CN107091969B - Intelligent detection device and method for direct current looped network - Google Patents
Intelligent detection device and method for direct current looped network Download PDFInfo
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- CN107091969B CN107091969B CN201710340268.3A CN201710340268A CN107091969B CN 107091969 B CN107091969 B CN 107091969B CN 201710340268 A CN201710340268 A CN 201710340268A CN 107091969 B CN107091969 B CN 107091969B
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- 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
- G01R31/08—Locating faults in cables, transmission lines, or networks
- G01R31/081—Locating faults in cables, transmission lines, or networks according to type of conductors
- G01R31/086—Locating faults in cables, transmission lines, or networks according to type of conductors in power transmission or distribution networks, i.e. with interconnected conductors
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- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
Abstract
The invention designs and develops a direct current ring network intelligent detection device and a direct current ring network intelligent detection method. The method comprises the steps of monitoring voltages of two sections of direct current buses, forming preliminary ring network type prejudgment according to the voltage change of the direct current buses, starting a corresponding decision algorithm, converting direct current grounding detection into a direct current ring network detection function, controlling a response load module and a direct current insulation system module according to different ring network types, and meanwhile effectively detecting and judging a direct current ring network according to the condition of measuring current and forming alarm feedback.
Description
Technical Field
The invention relates to the technical field of transformer substation power supply direct current systems, in particular to a direct current looped network intelligent detection device and method.
Background
The direct current system is an important power supply system of the transformer substation and is mainly responsible for power supply of relay protection equipment, automation equipment, a breaker opening and closing loop and a monitoring signal loop in the transformer substation, and the direct current system is related to measurement and control operation of a secondary system of the transformer substation and whether protection can be normally opened under the condition of failure of main network equipment. Different from a low-voltage 380V alternating-current power supply system in a station, two-pole buses of a direct-current system are an ungrounded system, so that the problems of insufficient insulation, voltage runaway and the like of the direct-current system are easily caused by circuit grounding, parasitic loops and an electric looped network, and serious consequences such as false alarm, false tripping of a circuit breaker and the like are caused when multiple points are grounded.
According to the requirements of the standard DL/T5044-2014 in the power industry, a direct current system with two groups of storage battery packs in a transformer substation adopts a two-section single bus connection mode, a contact breaker is arranged between two sections of buses, and the two sections of buses respectively and independently operate during normal operation. Therefore, under normal conditions, two groups of direct current power supplies should not have looped network connection conditions, however, most of the existing transformer substations are subjected to technical improvement and repair projects such as changing a storage battery pack into a single-double mode, replacing a charging machine, changing and expanding an interval of a new outgoing line in a station and the like, a direct current system easily leaves over homopolar looped networks or heteropolar single-ended looped networks, because output voltages controlled by two groups of direct current bus voltages are basically close, the conditions of a positive looped network, a negative looped network and a positive looped network and a negative looped network are difficult to find through a monitoring person, particularly, the looped networks at the different ends of the positive and the negative electrodes are closely related to the actual looped network resistance, if the looped network resistance tends to a large value, two groups of buses of the looped networks are also lack of effective devices to detect and alarm in time, and a large compensation space exists in the field of direct current looped network detection.
Disclosure of Invention
The current-stage direct-current ring network detection method mainly comprises a voltage regulation method, a grounding judgment method and a signal injection method.
The voltage regulation method is characterized in that the output voltage of one set of direct current charger is regulated under the safe condition, if the voltage of the other set of direct current system is correspondingly increased, the looped network condition of the two sets of direct current systems can be judged, and the change condition of the buses at all levels to the ground voltage is further deeply analyzed to refine and analyze whether the buses are anode looped networks or cathode looped networks. The looped network judgment of the method is visual, then the charger voltage of one group of buses in the direct current system needs to be adjusted to a greater degree, the voltage value is increased, the normal floating range and the measurement error of the direct current voltage need to be avoided, the load of the group of buses is inevitably influenced, and the protection equipment with high rated voltage requirement is not favorable for bearing qualified voltage. In addition, the method is only suitable for homopolar ring network consideration, is not suitable for heteropolar ring network detection, and has limited detection function.
The grounding judgment method is that one pole of one group of buses is manually set to be grounded under the safety condition of the direct current system, then the ground potential of the reorganized buses is correspondingly changed, at the moment, the condition of the other group of buses to the ground potential is judged, whether the ground potentials of the buses are consistent or not is compared, and if the ground potentials of the buses are the same, the condition that looped networks exist in the two groups of direct current buses can be judged. The method can also be used for judging whether two sets of direct current systems always have ground faults or not when the direct current systems have ground alarm under the abnormal condition, and if yes, the looped network fault is indicated. The method is used for auxiliary judgment of the looped network under the condition of direct current grounding, and has the following three problems:
1. the extra grounding point arranged on the direct current bus actually influences a balance bridge of an inherent insulation detection device of the direct current system, so that the insulation detection alarm of the direct current system is inevitably triggered, and the correct judgment of substation operation and maintenance personnel is interfered under the condition that the direct current system has a real ground fault, and the risk potential exists;
2. after the DC system considers that the grounding point is arranged, if the control loop at a certain breaker interval at the load end of the DC system is grounded at one point, the DC system is grounded at multiple points, the control loop is easy to be conducted to send a tripping command of the circuit breaker, so that serious consequences such as mistaken tripping of main network switch equipment, voltage loss and power failure of the whole network and the like are caused;
3. aiming at the condition that the grounding polarity of two sections of buses is connected with opposite heteropolar looped networks, the grounding judgment method will aggravate the existing looped network problem of the direct current system, increase the leakage current of the looped network, and complicate the looped network problem, thus being not beneficial to intuitively and effectively judging the heteropolar looped network condition.
The signal injection method is to inject low-frequency alternating-current signals into two-pole direct-current buses, then detect signals on feeder lines one by using a special detection clamp-type ammeter, and when low-frequency signals exist on two sections of buses, the existence of a direct-current ring network can be judged, and then the detection and judgment are continued on a lower branch. The method is suitable for searching a complex loop structure, but the detection method depends on the sensitivity of a detecting instrument, and the transmission communication between a direct current system and a load basically adopts a cable carrier with large earth distribution capacitance, the injected low-frequency alternating current signal is easily subjected to interference attenuation, so that the detection clamp meter is often judged by mistake, in addition, the signal injection method also generates unnecessary ripple influence on a direct current system, signal misoperation is possibly caused, and the practical application effect is poor.
In summary, it can be known that the existing techniques for detecting the dc ring network have advantages and disadvantages, but have a large interference effect on the dc system, or have incomplete functions, which is not favorable for the safe and stable operation of the dc system, and the detection method needs to be improved.
In addition, a direct current insulation detection system is mostly adopted in a direct current system at present, but the direct current insulation detection system aims at the direct current grounding condition and has no looped network detection technology. Meanwhile, the looped network detection method does not well consider the influence of the direct current looped network detection technology on the direct current insulation detection system, and the engineering practical consideration is not good.
In order to overcome at least one defect in the prior art, the invention adopts the technical scheme that:
a kind of direct current looped netowrk intellectual detection system, including:
a direct current bus voltage monitoring instrument connected with the decision processing unit, monitoring the earth pressure difference of the positive electrode and the negative electrode of two sections of direct current buses of the direct current system in real time, and feeding back and transmitting the measurement result to the decision processing unit;
a charging unit current measuring instrument connected with the decision processing unit, monitoring output currents of a charger and a storage battery connected with two sections of direct current buses of the direct current system in real time, and feeding back and transmitting a measurement result to the decision processing unit;
the decision processing unit is an algorithm operation and central control module of the direct current ring network intelligent detection device, starts a decision algorithm according to the detection condition of each instrument, controls the response load module and the direct current insulation system module to execute the direct current ring network intelligent detection process, obtains a direct current ring network detection conclusion by combining the measurement result of the instrument, outputs a response and alarm signal to a human-computer interaction interface, and reminds a user to master the detection result;
the response load module is connected with the decision processing unit and is an execution module with a direct current ring network intelligent detection function; the response load module controls the response load module to be switched on or switched off or changes the load of the response load module according to the command output by the decision processing unit, and feeds back an action completion signal and the direct current measuring instrument result to the decision processing unit;
the direct current insulation system module is connected with the decision processing unit and is an execution module with an intelligent detection function of a direct current ring network; the direct-current insulation system module has the grounding detection function of the direct-current system bus insulation detector, the grounding condition of the direct-current bus is detected in real time by combining with direct-current bus voltage monitoring, the ground potential condition of two sections of buses of the direct-current system is changed when direct-current ring network detection is carried out, and an action completion signal is fed back to the decision processing unit.
Preferably, the charging unit current measuring instrument includes: a current detector of the charger and an output current detector of the storage battery.
Preferably, the response load module is loaded and communicated with two sections of direct current buses; the responsive load module includes: the direct current circuit breaker capable of controlling on-off, the direct current measuring instrument and the resistive load capable of controlling variable resistance are connected in series; the response load module is used for controlling the direct current circuit breaker which can be controlled to be switched on and switched off or changing the resistance value of the resistive load which can be controlled to change the resistance value so as to realize the switching-on and switching-off of the response load module or change the load size of the response load module.
Preferably, the dc insulation system module has two groups of control circuits, each group of control circuits includes a balance bridge and a grounding unit, wherein the grounding unit has a dc breaker capable of controlling breaking, and the control circuits are respectively connected in parallel to two dc buses;
the direct current insulation system module realizes the grounding detection function of the direct current system bus insulation detector through the balance bridge;
and the direct current insulation system module changes the ground potential condition of two sections of buses of the direct current system by controlling the direct current circuit breaker of the grounding unit.
A detection method utilizing a direct current looped network intelligent detection device monitors the ground potential condition of two sections of buses of a direct current system in real time through the direct current looped network intelligent detection device,
the detection method comprises the following steps:
s1: starting;
s2: detecting the ground potential of the two sections of direct current buses, and turning to the step S3;
s3: judging whether the direct current system has a ground fault according to the ground potential in the step S2, if so, switching to a step S9, and if not, switching to a step S4;
s4: detecting whether the bus potential meets the pre-judgment condition, and turning to the step S5;
s5: starting a looped network prejudgment program, and turning to the step S6;
s6: starting corresponding secondary judgment detection, and turning to the step S7;
s7: judging whether a ring network exists or not, if so, turning to the step S8, and if not, returning to the step S2;
s8: sending a ring network alarm, and turning to the step S11;
s9: sending a direct current system grounding alarm, and turning to a step S10;
s10: locking the direct current ring network detection function, and turning to the step S11;
s11: and detecting whether the looped network detection device is locked, if the looped network detection device is locked, switching to a step S12, and if the looped network detection device is not locked, switching to a step S2.
S12: and (6) ending.
Preferably, the ring network prejudging program comprises the following steps:
the method comprises the following steps: measuring the positive electrode-to-ground potential of the direct current bus 1 and the positive electrode-to-ground potential of the direct current bus 2;
step two: measuring the ground potential of the negative electrode of the direct current bus 1 and the ground potential of the negative electrode of the direct current bus 2;
step three: and obtaining a looped network prejudgment conclusion.
The invention designs and develops a direct current ring network intelligent detection device and a direct current ring network intelligent detection method. The method comprises the steps of monitoring voltages of two sections of direct current buses, forming preliminary ring network type prejudgment according to the voltage change of the direct current buses, starting a corresponding decision algorithm, converting direct current grounding detection into a direct current ring network detection function, controlling a response load module and a direct current insulation system module according to different ring network types, and meanwhile effectively detecting and judging a direct current ring network according to the condition of measuring current and forming alarm feedback.
Drawings
Fig. 1 is a schematic working diagram of an intelligent detection device for a direct current loop network.
Fig. 2 is a schematic diagram of the intelligent detection process of the direct current loop network.
Description of reference numerals:
the system comprises a direct current bus voltage monitoring instrument 1, a direct current bus voltage monitoring instrument 2, a tie switch K12, a decision processing unit 3, a 4-response load module, a 41-direct current circuit breaker capable of controlling on and off, a 42-direct current measuring instrument 43, a resistive load capable of controlling resistance value change, a 5-response load module, a 51-direct current circuit breaker capable of controlling on and off, a 52-direct current measuring instrument 53, a resistive load capable of controlling resistance value change, a 7-direct current insulation system module 71, a grounding circuit breaker K1, a 72-balance resistor R11, a 73-balance resistor R12, an 8-direct current insulation system module 81, a grounding circuit breaker K2, a 72-balance resistor R21, a 73-balance resistor R22, a 9-number 1 charger, a 10-number 1 storage battery, a 11-number 2 charger, and a 12-number 2 storage battery.
Detailed Description
The drawings are for illustrative purposes only and are not to be construed as limiting the patent; for the purpose of better illustrating the embodiments, certain features of the drawings may be omitted, enlarged or reduced, and do not represent the size of an actual product; it will be understood by those skilled in the art that certain well-known structures in the drawings and descriptions thereof may be omitted. The positional relationships depicted in the drawings are for illustrative purposes only and should not be construed as limiting the present patent.
As shown in fig. 1, an intelligent detection device for a dc ring network includes: the system comprises a direct current bus voltage monitoring instrument 1, a charging unit current measuring instrument, a decision processing unit 3, a response load module 4 and a direct current insulation system module 7.
The direct current bus voltage monitoring instrument 1 is connected with the decision processing unit 3, monitors the ground pressure difference of the positive pole and the negative pole of the two segments of direct current buses of the direct current system in real time, and feeds back the measurement result to the decision processing unit 3.
The charging unit current measuring instrument includes: the system comprises a current detector 21 of a charger on a direct current bus 1 (KM 1), a current detector 21 of a charger on a direct current bus 2 (KM 2), an output current detector 22 of a storage battery pack on the direct current bus 1 (KM 1) and an output current detector 22 of a storage battery pack on the direct current bus 2 (KM 2), wherein a charging unit current measuring instrument is connected with a decision processing unit 3, monitors output currents of the chargers 9 and 11 and the storage batteries 10 and 12 connected with two sections of direct current buses of a direct current system in real time, and feeds back and transmits a measuring result to the decision processing unit 3.
The decision processing unit 3 is an arithmetic operation and central control module of the direct current ring network intelligent detection device, starts a decision algorithm according to the detection condition of each instrument, controls the response load module and the direct current insulation system module to execute the direct current ring network intelligent detection process, obtains a direct current ring network detection conclusion by combining the measurement result of the instrument, outputs a response and alarm signal to a human-computer interaction interface, and reminds a user to master the detection result;
the response load modules 4 and 5 are connected with the decision processing unit 3, are execution modules of the intelligent detection function of the direct current ring network and are execution modules of the intelligent detection function of the direct current ring network; each responsive load module includes: the direct current circuit breakers 41 and 51 capable of controlling on and off, the direct current measuring instruments 42 and 52 and the resistive loads 43 and 53 capable of controlling resistance values, the direct current circuit breakers 41 and 51 capable of controlling on and off, the direct current measuring instruments 42 and 52 and the resistive loads 43 and 53 capable of controlling resistance values are connected in series, two responding load modules are respectively loaded and communicated with two direct current buses, the responding load modules control the direct current circuit breakers 41 and 51 capable of controlling on and off to be connected or change the resistance values of the resistive loads 43 and 53 capable of controlling resistance values to be changed according to an output command of the decision processing unit 3, and action completion signals and results of the direct current measuring instruments 42 and 52 are fed back to the decision processing unit 3.
The direct current insulation system modules 7 and 8 are connected with the decision processing unit 3 and are execution modules with the intelligent detection function of the direct current ring network; the direct current insulation system modules 7 and 8 are provided with two groups of control circuits, each group of control circuits comprises a balance bridge and a grounding unit, the grounding unit is provided with direct current breakers 71 and 81 capable of controlling breaking, and the control circuits are respectively connected in parallel to two sections of direct current buses; the direct current insulation system modules 7 and 8 have the grounding detection function of a common direct current system bus insulation detector through a balance bridge, can detect the grounding condition of the direct current bus in real time by combining with direct current bus voltage monitoring, and control direct current circuit breakers 71 and 81 of a grounding unit when direct current ring network detection is carried out, so that the ground potential condition of two sections of buses of the direct current system is changed, and an action completion signal is fed back to the decision processing unit 3.
As shown in fig. 2, a detection method using an intelligent detection device of a dc ring network, the detection method monitors the ground potential condition of two segments of buses of a dc system in real time through the intelligent detection device of the dc ring network,
the detection method comprises the following steps:
s1: starting;
s2: detecting the ground potential of the two sections of direct current buses, and turning to the step S3;
s3: judging whether the direct current system has a ground fault according to the ground potential in the step S2, if so, switching to a step S9, and if not, switching to a step S4;
s4: detecting whether the bus potential meets the pre-judgment condition, and turning to the step S5;
s5: starting a looped network prejudgment program, and turning to the step S6;
s6: starting corresponding secondary judgment detection, and turning to the step S7;
s7: judging whether a ring network exists or not, if so, turning to the step S8, and if not, returning to the step S2;
s8: sending out ring network alarm, and turning to step S11;
s9: sending out a direct current system grounding alarm, and turning to the step S10;
s10: locking the direct current ring network detection function, and turning to the step S11;
s11: and detecting whether the looped network detection device is locked, if the looped network detection device is locked, switching to the step S12, and if the looped network detection device is not locked, switching to the step S2.
S12: and (6) ending.
Specifically, with reference to fig. 1 and 2, the dc loop network intelligent detection apparatus monitors the ground potential condition of two bus bars of the dc system in real time under a normal condition, and when the dc bus potential is found to meet the loop network pre-judgment condition, starts the dc loop network detection algorithm of the decision processing unit, where the dc loop network detection algorithm is divided into a loop network pre-judgment program and a secondary judgment stage, where the secondary judgment stage controls the actions of the response load module and the dc insulation system module, and obtains a secondary judgment conclusion by combining with signal feedback generated by the actions, and obtains a final loop network detection result by combining with the pre-judgment conclusion.
The looped network prejudgment program comprises:
the method comprises the following steps: measuring the positive electrode-to-ground potential of the direct current bus 1 and the positive electrode-to-ground potential of the direct current bus 2;
step two: measuring the ground potential of the negative electrode of the direct current bus 1 and the ground potential of the negative electrode of the direct current bus 2;
step three: and obtaining a looped network prejudgment conclusion.
The looped network prejudgment conclusion is I: when the positive electrode-to-ground potential of the direct current bus 1 and the positive electrode-to-ground potential of the direct current bus 2 are positive at the same time, the difference of potential values is smaller than 0.5% of the rated potential, and the negative electrode-to-ground potential of the direct current bus 1 and the negative electrode-to-ground potential of the direct current bus 2 are negative at the same time, the pre-judging direct current system possibly has a positive looped network, and a pre-judging conclusion of the positive single-ended looped network is obtained.
The looped network prejudges a conclusion II: when the negative electrode-to-ground potential of the direct current bus 1 and the negative electrode-to-ground potential of the direct current bus 2 are negative at the same time and the difference between the potential values is smaller than 0.5% of the rated potential, the positive electrode-to-ground potential of the direct current bus 1 and the positive electrode-to-ground potential of the direct current bus 2 are positive at the same time, the possibility of existence of a negative looped network in the direct current system is pre-judged, and a pre-judgment conclusion of the negative single-ended looped network is obtained.
The looped network prejudges the conclusion three: when the positive electrode-to-ground potential of the direct current bus 1 and the positive electrode-to-ground potential of the direct current bus 2 are positive at the same time, the potential difference is smaller than 0.5% of the rated potential, the negative electrode-to-ground potential of the direct current bus 1 and the negative electrode-to-ground potential of the direct current bus 2 are negative at the same time, and the potential difference is smaller than 0.5% of the rated potential, the simultaneous looped networks of the positive electrode and the negative electrode exist in the pre-judging direct current system, and the pre-judging conclusion of the looped networks at the two ends of the positive electrode and the negative electrode is obtained.
The looped network prejudgment conclusion is four: when the positive electrode of the direct current bus 1 is positive to the ground potential and the positive electrode of the direct current bus 2 is positive to the ground potential simultaneously, the potential difference is larger than the rated potential by 2%, the negative electrode of the direct current bus 1 is negative to the ground potential and the negative electrode of the direct current bus 2 is negative to the ground potential simultaneously, and the potential difference is larger than the rated potential by 2%.
Step four: if the looped network prejudgment conclusion is obtained, if the looped network prejudgment conclusion is four, the condition of the bus voltage of the direct current system is further judged, and a secondary looped network prejudgment conclusion is obtained.
The second looped network prejudgment conclusion is one: when the positive electrode-to-ground potential of the direct current bus 1 is smaller than the positive electrode-to-ground potential of the direct current bus 2, and when the absolute value of the negative electrode-to-ground potential of the direct current bus 1 is larger than the absolute value of the negative electrode-to-ground potential of the direct current bus 2, the pre-judgment direct current system possibly has an electrical looped network between the positive electrode of the direct current bus 1 and the negative electrode of the direct current bus 2, and a pre-judgment conclusion of the heteropolar single-ended looped network between the positive electrode of the direct current bus 1 and the negative electrode of the direct current bus 2 is obtained.
And a second looped network prejudgment conclusion is two: when the positive electrode-to-ground potential of the direct current bus 1 is larger than the positive electrode-to-ground potential of the direct current bus 2, and when the absolute value of the negative electrode-to-ground potential of the direct current bus 1 is smaller than the absolute value of the negative electrode-to-ground potential of the direct current bus 2, the pre-judgment of the direct current system can cause the existence of an electrical looped network between the negative electrode of the direct current bus 1 and the positive electrode of the direct current bus 2, and a pre-judgment conclusion of the heteropolar single-ended looped network between the negative electrode of the direct current bus 1 and the positive electrode of the direct current bus 2 is obtained.
The second looped network prejudgment conclusion is three: when the difference between the positive electrode-to-ground potential of the direct current bus 1 and the positive electrode-to-ground potential of the direct current bus 2 is smaller than 5% of the rated potential from zero potential, the difference between the negative electrode-to-ground potential of the direct current bus 1 and the negative electrode-to-ground potential of the direct current bus 2 is smaller than 5% of the rated potential from zero potential, an electrical looped network may exist between the negative electrode of the direct current bus 1 and the positive electrode of the direct current bus 2 in the pre-judging direct current system, and an electrical looped network exists between the positive electrode of the direct current bus 1 and the negative electrode of the direct current bus 2, so that a pre-judging conclusion of two sections of direct current bus heteropolar double-end looped networks is obtained.
And after a looped network pre-judgment conclusion is obtained, starting an execution module to perform secondary judgment detection according to the pre-judgment conclusion, wherein the secondary judgment detection method starts two action strategies aiming at one to three looped network pre-judgment conclusions of homopolar looped networks.
Action strategy 1: determining that switches and controllers of the direct current system and the direct current looped network intelligent detection device recover to normal states, controlling to disconnect a grounding circuit breaker K2 in a direct current insulation system module 8, then adjusting a resistive load 53 with controllable variable resistance in a response load module 5 to a maximum value, controlling to close a direct current circuit breaker 51 in the response load module 5, controlling the resistive load 53 with controllable variable resistance to gradually adjust and reduce the resistance, and simultaneously judging that [ P1] of a direct current measuring instrument 52 in the response load module 5 and a charging unit current measuring instrument detect current changes in a direct current bus 1 and a direct current bus 2.
Action strategy 2: determining that switches and controllers of the direct current system and the direct current looped network intelligent detection device recover to normal states, controlling to disconnect a grounding circuit breaker K2 71 in a direct current insulation system module 7, then adjusting a resistive load 43 capable of controlling a variable resistance value in a response load module 4 to a maximum value, controlling to close a direct current circuit breaker 41 in the response load module 4, controlling the resistive load 43 capable of controlling the variable resistance value to gradually adjust and reduce the resistance value, and simultaneously judging that [ P2] of a direct current measuring instrument 42 in the response load module 4 and a charging unit current measuring instrument detect current changes in a direct current bus 1 and the direct current bus 2.
Wherein, non-looped network detects and judges: if the ground potential of the direct current bus 2 rises in the action strategy 1 process, the vector sum of the current measured by the current detector 21 of the charger on the direct current bus 1 (KM 1) and the current measured by the current detector 22 of the storage battery pack on the direct current bus 1 (KM 1) is defined below as "the output current of the charging unit of the direct current bus 1", and the vector sum of the current measured by the current detector 21 of the charger on the direct current bus 2 (KM 2) and the current measured by the output current detector 22 of the storage battery pack on the direct current bus 2 (KM 2) "is defined below as" the output current of the charging unit of the direct current bus 2 (KM 2) ") does not increase with the change of the resistance of the resistive load 53 with controllable change resistance, the current 1 measured by the response load module 5 is zero, while the direct current bus 1 rises in the action strategy 2 process, the output current of the charging unit of the direct current bus 1 and the output current of the charging unit of the direct current bus 2 do not increase with the change of the resistance of the controllable change of the resistive load 43, the measurement of the response load module 4 is zero, and the direct current bus 2 charging unit output current circuit breaker does not return to the ground potential of the direct current loop system, and the direct current loop circuit breaker 41 does not need to be judged immediately.
And (3) detecting and judging the anode homopolar looped network: if the difference between the ground potential of the direct current bus 2 and the rated value is 5% in the action strategy 1 process, the output current of the charging unit of the direct current bus 1 is not increased, the response load module 5 measures that the current 1 is increased, the output current of the charging unit of the direct current bus 2 is increased, the response load module 5 measures that the current 1 is equal to the output current increment of the charging unit of the direct current bus 2, and the difference between the ground potential of the direct current bus 1 and the rated value is 5% in the action strategy 2 process, the output current of the charging unit of the direct current bus 2 is not increased, the response load module 4 measures that the current 2 is increased, the output current of the charging unit of the direct current bus 1 is increased, and when the response load module 4 measures that the current 2 is equal to the increment of the output current of the charging unit of the direct current bus 1, the direct current system can be judged to have a positive homopolar looped network, and a secondary judgment conclusion of a positive homopolar looped network can be obtained.
And (3) detecting and judging a cathode homopolar looped network: if the difference between the ground potential and the rated value of the direct current bus 2 in the action strategy 1 process is 5%, the output current of the charging unit of the direct current bus 1 is increased, the measured current 1 of the response load module 5 is increased, the output current of the charging unit of the direct current bus 2 is not increased, the measured current 1 of the response load module 5 is equal to the increment of the output current of the charging unit of the direct current bus 1, the difference between the ground potential and the rated value of the direct current bus 1 in the action strategy 2 process is 5%, the output current of the charging unit of the direct current bus 2 is increased, the measured current 2 of the response load module 4 is increased, the output current of the charging unit of the direct current bus 1 is not increased, and the increment of the output current of the charging unit of the direct current bus 2 is equal to the measured current 2 of the response load module 4, the existence of a negative homopolar looped network in the direct current system can be judged, and a negative homopolar looped network secondary judgment conclusion can be obtained.
And (3) detecting and judging the homopolar looped network at the two ends of the anode and the cathode: if the current 1 measured by the responsiveload module 5 increases during the action strategy 1, and if the current 2 measured by the responsiveload module 4 increases during the action strategy 2, one of the following feedback conditions is satisfied:
(1) The measured current 1 of the response load module 5 in the action strategy 1 is equal to the increment of the output current of the charging unit of the direct current bus 1, and the measured current 2 of the response load module 4 in the action strategy 2 is equal to the increment of the output current of the charging unit of the direct current bus 2;
(2) The measured current 1 of the response load module 5 in the action strategy 1 is equal to the output current increment of the charging unit of the direct current bus 1, and the measured current 2 of the response load module 4 in the action strategy 2 is equal to the output current increment of the charging unit of the direct current bus 1;
(3) The measured current 1 of the response load module 5 in the action strategy 1 is equal to the output current increment of the charging unit of the direct current bus 2, and the measured current 2 of the response load module 4 in the action strategy 2 is equal to the output current increment of the charging unit of the direct current bus 2;
(4) In the action strategy 1, the measured current 1 of the response load module 5 is equal to the increment of the output current of the charging unit of the direct current bus 1 and the increment of the output current of the charging unit 2, and in the action strategy 2, the measured current 2 of the response load module 4 is equal to the increment of the output current of the charging unit of the direct current bus 1 and the increment of the output current of the charging unit 2;
the direct current system can be judged to have the anode and cathode double-end homopolar looped networks, and a secondary judgment conclusion of the anode and cathode double-end homopolar looped networks is obtained.
And (3) detecting and judging a single-ended heteropolar ring network of the anode and the cathode: aiming at the first secondary looped network pre-judgment conclusion of the heteropolar looped network (the heteropolar single-ended looped network pre-judgment conclusion of the anode of the direct current bus 1 and the cathode of the direct current bus 2), the resistive load 53 capable of controlling the variable resistance in the response load module is adjusted to the maximum value, the direct current breaker 51 in the response load module is controlled to be closed, the resistive load 53 capable of controlling the variable resistance is controlled to gradually adjust and reduce the resistance value, when the resistance value is reduced to a certain value, the fact that the measured current of the response load module is increased is detected, the anode of the direct current bus 1 is reduced to the ground potential, meanwhile, the cathode of the direct current bus 2 is increased to the ground potential, a secondary judgment conclusion of the heteropolar single-ended looped network of the anode of the direct current bus 1 and the cathode of the direct current bus 2 is obtained, and other voltage change conditions return to judgment of non-corresponding information.
Aiming at the second looped network pre-judgment conclusion II (a pre-judgment conclusion of the heteropolar single-ended looped network of the negative electrode of the direct current bus 1 and the positive electrode of the direct current bus 2), the resistive load 43 capable of controlling the variable resistance in the response load module is adjusted to the maximum value, the direct current breaker 41 in the response load module is controlled to be closed, the resistive load 43 capable of controlling the variable resistance is controlled to gradually adjust and reduce the resistance, when the resistance is reduced to a certain value, the detected result shows that the current measured by the response load module is increased, the positive electrode of the direct current bus 2 is reduced to the ground potential, and meanwhile, when the negative electrode of the direct current bus 1 is increased to the ground potential, the secondary judgment conclusion of the heteropolar single-ended looped network of the negative electrode of the direct current bus 1 and the positive electrode of the direct current bus 2 can be obtained.
And (3) detecting and judging the heteropolar ring network at the two ends of the anode and the cathode: aiming at the third prejudgment condition of the heteropolar looped network (a prejudgment conclusion of the heteropolar two-end looped network of the two direct current buses), at the moment, direct current charging units of the two direct current buses are equivalent to series short circuit, the main output of a charger is used, the charging current is very large, the inherent power-off protection and fuse burning of the charger are started to cut off a loop, if the current of the charger is detected to be larger than a set value (the set value is lower than the overcurrent protection value of the two buses and higher than the rated current value of the two buses by 1.1 time) and continuously exceeds 3s, a secondary judgment conclusion of the heteropolar two-end looped network is obtained, and an emergency alarm is sent immediately.
And (5) explaining the intelligent detection principle of the direct current ring network.
Aiming at the anode single-end homopolar looped network, the voltage of the anode bus basically keeps consistent, if the output voltage difference of the chargers of the two sections of buses is different, the cathode is different from the ground potential, and therefore the prejudgment conclusion of the anode single-end homopolar looped network can be obtained. Based on the result, the response load module and the direct current insulation system module are controlled, and the reaction result is checked to further authenticate the prejudgment conclusion. Firstly, one section of direct current bus (such as the direct current bus 2) is enabled to remove the function of bus insulation detection to the ground, so as to eliminate the leakage current interference formed by the looped network through the electric bridge grounding loop. Then, after the resistance value of the response load module (such as the resistive load 53 capable of controlling the change of the resistance value) is maximized, the electric connection that the two sections of direct current systems have the maximum insulation property after the direct current breaker module is closed is ensured, the direct current positive and negative poles of the direct current circuit breaker (the direct current circuit breaker 51) lose the direct current positive and negative poles to the earth bridge bus (such as the direct current bus 2) to the earth potential is immediately judged after the direct current circuit breaker is closed, if the positive pole of the bus to the earth potential is increased, the negative pole is the same as the positive pole to the earth potential of the other section of bus (the direct current bus 1), so that the response load module is a unique electric connection loop, and the direct current system does not have the looped network problem;
if the potential is similar to the normal condition, namely the positive electrode-to-ground potential and the negative electrode-to-ground potential of the bus of the ground-to-ground bridge are lost and are similar to the ground-to-ground potential before the bridge is lost, the looped network exists, and the loop circuit is required to be led out by further adjusting the resistive load. When the output current of a certain section of direct current charging unit (such as a direct current bus 1, which is mainly the output of a charger) and the measured current of the same-side response load module (such as the measured current 1 of the response load) are increased at the same time, it can be seen that the loop current path is as follows: the method comprises the steps of charging a direct current bus 1 through a direct current charger anode, a charger current measuring instrument, a direct current bus 1 anode bus, a response load module 5 (sequentially passing through the current measuring instrument, a direct current breaker and a resistive load), a direct current bus 2 cathode bus, a direct current bus 1 cathode bus and a direct current bus 1 direct current charger cathode. The action strategy 1 and the action strategy 2 are in practical consistency, and the feedback results of the two action processes simultaneously meet the requirement of effectively detecting the existence of the negative single-ended homopolar looped network.
When the output current of a certain section of direct current charging unit (such as a direct current bus 2, which is mainly the output of a charger) and the measurement current of the opposite side response load (such as the measurement current 1 of the response load) are increased simultaneously, the loop current path is as follows: the direct current bus 2 is a positive electrode of the direct current charger, a current measuring instrument of the charger, a positive electrode bus of the direct current bus 2, a positive electrode bus of the direct current bus 1, a response load module 5 (sequentially passes through the current measuring instrument, a direct current breaker and a resistive load), a negative electrode bus of the direct current bus 2 and a negative electrode of the direct current bus 2. And in the same way, two action strategy processes are adopted for simultaneous judgment, so that the single-ended homopolar ring network of the positive electrode can be effectively detected.
When the condition of a homopolar looped network with two ends of a positive electrode and a negative electrode exists, the resistive current flowing through the response load module under the control of two action strategies may only supply current to the direct-current bus charger on the same side, or may be supplied current to the direct-current bus charger on one side under the control of the two action strategies, or may be supplied current to the single response load module by the direct-current bus chargers on two sides, or supplied current to the other response load module by the direct-current bus charger on one side, depending on the potential difference of the direct-current buses caused by the resistance of the homopolar looped network. The condition of the anode and cathode double-end homopolar looped network can be effectively monitored by detecting the output current change of the charger and the current change measured by the response load module.
Aiming at the condition of a positive and negative single-end heteropolar looped network, the positive electrode of the looped network is grounded and the negative electrode of the looped network is groundedThe potential will change correspondingly with different loop network resistances. Therefore, under the condition of the ring network (assuming that the ring network is formed by the anode of the direct current bus 1 and the cathode of the direct current bus 2), the uncertain ring network resistance can reduce the insulating performance of the anode of the bus 1 and the cathode of the bus 2 connected with the ring network to the ground. As can be derived from the formula,
，
in the above formula, the first and second carbon atoms are,
the output voltage (the voltage difference between the positive electrode and the negative electrode) of the direct current system charger 1 is changed>
The output voltage of a DC system charger 2 is combined>
Is a ring network resistor.
Thus when
At infinity time>
，/>
The ground potential of the two busbar sections is equal to the desired value and is normally set->
、/>
、/>
、/>
The four balancing resistances are equal. Therefore, by>
，
。
When in use
When the resistance value is decreased from large to small, it can be known>
Will be decreased and/or be greater or smaller>
Will be increased (decreased in absolute value), but->
Then, get
Namely, the two-pole equivalent of the ring network is zero to the ground potential. So that the uncertainty resistance->
Connected in parallel with a control variable resistor, i.e. responsive to the resistive resistance of the load module>
Or->
When approaching->
Will affect the two-section motherAnd (4) effectively detecting and judging the anode and cathode single-ended heteropolar ring network according to the potential variation trend on the ground potential condition.
Aiming at the condition of a ring network with heteropolar poles at two ends of a positive pole and a negative pole, the direct current system power supply system is equivalent to the condition that the direct current system power supply systems are mutually connected in series through a ring network resistor, so that a great series current is caused, and the inherent overcurrent protection action of a direct current system charger is started under the normal condition, or a fuse is blown due to overcurrent, so that the power supply is cut off. If the resistance of the looped network is very large and is not enough to cause the protection action, the overcurrent and the duration of the charger can be detected, when the overcurrent value is lower than the overcurrent protection value of the two segments of buses and is higher than 1.1 times of the rated current value of the two segments of buses, a secondary judgment conclusion of the looped network with the different poles and the two ends can be directly obtained, and an emergency alarm signal is immediately sent for feedback.
It should be understood that the above-described embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the claims of the present invention.
Claims (6)
1. The utility model provides a direct current looped netowrk intellectual detection system device which characterized in that includes:
the direct current bus voltage monitoring instrument (1) is connected with the decision processing unit (3), the positive and negative electrode ground voltage difference of two sections of direct current buses of the direct current system is monitored in real time, and the measurement result is fed back and transmitted to the decision processing unit (3);
the charging unit current measuring instrument is connected with the decision processing unit (3), monitors output currents of chargers (9 and 11) and storage batteries (10 and 12) connected with two sections of direct current buses of the direct current system in real time, and transmits a measuring result to the decision processing unit (3) in a feedback mode;
the decision processing unit (3) is an arithmetic operation and central control module of the direct current ring network intelligent detection device, starts a decision algorithm according to the detection condition of each instrument, controls the response load modules (4 and 5) and the direct current insulation system modules (7 and 8) to execute the direct current ring network intelligent detection process, obtains a direct current ring network detection conclusion by combining the measurement result of the instrument, and outputs a response and alarm signal to a human-computer interaction interface to remind a user of mastering the detection result;
the response load modules (4, 5) are connected with the decision processing unit (3) and are execution modules of the intelligent detection function of the direct current looped network; the response load modules (4, 5) control the response load modules (4, 5) to be switched on or switched off or change the load of the response load modules (4, 5) according to the output command of the decision processing unit (3), and feed back an action completion signal and the results of the direct current measuring instruments (42, 52) to the decision processing unit (3);
the direct current insulation system modules (7, 8), the direct current insulation system modules (7, 8) are connected with the decision processing unit (3) and are execution modules of the intelligent detection function of the direct current ring network; the direct-current insulation system modules (7 and 8) have the grounding detection function of a direct-current system bus insulation detector, the grounding condition of the direct-current bus is detected in real time by combining with direct-current bus voltage monitoring, the ground potential condition of two sections of buses of the direct-current system is changed when direct-current ring network detection is carried out, and an action completion signal is fed back to the decision processing unit (3).
2. The intelligent detection device for the direct current ring network according to claim 1, characterized in that: the charging unit current measuring instrument includes: a current detector of the charger and an output current detector of the storage battery.
3. The intelligent detection device for the direct current looped network according to claim 1, characterized in that: the response load modules (4 and 5) are loaded and communicated with two sections of direct current buses; the responsive load module (4, 5) comprises: the direct current circuit breakers (41, 51) capable of controlling on-off, the direct current measuring instruments (42, 52), the resistive loads (43, 53) capable of controlling resistance value change, the direct current circuit breakers (41, 51) capable of controlling on-off, the direct current measuring instruments (42, 52) and the resistive loads (43, 53) capable of controlling resistance value change are connected in series;
the response load modules (4 and 5) are controlled to be switched on and off by the direct current circuit breakers (41 and 51) capable of controlling switching-on and switching-off or the resistance values of the resistive loads (43 and 53) capable of controlling resistance values to change are controlled to realize switching-on and switching-off of the response load modules (4 and 5) or change the load sizes of the response load modules (4 and 5).
4. The intelligent detection device for the direct current looped network according to claim 1 or 3, characterized in that: the direct current insulation system modules (7 and 8) are provided with two groups of control circuits, each group of control circuits comprises a balance bridge and a grounding unit, the grounding unit is provided with direct current breakers (41 and 51) capable of controlling breaking, and the control circuits are respectively connected in parallel to two sections of direct current buses;
the direct-current insulation system modules (7 and 8) realize the grounding detection function of the direct-current system bus insulation detector through the balance bridge;
the direct current insulation system modules (7, 8) change the ground potential condition of two sections of buses of the direct current system by controlling the direct current breakers (41, 51) of the grounding unit.
5. A detection method using the intelligent detection device for the DC loop network as claimed in one of claims 1 to 4, wherein the detection method monitors the ground potential condition of two segments of buses of the DC system in real time through the intelligent detection device for the DC loop network,
the detection method comprises the following steps:
s1: starting;
s2: detecting the ground potential of the two sections of direct current buses, and turning to the step S3;
s3: judging whether the direct current system has a ground fault according to the ground potential in the step S2, if so, switching to a step S9, and if not, switching to a step S4;
s4: detecting whether the bus potential meets the pre-judgment condition, and turning to the step S5;
s5: starting a looped network prejudgment program, and turning to the step S6;
s6: starting corresponding secondary judgment detection, and turning to the step S7;
s7: judging whether a ring network exists or not, if so, turning to the step S8, and if not, returning to the step S2;
s8: sending a ring network alarm, and turning to the step S11;
s9: sending out a direct current system grounding alarm, and turning to the step S10;
s10: locking the direct current ring network detection function, and turning to the step S11;
s11: detecting whether the looped network detection device is locked, if the looped network detection device is locked, switching to the step S12, and if the looped network detection device is not locked, switching to the step S2;
s12: and (6) ending.
6. The detection method according to claim 5, characterized in that: the looped network prejudgment program comprises the following steps:
the method comprises the following steps: measuring the positive electrode-to-ground potential of the direct current bus 1 and the positive electrode-to-ground potential of the direct current bus 2;
step two: measuring the ground potential of the negative electrode of the direct current bus 1 and the ground potential of the negative electrode of the direct current bus 2;
step three: and obtaining a looped network prejudgment conclusion.
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| CN106646141B (en) * | 2017-02-28 | 2019-03-01 | 深圳市汇业达通讯技术有限公司 | The automatic testing method and its system of direct current supply bus cyclization |
| CN108008235B (en) * | 2017-11-17 | 2021-02-26 | 珠海格力电器股份有限公司 | Direct current bus short circuit detection method, device and detection circuit |
| CN110398668A (en) * | 2019-09-11 | 2019-11-01 | 广东电网有限责任公司 | A kind of looped network of DC power on-line monitoring system and method |
| CN110398667A (en) * | 2019-09-11 | 2019-11-01 | 广东电网有限责任公司 | A kind of looped network of DC power on-line monitoring system and method |
| CN111650450B (en) * | 2020-04-03 | 2022-07-15 | 杭州奥能电源设备有限公司 | Identification method based on direct current mutual string identification device |
| CN113608065A (en) * | 2021-07-02 | 2021-11-05 | 中国电力科学研究院有限公司 | Multi-direct-current system ring network fault monitoring device and method |
| CN114325195B (en) * | 2021-12-31 | 2022-09-23 | 珠海视熙科技有限公司 | Wired charging detection method and device and computer readable storage medium |
| CN117007911A (en) * | 2023-09-27 | 2023-11-07 | 陕西陶网新智软件科技有限公司 | Fault detection device, system and use method of Direct Current (DC) bus line |
| CN117826007A (en) * | 2024-03-06 | 2024-04-05 | 三峡金沙江川云水电开发有限公司 | Ring network fault detection system and method for direct current system |
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