CN111208369B - Method and device for calculating short-circuit current of direct-current system of nuclear power plant - Google Patents

Method and device for calculating short-circuit current of direct-current system of nuclear power plant Download PDF

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CN111208369B
CN111208369B CN202010032023.6A CN202010032023A CN111208369B CN 111208369 B CN111208369 B CN 111208369B CN 202010032023 A CN202010032023 A CN 202010032023A CN 111208369 B CN111208369 B CN 111208369B
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power plant
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CN111208369A (en
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齐索妮
陈怀宇
沈岩
姜庆水
曾敬梅
周晓斌
王贵
姜博文
黄艺昀
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China Nuclear Power Engineering Co Ltd
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Abstract

The embodiment of the disclosure provides a method and a device for calculating short-circuit current of a direct-current system of a nuclear power plant, wherein the method comprises the following steps: determining the maximum operation condition and the minimum operation condition of a direct current system of a nuclear power plant; calculating the maximum short-circuit current of a direct-current bus in the direct-current system of the nuclear power plant based on the maximum operation condition of the direct-current system of the nuclear power plant; and calculating the minimum short-circuit current of the direct current bus in the direct current system of the nuclear power plant based on the minimum operation condition of the direct current system of the nuclear power plant. The embodiment of the disclosure determines the maximum and minimum operation conditions of the nuclear power plant, and calculates the maximum and minimum short-circuit currents in the direct-current system of the nuclear power plant based on the maximum and minimum operation conditions, so as to solve the problems that when the direct-current system protection is matched according to a single short-circuit current value in the related art, the protection matching element blocking capacity possibly caused is insufficient, the sensitivity is lower than a calculated value when a short circuit occurs, and the like, better perform short-circuit protection on a line, and reduce the safety and economic losses caused by a short-circuit fire.

Description

Method and device for calculating short-circuit current of direct-current system of nuclear power plant
Technical Field
The disclosure relates to the technical field of power engineering, in particular to a method for calculating short-circuit current of a direct-current system of a nuclear power plant and a device for calculating short-circuit current of the direct-current system of the nuclear power plant.
Background
In a nuclear power plant dc system, the short circuit current is a significant hazard. Statistically, electrical fires are mainly caused by short circuits, and the loss of life and property due to a short circuit fire is far comparable to the value of an unprotected section of line, especially when the fire causes an explosion, the consequences are more severe. Therefore, short-circuit protection equipment is needed to prevent short circuit from firing and protect the normal operation of the circuit. In order to ensure that the short-circuit protection equipment can correctly break the short-circuit current, the maximum and minimum short-circuit currents need to be accurately calculated when the protection matching capability of the short-circuit protection equipment is verified. The maximum short-circuit current is used for verifying the breaking capacity of the short-circuit protection equipment, and the minimum short-circuit current is used for verifying the sensitivity of the short-circuit protection equipment.
In the existing short-circuit current calculation method, the short-circuit current of a direct current system is provided for a storage battery, the short-circuit current calculated by the method is a certain value, the specific calculation process of the maximum short-circuit current and the minimum short-circuit current of the direct current system is not clear, the short-circuit current calculated by the method cannot be used for checking the breaking capacity of switches under different operation conditions of the system, particularly in power stations with special operation requirements, such as nuclear power stations, the storage battery needs to be checked and charged in each shutdown and refueling period, the operation conditions of the system have great difference, and if the short-circuit current is calculated according to a conventional method, the conditions that the breaking capacity of a protective electric appliance is insufficient or the sensitivity of the protective equipment is insufficient can occur.
Therefore, it is an urgent need to solve the above-mentioned problems to provide a scheme capable of accurately calculating the maximum and minimum short-circuit currents in the dc system.
Disclosure of Invention
The disclosure provides a method and a device for calculating short-circuit current of a direct-current system of a nuclear power plant, which are used for solving the problems that when the short-circuit current value is calculated to carry out direct-current system protection matching in the related art, the blocking capacity of a protection matching element is insufficient, the sensitivity is lower than a calculated value when a short circuit occurs, and the like.
According to an aspect of the embodiments of the present disclosure, a method for calculating a short-circuit current of a dc system of a nuclear power plant is provided, where the method includes:
determining the maximum operation condition and the minimum operation condition of a direct current system of a nuclear power plant;
calculating the maximum short-circuit current of a direct-current bus in the direct-current system of the nuclear power plant based on the maximum operation condition of the direct-current system of the nuclear power plant; and the number of the first and second groups,
and calculating the minimum short-circuit current of a direct-current bus in the direct-current system of the nuclear power plant based on the minimum operation condition of the direct-current system of the nuclear power plant.
In one embodiment, the determining the maximum operation condition and the minimum operation condition of the direct current system of the nuclear power plant comprises:
analyzing a wiring mode of a direct current system of the nuclear power plant;
and determining the maximum operation working condition and the minimum operation working condition of the direct current system of the nuclear power plant based on the wiring mode of the direct current system of the nuclear power plant.
In an embodiment, the determining the maximum operating condition and the minimum operating condition of the dc system of the nuclear power plant based on the connection mode of the dc system of the nuclear power plant specifically includes:
if the wiring mode of the direct current system of the nuclear power plant is the on-load charging and discharging of the storage battery, the maximum operation working condition is the balanced charging operation state of the storage battery, and the minimum operation working condition is the final stage of the accident discharging of the storage battery;
if the direct current system wiring mode of the nuclear power plant is off-line equalizing charge and discharge of the storage battery, the maximum operation working condition is a full-charge floating charge operation state of the storage battery, and the minimum operation working condition is the last stage of discharge of the storage battery accident.
In an embodiment, the maximum short-circuit current of the dc bus in the dc system of the nuclear power plant is calculated based on the maximum operating condition of the dc system of the nuclear power plant, and the calculation formula is as follows:
Figure BDA0002364662160000021
wherein, Ib.maxRepresenting the maximum short-circuit current of a direct-current bus in a direct-current system of the nuclear power plant; u shapefcRepresenting the upper limit voltage value of the storage battery in the maximum operation condition; n represents the number of storage batteries; r isBRepresenting the internal resistance of the storage battery in the maximum operation working condition; r islThe resistance of a connecting cable inside the storage battery is represented; r islbbThe resistance of the battery to dc distribution board cable is shown.
In one embodiment, the method further comprises:
obtaining rated current and the number of chargers on a direct current bus in a direct current system of a nuclear power plant;
the maximum short-circuit current of the direct-current bus in the direct-current system of the nuclear power plant is calculated based on the maximum operation condition of the direct-current system of the nuclear power plant, and the calculation formula is as follows:
Figure BDA0002364662160000031
wherein, Ib.maxRepresenting the maximum short-circuit current of a direct-current bus in a direct-current system of the nuclear power plant; u shapefcRepresenting the upper limit voltage value of the storage battery in the maximum operation condition; n represents the number of storage batteries; r isBRepresenting the internal resistance of the storage battery in the maximum operation working condition; r islThe resistance of a connecting cable inside the storage battery is represented; r islbbRepresenting the resistance of the battery to dc distribution board cable; m represents the number of chargers connected and operated on the direct current bus; i isRIndicating the charger current rating.
In one embodiment, the minimum short-circuit current of the dc bus in the dc system of the nuclear power plant is calculated based on the minimum operating condition of the dc system of the nuclear power plant, and the calculation formula is as follows:
Figure BDA0002364662160000032
wherein, Ib.minRepresenting the minimum short-circuit current of a direct current bus in a direct current system of the nuclear power plant; u shapefzRepresenting the lower limit voltage value of the storage battery in the minimum operation condition; n representsThe number of storage batteries; r isB.NRepresenting the internal resistance of the storage battery in the minimum operation condition; r islThe resistance of a connecting cable inside the storage battery is represented; r islbbThe resistance of the battery to dc distribution board cable is shown.
According to another aspect of the disclosed embodiments, there is provided a device for calculating short-circuit current of a direct current system of a nuclear power plant, the device including:
a determination module configured to determine a maximum operating condition and a minimum operating condition of a direct current system of a nuclear power plant;
the first calculation module is arranged for calculating the maximum short-circuit current of a direct-current bus in the direct-current system of the nuclear power plant based on the maximum operation condition of the direct-current system of the nuclear power plant; and the number of the first and second groups,
and the second calculation module is configured to calculate the minimum short-circuit current of the direct-current bus in the direct-current system of the nuclear power plant based on the minimum operation condition of the direct-current system of the nuclear power plant.
In one embodiment, the determining module comprises:
an analysis unit configured to analyze a wiring manner of a direct current system of a nuclear power plant;
a determination unit configured to determine a maximum operation condition and a minimum operation condition of the nuclear plant dc system based on a wiring manner of the nuclear plant dc system.
In one embodiment, the determining unit is specifically configured to:
if the wiring mode of the direct current system of the nuclear power plant is the on-load charging and discharging of the storage battery, the maximum operation working condition is the balanced charging operation state of the storage battery, and the minimum operation working condition is the final stage of the accident discharging of the storage battery;
if the direct current system wiring mode of the nuclear power plant is off-line equalizing charge and discharge of the storage battery, the maximum operation working condition is a full-charge floating charge operation state of the storage battery, and the minimum operation working condition is the last stage of discharge of the storage battery accident.
In one embodiment, the first calculation module calculates the formula as:
Figure BDA0002364662160000041
wherein, Ib.maxRepresents the maximum short-circuit current, U, of a DC bus in a DC system of a nuclear power plantfcRepresenting the upper limit voltage value of the storage battery in the maximum operation condition; n represents the number of storage batteries; r isBRepresenting the internal resistance of the storage battery in the maximum operation working condition; r islThe resistance of a connecting cable inside the storage battery is represented; r islbbThe resistance of the battery to dc distribution board cable is shown.
In one embodiment, the apparatus further comprises:
the system comprises an acquisition module, a control module and a control module, wherein the acquisition module is used for acquiring the rated current and the number of chargers on a direct current bus in a direct current system of a nuclear power plant;
the first calculation module has a calculation formula as follows:
Figure BDA0002364662160000042
wherein, Ib.minRepresenting the minimum short-circuit current of a direct current bus in a direct current system of the nuclear power plant; u shapefcRepresenting the upper limit voltage value of the storage battery in the maximum operation condition; n represents the number of storage batteries; r isBRepresenting the internal resistance of the storage battery in the maximum operation working condition; r islThe resistance of a connecting cable inside the storage battery is represented; r islbbRepresenting the resistance of the battery to dc distribution board cable; m represents the number of chargers connected and operated on the direct current bus; i isRIndicating the charger current rating.
In one embodiment, the second calculation module calculates the formula as:
Figure BDA0002364662160000043
wherein, UfzRepresenting the lower limit voltage value of the storage battery in the minimum operation condition; n represents the number of storage batteries; r isB.NRepresenting the internal resistance of the storage battery in the minimum operation condition; r islIndicating electricity of connecting cables inside the accumulatorBlocking; r islbbThe resistance of the battery to dc distribution board cable is shown.
The technical scheme provided by the embodiment of the disclosure can have the following beneficial effects:
the method for calculating the short-circuit current of the direct-current system of the nuclear power plant provided by the embodiment of the disclosure determines the maximum and minimum operation conditions of the nuclear power plant by analyzing the operation condition when the maximum and minimum short-circuit currents occur in the direct-current system of the nuclear power plant, and calculates the actual maximum and minimum short-circuit currents in the direct-current system of the nuclear power plant based on the maximum and minimum operation conditions, so that the problems that the breaking capacity of a protection matching element is insufficient and the sensitivity is lower than a calculated value when a short circuit occurs and the like when the direct-current system is protected and matched according to a single short-circuit current value by a calculation method in the related technology can be at least solved, the short-circuit protection is better performed on a line, and the safety and economic losses caused by short-circuit fire are reduced.
Additional features and advantages of the disclosure will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by the practice of the disclosure. The objectives and other advantages of the disclosure may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
Drawings
The accompanying drawings are included to provide a further understanding of the disclosed embodiments and are incorporated in and constitute a part of this specification, illustrate embodiments of the disclosure and together with the example serve to explain the principles of the disclosure and not to limit the disclosure.
Fig. 1 is a schematic flowchart of a method for calculating a short-circuit current of a nuclear power plant system according to an embodiment of the present disclosure;
FIG. 2 is a wiring diagram of a nuclear power plant DC system in an embodiment of the present disclosure;
fig. 3 is a schematic structural diagram of a computing device for short-circuit current of a nuclear power plant system according to an embodiment of the present disclosure.
Detailed Description
To make the objects, technical solutions and advantages of the embodiments of the present disclosure more apparent, specific embodiments of the present disclosure are described below in detail with reference to the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating the present disclosure, are given by way of illustration and explanation only, not limitation.
It should be noted that, in the present disclosure, the embodiments and features of the embodiments may be arbitrarily combined with each other without conflict.
In which the terminology used in the embodiments of the disclosure is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used in the disclosed embodiments and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.
In the following description, suffixes such as "module", "component", or "unit" used to denote elements are used only for the convenience of explanation of the present disclosure, and have no specific meaning in themselves. Thus, "module", "component" or "unit" may be used mixedly.
Referring to fig. 1, fig. 1 is a schematic flow chart of a method for calculating a short-circuit current of a nuclear power plant system according to an embodiment of the present disclosure, which is used to solve the problems in the related art that calculating a short-circuit current of a dc system of a nuclear power plant is usually based on calculating a short-circuit current of a storage battery, and it is difficult to check a breaking capability of a switch under maximum and minimum operating conditions of the dc system, so that an interruption capacity of a protection device is not sufficient or a sensitivity of the protection device is not sufficient, and the like, in the embodiment of the present disclosure, by analyzing a maximum operating condition and a minimum operating condition of the dc system first to accurately calculate maximum and minimum short-circuit currents of the dc system of the nuclear power plant, so that the protection device can interrupt the maximum short-circuit current under a special operating condition, and at the same time, the sensitivity of line protection is checked by using the minimum short-circuit current, so as to solve the problems that a change of the short-circuit current of the dc system of the nuclear power plant due to different operating conditions cannot be correctly protected and matched, specifically, the method comprises steps S101-S103.
In step S101, a maximum operating condition and a minimum operating condition of the dc system of the nuclear power plant are determined.
It should be noted that the operating condition of the nuclear power plant is a generic name of a normal operating condition and an abnormal operating condition (a predicted operating event) of the nuclear power plant, and in this embodiment, a maximum operating condition and a minimum operating condition of the dc system under the normal operating condition of the nuclear power plant are mainly considered, where the maximum operating condition is an operating condition when a maximum short-circuit current occurs when a dc bus is short-circuited in the design of the dc system of the nuclear power plant, and the minimum operating condition is an operating condition when a minimum short-circuit current occurs when the dc bus is short-circuited in the design of the dc system of the nuclear power plant.
In the calculation process of the short-circuit current, for different nuclear power plant designs, a large difference may exist between the maximum operation condition and the minimum operation condition, and if the short-circuit current is calculated according to the related technology, the conditions that the breaking capacity of the protection electric appliance is insufficient, or the sensitivity of the protection equipment is insufficient, etc. may occur. In the embodiment, before the short-circuit current is calculated, the maximum operation condition and the minimum operation condition of the direct-current system of the nuclear power plant are firstly analyzed and determined, so that a foundation is laid for calculating the short-circuit current, and the problems of equipment safety and the like caused by inaccurate short-circuit current calculation results due to differences of the operation conditions of the nuclear power plant in the related technology are solved.
In a specific embodiment, the determining the maximum operation condition and the minimum operation condition of the dc system of the nuclear power plant (i.e., step S101) includes the following steps:
analyzing a wiring mode of a direct current system of the nuclear power plant;
and determining the maximum operation working condition and the minimum operation working condition of the direct current system of the nuclear power plant based on the wiring mode of the direct current system of the nuclear power plant.
In practical application, the difference of the direct current system connection modes may cause a large difference in operation conditions, and the maximum operation condition and the minimum operation condition of the direct current system of the nuclear power plant are determined by analyzing the connection mode of the direct current system of the nuclear power plant and based on the connection mode of the direct current system of the nuclear power plant, so that the conditions of the maximum operation condition and the minimum operation condition in the direct current system of the nuclear power plant are further determined.
In a specific embodiment, the determining the maximum operating condition and the minimum operating condition of the dc system of the nuclear power plant based on the connection mode of the dc system of the nuclear power plant specifically includes:
if the wiring mode of the direct current system of the nuclear power plant is the on-load charging and discharging of the storage battery, the maximum operation working condition is the balanced charging operation state of the storage battery, and the minimum operation working condition is the final stage of the accident discharging of the storage battery;
if the direct current system wiring mode of the nuclear power plant is off-line equalizing charge and discharge of the storage battery, the maximum operation working condition is a full-charge floating charge operation state of the storage battery, and the minimum operation working condition is the last stage of discharge of the storage battery accident.
As shown in fig. 2, fig. 2 is a wiring diagram of a dc system of a nuclear power plant provided in this embodiment, where the wiring diagram includes a dc bus 21, a storage battery 22, two chargers 23, two ac buses 24, two dc loads 25, a DSC load 26, an inverter with a bypass transformer 27, and a storage battery discharge test loop 28 connected to the dc bus 21, and the wiring manner is a case of an operation condition of offline balanced charging and discharging of the storage battery, in this embodiment, when the dc bus is short-circuited, an operation condition of a maximum short-circuit current is full-capacity operation of the storage battery, and the charger supplies power to the dc bus and simultaneously charges the storage battery in a floating manner, that is, the maximum operation condition; the operation condition when the minimum short circuit current appears is that the bus is only powered by the storage battery, and meanwhile, the storage battery is in the last stage of N hours (N is the accident discharge time designed by the direct current system) of accident discharge, namely the minimum operation condition.
In step S102, a maximum short-circuit current of a dc bus in the dc system of the nuclear power plant is calculated based on a maximum operating condition of the dc system of the nuclear power plant.
In the embodiment, the maximum operation condition and the minimum operation condition when the direct current bus is in short circuit are determined by analyzing the operation characteristics of the direct current system of the nuclear power plant firstly, and the actual maximum and minimum short-circuit currents are obtained based on the operation conditions of the direct current system under the maximum and minimum operation conditions of the nuclear power plant, so that the calculation result of the short-circuit currents is more consistent with the actual operation condition in the direct current system of the nuclear power plant, the problems that the interdiction capacity of a protective electric appliance is insufficient or the sensitivity of the protective equipment is insufficient due to the fact that a storage battery needs to be subjected to a checking charge-discharge test in each shutdown refueling cycle in the nuclear power plant, and the maximum and minimum operation conditions of the direct current system are greatly different if the short-circuit currents are calculated according to a conventional method are solved.
In a specific embodiment, the maximum short-circuit current of the dc bus in the dc system of the nuclear power plant is calculated based on the maximum operating condition of the dc system of the nuclear power plant, and the calculation formula is as follows:
Figure BDA0002364662160000081
wherein, Ib.maxRepresenting the maximum short-circuit current of a direct-current bus in a direct-current system of the nuclear power plant; u shapefcRepresenting the upper limit voltage value of the storage battery in the maximum operation condition; n represents the number of storage batteries; r isBRepresenting the internal resistance of the storage battery in the maximum operation working condition; r islThe resistance of a connecting cable inside the storage battery is represented; r islbbThe resistance of the battery to dc distribution board cable is shown.
It is understood that, in the present embodiment, UfcThe floating charge voltage value of a single storage battery is shown, namely, the calculated voltage of the maximum short-circuit current operating condition is the bus voltage during floating charge (the minimum short-circuit current operating condition is the bus voltage at the last stage of accidental discharge of the storage battery), rBThe internal resistance value of the single storage battery at full capacity is shown, and can be test data provided by a manufacturer.
Because a large-capacity storage battery and a large-capacity charger are generally used in some nuclear power plants, when a short circuit occurs, the injection current of the charger may reach thousands of amperes, and the current of the charger is not considered in calculating the short circuit current in the related art, which results in greatly reduced accuracy of the calculation result.
And obtaining the rated current and the number of the chargers on the direct current bus in the direct current system of the nuclear power plant.
According to the method, the rated current and the number of the chargers on the direct current bus in the direct current system of the nuclear power plant are obtained, and the short-circuit current contributed by the chargers is considered in the calculation of the maximum short-circuit current of the direct current system, so that the accuracy of the calculation result of the maximum short-circuit current is guaranteed. It will be appreciated that the short circuit current contributed by the charger need not be taken into account in the minimum short circuit current calculation.
The maximum short-circuit current of the direct-current bus in the direct-current system of the nuclear power plant is calculated based on the maximum operation condition of the direct-current system of the nuclear power plant, and the calculation formula is as follows:
Figure BDA0002364662160000091
wherein, Ib.maxRepresenting the maximum short-circuit current of a direct-current bus in a direct-current system of the nuclear power plant; u shapefcRepresenting the upper limit voltage value of the storage battery in the maximum operation condition; n represents the number of storage batteries; r isBRepresenting the internal resistance of the storage battery in the maximum operation working condition; r islThe resistance of a connecting cable inside the storage battery is represented; r islbbRepresenting the resistance of the battery to dc distribution board cable; m represents the number of chargers connected and operated on the direct current bus; i isRIndicating the charger current rating.
It will be appreciated that the charger provides a short circuit current of 1.5 times the constant current due to the current limiting effect of the charger.
In step S103, a minimum short-circuit current of the dc bus in the dc system of the nuclear power plant is calculated based on a minimum operating condition of the dc system of the nuclear power plant.
It should be noted that, this embodiment only illustrates one sequence of step S102 and step S103, and the sequence of these two steps is not limited, and may be other sequences in some embodiments.
In one embodiment, the minimum short-circuit current of the dc bus in the dc system of the nuclear power plant is calculated based on the minimum operating condition of the dc system of the nuclear power plant, and the calculation formula is as follows:
Figure BDA0002364662160000092
wherein, Ib.minRepresenting the minimum short-circuit current of a direct current bus in a direct current system of the nuclear power plant; u shapefzRepresenting the lower limit voltage value of the storage battery in the minimum operation condition; n represents the number of storage batteries; r isB.NRepresenting the internal resistance of the storage battery in the minimum operation condition; r islThe resistance of a connecting cable inside the storage battery is represented; r islbbThe resistance of the battery to dc distribution board cable is shown.
In this embodiment, UfzI.e. the value of the battery end discharge voltage, and similarly, rB.NThe internal resistance of a single storage battery after N hours of discharge is the experimental data provided by a manufacturer.
Based on the same technical concept, the embodiment of the present disclosure correspondingly provides a device for calculating a short-circuit current of a direct-current system of a nuclear power plant, which includes a determination module 31, a first calculation module 32, and a second calculation module 33, as shown in fig. 3. Wherein,
the determining module 31 is configured to determine a maximum operating condition and a minimum operating condition of the direct current system of the nuclear power plant;
the first calculation module 32 is configured to calculate a maximum short-circuit current of a dc bus in the dc system of the nuclear power plant based on a maximum operation condition of the dc system of the nuclear power plant; and the number of the first and second groups,
the second calculation module 33 is configured to calculate a minimum short-circuit current of a dc bus in the dc system of the nuclear power plant based on a minimum operating condition of the dc system of the nuclear power plant.
In a specific embodiment, the determining module 31 includes:
an analysis unit configured to analyze a wiring manner of a direct current system of a nuclear power plant;
a determination unit configured to determine a maximum operation condition and a minimum operation condition of the nuclear plant dc system based on a wiring manner of the nuclear plant dc system.
In a specific embodiment, the determining unit is specifically configured to:
if the wiring mode of the direct current system of the nuclear power plant is the on-load charging and discharging of the storage battery, the maximum operation working condition is the balanced charging operation state of the storage battery, and the minimum operation working condition is the final stage of the accident discharging of the storage battery;
if the direct current system wiring mode of the nuclear power plant is off-line equalizing charge and discharge of the storage battery, the maximum operation working condition is a full-charge floating charge operation state of the storage battery, and the minimum operation working condition is the last stage of discharge of the storage battery accident.
In a specific embodiment, the first calculating module 32 calculates the formula as:
Figure BDA0002364662160000102
wherein, Ib.maxRepresenting the maximum short-circuit current of a direct-current bus in a direct-current system of the nuclear power plant; u shapefcRepresenting the upper limit voltage value of the storage battery in the maximum operation condition; n represents the number of storage batteries; r isBRepresenting the internal resistance of the storage battery in the maximum operation working condition; r islThe resistance of a connecting cable inside the storage battery is represented; r islbbThe resistance of the battery to dc distribution board cable is shown.
In one embodiment, the computing device further comprises:
the system comprises an acquisition module, a control module and a control module, wherein the acquisition module is used for acquiring the rated current and the number of chargers on a direct current bus in a direct current system of a nuclear power plant;
the first calculating module 32 has a calculation formula of:
Figure BDA0002364662160000101
wherein, Ib.maxRepresenting the maximum short-circuit current of a direct-current bus in a direct-current system of the nuclear power plant; u shapefcRepresenting the upper limit voltage value of the storage battery in the maximum operation condition; n represents the number of storage batteries; r isBRepresenting the internal resistance of the storage battery in the maximum operation working condition; r islThe resistance of a connecting cable inside the storage battery is represented; r islbbRepresenting the resistance of the battery to dc distribution board cable; m represents the number of chargers connected and operated on the direct current bus; i isRIndicating the charger current rating.
In a specific embodiment, the second calculating module 33 calculates the formula as:
Figure BDA0002364662160000111
wherein, Ib.minRepresenting the minimum short-circuit current of a direct current bus in a direct current system of the nuclear power plant; u shapefzRepresenting the lower limit voltage value of the storage battery in the minimum operation condition; n represents the number of storage batteries; r isB.NRepresenting the internal resistance of the storage battery in the minimum operation condition; r islThe resistance of a connecting cable inside the storage battery is represented; r islbbThe resistance of the battery to dc distribution board cable is shown.
It should be noted that, relevant modules of the apparatus embodiment execute corresponding steps in the foregoing method embodiment, and are not described herein again.
To sum up, the method and the device for calculating the short-circuit current of the direct-current system of the nuclear power plant provided by the embodiment of the disclosure determine the maximum and minimum operating conditions in the direct-current system of the nuclear power plant, and calculate the maximum and minimum short-circuit current based on the maximum and minimum operating conditions of the nuclear power plant, so that the calculation result better conforms to the actual situation, and the problems that the interruption capacity of a protection matching element is insufficient, the sensitivity is lower than the calculated value when a short circuit occurs and the like due to inaccurate calculation of the short-circuit current can be effectively avoided, so that the protection equipment can interrupt the maximum short-circuit current under the special operating conditions, and meanwhile, the sensitivity of line protection can be verified by using the minimum short-circuit current, thereby better performing short-circuit protection on a line and reducing the safety and economic losses caused by a short-circuit fire.
Finally, it should be noted that: the above embodiments are only used for illustrating the technical solutions of the present disclosure, and not for limiting the same; while the present disclosure has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art will understand that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present disclosure.

Claims (8)

1. A method for calculating short-circuit current of a direct-current system of a nuclear power plant is characterized by comprising the following steps:
analyzing a wiring mode of a direct current system of the nuclear power plant;
determining the maximum operation working condition and the minimum operation working condition of the direct current system of the nuclear power plant based on the wiring mode of the direct current system of the nuclear power plant;
calculating the maximum short-circuit current of a direct-current bus in the direct-current system of the nuclear power plant based on the maximum operation condition of the direct-current system of the nuclear power plant;
calculating the minimum short-circuit current of a direct-current bus in the direct-current system of the nuclear power plant based on the minimum operation condition of the direct-current system of the nuclear power plant;
the method comprises the following steps of determining the maximum operation working condition and the minimum operation working condition of the direct current system of the nuclear power plant based on the wiring mode of the direct current system of the nuclear power plant, and specifically comprises the following steps:
if the wiring mode of the direct current system of the nuclear power plant is the on-load charging and discharging of the storage battery, the maximum operation working condition is the balanced charging operation state of the storage battery, and the minimum operation working condition is the final stage of the accident discharging of the storage battery;
if the direct current system wiring mode of the nuclear power plant is off-line equalizing charge and discharge of the storage battery, the maximum operation working condition is a full-charge floating charge operation state of the storage battery, and the minimum operation working condition is the last stage of discharge of the storage battery accident.
2. The computing method according to claim 1,
the maximum short-circuit current of the direct-current bus in the direct-current system of the nuclear power plant is calculated based on the maximum operation condition of the direct-current system of the nuclear power plant, and the calculation formula is as follows:
Figure FDA0003487373650000011
wherein, Ib.maxRepresenting the maximum DC bus in a DC system of a nuclear power plantA large short circuit current; u shapefcRepresenting the upper limit voltage value of the storage battery in the maximum operation condition; n represents the number of storage batteries; r isBRepresenting the internal resistance of the storage battery in the maximum operation working condition; r islThe resistance of a connecting cable inside the storage battery is represented; r islbbThe resistance of the battery to dc distribution board cable is shown.
3. The computing method of claim 1, further comprising:
obtaining rated current and the number of chargers on a direct current bus in a direct current system of a nuclear power plant;
the maximum short-circuit current of the direct-current bus in the direct-current system of the nuclear power plant is calculated based on the maximum operation condition of the direct-current system of the nuclear power plant, and the calculation formula is as follows:
Figure FDA0003487373650000021
wherein, Ib.maxRepresenting the maximum short-circuit current of a direct-current bus in a direct-current system of the nuclear power plant; u shapefcRepresenting the upper limit voltage value of the storage battery in the maximum operation condition; n represents the number of storage batteries; r isBRepresenting the internal resistance of the storage battery in the maximum operation working condition; r islThe resistance of a connecting cable inside the storage battery is represented; r islbbRepresenting the resistance of the battery to dc distribution board cable; m represents the number of chargers connected and operated on the direct current bus; i isRIndicating the charger current rating.
4. The calculation method according to claim 1, wherein the minimum short-circuit current of the direct current bus in the direct current system of the nuclear power plant is calculated based on the minimum operation condition of the direct current system of the nuclear power plant, and the calculation formula is as follows:
Figure FDA0003487373650000022
wherein, Ib.minRepresenting dc in a dc system of a nuclear power plantMinimum short circuit current of the current bus; u shapefzRepresenting the lower limit voltage value of the storage battery in the minimum operation condition; n represents the number of storage batteries; r isB.NRepresenting the internal resistance of the storage battery in the minimum operation condition; r islThe resistance of a connecting cable inside the storage battery is represented; r islbbThe resistance of the battery to dc distribution board cable is shown.
5. A calculating device for short-circuit current of a direct-current system of a nuclear power plant is characterized by comprising:
the system comprises a determining module, a judging module and a judging module, wherein the determining module is used for analyzing the wiring mode of the direct current system of the nuclear power plant and determining the maximum operation working condition and the minimum operation working condition of the direct current system of the nuclear power plant based on the wiring mode of the direct current system of the nuclear power plant;
the first calculation module is arranged for calculating the maximum short-circuit current of a direct-current bus in the direct-current system of the nuclear power plant based on the maximum operation condition of the direct-current system of the nuclear power plant;
the second calculation module is set to calculate the minimum short-circuit current of a direct-current bus in the direct-current system of the nuclear power plant based on the minimum operation working condition of the direct-current system of the nuclear power plant;
wherein the determining unit is specifically configured to:
if the wiring mode of the direct current system of the nuclear power plant is the on-load charging and discharging of the storage battery, the maximum operation working condition is the balanced charging operation state of the storage battery, and the minimum operation working condition is the final stage of the accident discharging of the storage battery;
if the direct current system wiring mode of the nuclear power plant is off-line equalizing charge and discharge of the storage battery, the maximum operation working condition is a full-charge floating charge operation state of the storage battery, and the minimum operation working condition is the last stage of discharge of the storage battery accident.
6. The computing device of claim 5,
the first calculation module has a calculation formula as follows:
Figure FDA0003487373650000031
wherein, Ib.maxRepresents the maximum short-circuit current, U, of a DC bus in a DC system of a nuclear power plantfcRepresenting the upper limit voltage value of the storage battery in the maximum operation condition; n represents the number of storage batteries; r isBRepresenting the internal resistance of the storage battery in the maximum operation working condition; r islThe resistance of a connecting cable inside the storage battery is represented; r islbbThe resistance of the battery to dc distribution board cable is shown.
7. The computing device of claim 5, further comprising:
the system comprises an acquisition module, a control module and a control module, wherein the acquisition module is used for acquiring the rated current and the number of chargers on a direct current bus in a direct current system of a nuclear power plant;
the first calculation module has a calculation formula as follows:
Figure FDA0003487373650000032
wherein, Ib.minRepresenting the minimum short-circuit current of a direct current bus in a direct current system of the nuclear power plant; u shapefcRepresenting the upper limit voltage value of the storage battery in the maximum operation condition; n represents the number of storage batteries; r isBRepresenting the internal resistance of the storage battery in the maximum operation working condition; r islThe resistance of a connecting cable inside the storage battery is represented; r islbbRepresenting the resistance of the battery to dc distribution board cable; m represents the number of chargers connected and operated on the direct current bus; i isRIndicating the charger current rating.
8. The computing device of claim 5, wherein the second computing module calculates the formula:
Figure FDA0003487373650000041
wherein, UfzRepresenting the lower limit voltage value of the storage battery in the minimum operation condition; n represents the electric power storageThe number of pools; r isB.NRepresenting the internal resistance of the storage battery in the minimum operation condition; r islThe resistance of a connecting cable inside the storage battery is represented; r islbbThe resistance of the battery to dc distribution board cable is shown.
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