states of the electric isolating switches and the feeder circuit breakers.
Compared with the prior art, the invention has the following beneficial effects:
the invention provides a single-phase grounding fault monitoring and fault section isolation method for an electrified highway direct current power supply system, which can rapidly realize fault monitoring and range determination of single-pole grounding of an electrified highway and can enable the electrified highway to recover power supply in a maximum range after the single-pole grounding fault occurs.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below. It will be apparent to those skilled in the art from this disclosure that the drawings described below are merely exemplary and that other embodiments may be derived from the drawings provided without undue effort.
FIG. 1 is a schematic diagram of an insulation monitoring circuit according to the present invention;
FIG. 2 is a schematic diagram of the DC power supply section of the electrified highway of the present invention;
FIG. 3 is a flow chart of a single pole ground fault section isolation determination for a DC power supply system according to the present invention;
FIG. 4 is a flow chart of a single pole ground fault section "one by one sequence" method determination for the DC power supply system of the present invention;
FIG. 5 is a flow chart of the determination of the "binary select" method for a single pole ground fault section of the DC power supply system of the present invention.
FIG. 6 is a schematic diagram of a single-phase earth fault monitoring and fault section isolation apparatus for an electrified highway DC power supply system of the present invention.
Detailed Description
Exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the present invention are shown in the drawings, it should be understood that the present invention may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. It should be noted that, without conflict, the embodiments of the present invention and features of the embodiments may be combined with each other. The invention will be described in detail below with reference to the drawings in connection with embodiments.
The invention provides setting value suggestions for the differential pressure ratio and the differential current of an insulation monitoring loop by utilizing a balance bridge type insulation monitoring principle aiming at an equivalent principle loop of a direct current power supply system of an electrified highway, and provides abnormal monitoring, fault isolation and power restoration of a monopole ground fault of a direct current power supply optimized zone of the electrified highway on the basis of the direct current power supply zone, positive and negative poles and uplink and downlink determined according to the setting value suggestions.
In the electrified highway direct current power supply system, a balance bridge loop is adopted for direct current positive and negative electrode insulation monitoring, and a circuit principle schematic diagram is shown in fig. 1.
R +: the positive electrode of the contact net has an insulation resistance to the ground, and the value is M omega-level and equal to R < - >;
r -: the negative electrode of the contact net has an insulation resistance to the ground, and the value is M omega-level and equal to R < + >;
R 0: the parallel resistor is selected as a k omega level;
The equivalent resistance of the DC positive electrode to the ground is R 0<<R+ under normal conditions, R 0//R+≈R0;
The equivalent resistance of the direct current negative electrode to the ground is Normally R 0<<R-, R 0//R-≈R0.
U m: the voltage between the DC pole and the anode pole is 1500V corresponding to the electrified highway;
U +: the positive electrode of the contact net is at the voltage to the ground, In the normal state, R +＝R- is set,
U -: the voltage of the negative electrode of the contact net to the ground,In the normal state, R +＝R- is set,
And U m＝|U+|+|U-.
Differential pressure ratio:
When the direct current power supply system has positive electrode monopole grounding fault, for example, the positive electrode insulation is reduced until the resistance value of R + is lower than LR 0 (0 < L < 1), L is the threshold coefficient of insulation reduction, namely R +≤LR0, the negative electrode insulation is normal, the resistance value of R - is still far greater than R 0, namely R ->>R0,
Since R- > > R 0,Then approximate calculation
I.e. pressure difference ratioWhen the resistance of the positive electrode to ground is reduced to L (0 < L < 1) times of the parallel resistance R 0, the single-point grounding of the positive electrode is judged.
Similarly, when the direct current power supply system has a negative electrode monopole ground fault, such as the negative electrode insulation is reduced until the R-resistance value is lower than LR 0 (0 < L < 1), L corresponds to the threshold coefficient of insulation reduction, namely R -≤LR0, the positive electrode insulation is normal, the R + resistance value is still far greater than R 0, namely R +>>R0,
Due to the fact that the R +>>R0,Then approximate calculation
I.e. pressure difference ratioWhen the negative electrode single-point ground is determined in response to the negative electrode ground insulation resistance decreasing to L (0 < L < 1) times the parallel resistance R 0.
From this, it is found that the differential pressure is weaker than the threshold coefficient L of insulation drop, and is also weaker than the parallel resistor R 0 and the insulation resistance of the non-ground electrode to the ground. When the insulation resistance of the non-grounding electrode to the ground is 20MΩ (according to TB/T3256-2014, the contact net insulation resistance to the ground is not lower than 20M, the equivalent insulation resistance is considered according to 10MΩ after the upper and lower insulation resistances are connected in parallel), different insulation drop threshold coefficients L (0.8, 0.5 and 0.3 are taken as different example values in Table 1 respectively) are connected in parallel with different parallel resistances R 0, when the insulation resistance of the grounding electrode is as low as different LR 0, the corresponding differential pressure ratio (accurate calculation ](Positive electrode is grounded),(Negative electrode grounded)) and approximation calculation(Positive electrode is grounded),(Anode ground)) is shown in table 1 below:
table 1 accurate and near calculated differential pressure ratio values corresponding to different parameters
I 0: the current flowing through the parallel resistor,
I +: the positive electrode of the power supply (after the parallel resistor R 0) flows out current, namely the input current of the positive electrode of the contact net,
I -: the negative electrode of the power supply (after the parallel resistor R 0) flows back to the current, namely the output current of the negative electrode of the contact net,
I d: the difference in the current is used to determine,
When the positive insulation drops until the resistance value of R + is lower than LR 0 (0 < l < 1), i.e., R +≤LR0, while the negative insulation is normal, the resistance value of R - is still much greater than R 0, i.e., R ->>R0,
Due to the fact that the R ->>R0,Then approximate calculation
Similarly, when the negative insulation decreases until the resistance of R - is lower than LR 0 (0 < L < 1), i.e., R -≤LR0, while the positive insulation is normal, the resistance of R + is still much greater than R 0, i.e., R +>>R0,
Due to the fact that the R +>>R0,Then approximate calculation In consideration of the direction factor of the light,
The difference current is related to the parallel resistance R 0 and the threshold coefficient L of insulation drop, as well as the voltage U m between the positive and negative electrodes, and is related to the weak insulation resistance of the non-ground electrode to the ground. When U m = 1500V, the insulation resistance of the non-ground electrode to the ground is 10mΩ, the different parallel resistances R 0 correspond to the differential currents I d (accurate calculation when the insulation resistance of the ground electrode is low to different LR 0 (Positive electrode is grounded),(Negative electrode ground) and approximation calculation) As shown in table 2 below (when the positive electrode is grounded, the current direction is that the bus line points to the feeder line; when the negative electrode is grounded, the current direction is that the feeder line points to the bus):
TABLE 2 accurate and near-calculated values of the corresponding differential currents under different parameters
When the pressure difference ratio k exceeds a set value, judging that an anode or cathode monopole ground fault occurs; and further monitoring the current of the uplink or downlink feeder switch to detect the differential current I d, so as to determine that the uplink or downlink feeder has a ground fault. From this comprehensive judgment, it can be known that a monopolar ground fault occurs in the positive electrode or the negative electrode of the upstream or the downstream.
From the selected threshold coefficient L of insulation drop, the input voltage U m, and the parallel resistor R 0, the set value corresponding to the differential pressure ratio k is a, the set value of the differential current I d is B (as can be seen from the foregoing tables 1 and 2, the difference between the accurate calculation and the approximate calculation is not large, so the determination process selects the approximate calculation value), and the monopolar ground fault determination flow is as follows:
S1, collecting current and voltage values of all power substation partitions in a power supply system. The method comprises the steps of direct-current positive electrode grounding voltage U+, direct-current negative electrode grounding voltage U-, differential current I d Upper part of an uplink feeder line and differential current I d Lower part(s) of a downlink feeder line.
S2, calculating a set value A of the pressure difference ratio k according to the input insulation drop threshold coefficient L.
S3, calculating a set value B of the differential current I d according to the input insulation falling threshold coefficient L, the input voltage U m and the parallel resistor R 0.
And S4, calculating a differential pressure ratio k according to the collected direct current positive electrode grounding voltage U + and the collected direct current negative electrode grounding voltage U - of each transformer substation.
S5, judging whether the difference current I d of the uplink feeder line and the downlink feeder line is larger than or equal to a set value B, and if so, judging that the corresponding uplink or downlink line has a ground fault; judging whether the pressure difference ratio k is larger than or equal to a set value A, if k is larger than or equal to A, grounding the negative electrode, and if not larger than-A, grounding the positive electrode.
The direct current power supply partition, the positive electrode or the negative electrode and the upward or downward direction which are caused by the ground fault can be judged.
In order to reduce the investigation range of the grounding fault point and rapidly and accurately detect the fault grounding point, the invention provides a single-phase grounding fault monitoring and fault section isolation method of an electrified highway direct current power supply system, which is used for finding out small subareas with grounding faults, isolating the fault subareas and recovering the power supply of other subareas.
In order to solve the problem of minimizing the influence range of single-phase grounding faults, a plurality of sectional insulation of normally-closed electric isolating switches connected in parallel are arranged in power supply subareas of a substation of the electrified highway direct current power supply system, and each power supply subarea is divided into a plurality of small subareas which are electrically communicated, as shown in fig. 2. Each direct current power supply partition is divided into N small partitions through N segmented insulators, N=n+1, and meanwhile, each segmented insulating parallel electric isolating switch is closed when the electric isolating switch is normal, so that the small partitions at the two ends of the electric isolating switch are kept in electrical communication, namely the power supply partition still maintains the original power supply range; when insulation drop and monopole grounding fault occur in a small partition, the electric isolating switch at two ends is opened, so that isolation of the faulty small partition and normal power supply of other small partitions are realized. When the number of small partitions in the power supply station partition is smaller than the installation number of insulators, namely when each small partition contains a plurality of insulators, determining a fault small partition, realizing fault isolation, recovering power supply of other small partitions, and then conducting one-by-one investigation on insulators installed in the isolated fault small partition to realize rapid and accurate positioning of the ground fault.
At present, the direct current power supply subarea range of the electrified highway is not more than 4km, and single-side power supply is realized; the contact net is suspended by insulators at about 50m intervals on the struts along the line. If about 80 insulators are provided in each dc powered section, then there are about 80 potential ground fault points for that section.
After the direct current power supply subareas of the electrified highway are converted into a plurality of small subareas, the small subareas with the ground fault, the corresponding positive electrode or negative electrode of the direct current bus and the ascending or descending are judged according to the differential pressure ratio k and the differential current I d. And then opening the corresponding feeder circuit breaker CB, opening the electric isolating switch GK, isolating a small partition behind the electric isolating switch from a power supply partition in front of the electric isolating switch, and closing the feeder circuit breaker CB. Judging the voltage difference ratio k and the difference current I d again, and if the fault disappears, generating the fault on the side, far away from the power supply, of the opening electric isolating switch GK; if the fault is still present, the fault occurs on the power supply side of the opening electric disconnector GK. And repeating the operation according to the judging result, and continuously reducing the range of the subareas until the small subareas where the faults are judged.
When the number of the electric isolating switches GK in the substation partition is small, according to the arrangement sequence of the electric isolating switches GK in the power supply partition, the small partitions are sequentially separated from the power supply partition from far to near according to the distance from the power substation, and the fault sections correspond to: the feeder circuit breaker CB is switched on, the ground fault disappears, and a small partition is arranged behind the last opened electric isolating switch GK; when all the electric isolating switches GK are opened one by one, the grounding fault still does not disappear, and the 1 st small partition is a fault section.
The judgment flow of the sequential method is shown in fig. 4, and the steps are described as follows:
S1, an initial value is given to a mark m of a pre-operated electric isolating switch GK, and the initial value is the last bit of the sequence in the direct current power supply partition. N-1 electric isolating switches are required to be arranged in the N small partitions, and the electric isolating switch at the last position is the N-1 electric isolating switch. Let m=n-1.
S2, opening the feeder circuit breaker.
S3, opening an mth electric isolating switch GK.
S4, closing the feeder circuit breaker.
S5, judging whether the fault disappears. If the fault disappears, a conclusion is drawn that the fault small partition is behind the mth electric isolating switch GK, and a conclusion is drawn that the fault is in the (m+1) th fault small partition.
If the fault does not disappear, it is determined whether the reference number m of the electric disconnecting switch GK just operated is smaller than 2. If the fault is smaller than 2, the conclusion is drawn that the fault small partition is before the 1 st electric isolating switch GK and the fault exists in the 1 st fault small partition.
If not (2 or more), the next pre-operated electric disconnecting switch GK is selected, and the reference numeral m of the next round of pre-operated electric disconnecting switch GK is set to be one bit forward, and m=m-1.
When the number of the electric isolating switches GK in the substation partition is large, the electric isolating switches GK positioned in the middle position are opened according to the arrangement sequence of the electric isolating switches GK in the power supply partition, and the whole power supply partition is divided into two groups, namely a front group and a rear group of the electric isolating switches GK. When the grounding fault disappears after the feeder circuit breaker CB is switched on, the fault small partition is positioned behind the switching-off electric isolating switch GK; otherwise, the switch is positioned before the opening electric isolating switch GK. After the 'half' fault range is judged through one round of 'half' operation of the electric isolating switch GK, the operation range of the next round is selected, and the operation is repeated until the 'half' fault range corresponds to a small partition. Only in the cycle of each round of judgment, when the fault small section is positioned in the 'half' fault range after the breakpoint, the separated electric isolating switch GK is switched on, and the original power supply partition is recovered. The fault section corresponds to: under the condition that the 'half' fault range corresponds to a small partition, closing the feeder circuit breaker CB, eliminating the ground fault, and opening the last small partition behind the electric isolating switch GK; the feeder circuit breaker CB is switched on, the ground fault does not disappear, and the small partition is arranged before the last opened electric isolating switch GK. The method is suitable for dividing into a plurality of small partition modes.
The operation flow of the "binary selection" method is shown in fig. 6, and the steps are described as follows:
S1, calculating the maximum operation times C according to the power supply small partition number N, c=roundup (log 2 N, 0).
S2, selecting the position of the electric isolating switch GK of the 1 st round of pre-operation, namely considering all the electric isolating switches in the virtual electric isolating switch (at the moment) and the electric isolating switch GK in the middle position.
S3, opening the corresponding feeder circuit breaker.
S4, opening an mth electric isolating switch GK. And carrying out 1 st round of operation on the middle position electric disconnecting switch GK.
S5, closing the corresponding feeder circuit breaker.
S6, judging whether the fault disappears. When judging as N, the method goes to S7; when "Y" is determined, the process goes to S12.
S7, concluding that the fault small partition is before the mth electric isolating switch GK.
S8, judging whether the operation times C are smaller than 2, namely, judging whether the operation times are over. When judging as N, the method goes to S9; when "Y" is determined, the process goes to S11.
S9, selecting the position of the electric disconnecting switch GK of the next round of pre-operation.
S10, resetting the operation times C, and reducing the operation times by 1 time.
And S11, the conclusion of 'the fault in the m-th fault small partition' is obtained.
S12, it is concluded that "the faulty small partition is behind the mth electric disconnector GK".
S13, judging whether the small partition number N is equal to the number m of the electric isolating switch GK operated by the current wheel plus 1, namely whether the electric isolating switch GK operated by the current wheel is the electric isolating switch GK at the last position. When judging as N, the method goes to S14; when "Y" is determined, the process goes to S20.
S14, judging whether the operation times C are smaller than 2, namely, whether the operation times are over. When judging as N, the method goes to S15; when "Y" is determined, the process goes to S20.
S15, closing an mth electric isolating switch GK. And after judging that the fault small partition is positioned on the opened GK, closing the electric isolating switch GK before the next operation of the incoming line.
S16, selecting the position of the electric disconnecting switch GK of the next round of pre-operation.
S17, resetting the operation times C, and reducing the operation times by 1 time.
S18, selecting whether the position of the pre-operated electric isolating switch GK is within the small partition number N, namely whether the position is a virtual position, and if so, the position is a virtual position which is greater than or equal to the small partition number N. When judging as 'N', go to S19; when "Y" is determined, the process goes to S4.
And S19, if the position of the pre-operated electric disconnecting switch GK is selected as the virtual position by the round, the position of the electric disconnecting switch GK operated by the previous round is retreated.
S20, the conclusion of 'the m+1th fault intra-small-area fault' is drawn.
After judging and isolating the fault cells, the power supply of other power supply cells can be realized. The power supply of other small partitions comprises the power supply of the partition and the power supply of the support adjacent partition, and the power supply recovery process is as follows:
Opening the regional feeder circuit breaker of the power substation, opening the electric isolating switches at the two ends of the small fault region, and closing the regional feeder circuit breaker of the power substation to realize the power supply of each small region between the small fault region and the power supply of the regional power substation; and opening the adjacent substation subarea feeder circuit breaker, closing the adjacent substation subarea feeder circuit breaker after closing a tie switch between two adjacent power supply subareas, and realizing power supply of each small subarea between the adjacent substation subarea with the fault and the adjacent power supply subarea.
Therefore, the determination flow of the monopole ground fault section isolation of the electrified highway direct current power supply system is shown in fig. 3, and specifically is as follows:
S1, calculating a differential pressure ratio set value A and a differential current set value B according to an input voltage U m of a power substation, a parallel resistor R 0 and an insulation resistance threshold drop coefficient L, wherein U m＝∣U+∣+∣U-∣,U+ is the positive voltage of a power supply, U - is the negative voltage of the power supply,
S2, collecting real-time data of the positive and negative electrode voltages to the ground and the up and down differential currents in each substation area, calculating the differential pressure ratio k,
S3, preliminarily judging the range of the ground fault partition:
If the uplink differential current is more than or equal to B, the uplink ground fault is generated, if the downlink differential current is more than or equal to B, the downlink ground fault is generated,
If k is more than or equal to A, the negative electrode is grounded, and if k is less than or equal to-A, the positive electrode is grounded;
s4, isolating switches arranged in the power substation partitions divide the power supply partitions into a plurality of small partitions, after the ascending and descending of the fault partitions and the positive electrode and the negative electrode are primarily judged, the corresponding isolating switches are selected to be closed and opened by a one-by-one sequential method or a binary selection method until the final fault small partition is determined;
The sequential method is suitable for small partition modes with smaller numbers in the direct current power supply partition, and the binary selection method is suitable for small partition modes with larger numbers in the direct current power supply partition. For the system, when 80 insulators are arranged in each direct current power supply partition and 79 small partition modes can be contained at maximum, the maximum operation times of the sequential method and the binary selection operation times corresponding to different fault small partition numbers are shown in the following table 3:
TABLE 3 comparison of the number of operations for different numbers of small partitions using the "sequential one by one" method and the "binary select" method
The number of operations of the "sequential" method is not determined, and the data shown in the table is the maximum number of operations corresponding to the number N of failed small partitions, and the final number of operations is related to the specific partition position where the failure occurs. According to the same calculation of the probability of faults of each partition position, the average operation times of the sequential method are as followsTherefore, when N is less than or equal to 7, adopting a sequential method; when N >7, a "binary selection" method is used.
S5, disconnecting switches at two ends of the small fault partition are opened to isolate the small fault partition, the partition substation supplies power to each small partition between the small fault partition and the power supply, the interconnection switch between the partition substation and the adjacent substation is closed, and the adjacent substation supplies power to each small partition between the small fault partition and the power supply partition of the adjacent power substation.
The invention will be further described with reference to specific examples.
The input voltage U m = 1500V of the traction substation of the direct current power supply system of the electrified highway, the insulation resistance of the non-grounding electrode to the ground meets the standard of 10MΩ, the parallel resistance R 0 = 60kΩ, and 11 electric isolating switches GK are arranged in the direct current power supply subarea of the electrified highway, so that after the direct current power supply subarea is converted into 12 small subareas, if the positive electrode ground fault occurs in the ascending of the 10 th small subarea, when the insulation resistance of the positive electrode to the ground is reduced to 20kΩ, the fault section judging process is as follows:
When the positive electrode insulation resistance R + is reduced to 20kΩ and the parallel resistance R 0 =60 kΩ,
The negative electrode-to-ground insulation resistance R - is assumed to be 10mΩ that satisfies the criterion, and when the parallel resistance R 0 =60 kΩ,
The measured positive electrode voltage to ground U + is U + =301.4v,
The measured negative voltage to ground U - is U - = -1198.6V,
The differential pressure ratio calculated from the measurement results is
The measured contact net upstream positive input current I + is I + = 15.1mA,
The measured upstream negative output current I - on the contact net is I - = -0.1mA,
The measured upstream differential current I d＝I++I- = 15.1-0.1 = 15mA.
According to the input voltage U m = 1500V, the parallel resistor R 0 = 60kΩ, and the insulation resistance threshold drop coefficient L is set toCalculated to obtain
According to the above, the differential pressure ratio k (-0.60) is smaller than the set value-A (-0.50), the upstream differential current Id (15 mA) is larger than the set value B (12.5 mA), and the upstream positive electrode ground fault is judged.
And then the specific position of the fault section is assessed according to a 'binary selection' method, the power supply partition is divided into 12 small partitions by 11 electric isolating switches GK, namely the small partition number N=12, the 'binary selection' method is satisfied, and the operation times C are equal to Roundup (log 2, 0) =4 times. The 13 th-16 th partition virtually exists in the decision program, and the operation steps are considered as n=16.
In the process of program execution (in which the 12-15 electric isolating switch GK and the corresponding 13-16 small partition virtually exist) is judged according to a binary selection method, 4 times of calculation are carried out, 3 times of electric isolating switch GK opening operation are actually carried out, and the judgment of a fault area is carried out according to whether the fault disappears after each GK operation.
Step 1: according to 16 small subareas, selecting an 8 th electric isolating switch GK for opening and closing operation, and judging that the fault section is behind the switch when the fault disappears after the switch is opened, and closing the switch;
Step 2: the 12 th electric isolating switch GK is selected for opening and closing operation, and because the switch is a set virtual switch, the opening and closing operation is not needed, and the fault section is in front of the 12 th electric isolating switch GK;
Step 3: selecting a 10 th electric isolating switch GK to perform switching operation, and judging that the fault section is in front of the switch if the fault does not disappear after the switch is disconnected;
step 4: and opening and closing the 9 th electric isolating switch GK, and judging that the fault section is behind the switch when the fault disappears after the switch is opened.
The faulty small partition is thus determined to be the 10 th small partition between the 9 th and 10 th electric disconnectors GK.
After judging and isolating the fault small partition, carrying out power supply of other power supply small partitions, including power supply of the partition and power supply of a support adjacent partition, wherein the number of the fault small partition is 10, 9 th and 10 th electric isolating switches GK before and after the small partition are switched on, and the other electric isolating switches are switched on, so that the power supply of the power substation partition to the small partitions 1-9 is realized. And closing a contact switch connecting the small subarea 12 with the adjacent substation subarea to realize the power supply of the adjacent substation subarea to the small subareas 11 and 12.
The invention also discloses a single-phase grounding fault monitoring and fault section isolating device of the electrified highway direct current power supply system, which comprises an input module, an A/D conversion module, a CPU processor module, a data storage module, an output module, a communication module and a display module as shown in figure 6. The input module is connected with the A/D conversion module. The input module, the A/D conversion module, the CPU processor module, the data storage module, the output module, the communication module and the display module are connected by adopting a universal protocol bus. The communication module adopts Ethernet.
The input module collects real-time data of the positive and negative electrode ground voltage and the up and down differential current, signals are converted by the A/D conversion module and then input into the CPU processor module, the CPU processor module analyzes and processes the data according to a fault judging logic flow, the ground fault occurrence range and the ground fault occurrence zone are judged, corresponding instructions are sent to the output module, the output module outputs instruction signals from the CPU processor module to the corresponding switch loop, the electric isolating switch and the feeder circuit breaker are controlled, and isolation of a fault cell and recovery power supply of other small cells are completed. While event information is uploaded to PSCADA via the communication module. The data storage module is used for storing the real-time data acquired by the input module and the data processed by the CPU processor module. The display module displays the operation information such as the working state, voltage, current, equipment operation state, function switching and the like of the device, and can be used for adjusting and viewing the data such as event information, self-checking information and the like.
The present invention has been described in detail by way of examples, but the description is merely exemplary of the invention and should not be construed as limiting the scope of the invention. The scope of the invention is defined by the claims. In the technical scheme of the invention, or under the inspired by the technical scheme of the invention, similar technical schemes are designed to achieve the technical effects, or equivalent changes or improvements to the application scope are still included in the protection scope of the patent coverage of the invention.
Claims (7)
1. The utility model provides a single-phase earth fault monitoring and fault section isolation method of electrified highway direct current power supply system, this direct current power supply system's power supply subregion is interior to set up the segmentation insulation of a plurality of parallelly connected normally closed electric isolating switch, separates into a plurality of electric intercommunication little subregion with every power supply subregion, its characterized in that includes following content:
monitoring real-time data of the ground voltage and the uplink and downlink differential current of the positive electrode and the negative electrode in each substation partition;
Calculating a differential pressure ratio set value A and a differential current set value B according to the input voltage U m of the substation, the parallel resistor R 0 and the insulation resistance threshold drop coefficient L, wherein U m＝|U+ I++ I U-I, U+ is the positive voltage of a power supply, U-is the negative voltage of the power supply, L is (0, 1);
Calculating the differential pressure ratio k according to the collected positive and negative electrode voltages to ground, If k is more than or equal to A, the negative electrode is grounded, and if k is less than or equal to-A, the positive electrode is grounded;
if the uplink differential current is more than or equal to B, an uplink ground fault is generated, and if the downlink differential current is more than or equal to B, a downlink ground fault is generated;
After judging that the fault partition is located in the uplink and the downlink and the positive and negative electrodes, selecting a corresponding isolating switch to conduct closing and opening operation by using a one-by-one sequence method or a binary selection method, and gradually judging the final fault small partition;
The method of sequential is specifically as follows: according to the arrangement sequence of the electric isolating switch in the power supply subarea, according to the distance from the power substation, sequentially switching off from far to near one by one, isolating the small subareas from the power supply subarea one by one, and correspondingly, the fault sections are as follows: if the grounding fault disappears after the feeder circuit breaker is switched on, the small partition behind the last opened electric isolating switch is the fault small partition; if the grounding faults still do not disappear after all the electric isolating switches are turned on one by one, the first small partition is a fault section;
The "binary selection" method is specifically: when the feeder circuit breaker is operated, according to the arrangement sequence of the electric isolating switches in the power supply subareas, the electric isolating switches positioned in the middle position are opened, the whole power supply subareas are divided into two groups, namely a front group and a rear group, if the grounding fault disappears after the feeder circuit breaker is closed, the small fault subarea is positioned behind the opening electric isolating switches; otherwise, the switch is positioned in front of the opening electric isolating switch; after judging a half fault range through one round of half operation of the electric isolating switch, selecting the operation range of the next round, and repeating the operation until the half fault range corresponds to a small fault partition; in each cycle of judgment, when the fault small section is positioned in a half fault range after the breakpoint, the electric disconnecting switch which is disconnected is switched on, so that the original power supply partition is recovered; the fault section corresponds to: if the grounding fault disappears after the feeder circuit breaker is switched on under the condition that the half fault range corresponds to the small partition, the small partition after the last opened electric isolating switch is the fault section; if the grounding fault does not disappear after the feeder circuit breaker is switched on, the small partition before the last opened electric isolating switch is a fault section;
And opening isolating switches at two ends of the fault small partition to isolate the fault small partition, supplying power to each small partition between the fault small partition and a power supply by a partition substation, closing a contact switch between the power supply and an adjacent substation partition, and supplying power to each small partition between the fault small partition and an adjacent power supply partition by the adjacent substation.
2. The method for monitoring single-phase earth faults and isolating fault sections of an electrified highway direct current power supply system according to claim 1, wherein the electric isolating switch operated each time in the binary selection method is related to the number of small partitions N, and the maximum operation times are C times when the number of small partitions N satisfies 2 C-1<N≤2C, c=roundup (log 2 N, 0), and Roundup is an EXCEL rounding function; when the number of small partitions N meets 2 C-1<N<2C, setting virtual small partitions from (n+1) to (2) C, and processing operation steps and corresponding electric isolating switches according to the number of small partitions n=2 C in the judging process.
3. The method for monitoring single-phase earth fault and isolating fault section of electric road dc power supply system according to claim 2, characterized in that the operation steps of the "binary selection" method are as follows:
s1, calculating the maximum operation times C according to the power supply small partition number N, wherein C=Roundup (log 2 N, 0);
s2, selecting the position of the electric isolating switch which is pre-operated in the 1 st round, namely considering all the electric isolating switches in the virtual electric isolating switch and the electric isolating switch which is positioned in the middle position;
s3, opening a corresponding feeder circuit breaker;
S4, opening an mth electric isolating switch, and performing 1 st-round operation on the middle electric isolating switch;
s5, closing the corresponding feeder circuit breaker;
S6, judging whether the fault disappears, and if not, going to S7; when the judgment is yes, the step S12 is carried out;
S7, concluding that the fault small partition is before the mth electric isolating switch;
S8, judging whether the operation times C is smaller than 2, namely, judging whether the operation times are over; if not, go to S9; when the judgment is yes, the step S11 is carried out;
s9, selecting the position of an electric isolating switch pre-operated in the next round;
s10, resetting the operation times C, wherein the operation times are reduced by 1 time;
S11, the conclusion of 'the fault in the mth fault small partition' is obtained;
s12, concluding that the fault small partition is behind the mth electric isolating switch;
S13, judging whether the number N of the small partitions is equal to the number m of the electric isolating switch operated by the current wheel plus 1, namely whether the electric isolating switch operated by the current wheel is the electric isolating switch at the last position; if no, go to S14; when the judgment is yes, the step goes to S20;
s14, judging whether the operation times C are smaller than 2, namely, judging whether the operation times are over; if not, go to S15; when the judgment is yes, the step goes to S20;
S15, closing an mth electric isolating switch; after judging that the fault small partition is positioned on the opened electric isolating switch, closing the electric isolating switch before the next operation of the incoming line;
S16, selecting the position of an electric isolating switch pre-operated in the next round;
s17, resetting the operation times C, wherein the operation times are reduced by 1 time;
S18, selecting whether the position of the pre-operated electric isolating switch is within the small partition number N, namely whether the position is a virtual position, and the position is more than or equal to the small partition number N; if no, go to S19; when the judgment is yes, the step S4 is carried out;
S19, the position of the pre-operated electric isolating switch is selected as a virtual position by the wheel, and the position of the electric isolating switch operated by the previous wheel is returned;
S20, the conclusion of 'the m+1th fault intra-small-area fault' is drawn.
4. A computer program product comprising computer program/instructions which, when executed by a processor, implement the steps of the electrified highway dc power supply system single phase ground fault monitoring and fault section isolation method of any of claims 1 to 3.
5. A computer readable storage medium, wherein a computer program is stored on the computer readable storage medium, the computer program when executed by a processor implementing the steps of the method for single-phase earth fault monitoring and fault section isolation of an electrified highway dc power supply system according to any one of claims 1 to 3.
6. An electronic device comprising a processor, a memory and a computer program stored on the memory and operable on the processor, the computer program when executed by the processor implementing the steps of the electrified highway dc power supply system single phase ground fault monitoring and fault zone isolation method of any of claims 1-3.
7. An apparatus for single-phase earth fault monitoring and fault section isolation of an electrified highway dc power supply system, the apparatus being configured to implement the method for single-phase earth fault monitoring and fault section isolation of an electrified highway dc power supply system as claimed in any one of claims 1 to 3, comprising:
The input module is used for collecting the positive and negative electrode voltages to the ground and the uplink and downlink differential currents in each substation area and carrying out real-time data monitoring;
The A/D conversion module converts the data signals acquired by the input module and inputs the data signals into the CPU processor module;
the CPU processor module judges whether a ground fault occurs according to the positive and negative electrode ground voltage and the uplink and downlink difference current values acquired by the input module, if the ground fault occurs, the position of the small fault partition is further judged according to a judging program, and isolation processing is carried out on the small fault partition;
the output module is used for outputting instructions sent by the CPU processor module to corresponding switch loops and controlling the opening and closing of the electric isolating switch and the feeder circuit breaker;
The data storage module is used for storing the collected and processed data information;
the communication module is used for being connected PSCADA and transmitting data;
The display module is used for displaying real-time operation data, checking event records and data information and the opening and closing states of the electric isolating switches and the feeder circuit breakers.
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