CN111181150B - Method and device for determining power grid voltage drop reason and wind power generation system - Google Patents
Method and device for determining power grid voltage drop reason and wind power generation system Download PDFInfo
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- CN111181150B CN111181150B CN201811346620.5A CN201811346620A CN111181150B CN 111181150 B CN111181150 B CN 111181150B CN 201811346620 A CN201811346620 A CN 201811346620A CN 111181150 B CN111181150 B CN 111181150B
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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
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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
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/70—Wind energy
- Y02E10/76—Power conversion electric or electronic aspects
Abstract
The invention discloses a method and a device for determining the cause of grid voltage drop and a wind power generation system, which are used for accurately determining the cause of grid voltage drop. The method for determining the cause of the grid voltage drop comprises the following steps: acquiring the grid side voltage of the wind power generation system and the load current of the wind power generation system; and when the network side voltage is determined to be lower than a preset voltage threshold value and the absolute value of the difference between the load current and the prestored fault current is greater than a first preset difference value threshold value, determining that the reason of the network voltage drop is that the network fails.
Description
Technical Field
The invention relates to the field of power electronics, in particular to a method and a device for determining a power grid voltage drop reason and a wind power generation system.
Background
The low-voltage ride through refers to a process that when the voltage of a power grid drops due to the fault of the power grid, the wind power generation system continues to provide required reactive power for the power grid under the condition that the wind power generation system is not disconnected, and the wind power generation system recovers to normal operation until the power grid recovers to normal.
In practical applications, a controller of the wind power generation system generally controls the wind power generation system to perform low voltage ride through when it is determined that the grid voltage drops. The method for determining the voltage drop of the power grid comprises the following steps: and collecting the power grid voltage, and determining that the power grid voltage drops when the collected power grid voltage is lower than a preset voltage threshold value.
However, the grid voltage drop may be caused by a fault of the grid or a fault of the wind power generation system, and only the grid voltage drop can be determined according to the collected grid voltage, and the reason of the grid voltage drop cannot be accurately determined, so that the wind power generation system may be controlled to perform low voltage ride through by mistake. For example, when the grid voltage drops due to a fault of the wind power generation system, the wind power generation system collects the grid voltage, determines that the grid voltage drops, and controls the wind power generation system to perform low-voltage ride through.
In summary, the method for determining the grid voltage drop in the prior art cannot accurately determine the reason of the grid voltage drop, and thus may erroneously control the wind power generation system to perform low voltage ride through.
Disclosure of Invention
The embodiment of the invention provides a method and a device for determining a power grid voltage drop reason and a wind power generation system, which are used for accurately determining the power grid voltage drop reason.
In a first aspect, an embodiment of the present invention provides a method for determining a cause of a voltage drop of a power grid, including:
acquiring network side voltage of a wind power generation system and load current of the wind power generation system;
and when the network side voltage is lower than a preset voltage threshold value and the absolute value of the difference between the load current and the prestored fault current is larger than a first preset difference value threshold value, determining that the reason of the network voltage drop is the fault of the power network.
In a possible implementation manner, the method provided by an embodiment of the present invention further includes:
and when the grid side voltage is lower than a preset voltage threshold value and the absolute value of the difference between the load current and the prestored fault current is smaller than a second preset difference value threshold value, determining that the reason of grid voltage drop is that the wind power generation system fails, wherein the first preset difference value threshold value is larger than the second preset difference value threshold value.
In a possible implementation, an embodiment of the present invention provides the above method, wherein the load current of the wind power generation system includes one or more of the following: grid side phase current of the wind power generation system and stator side phase current of the wind power generation system;
the pre-stored fault currents include: a first fault current and a second fault current;
when the load current of the wind power generation system comprises the grid side phase current of the wind power generation system, when the grid side voltage is determined to be lower than a preset voltage threshold value and the absolute value of the difference between the load current and the prestored fault current is greater than a first preset difference value threshold value, determining that the reason of grid voltage drop is that the grid fails, and the method comprises the following steps:
when the grid side voltage is lower than a preset voltage threshold value and the absolute value of the difference between the grid side phase current of the wind power generation system and the first fault current is larger than a first preset difference value threshold value, determining that the reason of grid voltage drop is that the grid fails;
when the load current of the wind power generation system comprises the stator side phase current of the wind power generation system, when the fact that the voltage of the grid side is lower than a preset voltage threshold value and the absolute value of the difference between the load current and the prestored fault current is larger than a first preset difference value threshold value is determined, the fact that the grid voltage drops is determined to be that the grid fails, the method comprises the following steps:
and when the grid side voltage is lower than a preset voltage threshold value and the absolute value of the difference between the stator side phase current and the second fault current of the wind power generation system is larger than a first preset difference value threshold value, determining that the reason of grid voltage drop is that the grid fails.
In a possible implementation manner, in the method provided by an embodiment of the present invention, when the first fault current includes a plurality of fault currents, and when it is determined that the grid-side voltage is lower than a preset voltage threshold and an absolute value of a difference between the grid-side phase current of the wind turbine generator system and the first fault current is greater than a first preset difference threshold, determining that the cause of the grid voltage drop is a fault of the grid, the method includes:
and when the grid side voltage is lower than a preset voltage threshold value and the absolute value of the difference between the grid side phase current of the wind power generation system and any fault current in the first fault current is larger than a first preset difference value threshold value, determining that the reason of grid voltage drop is the fault of the power grid.
In a possible implementation manner, in the method provided by an embodiment of the present invention, when the second fault current includes a plurality of fault currents, and when it is determined that the grid-side voltage is lower than a preset voltage threshold and an absolute value of a difference between the stator-side phase current of the wind turbine generator system and the second fault current is greater than a first preset difference threshold, determining that the cause of the grid voltage drop is a fault of the grid, includes:
and when the grid side voltage is lower than a preset voltage threshold value and the absolute value of the difference between the stator side phase current of the wind power generation system and any fault current of the second fault currents is larger than a first preset difference value threshold value, determining that the reason of grid voltage drop is the fault of the power grid.
In a second aspect, an embodiment of the present invention provides an apparatus for determining a cause of a voltage drop of a power grid, including:
the acquiring unit is used for acquiring the grid side voltage of the wind power generation system and the load current of the wind power generation system;
and a processing unit. And the method is used for determining that the reason of the grid voltage drop is the grid fault when the grid side voltage is lower than the preset voltage threshold and the absolute value of the difference between the load current and the prestored fault current is larger than a first preset difference threshold.
In a possible implementation manner, an embodiment of the present invention provides the apparatus, wherein the processing unit is further configured to:
and when the grid side voltage is lower than a preset voltage threshold value and the absolute value of the difference between the load current and the prestored fault current is smaller than a second preset difference value threshold value, determining that the grid voltage drop reason is that the wind power generation system fails, wherein the first preset difference value threshold value is larger than the second preset difference value threshold value.
In a possible implementation manner, the embodiment of the present invention provides the above apparatus, wherein the load current of the wind power generation system includes one or more of the following: grid side phase current of the wind power generation system and stator side phase current of the wind power generation system;
the pre-stored fault currents include: a first fault current and a second fault current;
when the load current of the wind power generation system includes the grid-side phase current of the wind power generation system, the processing unit is specifically configured to:
when the grid side voltage is lower than a preset voltage threshold value and the absolute value of the difference between the grid side phase current of the wind power generation system and the first fault current is larger than a first preset difference value threshold value, determining that the reason of grid voltage drop is that the grid fails;
when the load current of the wind power generation system includes a stator side phase current of the wind power generation system, the processing unit is specifically configured to:
and when the grid side voltage is lower than a preset voltage threshold value and the absolute value of the difference between the stator side phase current and the second fault current of the wind power generation system is larger than a first preset difference value threshold value, determining that the reason of grid voltage drop is that the grid fails.
In a possible implementation manner, in the above apparatus provided by an embodiment of the present invention, when the first fault current includes a plurality of fault currents, the processing unit is specifically configured to:
and when the grid side voltage is lower than a preset voltage threshold value and the absolute value of the difference between the grid side phase current of the wind power generation system and any fault current in the first fault current is larger than a first preset difference value threshold value, determining that the reason of grid voltage drop is the fault of the power grid.
In a possible implementation manner, in the above apparatus provided by an embodiment of the present invention, when the second fault current includes a plurality of fault currents, the processing unit is specifically configured to:
and when the grid side voltage is lower than a preset voltage threshold value and the absolute value of the difference between the stator side phase current of the wind power generation system and any fault current of the second fault currents is larger than a first preset difference value threshold value, determining that the reason of grid voltage drop is the fault of the power grid.
In a third aspect, an embodiment of the present invention provides a wind power generation system, including the apparatus for determining a cause of a grid voltage drop according to the second aspect provided in an embodiment of the present invention.
The embodiment of the invention has the following beneficial effects:
according to the method and the device for determining the cause of the voltage drop of the power grid and the wind power generation system, the grid side voltage of the wind power generation system and the load current of the wind power generation system are obtained, and when the fact that the grid side voltage is lower than a preset voltage threshold value and the absolute value of the difference between the load current and the prestored fault current is larger than a first preset difference value threshold value is determined, the cause of the voltage drop of the power grid is determined to be that the power grid fails.
According to the scheme for determining the cause of the grid voltage drop, after the grid voltage drop is determined according to the acquired grid side voltage, the cause of the grid voltage drop is further determined according to the acquired load current of the wind power generation system, so that the cause of the grid voltage drop can be accurately determined while the grid voltage drop is determined, and the wind power generation system is prevented from being controlled to perform low-voltage ride through by mistake due to the fact that the cause of the grid voltage drop cannot be accurately determined.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
Fig. 1 is a schematic flow chart of a method for determining a cause of a voltage drop of a power grid according to an embodiment of the present invention;
fig. 2 is a schematic flow chart of a method for determining a cause of a voltage drop of a power grid according to an embodiment of the present invention;
fig. 3 is a schematic structural diagram of a circuit topology for obtaining a network-side voltage and a network-side phase current according to an embodiment of the present invention;
fig. 4 is a schematic flow chart of a specific process of a method for determining a cause of a voltage drop of a power grid according to an embodiment of the present invention;
fig. 5 is a schematic flow chart of a method for determining a cause of a voltage drop of a power grid according to a second embodiment of the present invention;
fig. 6 is a schematic structural diagram of a circuit topology for obtaining a network-side voltage and a network-side phase current according to a second embodiment of the present invention;
fig. 7 is a schematic flow chart of a specific flow of a method for determining a cause of a voltage sag of a power grid according to a second embodiment of the present invention;
fig. 8 is a schematic structural diagram of a device for determining a cause of a voltage drop of a power grid according to an embodiment of the present invention;
fig. 9 is a schematic structural diagram of a device for determining a cause of a voltage drop of a power grid according to an embodiment of the present invention.
Detailed Description
Embodiments of the present application will be described with reference to the accompanying drawings, and it should be understood that the embodiments described herein are merely illustrative and explanatory of the application and are not restrictive of the application.
The following describes specific embodiments of a method, an apparatus and a wind power generation system for determining a cause of a grid voltage drop according to embodiments of the present invention with reference to the accompanying drawings.
The embodiment of the invention provides a method for determining a power grid voltage drop reason, which comprises the following steps of:
And 102, when the network side voltage is lower than a preset voltage threshold value and the absolute value of the difference between the load current and the prestored fault current is larger than a first preset difference value threshold value, determining that the reason of the network voltage drop is the fault of the power network.
The load current of the wind power generation system mentioned in the embodiment of the present invention may include, but is not limited to: the network side phase current of the wind power generation system and the stator side phase current of the wind power generation system. In specific implementation, the embodiments of the present invention can be divided into the following two embodiments according to the difference of the load current of the wind power generation system.
Example one
The embodiment of the invention provides a method for determining a cause of a voltage drop of a power grid, which comprises the following steps of:
The specific method for acquiring the grid-side voltage and the grid-side phase current of the wind turbine generator system will be described in detail below with reference to fig. 3.
As shown in fig. 3, the electric power generated by the generator 101 in the wind power generation system 10 is merged into the grid 30 through the transformer 20. Specifically, when the grid-side voltage of the wind power generation system 10 is acquired, the grid-side voltage may be acquired by the voltage detection unit 102 disposed on the grid side, and when the grid-side phase current of the wind power generation system 10 is acquired, the grid-side phase current may be acquired by the current transformer 103 disposed on the grid side.
In specific implementation, the voltage detection unit 102 may acquire the grid-side voltage of the wind power generation system 10 in real time or periodically, and the current transformer 103 may acquire the grid-side phase current of the wind power generation system 10 in real time or periodically, which is not limited in the embodiment of the present invention.
It should be noted that, when the grid-side voltage of the wind power generation system is obtained, the grid-side phase voltage of the wind power generation system may be obtained, and the grid-side line voltage of the wind power generation system may also be obtained.
In specific implementation, when the wind power generation system breaks down, at least one phase of current can be changed, so that when the network side phase current of the wind power generation system is obtained, three network side phase currents can be collected through three or more current transformers.
In specific implementation, when the grid side voltage is determined to be lower than the preset voltage threshold, the grid voltage can be determined to drop, under the condition, the grid side phase current is compared with the prestored fault current, if the difference value between the grid side phase current and the prestored fault current is large, the reason of the grid voltage drop can be determined to be that the grid fails, and conversely, if the grid side phase current is closer to the prestored fault current, the reason of the grid voltage drop can be determined to be that the wind power generation system fails. The pre-stored fault current is the grid-side phase current of the wind power generation system when the pre-stored wind power generation system fails.
In specific implementation, if the acquired grid-side voltage is the grid-side phase voltage, and the acquired grid-side phase voltages are three, when the grid-side voltage is determined to be lower than a preset voltage threshold, and when any one of the acquired three grid-side phase voltages is determined to be lower than the preset voltage threshold, the grid-side voltage is determined to be lower than the preset voltage threshold.
The preset voltage threshold value can be flexibly set according to actual conditions, and is not limited in the embodiment of the invention, and different preset voltage threshold values can be set for the network side phase voltage and the network side line voltage. For example, the preset voltage threshold may be set to 80% of the normal grid side phase voltage for the grid side phase voltage and 70% of the normal grid side line voltage for the grid side line voltage.
The first preset difference threshold may be set according to the actual condition of the wind power generation system and the experience of the operator, which is not limited in the present invention. For example, the first preset difference threshold may be set to 6 Kiloamperes (KA).
In a possible implementation manner, when the pre-stored fault current comprises a first fault current and the first fault current comprises a plurality of fault currents, when it is determined that the grid-side voltage is lower than a preset voltage threshold and the absolute value of the difference between the grid-side phase current of the wind power generation system and any fault current in the first fault current is greater than a first preset difference threshold, the cause of the grid voltage drop is determined to be the grid fault.
It should be noted that the fault current in the first fault current may include, but is not limited to: when three phases at the stator side of a wind driven generator in a wind power generation system are short-circuited, the short-circuit current value at the grid side is obtained; when a filter branch device on the network side of a converter in the wind power generation system is short-circuited, the short-circuit current value on the network side is obtained; when a network side module of a converter in the wind power generation system is in short circuit, the short-circuit current value of the network side is obtained; and instantaneous value of the grid-connected switch.
In other embodiments of the present invention, when another fault occurs in the wind turbine generator system, the current value on the grid side may be used as the fault current in the first fault current, which is not limited in the present invention.
In one possible embodiment, when it is determined that the grid-side voltage is lower than a preset voltage threshold and the absolute value of the difference between the grid-side phase current and the pre-stored fault current is smaller than a second preset difference threshold, it is determined that the cause of the grid voltage drop is a fault of the wind power generation system, wherein the first preset difference threshold is larger than the second preset difference threshold.
The second preset difference threshold may be set according to an actual condition of the system, for example, the second preset difference threshold is set to 2 Kiloamperes (KA).
The specific steps of the method for determining the cause of the grid voltage drop according to the embodiment of the present invention are described in detail below with reference to fig. 4, taking the load current of the wind power generation system as the grid-side phase current as an example.
As shown in fig. 4, the method for determining a cause of a voltage drop of a power grid according to an embodiment of the present invention includes:
In step 403, when it is determined that the grid-side voltage is lower than the preset voltage threshold, it is determined whether an absolute value of a difference between the grid-side phase current and any fault current in the first fault current is greater than a first preset difference threshold, if so, step 404 is executed, otherwise, step 405 is executed.
And step 404, when the absolute value of the difference between the grid-side phase current and any fault current in the first fault current is larger than a first preset difference value threshold, determining that the reason of grid voltage drop is that the grid fails.
Example two
The embodiment of the invention provides a method for determining a cause of a voltage drop of a power grid, which comprises the following steps of:
A specific method for acquiring the grid-side voltage and the stator-side phase current of the wind turbine generator system will be described in detail below with reference to fig. 6.
As shown in fig. 6, the electric power generated by the generator 110 in the wind power generation system 10 is merged into the grid 30 through the transformer 20. Specifically, the grid-side voltage of the wind turbine generator system 10 may be obtained by the voltage detection unit 101 disposed on the grid side, and the stator-side phase current of the wind turbine generator system 10 may be obtained by the current transformer 111 disposed on the stator side.
In specific implementation, the voltage detection unit 101 may acquire the grid-side voltage of the wind power generation system 10 in real time or periodically, and the current transformer 111 may acquire the stator-side phase current of the wind power generation system 10 in real time or periodically, which is not limited in the embodiment of the present invention.
It should be noted that, when the grid-side voltage of the wind power generation system is obtained, the grid-side phase voltage of the wind power generation system may be obtained, and the grid-side line voltage of the wind power generation system may also be obtained.
In specific implementation, when the wind power generation system breaks down, at least one phase current can be changed, so that when the stator side phase current of the wind power generation system is obtained, three stator side phase currents can be collected through three or more current transformers.
In the specific implementation, when the grid side voltage is determined to be lower than the preset voltage threshold, the grid voltage drop can be determined, under the condition, the stator side phase current is compared with the prestored fault current, if the difference value between the stator side phase current and the prestored fault current is large, the reason of the grid voltage drop can be determined to be that the grid fails, and conversely, if the stator side phase current is closer to the prestored fault current, the reason of the grid voltage drop can be determined to be that the wind power generation system fails. The pre-stored fault current is a stator side phase current of the wind power generation system when the pre-stored wind power generation system has a fault.
In specific implementation, if the acquired grid-side voltage is the grid-side phase voltage, and the acquired grid-side phase voltages are three, when the grid-side voltage is determined to be lower than a preset voltage threshold, and when any one of the acquired three grid-side phase voltages is determined to be lower than the preset voltage threshold, the grid-side voltage is determined to be lower than the preset voltage threshold.
The preset voltage threshold value can be flexibly set according to actual conditions, and is not limited in the embodiment of the invention, and different preset voltage threshold values can be set for the network side phase voltage and the network side line voltage. For example, the preset voltage threshold may be set to 80% of the normal grid side phase voltage for the grid side phase voltage and 70% of the normal grid side line voltage for the grid side line voltage.
The first preset difference threshold may be set according to the actual condition of the wind power generation system and the experience of the operator, which is not limited in the present invention. For example, the first preset difference valve may be set to 6 Kiloamperes (KA).
In a possible implementation manner, when the prestored fault current includes a second fault current and the second fault current includes a plurality of fault currents, when it is determined that the grid-side voltage is lower than a preset voltage threshold and the absolute value of the difference between the stator-side phase current of the wind power generation system and any fault current in the second fault current is greater than a first preset difference threshold, it is determined that the cause of grid voltage drop is a fault of the grid.
It should be noted that the fault current in the second fault current may include, but is not limited to: when three phases at the stator side of a wind driven generator in a wind power generation system are short-circuited, the fault current value at the stator side is obtained; and when a filter branch device at the network side of the converter in the wind power generation system is in short circuit, the short-circuit current value at the stator side and the short-circuit current value at the stator side when a module at the network side of the converter in the wind power generation system is in short circuit.
In other embodiments of the present invention, when another fault occurs in the wind turbine generator system, the current value on the stator side may be used as the fault current in the second fault current, which is not limited in the present invention.
In one possible embodiment, when it is determined that the grid-side voltage is lower than a preset voltage threshold and the absolute value of the difference between the stator-side phase current and the prestored fault current is smaller than a second preset difference threshold, it is determined that the cause of the grid voltage drop is a fault of the wind power generation system, wherein the first preset difference threshold is larger than the second preset difference threshold.
The second preset difference threshold may be set according to an actual condition of the system, for example, the second preset difference threshold may be set to 2 Kiloamperes (KA).
The specific steps of the method for determining the cause of the grid voltage drop according to the embodiment of the present invention are described in detail below with reference to fig. 7, taking the load current of the wind power generation system as the stator side phase current as an example.
As shown in fig. 7, the method for determining a cause of a voltage drop of a power grid according to an embodiment of the present invention includes:
And 702, judging whether the grid side voltage is lower than a preset voltage threshold value, if so, executing 703, otherwise, executing 701 to continuously obtain the grid side voltage of the wind power generation system and the stator side phase current of the wind power generation system.
In step 703, when it is determined that the grid-side voltage is lower than the preset voltage threshold, it is determined whether an absolute value of a difference between the stator-side phase current and any fault current of the second fault currents is greater than a first preset difference threshold, if so, step 704 is executed, otherwise, step 705 is executed.
Based on the same inventive concept, the embodiment of the invention also provides a device for determining the cause of the voltage drop of the power grid.
As shown in fig. 8, the apparatus for determining a cause of a voltage drop of a power grid according to an embodiment of the present invention includes:
an obtaining unit 801, configured to obtain a grid-side voltage of the wind power generation system and a load current of the wind power generation system;
the processing unit 802 is configured to determine that a cause of a grid voltage drop is a fault of the power grid when it is determined that the grid-side voltage is lower than a preset voltage threshold and an absolute value of a difference between the load current and a pre-stored fault current is greater than a first preset difference threshold.
In one possible implementation, the processing unit 802 is further configured to: and when the grid side voltage is lower than a preset voltage threshold value and the absolute value of the difference between the load current and the prestored fault current is smaller than a second preset difference value threshold value, determining that the reason of grid voltage drop is that the wind power generation system fails, wherein the first preset difference value threshold value is larger than the second preset difference value threshold value.
In one possible embodiment, the load current of the wind power system comprises one or more of: grid side phase current of the wind power generation system and stator side phase current of the wind power generation system; the pre-stored fault currents include: a first fault current and a second fault current;
when the load current of the wind power generation system includes the grid-side phase current of the wind power generation system, the processing unit 802 is specifically configured to:
when the grid side voltage is lower than a preset voltage threshold value and the absolute value of the difference between the grid side phase current of the wind power generation system and the first fault current is larger than a first preset difference value threshold value, determining that the reason of grid voltage drop is that the grid fails;
when the load current of the wind power generation system includes a stator-side phase current of the wind power generation system, the processing unit 802 is specifically configured to:
and when the grid side voltage is lower than a preset voltage threshold value and the absolute value of the difference between the stator side phase current and the second fault current of the wind power generation system is larger than a first preset difference value threshold value, determining that the reason of grid voltage drop is that the grid fails.
In a possible implementation manner, when the first fault current includes a plurality of fault currents, the processing unit 802 is specifically configured to: and when the grid side voltage is lower than a preset voltage threshold value and the absolute value of the difference between the grid side phase current of the wind power generation system and any fault current in the first fault current is larger than a first preset difference value threshold value, determining that the reason of grid voltage drop is the fault of the power grid.
In a possible implementation manner, when the second fault current includes a plurality of fault currents, the processing unit 802 is specifically configured to: and when the grid side voltage is lower than a preset voltage threshold value and the absolute value of the difference between the stator side phase current of the wind power generation system and any fault current of the second fault currents is larger than a first preset difference value threshold value, determining that the reason of grid voltage drop is the fault of the power grid.
In addition, the embodiment of the invention also provides a wind power generation system which comprises a device for determining the cause of the grid voltage drop in the embodiment of the invention.
In addition, the method and the device for determining the cause of the grid voltage sag of the embodiments of the present invention described in conjunction with fig. 1 to 8 can be implemented by a device for determining the cause of the grid voltage sag. Fig. 9 is a schematic diagram of a hardware structure of the device for determining the cause of the grid voltage drop according to the embodiment of the present invention.
The determination device of the cause of the grid voltage sag may comprise a processor 901 and a memory 902 in which computer program instructions are stored.
Specifically, the processor 901 may include a Central Processing Unit (CPU), or an Application Specific Integrated Circuit (ASIC), or may be configured as one or more Integrated circuits implementing the embodiments of the present invention.
The processor 901 reads and executes the computer program instructions stored in the memory 902 to implement the method for determining the cause of the grid voltage sag according to any one of the above embodiments.
In one example, the determination device of the cause of the grid voltage sag may further comprise a communication interface 903 and a bus 910. As shown in fig. 9, the processor 901, the memory 902, and the communication interface 903 are connected via a bus 910 to complete communication with each other.
The communication interface 903 is mainly used for implementing communication between modules, apparatuses, units and/or devices in the embodiments of the present invention.
The bus 910 includes hardware, software, or both to couple the components of the device responsible for the grid voltage sag to each other. By way of example, and not limitation, a bus may include an Accelerated Graphics Port (AGP) or other graphics bus, an Enhanced Industry Standard Architecture (EISA) bus, a Front Side Bus (FSB), a Hypertransport (HT) interconnect, an Industry Standard Architecture (ISA) bus, an infiniband interconnect, a Low Pin Count (LPC) bus, a memory bus, a Micro Channel Architecture (MCA) bus, a Peripheral Component Interconnect (PCI) bus, a PCI-Express (PCI-X) bus, a Serial Advanced Technology Attachment (SATA) bus, a video electronics standards association local (VLB) bus, or other suitable bus or a combination of two or more of these. Bus 910 can include one or more buses, where appropriate. Although specific buses have been described and shown in the embodiments of the invention, any suitable buses or interconnects are contemplated by the invention.
The device for determining the cause of the grid voltage sag may execute the method for determining the cause of the grid voltage sag in the embodiment of the present invention based on the grid-side voltage of the wind power generation system and the load current of the wind power generation system, so as to implement the method and the apparatus for determining the cause of the grid voltage sag described in conjunction with fig. 1 to 8.
In addition, in combination with the method for determining the cause of the grid voltage drop in the foregoing embodiments, the embodiments of the present invention may provide a computer-readable storage medium to implement. The computer readable storage medium having stored thereon computer program instructions; the computer program instructions, when executed by a processor, implement the method for determining a cause of a grid voltage sag of any of the above embodiments.
As will be appreciated by one skilled in the art, embodiments of the present invention may be provided as a method, system, or computer program product. Accordingly, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, optical storage, and the like) having computer-usable program code embodied therein.
The present invention is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.
Claims (9)
1. A method for determining the cause of a grid voltage drop is characterized by comprising the following steps:
acquiring the grid side voltage of a wind power generation system and the load current of the wind power generation system;
when the network side voltage is lower than a preset voltage threshold value and the absolute value of the difference between the load current and the prestored fault current is larger than a first preset difference value threshold value, determining that the reason of the network voltage drop is that the network fails;
wherein the load current of the wind power system comprises one or more of: grid side phase current of the wind power generation system and stator side phase current of the wind power generation system;
the pre-stored fault current includes: a first fault current and a second fault current;
when the load current of the wind power generation system comprises the grid side phase current of the wind power generation system, and when it is determined that the grid side voltage is lower than a preset voltage threshold and the absolute value of the difference between the load current and the prestored fault current is greater than a first preset difference threshold, determining that the reason of the grid voltage drop is that the grid fails, including:
when it is determined that the grid-side voltage is lower than a preset voltage threshold and the absolute value of the difference between the grid-side phase current of the wind power generation system and the first fault current is larger than a first preset difference threshold, determining that the reason of the grid voltage drop is that the grid fails;
when the load current of the wind power generation system comprises the stator side phase current of the wind power generation system, when it is determined that the grid side voltage is lower than a preset voltage threshold and the absolute value of the difference between the load current and the prestored fault current is greater than a first preset difference threshold, determining that the reason of grid voltage drop is that the grid fails, including:
and when it is determined that the grid side voltage is lower than a preset voltage threshold value and the absolute value of the difference between the stator side phase current of the wind power generation system and the second fault current is larger than a first preset difference value threshold value, determining that the reason of grid voltage drop is that the grid fails.
2. The method of claim 1, further comprising:
and when the grid side voltage is lower than the preset voltage threshold value and the absolute value of the difference between the load current and the prestored fault current is smaller than a second preset difference value threshold value, determining that the reason of grid voltage drop is that the wind power generation system fails, wherein the first preset difference value threshold value is larger than the second preset difference value threshold value.
3. The method according to claim 1, wherein when the first fault current comprises a plurality of fault currents, determining that the grid voltage drop is caused by the grid fault when it is determined that the grid-side voltage is lower than a preset voltage threshold and the absolute value of the difference between the grid-side phase current of the wind power generation system and the first fault current is greater than a first preset difference threshold comprises:
and when the grid side voltage is determined to be lower than a preset voltage threshold value and the absolute value of the difference between the grid side phase current of the wind power generation system and any fault current in the first fault current is greater than a first preset difference value threshold value, determining that the reason of the grid voltage drop is the fault of the power grid.
4. The method according to claim 1, wherein when the second fault current comprises a plurality of fault currents, determining that the grid voltage drop is due to the grid fault when it is determined that the grid-side voltage is lower than a preset voltage threshold and the absolute value of the difference between the stator-side phase current of the wind power generation system and the second fault current is greater than a first preset difference threshold comprises:
and when the grid side voltage is determined to be lower than a preset voltage threshold value and the absolute value of the difference between the stator side phase current of the wind power generation system and any fault current in the second fault current is greater than a first preset difference value threshold value, determining that the reason of the grid voltage drop is that the grid fails.
5. An apparatus for determining a cause of a voltage sag in a power grid, comprising:
the system comprises an acquisition unit, a control unit and a control unit, wherein the acquisition unit is used for acquiring the grid-side voltage of a wind power generation system and the load current of the wind power generation system;
the processing unit is used for determining that the reason of the grid voltage drop is the grid fault when the grid side voltage is lower than a preset voltage threshold value and the absolute value of the difference between the load current and the prestored fault current is larger than a first preset difference value threshold value;
wherein the load current of the wind power system comprises one or more of: grid side phase current of the wind power generation system and stator side phase current of the wind power generation system;
the pre-stored fault current includes: a first fault current and a second fault current;
when the load current of the wind power generation system includes the grid-side phase current of the wind power generation system, the processing unit is specifically configured to:
when it is determined that the grid-side voltage is lower than a preset voltage threshold and the absolute value of the difference between the grid-side phase current of the wind power generation system and the first fault current is larger than a first preset difference threshold, determining that the reason of the grid voltage drop is that the grid fails;
when the load current of the wind power generation system includes the stator side phase current of the wind power generation system, the processing unit is specifically configured to:
and when it is determined that the grid side voltage is lower than a preset voltage threshold value and the absolute value of the difference between the stator side phase current of the wind power generation system and the second fault current is larger than a first preset difference value threshold value, determining that the reason of grid voltage drop is that the grid fails.
6. The apparatus of claim 5, wherein the processing unit is further configured to:
and when the grid side voltage is lower than the preset voltage threshold value and the absolute value of the difference between the load current and the prestored fault current is smaller than a second preset difference value threshold value, determining that the reason of grid voltage drop is that the wind power generation system fails, wherein the first preset difference value threshold value is larger than the second preset difference value threshold value.
7. The apparatus of claim 5, wherein when the first fault current comprises a plurality of fault currents, the processing unit is specifically configured to:
and when the grid side voltage is determined to be lower than a preset voltage threshold value and the absolute value of the difference between the grid side phase current of the wind power generation system and any fault current in the first fault current is greater than a first preset difference value threshold value, determining that the reason of the grid voltage drop is the fault of the power grid.
8. The apparatus of claim 5, wherein when the second fault current comprises a plurality of fault currents, the processing unit is specifically configured to:
and when the grid side voltage is determined to be lower than a preset voltage threshold value and the absolute value of the difference between the stator side phase current of the wind power generation system and any fault current in the second fault current is greater than a first preset difference value threshold value, determining that the reason of the grid voltage drop is that the grid fails.
9. Wind power system, characterized in that it comprises a device for determining the cause of a grid voltage drop according to any of claims 5-8.
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