CN108933443B - Wind power plant power coordination control method and system - Google Patents
Wind power plant power coordination control method and system Download PDFInfo
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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
- H02J3/18—Arrangements for adjusting, eliminating or compensating reactive power in networks
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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
- H02J3/12—Circuit arrangements for ac mains or ac distribution networks for adjusting voltage in ac networks by changing a characteristic of the network load
- H02J3/16—Circuit arrangements for ac mains or ac distribution networks for adjusting voltage in ac networks by changing a characteristic of the network load by adjustment of reactive power
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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
- H02J3/46—Controlling of the sharing of output between the generators, converters, or transformers
- H02J3/50—Controlling the sharing of the out-of-phase component
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- 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
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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
- Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
- Y02E40/30—Reactive power compensation
Abstract
The invention provides a method and a system for coordinated control of power of a wind power plant, which are characterized by comprising the following steps: determining a reactive power control working mode of a wind power plant according to a power grid dispatching instruction; calculating reactive loss of the wind power plant; calculating the total reactive power demand of the wind power plant according to the reactive power control working mode of the wind power plant and the reactive power loss of the wind power plant; the method comprises the steps of distributing total reactive demand of the wind power plant according to a preset total reactive demand distribution principle of the wind power plant, judging whether the total reactive demand of the wind power plant exceeds the reactive output limit of the wind power plant, if not, bearing the total reactive demand of the wind power plant by the wind power plant, if so, bearing the total reactive demand of the wind power plant by the wind power plant, and bearing the excess part by a reactive compensation device. The technical method provided by the invention improves the power grid friendliness of the wind power plant, improves the safe and stable operation level of the power grid in the large-scale centralized wind power access region, and promotes the improvement of the wind power consumption capability of the power grid.
Description
Technical Field
The invention relates to new energy access and control, in particular to a method and a system for coordinated control of power of a wind power plant.
Background
Wind power generation has the advantages of rich resources, little pollution and the like, and is increasingly paid more attention by various countries in the world. Wind power technology is rapidly developed, at present, wind power surpasses water power and becomes the second largest power supply, and wind power is undergoing the role of changing from supplementary energy to alternative energy. The network source structure and the operation mode of the power system are changing deeply, the operation risk of the power network of the large-scale centralized access area of wind power is increased, and the safety margin is reduced.
Wind energy has volatility, and wind speed and wind direction are uncontrollable randomly, which becomes a root cause of poor stability of wind power generation. When the wind speed fluctuates strongly, the output of the wind turbine generator changes greatly, and the tidal current distribution and the voltage fluctuation of the system are influenced. On the other hand, when the power grid fails or is disturbed, the asynchronous wind generating set needs to absorb a large amount of reactive power from the power grid, and the stability of the operation of the power grid is affected. With the progress of wind power technology, the updating of technical standards and the change of a grid source structure and an operation mode of a power grid, higher requirements are provided for the grid connection performance of a wind power plant.
Disclosure of Invention
According to the invention, the reactive voltage regulation technology of the wind power plant is developed according to the reactive compensation principle of 'layered partition and local balance' of the power system, so that the reactive power control in the wind power plant is realized.
The invention provides a power coordination control method for a wind power plant, which comprises the following steps:
determining a reactive power control working mode of a wind power plant according to a power grid dispatching instruction;
calculating reactive loss of the wind power plant;
calculating the total reactive power demand of the wind power plant according to the reactive power control working mode of the wind power plant and the reactive power loss of the wind power plant;
the method comprises the steps of distributing total reactive demand of the wind power plant according to a preset total reactive demand distribution principle of the wind power plant, judging whether the total reactive demand of the wind power plant exceeds the reactive output limit of the wind power plant, if not, bearing the total reactive demand of the wind power plant by the wind power plant, if so, bearing the total reactive demand of the wind power plant by the wind power plant, and bearing the excess part by a reactive compensation device.
The wind power plant reactive power control working mode comprises the following steps: a constant grid-connected point voltage mode and a constant grid-connected point reactive mode;
the power grid dispatching instruction in the constant grid-connected point voltage mode is a grid-connected point reference voltage UgrefThe calculation formula is as follows:
Qref＝QWFref+Qloss
in the formula, QrefFor total reactive demand, Q, of the wind farmWFrefFor reactive setting, Q, of wind farmslossReactive power loss for the wind farm;
the power grid dispatching instruction in the constant grid-connected point reactive power mode is a grid-connected point reference reactive power QgrefThe calculation formula is as follows:
Qref＝Qgref+Qloss
calculating reactive power setting value Q of wind power plant according to the following formulaWFref：
In the formula of UdFor voltage regulation of dead zone, k1、k2For regulating the sag factor, Δ U is equal to Ugref-Un，UgrefFor grid-connected point reference voltage, UnFor rated grid voltage, PnThe rated power of the wind power plant.
The total reactive power demand of the wind power plant is distributed according to the following distribution principle of the total reactive power demand of the wind power plant:
the wind turbine preferentially compensates the reactive loss of the box transformer of the wind turbine, then compensates the reactive loss of the current collecting wire where the wind turbine is located, and finally compensates the reactive integral quantity of the wind power plant or the dispatching reactive quantity, namely the reference reactive power of the grid-connected point, the reactive loss of the booster transformer of the wind power plant bus station and the reactive loss of the wind power plant output line.
Calculating the reactive power demand distributed to the mth wind turbine generator set of the nth current collecting line according to the following formula:
in the formula: qWTnmFor the reactive demand, Q is the reactive setting value Q of the wind power plantWFrefOr grid point reference reactive power Qgref，PWTijActive power output, P, of the j-th wind power unit of the i-th current collectorWTnjActive power output, Q, of the jth wind turbine generator of the nth current collectorBFor reactive losses, Q, of step-up transformers of wind farm substationsSThe reactive loss of the high-voltage grid-connected line is 50 percent, and the reactive loss Q of the nth current collecting wire of the wind power plantJn，PWTnmAnd the active power output of the mth wind turbine generator set of the nth current collecting wire.
Calculating the reactive loss of the wind power plant according to the following formula:
in the formula, QlossFor the reactive loss of the wind power plant, N is the number of collecting lines in the wind power plant, M is the number of wind power units connected with each collecting line, and QbnmReactive loss, Q, of the m-th wind turbine group box transformer for the n-th current collectorJnFor reactive loss of the nth current collector, QBFor reactive losses, Q, of step-up transformers of wind farm substationsSThe reactive loss is 50% of the high-voltage grid-connected line.
The reactive loss Q of the mth wind turbine generator set box type transformer on the nth collecting wire in the wind power plant is calculated according to the following formulabnm：
Qbnm＝[UkIm/(100Ie)+I0/100]Se
In the formula of UkIs the impedance voltage percentage value of the transformer, ImThe value of the operating current to be compensated for the transformer, IeRated current value, I, of the transformer side to be compensated0Is the percentage of the no-load current of the transformer, SeIs the rated capacity of the transformer.
Calculating the absence of step-up transformer of wind power station by the following formulaWork loss QB：
QB＝[UkIm/(100Ie)+I0/100]Se
In the formula of UkIs the impedance voltage percentage value of the transformer, ImThe value of the operating current to be compensated for the transformer, IeRated current value, I, of the transformer side to be compensated0Is the percentage of the no-load current of the transformer, SeIs the rated capacity of the transformer.
Calculating the reactive loss Q of the nth current collecting wire of the wind power plant according to the following formulaJn：
QJn＝-U2ωCln+3I2ωLln
Where U is the rated voltage of the line, lnThe length of an overhead power collecting line of a wind power plant is shown as I, the working current flowing through the line is shown as omega, the grid frequency is shown as omega, the unit capacitance of the overhead power line is shown as C, and the unit inductance of the overhead power line is shown as L.
Calculating 50% reactive loss Q of the high-voltage grid-connected line according to the following formulaS：
QS＝-U2ωCl/2+3I2ωLl/2
In the formula: u is the rated voltage of the calculated line, L is the length of the line sent out by the wind power plant, I is the working current flowing through the line, omega is the grid frequency, C is the unit capacitance of the overhead power line, and L is the unit inductance of the overhead power line.
The invention provides a wind power plant power coordination control system, which comprises: the working mode determining module is used for determining a reactive power control working mode of the wind power plant according to the power grid dispatching instruction;
the first calculation module is used for calculating the reactive loss of the wind power plant;
the second calculation module is used for calculating the total reactive power demand of the wind power plant according to the reactive power control working mode of the wind power plant and the reactive power loss of the wind power plant;
the reactive power demand distribution module distributes total reactive power demand of the wind power plant according to a preset total reactive power demand distribution principle of the wind power plant, judges whether the total reactive power demand of the wind power plant exceeds the reactive power output limit of the wind power plant, if not, the total reactive power demand of the wind power plant is completely borne by the wind power plant, if so, the wind power plant bears the total reactive power demand of the wind power plant, and the excess part of the total reactive power demand of the wind power plant is borne by the reactive power compensation device.
The second calculation module calculates as follows:
the power grid dispatching instruction in the constant grid-connected point voltage mode is a grid-connected point reference voltage UgrefThe calculation formula is as follows:
Qref＝QWFref+Qloss
in the formula, QrefFor total reactive demand, Q, of the wind farmWFrefFor reactive setting, Q, of wind farmslossReactive power loss for the wind farm;
grid dispatching instruction is grid reference reactive power Q under constant grid-connected point reactive modegrefThe calculation formula is as follows:
Qref＝Qgref+Qloss
calculating reactive power setting value Q of wind power plant according to the following formulaWFref：
In the formula of UdFor voltage regulation of dead zone, k1、k2For regulating the sag factor, Δ U is equal to Ugref-Un，UgrefFor grid-connected point reference voltage, UnFor rated grid voltage, PnThe rated power of the wind power plant.
The reactive power distribution principle of the reactive power demand distribution module is as follows:
the wind turbine preferentially compensates the reactive loss of the box transformer of the wind turbine, then compensates the reactive loss of the current collecting wire where the wind turbine is located, and finally compensates the reactive integral quantity of the wind power plant or the dispatching reactive quantity, namely the reference reactive power of the grid-connected point, the reactive loss of the booster transformer of the wind power plant bus station and the reactive loss of the wind power plant output line.
Compared with the closest prior art, the technical scheme provided by the invention has the following beneficial effects:
according to the technical scheme provided by the invention, the dynamic reactive power regulation of the whole wind power plant is realized by regulating the output reactive power of each wind power generation set in the wind power plant from the dynamic reactive power loss calculation of the wind power plant, so that the stability of the grid voltage of the access region is maintained.
According to the technical scheme provided by the invention, the reactive power control strategy of the wind power plant is optimized by setting the voltage dead zone, so that frequent actions of the wind turbine generator are avoided, and the networking operation safety of the wind power plant is improved.
The technical method provided by the invention improves the power grid friendliness of the wind power plant, improves the safe and stable operation level of the power grid in the large-scale centralized wind power access region, and promotes the improvement of the wind power consumption capability of the power grid.
Drawings
FIG. 1 is a flow chart of a method for coordinating and controlling power of a wind farm according to the present invention;
FIG. 2 is a topological diagram of a wind farm power coordination control system according to an embodiment of the present invention;
FIG. 3 is a flow chart of a wind farm power coordination control method according to an embodiment of the invention;
FIG. 4 is a voltage-reactive characteristic curve diagram of a wind farm according to an embodiment of the invention.
Detailed Description
The invention is described in further detail below with reference to the accompanying drawings:
GB/T19963 plus 2011 in China requires that the wind turbine generator has +/-0.95 power factor regulation capacity, the ratio of reactive power to active power is about 1:3, however, the reactive limit of the actual wind turbine generator is far greater than a standard specified value, and the reactive power regulation capacity of the wind turbine generator in actual operation cannot be effectively utilized. Therefore, the reactive power distribution of the wind power plant can preferentially utilize the reactive capacity of the wind turbine generator, and fully considers the influence of the reactive power output of the fans at different positions on the reactive power output of the wind power plant outlet; and when the target reactive power value of the wind power plant exceeds the adjustable reactive power limit of the generator set in the plant, adjusting by using a reactive power compensation device configured in the wind power plant.
The reactive power voltage regulation of the wind power plant is integrally realized by a wind power plant power coordination control system, and the block diagram of the system is shown in the attached figure 2. The wind power plant power coordination control system receives active and voltage control instructions issued by a dispatching master station system or locally in a communication mode, uniformly coordinates and controls the wind power machine group and the reactive power compensation device, and continuously adjusts the active power and the reactive power. The wind power plant power coordination control system collects real-time voltage and frequency of a grid-connected point through a grid information measuring module of the grid-connected point, and calculates and optimally distributes active power and reactive power of a wind power machine group, a reactive power compensation device and the like.
The invention provides a wind power plant power coordination control method as shown in FIG. 1, which comprises the following steps:
determining a reactive power control working mode of a wind power plant according to a power grid dispatching instruction;
calculating reactive loss of the wind power plant;
calculating the total reactive power demand of the wind power plant according to the reactive power control working mode of the wind power plant and the reactive power loss of the wind power plant;
the method comprises the steps of distributing total reactive demand of the wind power plant according to a preset total reactive demand distribution principle of the wind power plant, judging whether the total reactive demand of the wind power plant exceeds the reactive output limit of the wind power plant, if not, bearing the total reactive demand of the wind power plant by the wind power plant, if so, bearing the total reactive demand of the wind power plant by the wind power plant, and bearing the excess part by a reactive compensation device.
The specific flow is shown in figure 3. Firstly, the control system receives a power grid dispatching or locally issued command and determines a reactive control working mode (a constant grid-connected point voltage mode and a constant grid-connected point reactive mode) of a wind power plant; then, acquiring operation data of the wind turbine generator, the wind power plant reactive power compensation device and the wind power plant booster station in real time, and calculating the reactive loss of the main part in the wind power plant, the total reactive demand of the wind power plant and the reactive power output limit of the wind turbine generator; if the total reactive power demand of the wind power plant does not exceed the reactive power output limit of the wind generation set, the reactive power demand is borne by the wind generation set, and if the total reactive power demand of the wind power plant exceeds the reactive power output limit of the wind generation set, the reactive power demand is borne by reactive power compensation equipment of the wind power plant.
The reactive output limit of the wind turbine generator is determined by the design capability of the wind turbine generator; the method is characterized in that the wind turbine generator corresponds to different reactive limits when the wind turbine generator has different active power outputs, parameters are given by a manufacturer of the whole wind turbine generator, and the parameters are directly inquired and counted.
(1) Reactive loss calculation in wind farms
The reactive loss of the wind power plant is mainly generated by a box type transformer, a current collecting circuit, a step-up transformer and a sending circuit, N current collecting wires are assumed in the wind power plant, each current collecting wire is connected with M wind power sets, the whole plant is transmitted to a power grid by one step-up transformer, and reactive calculation modes of all parts are as follows:
1) the reactive power consumed by the mth wind turbine unit box type transformer of the nth power collecting wire in the wind power plant is calculated as
Qbnm＝[UkIm/(100Ie)+I0/100]Se (1)
2) The reactive power consumed by the booster transformer of the wind power station is calculated as
QB＝[UkIm/(100Ie)+I0/100]Se (2)
3) The reactive power consumed by the nth collecting line of the wind power plant is calculated by
QJn＝-U2ωCln+3I2ωLln (3)
4) If the grid-connected line is longer, 50% of reactive loss of the high-voltage grid-connected line is also considered, and the calculation formula is
QS＝-U2ωCl/2+3I2ωLl/2 (4)
In the formula: in the formula of UkIs the impedance voltage percentage value of the transformer, ImThe value of the operating current to be compensated for the transformer, IeRated current value, I, of the transformer side to be compensated0Is the percentage of the no-load current of the transformer, SeFor the rated capacity of the transformer, U is the rated voltage of the calculated line, lnThe method is characterized in that the length of an overhead power collecting wire of a wind power plant is represented by I, omega, grid frequency and C, wherein I is working current flowing through the wire, C is unit capacitance of the overhead power line, 7-9 pF/m is generally taken, and L is unit inductance of the overhead power lineGenerally, 1-1.5 muH/m, l is the length of the wind power plant sending line.
In summary, the total reactive power loss of the wind power plant is:
in the formula, N is the number of collecting lines in the wind power plant, M is the number of wind turbine generators connected with each collecting line, and QbnmReactive loss, Q, of the m-th wind turbine group box transformer for the n-th current collectorJnFor reactive loss of the nth current collector, QBFor reactive losses, Q, of step-up transformers of wind farm substationsSThe reactive loss is 50% of the high-voltage grid-connected line.
As can be seen from the above calculation formula, the reactive loss of the wind power plant is changed along with the change of the generated power. Therefore, when the wind power plant performs reactive power control, the loss in the wind power plant should be dynamically compensated at the same time so as to prevent over-compensation or under-compensation.
(2) Wind farm total reactive demand acquisition
Grid dispatching instruction is grid-connected point reference reactive power QgrefTime, wind farm total reactive power demand QrefIs calculated as
Qref＝Qgref+Qloss (6)
The power grid dispatching instruction is a grid-connected point reference voltage UgrefThe total reactive power demand of the wind power plant is calculated as
Qref＝QWFref+Qloss (7)
In the formula, QWFrefReactive setting value for wind power plant
Wind power plant reactive setting value QWFrefCan be obtained by a voltage-reactive characteristic curve, as shown in figure 4. Wherein U isdFor voltage regulation dead zone, Ud0.02, regulating droop coefficient k1＝k2Q5, and the dead band and droop factor can be setWFrefThe specific expression of (4) is shown in (8).
In the formula: Δ U ═ Ugref-Un，UnFor rated grid voltage, PnThe rated power of the wind power plant.
(3) Wind farm total reactive demand distribution
The method adopts the basic principle of reactive power distribution: and distributing reactive power according to the active power output proportion of the wind turbine generator.
1) Wind power plant reactive setting QWFrefOr grid point reference reactive power QgrefThe reactive loss of a step-up transformer of the wind power plant confluence station and the reactive loss of a transmission line of the wind power plant are shared by a full wind turbine;
2) the reactive loss of the power collecting wire is compensated by the wind turbine generator set of the power collecting wire;
3) the reactive power loss of the box transformer substation of the wind turbine generator set is compensated by the corresponding wind turbine generator set;
1) -3) the priority is gradually increased, if the reactive power distribution exceeds the limit of the set, the wind generation set preferentially undertakes the reactive power loss of the box transformer, then the reactive power loss of the current collecting line is achieved, finally the reactive power integral quantity or the dispatching reactive power quantity of the wind generation set is achieved, and the total reactive power requirement of the wind generation set is completely undertaken by the reactive power compensation device.
As can be seen from the above, the reactive power value assigned to the mth wind turbine generator set of the nth power collecting line is:
in the formula: q is a reactive setting value Q of the wind power plantWFrefOr grid point reference reactive power Qgref，PWTijActive power output, P, of the j-th wind power unit of the i-th current collectorWTnjActive power output, Q, of the jth wind turbine generator of the nth current collectorBFor reactive losses, Q, of step-up transformers of wind farm substationsSThe reactive loss of the high-voltage grid-connected line is 50 percent, and the reactive loss Q of the nth current collecting wire of the wind power plantJn，PWTnmN-th collectorActive power output of the mth wind power generator set of the line.
Based on the same concept, the invention provides a wind power plant power coordination control system, which comprises: the working mode determining module is used for determining a reactive power control working mode of the wind power plant according to the power grid dispatching instruction;
the first calculation module is used for calculating the reactive loss of the wind power plant;
the second calculation module is used for calculating the total reactive power demand of the wind power plant according to the reactive power control working mode of the wind power plant and the reactive power loss of the wind power plant;
the reactive power demand distribution module distributes total reactive power demand of the wind power plant according to a preset total reactive power demand distribution principle of the wind power plant, judges whether the total reactive power demand of the wind power plant exceeds the reactive power output limit of the wind power plant, if not, the total reactive power demand of the wind power plant is completely borne by the wind power plant, if so, the wind power plant bears the total reactive power demand of the wind power plant, and the excess part of the total reactive power demand of the wind power plant is borne by the reactive power compensation device.
The second calculation module calculates as follows:
the power grid dispatching instruction in the constant grid-connected point voltage mode is a grid-connected point reference voltage UgrefThe calculation formula is as follows:
Qref＝QWFref+Qloss
in the formula, QrefFor total reactive demand, Q, of the wind farmWFrefFor reactive setting, Q, of wind farmslossReactive power loss for the wind farm;
grid dispatching instruction is grid reference reactive power Q under constant grid-connected point reactive modegrefThe calculation formula is as follows:
Qref＝Qgref+Qloss
calculating reactive power setting value Q of wind power plant according to the following formulaWFref：
In the formula of UdFor voltage regulation of dead zone, k1、k2For regulating sagCoefficient, Δ U ═ Ugref-Un，UgrefFor grid-connected point reference voltage, UnIs the rated grid voltage.
The reactive power distribution principle of the reactive power demand distribution module is as follows:
the wind turbine preferentially compensates the reactive loss of the box transformer of the wind turbine, then compensates the reactive loss of the current collecting wire where the wind turbine is located, and finally compensates the reactive integral quantity of the wind power plant or the dispatching reactive quantity, namely the reference reactive power of the grid-connected point, the reactive loss of the booster transformer of the wind power plant bus station and the reactive loss of the wind power plant output line.
As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application 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, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. 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.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting the scope of protection thereof, and although the present application is described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: numerous variations, modifications, and equivalents will occur to those skilled in the art upon reading the present application and are within the scope of the claims appended hereto.
Claims (10)
1. A method for coordinated control of power of a wind power plant is characterized by comprising the following steps:
determining a reactive power control working mode of a wind power plant according to a power grid dispatching instruction;
calculating reactive loss of the wind power plant;
calculating the total reactive power demand of the wind power plant according to the reactive power control working mode of the wind power plant and the reactive power loss of the wind power plant;
distributing total reactive power demand of the wind power plant according to a preset total reactive power demand distribution principle of the wind power plant, judging whether the total reactive power demand of the wind power plant exceeds the reactive output limit of the wind power plant, if not, bearing the total reactive power demand of the wind power plant by the wind power plant, if so, bearing the total reactive power demand of the wind power plant by the wind power plant, and if so, bearing the excess part by a reactive power compensation device;
the wind power plant reactive power control working mode comprises the following steps: a constant grid-connected point voltage mode and a constant grid-connected point reactive mode;
the power grid dispatching instruction in the constant grid-connected point voltage mode is a grid-connected point reference voltage UgrefThe calculation formula is as follows:
Qref＝QWFref+Qloss
in the formula, QrefFor total reactive demand, Q, of the wind farmWFrefFor reactive setting, Q, of wind farmslossReactive power loss for the wind farm;
the power grid dispatching instruction in the constant grid-connected point reactive power mode is a grid-connected point reference reactive power QgrefThe calculation formula is as follows:
Qref＝Qgref+Qloss
calculating reactive power setting value Q of wind power plant according to the following formulaWFref：
In the formula of UdFor voltage regulation of dead zone, k1、k2For regulating the sag factor, Δ U is equal to Ugref-Un，UgrefFor grid-connected point reference voltage, UnFor rated grid voltage, PnThe rated power of the wind power plant.
2. The wind farm power coordination control method according to claim 1, characterized in that the wind farm total reactive demand is distributed according to the following wind farm total reactive demand distribution principle:
the wind turbine preferentially compensates the reactive loss of the box transformer of the wind turbine, then compensates the reactive loss of the current collecting wire where the wind turbine is located, and finally compensates the reactive integral quantity of the wind power plant or the dispatching reactive quantity, namely the reference reactive power of the grid-connected point, the reactive loss of the booster transformer of the wind power plant bus station and the reactive loss of the wind power plant output line.
3. The wind farm power coordination control method according to claim 2, wherein the reactive demand allocated to the mth wind turbine generator of the nth current collecting line is calculated according to the following formula:
in the formula: qWTnmFor the reactive demand, Q is the reactive setting value Q of the wind power plantWFrefOr grid point reference reactive power Qgref，PWTijActive power output, P, of the j-th wind power unit of the i-th current collectorWTnjActive power output, Q, of the jth wind turbine generator of the nth current collectorBFor reactive losses, Q, of step-up transformers of wind farm substationsSThe reactive loss of the high-voltage grid-connected line is 50 percent, and the reactive loss Q of the nth current collecting wire of the wind power plantJn，PWTnmAnd the active power output of the mth wind turbine generator set of the nth current collecting wire.
4. The wind farm power coordinated control method of claim 1, wherein the wind farm reactive loss is calculated as follows:
in the formula, QlossFor the reactive loss of the wind power plant, N is the number of collecting lines in the wind power plant, M is the number of wind power units connected with each collecting line, and QbnmReactive loss, Q, of the m-th wind turbine group box transformer for the n-th current collectorJnFor reactive loss of the nth current collector, QBFor reactive losses, Q, of step-up transformers of wind farm substationsSThe reactive loss is 50% of the high-voltage grid-connected line.
5. The wind farm power coordinated control method according to claim 4, wherein the reactive loss Q of the mth wind farm box transformer on the nth collection line in the wind farm is calculated according to the following formulabnm：
Qbnm＝[UkIm/(100Ie)+I0/100]Se
In the formula of UkIs the impedance voltage percentage value of the transformer, ImThe value of the operating current to be compensated for the transformer, IeRated current value, I, of the transformer side to be compensated0Is the percentage of the no-load current of the transformer, SeIs the rated capacity of the transformer.
6. The wind farm power coordinated control method according to claim 4, wherein the reactive loss Q of the wind farm substation step-up transformer is calculated according to the following formulaB：
QB＝[UkIm/(100Ie)+I0/100]Se
In the formula of UkIs the impedance voltage percentage value of the transformer, ImThe value of the operating current to be compensated for the transformer, IeRated current value, I, of the transformer side to be compensated0Is the percentage of the no-load current of the transformer, SeIs the rated capacity of the transformer.
7. The wind farm power coordinated control method according to claim 4, wherein the reactive loss Q of the nth collector wire of the wind farm is calculated according to the following formulaJn：
QJn＝-U2ωCln+3I2ωLln
Where U is the rated voltage of the line, lnThe length of an overhead power collecting line of a wind power plant is shown as I, the working current flowing through the line is shown as omega, the grid frequency is shown as omega, the unit capacitance of the overhead power line is shown as C, and the unit inductance of the overhead power line is shown as L.
8. The wind farm power coordinated control method according to claim 4, wherein the reactive loss Q of the high voltage grid-connected line of 50% is calculated according to the following formulaS：
QS＝-U2ωCl/2+3I2ωLl/2:
In the formula: u is the rated voltage of the calculated line, L is the length of the line sent out by the wind power plant, I is the working current flowing through the line, omega is the grid frequency, C is the unit capacitance of the overhead power line, and L is the unit inductance of the overhead power line.
9. A wind farm power coordinated control system, characterized in that the system comprises: the working mode determining module is used for determining a reactive power control working mode of the wind power plant according to the power grid dispatching instruction;
the first calculation module is used for calculating the reactive loss of the wind power plant;
the second calculation module is used for calculating the total reactive power demand of the wind power plant according to the reactive power control working mode of the wind power plant and the reactive power loss of the wind power plant;
the reactive power demand distribution module is used for distributing total reactive power demand of the wind power plant according to a preset total reactive power demand distribution principle of the wind power plant, judging whether the total reactive power demand of the wind power plant exceeds the reactive power output limit of the wind power plant, if not, the total reactive power demand of the wind power plant is borne by the wind power plant, and if so, the wind power plant bears the excess part firstly, and the reactive power compensation device bears the excess part;
the second calculation module calculates as follows:
the power grid dispatching instruction in the constant grid-connected point voltage mode is a grid-connected point reference voltage UgrefThe calculation formula is as follows:
Qref＝QWFref+Qloss
in the formula, QrefFor total reactive demand, Q, of the wind farmWFrefFor reactive setting, Q, of wind farmslossReactive power loss for the wind farm;
grid dispatching instruction is grid reference reactive power Q under constant grid-connected point reactive modegrefThe calculation formula is as follows:
Qref＝Qgref+Qloss
calculating reactive power setting value Q of wind power plant according to the following formulaWFref：
In the formula of UdFor voltage regulation of dead zone, k1、k2For regulating the sag factor, Δ U is equal to Ugref-Un，UgrefFor grid-connected point reference voltage, UnFor rated grid voltage, PnThe rated power of the wind power plant.
10. The wind farm power coordinated control system of claim 9, wherein the reactive power demand distribution module has a reactive power distribution principle as follows:
the wind turbine preferentially compensates the reactive loss of the box transformer of the wind turbine, then compensates the reactive loss of the current collecting wire where the wind turbine is located, and finally compensates the reactive integral quantity of the wind power plant or the dispatching reactive quantity, namely the reference reactive power of the grid-connected point, the reactive loss of the booster transformer of the wind power plant bus station and the reactive loss of the wind power plant output line.
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