CN103855715B - The method and system of wind power plant reactive voltage control - Google Patents
The method and system of wind power plant reactive voltage control Download PDFInfo
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Abstract
The present invention is applicable to power domain, provide the method and system of a kind of wind power plant reactive voltage control, described system includes multiple sub-controller and is arranged at the central controller of booster stations, each grid branch arranges at least one sub-controller, and each sub-controller communicates to connect with described central controller;Wherein, described central controller, for changing, according to wind energy turbine set internal network parameter and external network reactive load, the reactive compensation power Q that the points of common connection voltage change causing calculates each grid branchZL‑Ref1, and under send instructions to corresponding sub-controller;Described sub-controller, is used for receiving described instruction and distributes to each blower fan, and the reactive compensation power that the central controller that the distribution of described each blower fan obtains issues is Qk_Ref1.The method and system that the present invention provides, the points of common connection voltage change that wind farm wind velocity fluctuation can be caused and the problem that reactive-load compensation is carried out to wind energy turbine set internal network.
Description
Technical Field
The invention belongs to the field of electric power, and particularly relates to a method and a system for controlling reactive voltage of a wind power plant.
Background
With the continuous increase of wind power installed capacity in China, reactive power control of a wind power plant becomes a problem to be solved urgently, at present, a plurality of wind farms have the problem of wind farm access power grid reactive power control, the voltage of a bus at the outlet of the wind farm in Jilin white city is unstable, so that the whole wind farm is cut off, further the overvoltage of the instantaneous bus voltage is caused to break down a transformer of a transformer substation, and a plurality of large-scale fan grid disconnections of Gansu Changma are also caused by the unstable voltage of the power grid.
Generally speaking, the electrical layout of a fan, a transformer and a booster station control center of a wind power plant is shown in fig. 1, the output voltage of a fan 1 is 690V, the output voltage is increased to 35KV through a transformer 2, the output voltage is connected with other fans on the branch line, and finally the output voltage is connected to a 220KV power grid 5 through a booster station transformer 3. The point of common connection 4 is the point of common connection of the entire wind farm to the external grid and the impedance 6 represents the line impedance.
In order to stabilize the voltage 4 of the common connection point of the wind farm, reactive compensation devices with certain capacity such as SVC, SVG and the like are often configured, but the construction and operation cost of the wind farm is increased. At present, most wind turbines (double-fed type and direct-drive type) have certain reactive power compensation capability, but are not started, and still run in a unit power factor or fixed power factor mode. If the fan unit is made to participate in reactive voltage control, the control capability of the reactive voltage of the wind power plant can be greatly improved, and even the capacity of a reactive compensation device can be reduced, so that the wind power plant is the best reactive voltage control mode at present.
Individual wind farms have been equipped with fan-group reactive voltage control (AVC) control functionality as an exemplary project, but still suffer from some drawbacks:
1) generally, the types of fans in a wind farm are not single, for example, the manufacturers of the fans are different, or the manufacturers of the fans are the same, but the models of the fans are different. Especially for fans of different manufacturers, due to different external interfaces, the management is very troublesome, and often, monitoring systems of multiple manufacturers are arranged in a control room of a wind power plant and are independent of each other. The data of the wind power plant is difficult to perform data interaction with the previous-stage dispatching center, and only isolated reactive voltage control of the local wind power plant can be realized, but unified regulation of regional reactive voltage which cannot be added is realized.
2) The reactive voltage of the existing wind power plant is regulated at a very low speed, and is generally regulated and controlled at a second-level frequency. In the existing scheme, an AVC (automatic voltage control) module is added to a booster station of a wind power plant, and the AVC module is communicated with Scada systems of different manufacturers to acquire information of each fan and issue a reactive instruction through the Scada systems of the manufacturers. The scheme not only increases the way of information acquisition and instruction issuing and the transfer times, but also processes the receiving and sending of the key information and the instruction by using common information frames without optimizing the sending processing, thereby causing the frequency of the whole AVC closed control to be very low, and generally finishing one instruction updating within several seconds or even longer time. The wind speed has the characteristics of time-varying property and randomness, so that the generated power of the wind power station also changes instantly, the voltage of a public connection point of a wind power station fluctuates, and the voltage of the public connection point of the wind power station cannot be accurately controlled by the conventional reactive voltage regulation technology.
Disclosure of Invention
The embodiment of the invention aims to provide a method and a system for controlling reactive voltage of a wind power plant, and aims to solve the problems that the conventional method for controlling reactive voltage of the wind power plant cannot perform reactive compensation on voltage change of a public connection point caused by wind speed fluctuation of the wind power plant and cannot perform compensation on an internal network of the wind power plant.
The embodiment of the invention is realized in such a way that a wind power plant reactive voltage control system comprises a plurality of power grid branches and a booster station which is respectively connected with each power grid branch, wherein each power grid branch comprises a plurality of fans, and the booster station outputs voltage to an external network through a public connection point; the system comprises a plurality of sub-controllers and a central controller arranged on the booster station, wherein each power grid branch is provided with at least one sub-controller, and each sub-controller is in communication connection with the central controller; wherein,
the central controller is used for calculating the reactive compensation power Q of each power grid branch according to the voltage change of the public connection point caused by the internal network parameters of the wind power plant and the reactive load change of the external networkZL-Ref1And issues instructions to the corresponding sub-controllers;
the sub-controller is used for receiving the instruction and distributing the instruction to each fan, and the reactive compensation power distributed by each fan is Qk_Ref1。
Further, the central controller includes:
a first calculation module for calculating the reactive output sum Q caused by the voltage change of the public connection point caused by the reactive load change of the internal network parameter and the external network of the wind power plantRef1;
A first distribution module for distributing the sum Q according to the reactive outputRef1Distributing to obtain the reactive compensation power Q of each power grid branchZL-Ref1。
Further, the sub-controller includes:
a second distribution module for distributing the reactive compensation power Q according to each power grid branchZL-Ref1Distribute the obtained bookReactive compensation power Q of each fan of power grid branchk-Ref1。
Further, the sub-controller further includes:
the second calculation module is used for calculating reactive compensation power Q of the power grid branch according to voltage change of the public connection point caused by wind speed fluctuation of the wind power plantZL-Ref2;
A third calculation module for calculating the reactive compensation power Q according to the branch of the power gridZL-Ref2Calculating reactive compensation power Q of each fan of the branch of the power gridk_Ref2;
A third distribution module used for calculating the reactive compensation power Q required to be sent by each fan of the branch of the power gridk_Ref=Qk_Ref1+Qk_Ref2And sent to each fan.
Further, the sub-controller further includes:
and the acquisition module is used for acquiring the fan information of the power grid branch, converting the fan information into a preset standard data format and then uploading the preset standard data format to the central controller.
The invention also provides a method for controlling the reactive voltage of the wind power plant, which comprises the following steps:
the central controller calculates the reactive compensation power Q of each power grid branch according to the voltage change of the public connection point caused by the internal network parameters of the wind power plant and the reactive load change of the external networkZL-Ref1And issues instructions to the corresponding sub-controllers;
the sub-controller receives the instruction and distributes the instruction to each fan, and reactive compensation power distributed by each fan is Qk_Ref1。
Further, the central controller calculates reactive compensation power Q of each power grid branch according to voltage changes of the public connection point caused by changes of internal network parameters and external network reactive loads of the wind power plantZL-Ref1Comprises that:
Calculating reactive output sum Q caused by voltage change of public connection point caused by reactive load change of internal network parameters and external network of wind power plantRef1;
According to the reactive output sum QRef1Distributing to obtain the reactive compensation power Q of each power grid branchZL-Ref1。
Further, the sub-controller receiving instructions and assigning to each fan includes:
the sub-controller is used for compensating the power Q according to the reactive power of each power grid branchZL-Ref1Distributing and obtaining the reactive compensation power Q of each fan of the power grid branchk-Ref1。
Further, the method further comprises:
the sub-controller calculates the reactive compensation power Q of the power grid branch according to the voltage change of the public connection point caused by wind speed fluctuation of the wind power plantZL-Ref2;
Reactive compensation power Q according to the branch of the power networkZL-Ref2Calculating reactive compensation power Q of each fan of the branch of the power gridk_Ref2;
Calculating reactive compensation power Q required to be sent by each fan of the branch of the power gridk_Ref=Qk_Ref1+Qk_Ref2And sent to each fan.
Further, the central controller calculates the reactive compensation power Q of each power grid branch according to the internal parameters of the wind power plant and the voltage change of the public connection point caused by the reactive load change of the external networkZL-Ref1Before, still include:
and the sub-controller collects the fan information of the power grid branch, converts the fan information into a preset standard data format and uploads the preset standard data format to the central controller.
The embodiment of the invention adds a new network equipment sub-controller and a central controller, and the central controller is used for carrying out reactive compensation on voltage change of the public connection point caused by impedance change of an internal network and external network of the wind power plant, and the sub-controller is used for calculating reactive compensation power on the voltage change of the public connection point caused by wind speed fluctuation of the wind power plant. The embodiment of the invention provides a new wind power plant network layout mode, which can track the change of generated power and quickly adjust reactive voltage, so that the voltage of a public connection point of a wind power plant is accurately controlled. In addition, the embodiment of the invention realizes unified reactive voltage control on fans of different manufacturers and different models by modifying the existing wind power plant, is convenient to interact with a superior dispatching center, and simplifies a wind power plant monitoring system. Furthermore, the embodiment of the invention solves the problem of slow regulation frequency of the reactive voltage of the wind power plant, and realizes more accurate control of the voltage of the public connection point.
Drawings
FIG. 1 is a block diagram of a prior art wind farm;
FIG. 2 is a block diagram of a system for controlling reactive voltage of a wind farm according to an embodiment of the present invention;
FIG. 3 is a simplified block diagram of a system for controlling reactive voltage of a wind farm according to an embodiment of the present invention;
FIG. 4 is a block diagram of a central controller of a system for reactive voltage control of a wind farm according to an embodiment of the present invention;
FIG. 5 is a block diagram of a sub-controller of a system for reactive voltage control of a wind farm according to an embodiment of the present invention;
FIG. 6 is a diagram of a relational model between a wind farm and a large power grid in the system for controlling reactive voltage of the wind farm according to the first embodiment of the present invention;
FIG. 7 is an equivalent circuit model of a fan to a common node in the system for controlling reactive voltage of a wind farm according to an embodiment of the present invention;
FIG. 8 is another equivalent circuit model of a fan to common connection point in a system for controlling reactive voltage of a wind farm according to an embodiment of the present invention;
FIG. 9 is a further equivalent circuit model of a fan to common connection point in the system for controlling reactive voltage of a wind farm according to the first embodiment of the present invention;
FIG. 10 is a further equivalent circuit model of a wind turbine to a point of common connection in the system for reactive voltage control of a wind farm according to an embodiment of the present invention;
fig. 11 is a flowchart of a method for controlling reactive voltage of a wind farm according to a second embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Example one
The embodiment of the invention provides a reactive voltage control system for a wind power plant. As shown in fig. 2, a wind farm according to a first embodiment of the present invention includes a plurality of grid branches, and a booster station 30 connected to each grid branch, where each grid branch includes a plurality of wind turbines 10, and the booster station 30 outputs a voltage to an external network through a common connection point 40; the system of the embodiment of the present invention includes a plurality of sub-controllers 70 and a central controller 80 provided to the booster station 30, at least one sub-controller 70 is provided to each grid branch, and each sub-controller 70 is communicatively connected to the central controller 80.
The system according to the first embodiment of the present invention can be simplified to the system shown in fig. 3, in which a sub-controller 70 is installed in the first fan (not limited thereto, the sub-controller 70 can be configured for each fan or several fans) on each grid branch, and the central controller 80 can be installed in the booster station 30 according to the adjustment of the actual requirement.
In the first embodiment of the present invention, the central controller 80 is configured to collect and count all the fan information sent by each sub-controller 70; calculating reactive compensation power Q of each power grid branch according to voltage changes of the public connection point 40 caused by changes of internal network parameters and external network reactive loads of the wind power plantZL-Ref1And sends down reactive compensation power QZL-Ref1To the corresponding sub-controllers 70, and the instructions are distributed by the corresponding sub-controllers 70 to each of the fans of the branch of the grid where the sub-controllers are located. As shown in fig. 4, the central controller 80 includes:
a first calculation module 81 for calculating the reactive output sum Q caused by the voltage change of the point of common connection caused by the reactive load change of the internal network parameters and the external network of the wind farmRef1;
A first distribution module 82 for summing the outputs Q according to said reactive outputsRef1Distributing to obtain the reactive compensation power Q of each power grid branchZL-Ref1。
In the first embodiment of the present invention, the sub-controller 70 is configured to collect fan information of a branch of the power grid, and upload the fan information to the central controller 80; receiving the reactive compensation power Q of each power grid branch issued by the central controller 80ZL-Ref1The instruction of (3) is combined with the on-off state of each fan 10 of the power grid branch, the impedance parameter of the power grid branch, the parameter of the local transformer, the fan capacity and other comprehensive calculations to obtain the reactive output power Q of each fan 10 of the power grid branchk_Ref1And the high-priority communication frame is rapidly distributed to the fan 10 of the branch of the power grid to be executed; and collecting the key operation states of the fans 10 of the power grid branch by using a high-priority communication frame, so that the local controller 70 can calculate the reactive compensation power Q of the power grid branch according to the voltage change of the public connection point 40 caused by the wind speed fluctuation of the wind farmZL-Ref2I.e. for the AVC control algorithm. As shown in fig. 5, the sub-controller 70 includesComprises the following steps:
a second distribution module 71 for distributing the reactive compensation power Q according to each of said network branchesZL-Ref1Distributing and obtaining the reactive compensation power Q of each fan of the power grid branchk-Ref1。
A second calculating module 72, configured to calculate reactive compensation power Q of the power grid branch according to voltage change of the common connection point caused by wind speed fluctuation of the wind farmZL-Ref2;
A third calculating module 73 for calculating the reactive compensation power Q according to the branch of the power gridZL-Ref2Calculating the reactive compensation power Q of each fan 10 of the branch of the power gridk_Ref2;
A third distribution module 74, configured to calculate a reactive compensation power Q that each fan 10 of the grid branch needs to sendk_Ref=Qk_Ref1+Qk_Ref2And sent to each fan 10.
The collection module 75 is configured to collect fan information of a power grid branch where the fan information is located, convert the fan information into a preset standard data format, and upload the converted fan information to the central controller 80, so that the fan 10 is compatible with fans 10 of different manufacturers of different models.
In order to control reactive voltage, a circuit model of the whole wind power plant needs to be established and is divided according to a network connection mode, and the circuit model comprises an external network and an internal network.
For the external network, the connection between the wind farm and the large power grid can be simplified as shown in model fig. 6, and the relationship between the voltage of the wind farm common connection point 40 and the voltage at the back end of the power grid can be obtained by a common formula of the power system.
Vg=VL+(PextRext+QextXext)/VL
(1)
Wherein VgIs the voltage value, V, of the common connection point 40LFor the value of the grid remote voltage, RextIs the internal resistance value, X, of the power grid lineextFor the reactance value of the grid line, PextValue of active power absorbed for the load at the far end of the network, QextAnd absorbing the reactive power value for the load at the far end of the power grid.
For the internal network, the equivalent circuit model of each fan 10 to the common connection point 40 is shown in fig. 7, and the kth fan W is establishedkEquivalent circuit diagram to common connection point due to transformer TkTo the fan WkShort distance, negligible line impedance, transformer TkThe internal resistance is small and negligible. If the transformer T is connectedkAfter the corresponding transformation ratio conversion of the line impedance, the equivalent circuit of fig. 8 is obtained, because of the transformer TkExciting reactance X ofkmUsually far greater than its leakage reactance, so that a further approximate equivalence can be made to obtain the equivalent circuit of fig. 9, and as can be seen from fig. 9, the system model is divided into three parts:
fan WkAnd transformer TkExciting reactance X ofkmAre connected in parallel to form a first part, XkmAbsorbing reactive power of Qkm=Vwk/jXkmIn which V iskmIs a kth fan WkLocal grid-connected point voltage value, XkmIs a kth fan WkTransformer TkThe excitation reactance of (1). The part of the idle work needs to be compensated by a fan, otherwise, the part of the idle work is provided by a power grid.
Excitation reactance X of power grid and booster station transformermConnected in parallel to form a second part, analogously XmAbsorbing reactive power of Qm=Vg/jXmIn which V isgIs the common junction voltage. The part needs to be provided by all fans together, otherwise, the part is provided by the power grid.
The third part comprises a line resistor RlkAnd line reactance XlkKth typhoon machine WkTransformer TkPrimary side leakage reactance Xkσ1And secondary reactance Xkσ2Primary and secondary leakage reactance X of booster station transformerσ1And secondary reactance Xσ2Let us put the fan WkTransformer TkCombined with the primary and secondary leakage impedances of the booster stage transformer, as shown in fig. 10, Zk=Rlk+j(Xlk+Xkσ+Xσ) Wherein X iskσ=Xkσ1+Xkσ2,Xσ=Xσ1+Xσ2. The line impedance varies in part due to the different wind turbine construction locations. This portion causes the fan outlet voltage to be different from the point of common connection voltage.
In order to achieve more precise control of the voltage of the common connection point 40, an embodiment of the present invention employs a strategy of combining multiple adjustment modes. Division according to reactive regulation speed, including fixed compensation (reactive compensation of internal network impedance), slow compensation (due to far-end network voltage V)LExternal network impedance reactive compensation due to fluctuations in wind farm), fast compensation (reactive compensation part due to fast changes in wind farm active power).
According to the circuit model established above, the factors causing the voltage variation at the common connection point 40 can be divided into the following three parts:
external voltage disturbances (due to grid load variations), which are slow and unpredictable, can be represented by (Q) in equation 1extXext)/VLCompensation is carried out, which belongs to a slow compensation part and is generally a second-level regulation rate.
Reactive Q for excitation impedance absorption of booster station transformermAnd reactive Q absorbed by transformer excitation impedance of each fan 10kmThis part belongs to the fixed compensation part, since the reactive power of this part can be considered approximately constant in relation to the bus voltage applied to the transformer, since the voltage fluctuation in actual operation is not so large.
The output power of the fan is fluctuated due to the fluctuation of the wind speed, so according to the formula 1 (P)extRext)/VLThis will cause the voltage at the point of common connection 40 to fluctuate and will necessarily cause the voltage at the point of common connection 40 to increase due to the rapidity of the wind speed variationThe speed fluctuates, and the second-level reactive power regulation cannot keep up with the change speed of the voltage. The adjustment speed must be increased (typically several tens of ms). This part belongs to the fast compensation part.
The reactive compensation is performed by the central controller 80 and the sub-controller 70.
The central controller 80 is responsible for the calculation of the reactive power compensation of the fixed reactive compensation and the slow reactive compensation, and the reactive output sum of all the wind turbines of the whole wind farm is as follows:
QRef=Qins+Qm+∑Qkm
wherein QinsReactive compensation power delivered by dispatching center, ∑ QkmFor the sum of the reactive compensation power absorbed by the excitation reactances of all the wind turbine 10 transformers, the central controller 80 distributes Q proportionally according to the reactive availability value of each grid branchRefThe central controller 80 may also distribute the reactive compensation power Q according to a preset weighting value for each grid branchRefObtaining the reactive compensation power Q of each power grid branchZL-Ref1。
The sub-controller 70 is responsible for calculating the reactive power of the fast reactive compensation, and in order to compensate the voltage difference caused by the active fluctuation in the formula 1, the sub-controller 70 calculates the reactive compensation power Q of the power grid branch which needs to be compensated in real time according to the real-time value of the active output of the power grid branchZL-Ref2And is distributed to each fan 10 to obtain the reactive compensation power Q of each fank_Ref2Then, the sub-controller 70 calculates the reactive compensation power Q of each fan of the power grid branch according to the start-stop state of each fan of the power grid branch, the impedance parameter of the power grid branch, the parameter of the local transformer, the capacity of the fan and the likek-Ref1。
The reactive compensation power of each wind turbine 10 is obtained, and the sub-controller 70 receives the reactive compensation power Q distributed by the central controller 80ZL-Ref1And each fan 10 allocated to the branch of the power grid is marked as Qk_Ref1Such that each fan 10 needs to sendHas a reactive power of Qk_Ref=Qk_Ref1+Qk_Ref2. When noteworthy, Qk_Ref1And Qk_Ref2Is different in update frequency, Qk_Ref1Mainly from the central controller 80, the speed is slow; qk_Ref2In order to compensate for power fluctuations, the speed is fast.
The embodiment of the invention provides a brand-new network layout and reactive voltage control strategy for reactive voltage control of a wind power plant, which comprises the following steps: fixed compensation reactive power, slow compensation reactive power and fast compensation reactive power. A sub-controller and a central controller are additionally arranged to complete the reactive voltage control. The system provided by the embodiment of the invention can track the change of the generated power and quickly adjust the reactive voltage, so that the voltage of the common connection point of the wind power plant is accurately controlled. In addition, according to the first embodiment of the invention, the existing wind power plant is improved, and the sub-controllers of each power grid branch can be compatible with different manufacturers and different types of fan interfaces; the fan monitoring data of the power grid branch are normalized, so that an interface between each sub-controller and the central controller is standardized, and the system is convenient to expand, maintain and upgrade. Furthermore, the number of fans facing each sub-controller of each power grid branch is relatively small, time delay caused by communication is reduced, control bandwidth is greatly improved, and necessary conditions are provided for a rapid reactive power compensation strategy.
Example two
The second embodiment of the invention provides a method for controlling reactive voltage of a wind power plant, which is used for the system in the first embodiment of the invention. As shown in fig. 11, the method of the second embodiment of the present invention includes the following steps:
s1, calculating reactive compensation power Q of each power grid branch by the central controller according to the voltage change of the public connection point caused by the internal network parameters of the wind power plant and the reactive load change of the external networkZL-Ref1。
The second embodiment of the invention adopts a strategy of combining a plurality of adjustment modes. According to the idle workRegulating the speed division, including fixed compensation (reactive compensation due to internal network impedance), slow compensation (due to the far-end grid voltage V)LExternal network impedance reactive compensation due to fluctuations in wind farm), fast compensation (reactive compensation part due to fast changes in wind farm active power). Wherein, the fixed compensation and the slow compensation are completed by the central processing unit, and the fast compensation is completed by the sub-controller.
The central controller collects all fan information reported by each sub-controller, and uploads the fan information to the dispatching center after statistics; and receiving reactive compensation power issued by the dispatching center, and carrying out distribution calculation of reactive instructions on each power grid branch by combining fan information (impedance change of an internal network and impedance change of an external network of the wind power plant and the like) uploaded by each sub-controller.
The reactive output sum of all the fans of the whole wind power plant is as follows:
QRef=Qins+Qm+∑Qkm
wherein Qins∑ Q reactive compensation power received by the central controller and transmitted by the dispatching centerkmFor the sum of reactive compensation power, Q, absorbed by the excitation reactance of all fan transformersmReactive compensation power absorbed by the excitation impedance of the booster station transformer. The central controller calculates the reactive output sum Q caused by the voltage change of the public connection point caused by the reactive load change of the internal network parameters and the external network of the wind power plantRef1The reactive compensation power Q on each power grid branch is obtained by distributing the reactive available value of each power grid branch in proportion or distributing the reactive compensation power according to the preset weighted value of each power grid branchZL-Ref1。
It should be noted that the sub-control in the second embodiment of the present invention may convert the collected fan information into a preset standard data format and upload the converted data to the central controller, so that the sub-control may be compatible with fans of different models and different manufacturers
S2, the central controller issues none of each power grid branchWork-compensating power QZL-Ref1To the corresponding sub-controller.
And S3, receiving the instruction by the sub-controller and distributing the instruction to each fan of the branch of the power grid. The sub-controller receives the reactive compensation power Q sent by the central controllerZL-Ref1After the instruction, the reactive compensation power Q of each fan of the power grid branch is obtained by combining the starting and stopping states of each fan of the power grid branch, the impedance parameter of the power grid branch, the parameter of the local transformer, the capacity of the fan and the like through comprehensive calculationk_Ref1And the high-priority communication frame is quickly distributed to the fans of the power grid branches for execution.
While performing step S3, the following steps are performed in parallel:
s4, calculating reactive compensation power Q of each power grid branch by the sub-controller according to voltage change of the public connection point caused by wind speed fluctuation of the wind power plantZL-Ref2. The sub-controller collects the key operation state (such as wind speed fluctuation of a wind power plant) of each fan of the power grid branch by using a high-priority communication frame, and calculates the reactive compensation power Q required for real-time compensation of the power grid branch according to the real-time value of the active output of the power grid branch in order to compensate the voltage difference of the public connection point caused by the active fluctuationZL-Ref2。
S5, according to the reactive compensation power Q of the branch of the power grid where the power grid is locatedZL-Ref2Calculating reactive compensation power Q of each fan of the branch of the power gridk_Ref2。
S6, calculating the reactive compensation power Q required to be sent by each fank_Ref=Qk_Ref1+Qk_Ref2And sent to each fan. When noteworthy, Qk_Ref1And Qk_Ref2Is different in update frequency, Qk_Ref1Mainly comes from a central controller, and has low speed; qk_Ref2In order to compensate for power fluctuations, the speed is fast.
The second embodiment of the invention provides a brand-new reactive voltage control strategy: fixed compensation reactive power, slow compensation reactive power and fast compensation reactive power. A sub-controller and a central controller are additionally arranged to complete the reactive voltage control. The method of the second embodiment of the invention can track the change of the generated power and quickly adjust the reactive voltage, so that the voltage of the common connection point of the wind power plant is accurately controlled. In addition, the embodiment of the invention improves the existing wind power plant, and the sub-controllers of each power grid branch can be compatible with different manufacturers and different types of fan interfaces; the fan monitoring data of the power grid branch are normalized, so that an interface between each sub-controller and the central controller is standardized, and the system is convenient to expand, maintain and upgrade.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.
Claims (10)
1. A reactive voltage control system of a wind power plant comprises a plurality of power grid branches and a booster station which is respectively connected with each power grid branch, wherein each power grid branch comprises a plurality of fans, and the booster station outputs voltage to an external network through a public connection point; the system is characterized by comprising a plurality of sub-controllers and a central controller arranged on a booster station, wherein each power grid branch is provided with at least one sub-controller, and each sub-controller is in communication connection with the central controller; wherein,
the central controller is used for controlling the wind powerCalculating reactive compensation power Q of each power grid branch circuit according to voltage change of public connection points caused by reactive load change of field internal network parameters and external networkZL-Ref1And issues instructions to the corresponding sub-controllers; the reactive compensation power QZL-Ref1The central controller distributes the reactive output sum Q according to the reactive availability value or the weighted value of each network branchRef1Obtaining;
the sub-controller is used for receiving the instruction and distributing the instruction to each fan, and the reactive compensation power distributed by each fan is calculated to be Q by combining the starting and stopping states of all fans of the power grid branch, the impedance parameter of the power grid branch, the parameter of the local transformer and the fan capacityk_Ref1。
2. The system of claim 1, wherein the central controller comprises:
a first calculation module for calculating the reactive output sum Q caused by the voltage change of the public connection point caused by the reactive load change of the internal network parameter and the external network of the wind power plantRef1;
A first distribution module for distributing the sum Q according to the reactive outputRef1Distributing to obtain the reactive compensation power Q of each power grid branchZL-Ref1。
3. The system of claim 2, wherein the sub-controller comprises:
a second distribution module for distributing the reactive compensation power Q according to each power grid branchZL-Ref1Distributing and obtaining the reactive compensation power Q of each fan of the power grid branchk-Ref1。
4. The system of any one of claims 1 to 3, wherein the sub-controller further comprises:
the second calculation module is used for calculating reactive compensation power Q of the power grid branch according to voltage change of the public connection point caused by wind speed fluctuation of the wind power plantZL-Ref2;
A third calculation module for calculating the reactive compensation power Q according to the branch of the power gridZL-Ref2Calculating reactive compensation power Q of each fan of the branch of the power gridk_Ref2;
A third distribution module used for calculating the reactive compensation power Q required to be sent by each fan of the branch of the power gridk_Ref=Qk_Ref1+Qk_Ref2And sent to each fan.
5. The system of claim 1, wherein the sub-controller further comprises:
and the acquisition module is used for acquiring the fan information of the power grid branch, converting the fan information into a preset standard data format and then uploading the preset standard data format to the central controller.
6. A method of wind farm reactive voltage control for a system according to any of claims 1 to 5, characterized in that the method comprises:
the central controller calculates the reactive compensation power Q of each power grid branch according to the voltage change of the public connection point caused by the internal network parameters of the wind power plant and the reactive load change of the external networkZL-Ref1And issues instructions to the corresponding sub-controllers; the reactive compensation power QZL-Ref1The central controller distributes the reactive output sum Q according to the reactive availability value or the weighted value of each network branchRef1Obtaining;
the sub-controller receives the instruction and distributes the instruction to each fan, and reactive compensation power distributed by each fan is calculated to be Q by combining the starting and stopping states of all fans of the power grid branch, the impedance parameter of the power grid branch, the parameter of the local transformer and the fan capacityk_Ref1。
7. Method according to claim 6, characterized in that the central controller calculates the reactive compensation power Q of each grid branch from the grid parameters internal to the wind farm and from the voltage variation of the point of common connection caused by the reactive load variation of the external networkZL-Ref1The method comprises the following steps:
calculating reactive output sum Q caused by voltage change of public connection point caused by reactive load change of internal network parameters and external network of wind power plantRef1;
According to the reactive output sum QRef1Distributing to obtain the reactive compensation power Q of each power grid branchZL-Ref1。
8. The method of claim 7, wherein the sub-controller receiving commands and assigning to each fan comprises:
the sub-controller is used for compensating the power Q according to the reactive power of each power grid branchZL-Ref1Distributing and obtaining the reactive compensation power Q of each fan of the power grid branchk-Ref1。
9. The method of any of claims 6 to 8, further comprising:
the sub-controller calculates the reactive compensation power Q of the power grid branch according to the voltage change of the public connection point caused by wind speed fluctuation of the wind power plantZL-Ref2;
Reactive compensation power Q according to the branch of the power networkZL-Ref2Calculating reactive compensation power Q of each fan of the branch of the power gridk_Ref2;
Calculating reactive compensation power Q required to be sent by each fan of the branch of the power gridk_Ref=Qk_Ref1+Qk_Ref2And sent to each fan.
10. Method according to any one of claims 6 to 8, characterized in that in execution the central controller calculates the reactive compensation power Q of each grid branch from the wind farm internal parameters and the point of common connection voltage variations caused by external network reactive load variationsZL-Ref1Before, still include:
and the sub-controller collects the fan information of the power grid branch, converts the fan information into a preset standard data format and uploads the preset standard data format to the central controller.
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