CN111817276A - Relay protection control system and method for micro-grid in park - Google Patents
Relay protection control system and method for micro-grid in park Download PDFInfo
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- CN111817276A CN111817276A CN202010504767.3A CN202010504767A CN111817276A CN 111817276 A CN111817276 A CN 111817276A CN 202010504767 A CN202010504767 A CN 202010504767A CN 111817276 A CN111817276 A CN 111817276A
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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
- H02H7/26—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured
- H02H7/28—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured for meshed systems
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
- H02J3/388—Islanding, i.e. disconnection of local power supply from the network
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
- H02J2300/20—The dispersed energy generation being of renewable origin
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Abstract
The invention belongs to the technical field of microgrid relay protection, and relates to a system and a method for controlling the microgrid relay protection in a park. A relay protection control system for a park microgrid comprises a main grid side and a microgrid side, wherein the main grid side comprises a high-voltage cabinet and a transformer, and the microgrid side mainly comprises a grid-connected cabinet, an AC/DC bidirectional converter and a DC/DC converter; the low-voltage power supply converted by the transformer is connected to the microgrid side through the grid-connected cabinet, a low-voltage alternating-current bus led out from the grid-connected cabinet is connected to an AC/DC bidirectional converter, a direct-current bus is led out from the AC/DC bidirectional converter, and the direct-current bus is connected to the DC/DC converter; and a protection device and a microgrid controller are arranged on the microgrid side, and the protection device is connected with the microgrid controller and is controlled by the microgrid controller. The invention carries out classification according to the composition positions to form a protection scheme of each key position, and carries out region setting, thereby realizing the relay protection measure of the integration of the micro-grid source network load system and ensuring the running safety of the micro-grid system.
Description
Technical Field
The invention belongs to the technical field of microgrid relay protection, and relates to a system and a method for controlling the microgrid relay protection in a park.
Background
Energy crisis and environmental pollution, so that the development and utilization of green, clean and renewable energy sources become the national important strategy. The construction of centralized photovoltaic and wind power generation stations causes the difficulty in the consumption of new energy power generation. In little grid technology development, combine together distributed generation and new forms of energy consumption to combine electric automobile's rapid development, with "become the light storage and fill the integration degree of depth and combine, high proportion consumes renewable energy electricity generation inside little grid, accomplishes and utilizes on the spot, and high-efficient conversion reduces long distance transport, is the effective solution that improves new forms of energy consumption, has high practicality and practical meaning. The new energy microgrid system innovatively realizes a multi-source system for multi-energy interactive management of a bidirectional distribution network, distributed photovoltaic power generation, intelligent energy storage, electric vehicle charging and discharging, electric heat conversion and the like. The energy magic cube integrates multiple functions of energy bidirectional routing, alternating current and direct current flexible mixed networks, grid-connected and off-grid switching, supply and demand side management and control, power grid friendly interaction, panoramic information fusion and the like.
The microgrid system integrates elements such as variable distribution light storage charging and discharging, multi-point output is available for the source of a power supply, the system alternating current and direct current equipment is composed of a low-voltage cabinet body as a basic unit, the system comprises a bus chamber, a secondary chamber, a function chamber and a wiring chamber which are spatially separated, the bus chamber is communicated with the low-voltage special system, so that the alternating current and direct current buses can be conveniently connected, each unit cabinet is spatially partitioned and connected by the basic structures of alternating current, direct current and input and output, the whole bus system and the access switch unit are easy to arrange and connect, and excessive crossing and circuitous buses with different properties are avoided. The cabinet panel can identify the input and output joints with different functional areas and different properties in an intuitive and clear manner. How to deal with the protection measures of various sources and loads is a key research and development work.
Traditional distribution network relay protection devices are installed in a dispersed mode, overcurrent protection of all protection devices is matched with each other through time sequences, the stability requirements of a micro-grid cannot be met in time, and due to the current limiting effect of a fan, a photovoltaic inverter and an energy storage inverter, when a micro-grid is in an internal fault, the short-circuit currents provided are different along with different distributed energy access capacities, the situation that the short-circuit current of a small number of distributed generation access distribution networks is possibly smaller than the load current of a large number of distributed generation access distribution networks can occur, the setting of a fixed value is extremely difficult, and therefore overcurrent protection cannot be used as main protection of the micro-grid.
The existing relay protection adopts a unit type protection principle, each protection device carries out corresponding logic judgment according to self acquired information, coordination and cooperation are lacked, only one-way protection can be realized, and two-way coordination protection of the whole microgrid system cannot be realized.
Disclosure of Invention
The invention aims to solve the problems in the prior art and provides a control and protection system and a method for source network loads of a park microgrid.
One of the technical schemes adopted by the invention for solving the technical problems is as follows: a relay protection control system for a park microgrid comprises a main grid side and a microgrid side, wherein the main grid side comprises a high-voltage cabinet and a transformer, and the microgrid side mainly comprises a grid-connected cabinet, an AC/DC bidirectional converter and a DC/DC converter; the low-voltage power supply converted by the transformer is connected to the microgrid side through the grid-connected cabinet, a low-voltage alternating-current bus led out from the grid-connected cabinet is connected to an AC/DC bidirectional converter, a direct-current bus is led out from the AC/DC bidirectional converter, and the direct-current bus is connected to the DC/DC bidirectional converter; and a protection device and a microgrid controller are arranged on the microgrid side, and the protection device is connected with the microgrid controller and is controlled by the microgrid controller.
As a preferred mode of the invention, the protection device comprises a sensor for acquiring electrical parameters and a switch for controlling the on-off of the circuit; and the microgrid controller is used for receiving the electric parameters and the switching value collected by the protection device and controlling the action of the switch through logic judgment.
Further preferably, the protection device comprises a first current sensor and a first switch, the first current sensor and the first switch are arranged in the grid-connected cabinet, the first current sensor is used for collecting current parameters of a grid-connected point, and the first switch is used for controlling the on-off of circuits on two sides of the grid-connected point.
Further preferably, the first current sensor adopts a 90-degree wiring mode and is used for collecting current parameters in a positive direction and a negative direction.
Further preferably, the protection device comprises a first voltage sensor, a second current sensor and a second switch which are arranged at the AC/DC bidirectional converter, wherein the voltage sensor is used for acquiring voltage parameters of the alternating current bus, and the second current sensor is used for acquiring current parameters of the alternating current bus; the second switch is used for controlling the on-off of circuits on two sides of the AC/DC bidirectional converter.
Further preferably, the protection device includes a second voltage sensor disposed on the dc bus, and the second voltage sensor is configured to acquire a voltage parameter of the dc bus.
Further preferably, the protection device includes a third current sensor and a third switch, the third current sensor is disposed at the DC/DC bidirectional converter, the third current sensor is configured to acquire a current parameter of the DC bus branch, and the third switch is configured to control on/off of a circuit between the DC bus branch and the low-voltage DC load.
The invention also provides a relay protection method for the park microgrid, which comprises the following steps:
island protection: the voltage and the frequency of the alternating current bus and the direct current bus are detected, and the normal voltage and the frequency are compared through the microgrid controller for judgment, so that the actions of the second switch and the third switch are realized;
and (3) protecting a grid connection point: bidirectional stage type overcurrent protection is adopted at the grid-connected cabinet, and the bidirectional stage type overcurrent protection comprises forward three-stage overcurrent protection and reverse three-stage overcurrent protection;
and (3) system side protection: the microgrid controller detects a main grid fault by detecting the forward current at the grid-connected cabinet, and the first switch is switched off;
protection of a microgrid side: and according to current data acquired by the first current sensor, the micro-grid controls and judges the current direction, and when a positive direction fault is detected, the positive direction three-stage overcurrent protection of a grid-connected point is adopted.
Further preferably, the grid-connected point protection further includes reverse power protection: and detecting current and voltage parameters at a grid-connected cabinet and an AC/DC bidirectional converter, and when detecting that the reverse power exceeds a rated value by 5%, switching off the first switch by the microgrid controller within 0.5-2 seconds.
The invention relates to a park microgrid relay protection control system and a method, which realize communication among areas to realize system protection by utilizing a protection device and a microgrid controller which are arranged on the side of a microgrid, form a station area protection area by connecting lines connected to an alternating current bus on the side of low voltage alternating current of a system, respectively install current collecting equipment on the side of low voltage of a transformer, each load line, the side of alternating current/direct current and other lines, install voltage collecting equipment on the alternating current bus, uniformly collect and judge by the controller and control the on-off of each switch. The invention carries out classification according to the composition positions to form a protection scheme of each key position, and carries out region setting, thereby realizing the relay protection measure of the integration of the micro-grid source network load system and ensuring the running safety of the micro-grid system.
Drawings
FIG. 1 is a schematic circuit connection diagram of a park microgrid relay protection control system according to an embodiment of the invention;
FIG. 2 is a schematic diagram of a relay protection method for a park microgrid in an embodiment of the invention;
FIG. 3 is a schematic diagram of low voltage ride through capability requirements.
Detailed Description
In order to facilitate an understanding of the invention, the invention is described in more detail below with reference to the accompanying drawings and specific examples. Preferred embodiments of the present invention are shown in the drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
One embodiment provided by the invention is as follows: a relay protection control system for a micro-grid in a park is mainly applied to box-type substation products, and as shown in figure 1, the system comprises: the system comprises a system side and a microgrid side, wherein the system side comprises a group of high-voltage cabinets 1 and transformers 2; the microgrid side mainly comprises a grid-connected cabinet 3, an AC/DC bidirectional converter 4, an alternating current load cabinet 5, a DC/DC bidirectional converter 6, an alternating current bus 7, a direct current bus 8 and a microgrid controller 9.
The high-voltage cabinet 1 is used for introducing a 10kV high-voltage power supply, and the transformer 2 is used for converting the 10kV high-voltage power supply introduced by the high-voltage cabinet 1 into a 0.4kV low-voltage power supply and is connected into the grid-connected cabinet 3. The grid-connected cabinet 3 is connected with the transformer 2 by copper bars. The grid-connected cabinet 3 is connected with the AC/DC bidirectional converter 4 through a copper bar, and grid-connected connection of a system side and a microgrid side is achieved. And a 0.4kV low-voltage alternating current bus 7 led out from the grid-connected cabinet 3 is connected into the AC/DC bidirectional converter 4, the AC/DC bidirectional converter 4 converts the 0.4kV low-voltage alternating current electric energy into 750V direct current electric energy, and a direct current bus 8 is led out for direct current electric energy transmission.
Two DC/DC bidirectional converters 6 are respectively connected to branches of the direct current bus 8, one of the DC/DC bidirectional converters is connected with the electric automobile, and the other DC/DC bidirectional converter is connected with the battery.
As shown in fig. 1, a first current sensor 31 and a first switch 32 are provided in the grid-connected cabinet 3; the first current sensor 31 adopts a 90-degree wiring mode and is used for collecting current parameters flowing through the grid-connected cabinet 3 in the positive and negative directions. The first switch 32 is used for disconnecting the circuits on both sides of the grid-connected cabinet 3 to realize protection.
The AC/DC bidirectional converter 4 is provided with a second current sensor 41, a second switch 42, and a first voltage sensor 43. The first voltage sensor 43 is used for acquiring the voltage of the 0.4kV low-voltage alternating-current bus 7 connected to the AC/DC bidirectional converter 4, the second current sensor 41 is used for acquiring the current parameter of the 0.4kV low-voltage alternating-current bus 7 flowing through the AC/DC bidirectional converter 4, and the second switch 42 is used for disconnecting the circuits on two sides of the AC/DC bidirectional converter 4 to realize protection.
And a second voltage sensor 81 is arranged on the 750V direct current bus 8, and the second voltage sensor 81 is used for acquiring voltage parameters of the direct current bus.
A third current sensor 61 and a third switch 62 are arranged at the DC/DC bidirectional converter 6; the third current sensor is used for collecting the branch current parameters flowing through the DC/DC bidirectional converter 6, and the third switch 62 is used for disconnecting the direct current bus branch from the circuit of the electric load (an electric automobile or a battery).
The 4 current sensors, the 2 voltage sensors and the 4 switches are all electrically connected with a microgrid controller, and the microgrid controller 9 is used for collecting electrical parameters of the current sensors and the voltage sensors, performing logical operation and judgment, controlling the switches of the nodes and realizing microgrid relay protection.
Based on the relay protection control system for the park microgrid, the invention also provides a relay protection control method for the park microgrid, which specifically comprises the following steps as shown in fig. 2:
first, island protection
Islanding refers to a power distribution subsystem powered by DER formed after the connection of a distribution line or a part of a distribution network and a main network is disconnected.
1.1 Voltage and frequency protection
When the island operates, the DER power output and the load power are unbalanced, so that the voltage drops or rises, and therefore the island protection can be realized through undervoltage, overvoltage and voltage loss protection.
At the moment of island occurrence, the operating voltage of the system voltage changes due to sudden change of load power, so that the voltage, frequency and phase of a sampling point change, the voltage and frequency at the alternating current bus 7 and the direct current bus 8 are collected through the first voltage sensor 43 and the second current sensor 41, and the normal voltage and frequency are compared through the microgrid controller 9 for judgment, so that the second switch and the third switch act, and island protection is realized.
Two, the protection integration of the point of connection
The microgrid grid-connected point has a corresponding relay protection function, so that various faults of the main network side and the microgrid side can be correctly dealt with, and the equipment safety and the personal safety can be guaranteed. The protection configuration of the grid-connected point needs to implement protection measures on the following two aspects:
2.1 dot over dot protection
1.1.1 bidirectional staged overcurrent protection
In consideration of the fault characteristics of two different fault positions, current collection needs to be set at the grid-connected cabinet 3, and switch control needs to be set at the current collection. When the main network side has a fault, the sensitivity and the selectivity can be set at the first switch 32 at the grid-connected cabinet 3; the current flowing through the grid-connected cabinet 3 is collected by the first current sensor 31 in a 90-degree wiring mode:
the positive direction action equation is:
the action equation in the opposite direction is:
the AC quantities Ir and Ur input by the three-phase directional elements DA and DB and DC are shown in the following table:
as shown in fig. 3, the forward I-section protection fixed value at the grid-connected cabinet 3 is set according to the three-phase short-circuit current at the end of the grid-connected point line or the transformer 2. The II section protection is matched with the quick-break protection of the lower-level load circuit and the truncation protection of the AC/DC bidirectional conversion device, and a time difference is increased. The III-stage protection method avoids the setting of the maximum load current in normal operation, and comprehensively considers the influence of the downstream load current when determining the maximum operation current. The section III protection is preferably provided with a configuration inverse time limit function.
And the reverse I section protection fixed value is set according to the three-phase short circuit at the tail end of the main network test transformer 2 of the connecting line, and simultaneously, the fault current provided when the adjacent line has a fault is avoided. Considering the characteristics of the fault current of the microgrid, the microgrid overcurrent protection circuit has higher sensitivity, and adopts a fast algorithm: the protection outlet trips in the transient period before the current drops significantly. And the reverse current protection II section has the possibility of action rejection considering that the fault current provided by the AC/DC bidirectional conversion device can be rapidly attenuated. The II-section protection has a low-voltage holding function, once the II-section overcurrent protection is started, the low-voltage condition is met, the protection is held by the low voltage and is always maintained in an action state, and the fault is guaranteed to be reliably removed.
2.1.2 reverse Power protection
According to the current and voltage collection of the microgrid system at the grid-connected cabinet 3 and the AC/DC bidirectional converter 4, when the reverse power is detected to exceed the rated value by 5%, the microgrid controller 9 should disconnect the first switch 32 at the grid-connected cabinet 3 within 0.5-2 seconds.
2.2 microgrid-side protection
Faults inside the microgrid are correctly cut off, and power failure of the power distribution network due to upstream protection actions is prevented. Setting circuit breaker protection, and setting stage protection at a grid-connected cabinet 3, namely setting a fixed value of the protection at a section I according to a three-phase short-circuit current at the tail end of a grid-connected point line or a transformer 2, and matching the protection at a section II with quick-break protection of a lower-level load line and cutoff protection of an AC/DC bidirectional converter 4 to increase a time difference; the III-stage protection is set according to the maximum load current avoiding normal operation, the current direction collected by the first current sensor 31 at the grid-connected cabinet 3 is judged, and when a fault occurs in the positive direction, the first switch 32 is controlled to disconnect the circuit.
2.3 System side protection
By detecting the forward current at the grid-connected cabinet 3, the microgrid controller 9 detects a main grid fault, trips the first switch 32 at the grid-connected cabinet 3, and switches to the off-grid operation mode, so as to ensure the safety of the system.
2.3.1 Low-Voltage AC protection configuration and setting
The protection configuration of the first switch 32 at the grid-connected cabinet 3 should be consistent under different operation modes. The line protection of the AC load 5 is configured according to the conventional current protection, the second switch 42 at the AC/DC bidirectional converter 4 is configured with the step-type overcurrent protection, and the configuration method is consistent with the configuration mode of the first switch 31 at the grid-connected cabinet 3. The alternating current load 5 line does not need to be provided with a direction element, the backup protection of the tail end line does not need to be provided with the direction element, if the fixed value setting is difficult to match, the quick-break protection of each line can be replaced by the regional protection, and the II-section protection and the III-section protection are reserved as the backup protection.
2.3.2 Low Voltage DC protection configuration and setting
The area protection on the low-voltage direct current side of the system is similar to the configuration of the protection on the alternating current side, the switches at the direct current bus 8 and the two DC/DC bidirectional converters 6 are set with stage-type overcurrent protection and current direction acquisition, a line connected to the direct current bus 8 forms an area protection area, a second voltage sensor 81 is installed on the direct current bus 8, and the acquisition and the judgment are carried out by the microgrid controller 9 in a unified mode.
2.3.3 Relay protection and Power electronics
In order to guarantee reliable action of overcurrent protection, the third switch 62 at the two DC/DC bidirectional converters 6 of the device is set with instantaneous overcurrent protection, and a quick protection algorithm of instantaneous value is adopted to trip the protection outlet in the instantaneous period before the current is obviously reduced. An improved method is to adopt the timing limit overcurrent protection of low-voltage retention, namely once the overcurrent protection acts and the low-voltage condition is met, the protection is retained by the low voltage and is always maintained in an action state, and the fault is ensured to be reliably cut off. The AC/DC bidirectional converter 4 has an isolation function, i.e., when a fault occurs on one side, no fault current is generated on the other side. If the matching is difficult, the alternating current/direct current directional pilot function can be realized based on the region protection.
Three, regional protection
The microgrid controller 9 realizes communication among all protections to realize system protection, lines connected to the alternating current bus 7 can form a station area protection area on the low-voltage alternating current side of the system, alternating current acquisition equipment is respectively arranged on the low-voltage side of the transformer 2, each load line, the alternating current side of the AC/DC bidirectional converter 4 and other lines, a first voltage sensor 43 is arranged on the alternating current bus 7, and the acquisition and the judgment are carried out by the microgrid controller 9 in a unified mode.
3.1 area differential protection
And (3) collecting the electrical quantity of each node in the system range in real time, wherein the microgrid controller 9 is used as a criterion according to the difference between the collected real-time electrical quantity and the normal operation and fault states. When any one group of loads has faults, only the fault branch is cut off, and other loads and power generation equipment of the microgrid can continuously operate.
3.2 zone Direction Pilot
Each protection needs to determine the positive direction and the upstream and downstream relation during configuration, and when a certain protection is started positively and a positive starting signal of downstream protection is not received, a fault point can be determined to be positioned in the section; on the contrary, if any forward starting signal of the downstream protection is received, the fault point is not in the section, and the downstream protection acts. The action effect of the area protection is similar to that of the conventional step type current protection.
Claims (9)
1. The utility model provides a little electric wire netting relay protection control system in garden, includes main network side, microgrid side, the main network side contain high-voltage board, transformer, its characterized in that: the micro-grid side mainly comprises a grid-connected cabinet, an AC/DC bidirectional converter and a DC/DC converter; the low-voltage power supply converted by the transformer is connected to the microgrid side through the grid-connected cabinet, a low-voltage alternating-current bus led out from the grid-connected cabinet is connected to an AC/DC bidirectional converter, a direct-current bus is led out from the AC/DC bidirectional converter, and the direct-current bus is connected to the DC/DC bidirectional converter; and a protection device and a microgrid controller are arranged on the microgrid side, and the protection device is connected with the microgrid controller and is controlled by the microgrid controller.
2. The campus microgrid relay protection control system of claim 1, characterized in that: the protection device comprises a sensor for acquiring electrical parameters and a switch for controlling the on-off of the circuit; and the microgrid controller is used for receiving the electric parameters and the switch states collected by the protection device and controlling the action of the switch through logic judgment.
3. The campus microgrid relay protection control system of claim 2, characterized in that: the protection device comprises a first current sensor and a first switch, wherein the first current sensor and the first switch are arranged in the grid-connected cabinet, the first current sensor is used for collecting current parameters of a grid-connected point, and the first switch is used for controlling the on-off of circuits on two sides of the grid-connected point.
4. The campus microgrid relay protection control system of claim 3, characterized in that: the first current sensor adopts a 90-degree wiring mode and is used for collecting current parameters in a positive direction and a negative direction.
5. The campus microgrid relay protection control system of claim 2, characterized in that: the protection device comprises a first voltage sensor, a second current sensor and a second switch which are arranged at the AC/DC bidirectional converter, wherein the voltage sensor is used for acquiring voltage parameters of the alternating current bus, and the second current sensor is used for acquiring current parameters of the alternating current bus; the second switch is used for controlling the on-off of circuits on two sides of the AC/DC bidirectional converter.
6. The campus microgrid relay protection control system of claim 2, characterized in that: the protection device comprises a second voltage sensor arranged on the direct current bus, and the second voltage sensor is used for acquiring voltage parameters of the direct current bus.
7. The campus microgrid relay protection control system of claim 2, characterized in that: the protection device comprises a third current sensor and a third switch, wherein the third current sensor and the third switch are arranged at the DC/DC bidirectional converter, the third current sensor is used for collecting current parameters of the direct current bus branch, and the third switch is used for controlling the on-off of a circuit between the direct current bus branch and the low-voltage direct current load.
8. A relay protection method for a park microgrid is characterized by comprising the following steps:
island protection: the voltage and the frequency of the alternating current bus and the direct current bus are detected, and the normal voltage and the frequency are compared through the microgrid controller for judgment, so that the actions of the second switch and the third switch are realized;
and (3) protecting a grid connection point: bidirectional stage type overcurrent protection is adopted at the grid-connected cabinet, and the bidirectional stage type overcurrent protection comprises forward three-stage overcurrent protection and reverse three-stage overcurrent protection;
and (3) system side protection: the microgrid controller detects a main grid fault by detecting the forward current at the grid-connected cabinet, and the first switch is switched off;
protection of a microgrid side: and according to current data acquired by the first current sensor, the micro-grid controls and judges the current direction, and when a positive direction fault is detected, the positive direction three-stage overcurrent protection of a grid-connected point is adopted.
9. The campus microgrid relay protection method of claim 8, wherein the grid-connected point protection further comprises reverse power protection: and detecting current and voltage parameters at a grid-connected cabinet and an AC/DC bidirectional converter, and when detecting that the reverse power exceeds a rated value by 5%, switching off the first switch by the microgrid controller within 0.5-2 seconds.
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| CN202010504767.3A CN111817276A (en) | 2020-06-05 | 2020-06-05 | Relay protection control system and method for micro-grid in park |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115241854A (en) * | 2022-09-26 | 2022-10-25 | 国网上海能源互联网研究院有限公司 | Method and system for low-voltage distributed photovoltaic grid-connected control and protection |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN115241854A (en) * | 2022-09-26 | 2022-10-25 | 国网上海能源互联网研究院有限公司 | Method and system for low-voltage distributed photovoltaic grid-connected control and protection |
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