CN112510655A - Single-phase grounding protection optimization method and device for photovoltaic access thermal power plant station system - Google Patents
Single-phase grounding protection optimization method and device for photovoltaic access thermal power plant station system Download PDFInfo
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- CN112510655A CN112510655A CN202011395891.7A CN202011395891A CN112510655A CN 112510655 A CN112510655 A CN 112510655A CN 202011395891 A CN202011395891 A CN 202011395891A CN 112510655 A CN112510655 A CN 112510655A
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/22—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for distribution gear, e.g. bus-bar systems; for switching devices
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/08—Locating faults in cables, transmission lines, or networks
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
- G01R31/52—Testing for short-circuits, leakage current or ground faults
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y04—INFORMATION OR COMMUNICATION TECHNOLOGIES HAVING AN IMPACT ON OTHER TECHNOLOGY AREAS
- Y04S—SYSTEMS INTEGRATING TECHNOLOGIES RELATED TO POWER NETWORK OPERATION, COMMUNICATION OR INFORMATION TECHNOLOGIES FOR IMPROVING THE ELECTRICAL POWER GENERATION, TRANSMISSION, DISTRIBUTION, MANAGEMENT OR USAGE, i.e. SMART GRIDS
- Y04S10/00—Systems supporting electrical power generation, transmission or distribution
- Y04S10/50—Systems or methods supporting the power network operation or management, involving a certain degree of interaction with the load-side end user applications
- Y04S10/52—Outage or fault management, e.g. fault detection or location
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Abstract
The invention discloses a single-phase grounding protection optimization method and a single-phase grounding protection optimization device for a photovoltaic access thermal power plant system, which comprise the following steps: whether the photovoltaic incoming line loop has single-phase ground fault or not is detected, and when the photovoltaic incoming line loop has single-phase ground fault, the single-phase ground protection optimization device instantaneously acts corresponding to the tripping of a breaker in the photovoltaic incoming line cabinet. Whether single-phase ground faults occur in the plant power system is detected, and when any one loop on the bus has the single-phase ground faults, the single-phase ground protection optimizing device carries out time-limited action on the ground transformer inlet cabinet and circuit breakers in all photovoltaic inlet cabinets to trip simultaneously. And detecting whether each feeder circuit has single-phase earth fault, and when the feeder circuit has single-phase earth fault, instantaneously operating the single-phase earth protection optimizing device on the earth transformer inlet cabinet and tripping the circuit breakers in all the photovoltaic inlet cabinets at the same time. The method and the device can effectively ensure the operation stability of the system and have better economical efficiency.
Description
Technical Field
The invention belongs to the technical field of power generation, and relates to a single-phase grounding protection optimization method and device for a photovoltaic access thermal power plant system.
Background
At present, photovoltaic construction is carried out in a large-scale thermal power plant which is built at present by utilizing an idle site (such as an idle site of an ash yard, a flat area after the ash yard is closed and a downstream dam face), a 'spontaneous self-use' mode is adopted to access a high-voltage station service system of the thermal power plant, the station service power rate is reduced, and an energy-saving and low-carbon 'green' thermal power plant is created.
The grounding capacitance current Ic of the high-voltage power system of the thermal power plant is mostly less than 10A, and the neutral point adopts a non-grounding mode. When a photovoltaic cable current collection circuit is connected, the current of the system grounding capacitor is obviously increased due to the longer newly added cable circuit. When the system grounding capacitance current exceeds 10A, according to DL/T5153-.
Aiming at the access of a photovoltaic system, the conventional scheme for transforming the high-voltage station service system and the single-phase earth fault protection mode are as follows:
(1) according to the number of the photovoltaic lines, a high-voltage switch cabinet with corresponding number of surfaces is added on a bus section for a high-voltage plant, and a comprehensive protection device is arranged in the cabinet. When the circuit has single-phase earth fault, the comprehensive protection device outputs a tripping command to act on the circuit breaker to trip.
(2) A special grounding transformer is added and connected to a high-voltage power station bus through a high-voltage switch cabinet, and a comprehensive protection device is arranged in the cabinet. When single-phase earth fault occurs in each loop of the system, the comprehensive protection device outputs a tripping command to trip the circuit breaker and the high-voltage and low-voltage side circuit breakers of the high-voltage plant in a time-limited mode, and the units are disconnected.
(3) And (3) transforming or replacing all original equipment such as fully-mechanized protection devices, zero-sequence CT (computed tomography) and the like in the feeder cabinet and secondary circuit wiring on the bus. When the circuit has single-phase earth fault, the comprehensive protection device changes the original output alarm signal into an output tripping command to act on the circuit breaker to trip.
(4) And (4) removing the low-current grounding line selection device arranged on the bus section for the high-voltage plant.
The disadvantages of the above solution are: the access of the medium-and-small-capacity photovoltaic in the system greatly reduces the power supply reliability of the original large-unit system, all original feeder cabinet equipment of the high-voltage station power system needs to be modified/replaced, and the related cost is low. After the high-voltage station service power is changed into a neutral point low-resistance grounding mode, when a single-phase grounding fault occurs, the protection effectively identifies a fault loop and acts on a corresponding loop to trip, although the probability that the single-phase grounding fault is converted into a double grounding fault is reduced, the tripping times of the load are increased, the reliability of the original system power supply is greatly reduced, if the single-phase grounding fault is refused to operate, the backup protection can cause the unit disconnection, and the risk is brought to the reliable operation of a large unit.
Generally speaking, the importance of a small-capacity photovoltaic system is relatively low, the small-capacity photovoltaic system is implemented according to a conventional scheme, the standard requirements are met, the single-phase earth fault protection mode of an original large-unit high-voltage station power system is thoroughly changed, uncertain risks are brought to the reliable operation of a large unit, and meanwhile, the scheme possibly relates to the transformation of an original large batch of high-voltage switch cabinets and is poor in economical efficiency.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides a single-phase grounding protection optimization method and device for a photovoltaic access thermal power plant system.
In order to achieve the purpose, the single-phase grounding protection optimization method of the photovoltaic access thermal power plant station system comprises the following steps:
the method comprises the steps that whether a photovoltaic incoming line loop has a single-phase ground fault or not is detected through a photovoltaic incoming line loop zero sequence CT, when the photovoltaic incoming line loop has the single-phase ground fault, a single-phase ground protection optimization device detects that the zero sequence current of the corresponding photovoltaic incoming line loop is larger than a set value, and a breaker in a corresponding photovoltaic incoming line cabinet is instantaneously tripped.
Whether single-phase earth faults occur in the plant power system is detected through the zero sequence CT of the wiring transformer neutral point loop, when any loop on the bus has the single-phase earth faults, the single-phase earth protection optimization device detects that the zero sequence current of the wiring transformer neutral point loop is larger than a set value, and circuit breakers acting in the grounding transformer inlet cabinet and all photovoltaic inlet cabinets with time limit trip simultaneously.
Whether each feeder circuit has single-phase ground fault is detected through the zero sequence CT of each original feeder circuit, when the single-phase ground fault occurs in the feeder circuit, the single-phase ground protection optimization device detects that the return zero sequence current of the corresponding feeder is larger than a set value, the circuit breakers which instantaneously act in the grounding transformer inlet cabinet and all the photovoltaic inlet cabinets trip simultaneously, the grounding mode of the neutral point of the high-voltage power plant system is changed into the ungrounded mode, and meanwhile, an alarm signal is sent to position the specific feeder circuit number with the single-phase ground fault.
A single-phase grounding protection optimization device of a photovoltaic access thermal power plant station system comprises a controller, a first detector, a second detector, a third detector, a switching value output module and an alarm, wherein the first detector is used for detecting whether a photovoltaic inlet wire loop has a single-phase grounding fault, the second detector is used for detecting whether a station power system has the single-phase grounding fault, the third detector is used for detecting whether a feeder line loop has the single-phase grounding fault, the switching value output module is used for acting on a breaker to trip, and the alarm is used for positioning a loop number corresponding to the feeder line single-phase grounding fault.
The input ends of the first detector, the second detector and the third detector are respectively connected with the photovoltaic incoming line loop zero sequence CT, the wiring neutral point loop zero sequence CT and the feeder line loop zero sequence CT. The input end of the controller is connected with the output ends of the first detector, the second detector and the third detector. The output end of the controller is connected with the input end of the switching value output module and the input end of the alarm. The output end of the switching value output module is connected with the breaker tripping circuit of the photovoltaic incoming line cabinet and the grounding transformer incoming line cabinet.
The invention has the following beneficial effects:
when the single-phase grounding protection optimization method and the single-phase grounding protection optimization device of the photovoltaic access thermal power plant station system are specifically operated, when a single-phase grounding fault occurs in a photovoltaic incoming line loop, the single-phase grounding protection of the photovoltaic incoming line loop acts, so that a circuit breaker in a photovoltaic incoming line cabinet trips; when any loop on the bus has single-phase earth fault, the earth becomes neutral point loop single-phase earth protection action, so that the circuit breakers in the earth becomes the inlet cabinet and all the photovoltaic inlet cabinets are tripped in a delayed mode at the same time; when the feeder line loop has single-phase earth fault, the single-phase earth protection of the feeder line loop acts, so that the circuit breakers in the earth transformer inlet cabinet and all the photovoltaic inlet cabinets instantly trip at the same time, and an alarm signal is sent out. By the aid of the method, the operation stability of the system is guaranteed, the system is prevented from being greatly transformed, uncertain risks are caused to the operation of a large unit system with high importance level by a newly-added photovoltaic system with low importance level, and the economy and the reliability are high.
Drawings
Fig. 1 is a schematic diagram of a system scheme of a photovoltaic access thermal power plant and a single-phase ground protection wiring in a first embodiment;
fig. 2 is a schematic structural diagram of the single-phase ground protection optimization device of the present invention.
Wherein, 0 is the controller, 1 is the first detector, 2 is the second detector, 3 is the third detector, 4 is the switching value output module, 5 is the alarm.
Detailed Description
The invention is described in further detail below with reference to the accompanying drawings:
the single-phase grounding protection optimization method of the photovoltaic access thermal power plant station system comprises the following steps:
the method comprises the steps that whether a photovoltaic incoming line loop has a single-phase ground fault or not is detected through a photovoltaic incoming line loop zero sequence CT, when the photovoltaic incoming line loop has the single-phase ground fault, a single-phase ground protection optimization device detects that the zero sequence current of the corresponding photovoltaic incoming line loop is larger than a set value, and a breaker in a corresponding photovoltaic incoming line cabinet is instantaneously tripped.
Whether a single-phase earth fault occurs in the station power system is detected through the zero sequence CT of the neutral point loop of the wiring transformer, when any loop on the bus has the single-phase earth fault, the single-phase earth protection optimization device detects that the zero sequence current of the neutral point loop of the wiring transformer is larger than a set value, circuit breakers in the grounding transformer inlet cabinet and all photovoltaic inlet cabinets are tripped simultaneously with time limit action, the grounding mode of the neutral point of the high-voltage station power system is changed back to the non-grounding mode, and at the moment, the total grounding capacitance current of the system is smaller than 10A.
Whether each feeder circuit has single-phase ground fault is detected through the zero sequence CT of each original feeder circuit, when the single-phase ground fault occurs in the feeder circuit, the single-phase ground protection optimization device detects that the return zero sequence current of the corresponding feeder is larger than a set value, the circuit breakers which instantaneously act in the grounding transformer inlet cabinet and all the photovoltaic inlet cabinets trip simultaneously, the grounding mode of the neutral point of the high-voltage power plant system is changed into the ungrounded mode, and meanwhile, an alarm signal is sent to position the specific feeder circuit number with the single-phase ground fault.
The single-phase ground protection optimization device of the photovoltaic access thermal power plant station system comprises a controller 0, a first detector 1 for detecting whether a photovoltaic inlet line loop has a single-phase ground fault, a second detector 2 for detecting whether the photovoltaic inlet line loop has the single-phase ground fault, a third detector 3 for detecting whether a feeder line loop has the single-phase ground fault, a switching value output module 4 for acting on a breaker to trip, and an alarm 5 for positioning a specific loop number of the feeder line single-phase ground fault. The input ends of the first detector 1, the second detector 2 and the third detector 3 are respectively connected with the photovoltaic incoming line loop zero sequence CT, the wiring neutral point loop zero sequence CT and the feeder line loop zero sequence CT. The input of the controller 0 is connected to the outputs of the first detector 1, the second detector 2 and the third detector 3. The output end of the controller 0 is connected with the input end of the switching value output module 4 and the input end of the alarm 5. The output end of the switching value output module 4 is connected with the tripping loop of the circuit breaker in the photovoltaic incoming line cabinet and the grounding transformer incoming line cabinet.
Example one
Fig. 1 is a schematic diagram of a photovoltaic access thermal power plant system scheme and a single-phase ground protection wiring diagram of a certain project.
Before photovoltaic access, grounding capacitance current Ic of a power system of a thermal power high-voltage power plant is 6A, a neutral point adopts a non-grounding mode, single-phase grounding protection in each integrated protection device in each cabinet is realized by collecting zero sequence current in the cabinet, and the protection action is carried out when an alarm signal is sent out.
The total capacity of the newly-added photovoltaic system is 8.8MWp, the newly-added photovoltaic system is connected to a high-voltage station service section through a two-circuit 6kV cable current collection line, and the total length of the 6kV cable is 20 kilometers.
Two-sided switch cabinet (namely #1 photovoltaic inlet cabinet and #2 photovoltaic inlet cabinet in the figure) is newly added for photovoltaic line access. After photovoltaic access, the new system grounding capacitance current Ic is 6+0.1x6.3x20 is 18.6A, which exceeds 10A, and the neutral point grounding mode is transformed into a low-resistance grounding system.
A special grounding transformer is added and connected to a high-voltage station power bus through a switch cabinet (namely a grounding transformer inlet cabinet in the figure), and in order to ensure the reliability of trip protection, the resistance current/rated value is properly larger, IRTaking 100A, the corresponding resistance value R is 6300/1.732/100 and 36.4 ohm, and the grounding variable capacity needs to be larger than 6.3/1.732, 100/10.5 and 34.6kVA, and taking 125 kVA.
The single-phase grounding protection method comprises the following steps:
1) single-phase grounding protection in photovoltaic incoming cabinet
#1(#2) photovoltaic inlet wire cabinet in the zero sequence current respectively connect to single-phase ground protection optimizing device, and when this return circuit takes place single-phase earth fault, the zero sequence current value that single-phase ground protection optimizing device received surpassed the protection setting value, and single-phase ground protection action was in this cabinet circuit breaker tripping operation.
2) Single-phase grounding protection in grounding transformer cabinet
When a single-phase earth fault occurs in any loop on the bus, the zero-sequence current received by the single-phase earth protection optimization device exceeds a protection setting value, and the single-phase earth protection belt acts in a time limit manner on the earth transformer incoming cabinet, the #1 photovoltaic incoming cabinet and the #2 photovoltaic incoming cabinet to trip the circuit breakers at the same time.
3) Single-phase grounding protection in original feeder cabinet
The comprehensive protection zero sequence current in the original feeder circuit cabinet is connected to the single-phase grounding protection optimization device. When any one circuit of the original feeder line has a single-phase earth fault, the zero-sequence current value received by the single-phase earth protection optimizing device exceeds the protection setting value, the single-phase earth protection instantaneously acts on the circuit breakers in the earth transformer incoming cabinet, #1 photovoltaic incoming cabinet and #2 photovoltaic incoming cabinet to trip simultaneously, and meanwhile, an alarm signal is sent out to position the specific circuit.
Claims (3)
1. A single-phase grounding protection optimization method of a photovoltaic access thermal power plant station system is characterized by comprising the following steps:
detecting whether the photovoltaic incoming line loop has a single-phase ground fault, and when the photovoltaic incoming line loop has the single-phase ground fault, operating the single-phase ground protection optimization device to trip a circuit breaker in the corresponding photovoltaic incoming line cabinet;
detecting whether a single-phase ground fault occurs in a plant power system, and when any loop on a bus has the single-phase ground fault, the single-phase ground protection optimizing device performs time-limited action on the ground transformer inlet cabinet and all circuit breakers in the photovoltaic inlet cabinets to trip simultaneously;
and detecting whether each feeder circuit has single-phase ground fault, and when the feeder circuit has single-phase ground fault, the single-phase ground protection optimization device acts on the ground-to-earth inlet cabinet and all the circuit breakers in the photovoltaic inlet cabinets to trip simultaneously and sends out an alarm signal to position the specific feeder circuit number of the single-phase ground fault.
2. The single-phase grounding protection optimization device of the photovoltaic access thermal power plant station system is characterized by comprising a controller (0), a first detector (1) for detecting whether a photovoltaic inlet line loop has single-phase grounding faults, a second detector (2) for detecting whether the photovoltaic inlet line loop has the single-phase grounding faults or not, a third detector (3) for detecting whether a feeder line loop has the single-phase grounding faults or not, a switching value output module (4) for acting on a breaker to trip, and an alarm (5) for positioning a loop number corresponding to the feeder line single-phase grounding faults;
the input ends of the first detector (1), the second detector (2) and the third detector (3) are respectively connected with a zero sequence CT of a photovoltaic incoming line loop, a zero sequence CT of a wiring neutral point loop and a zero sequence CT of a feeder line loop, the input end of the controller (0) is connected with the output ends of the first detector (1), the second detector (2) and the third detector (3), the output end of the controller (0) is connected with the input end of the switching value output module (4) and the input end of the alarm (5), and the output end of the switching value output module (4) is connected with a tripping loop of a breaker in a photovoltaic incoming line cabinet and a grounding incoming line cabinet.
3. The single-phase ground protection optimization device of the photovoltaic access thermal power plant station system according to claim 2, characterized in that the first detector (1) is a photovoltaic incoming line loop zero sequence CT.
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| CN202011395891.7A CN112510655A (en) | 2020-12-03 | 2020-12-03 | Single-phase grounding protection optimization method and device for photovoltaic access thermal power plant station system |
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| CN202011395891.7A CN112510655A (en) | 2020-12-03 | 2020-12-03 | Single-phase grounding protection optimization method and device for photovoltaic access thermal power plant station system |
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