Method for wind power plant static synchronous phase modifier to participate in AVC control

Abstract

The invention belongs to the technical field of automatic voltage control of a power grid, and particularly relates to a method for a static synchronous phase modifier of a wind power plant to participate in AVC control. The method comprises the steps that when each control cycle arrives, a wind power plant AVC substation firstly eliminates voltage out-of-limit and completes voltage regulation; then, reactive calculation iteration values of reactive equipment including the static synchronous phase modifier are calculated; judging whether the reactive power sent by the reactive power equipment is in a capacitive interval or an inductive interval, and adjusting a reactive power calculation iteration value of the static synchronous phase modifier through secondary distribution of the reactive power so as to obtain a corresponding reactive power set value; and the AVC substation issues a corresponding control mode, an outlet voltage set value, a reactive power set value and voltage upper and lower limit set values to the static synchronous phase modifier. According to the invention, anchoring of reactive voltage operation points of the static synchronous phase modifier is realized through reactive secondary distribution, ring current of each reactive device is avoided or reduced, and automatic switching of a voltage source control mode and a reactive source control mode of the static synchronous phase modifier is realized.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of automatic voltage control of power grid, and particularly relates to a method for participating in AVC control by a static synchronous compensator of a wind farm. BACKGROUND

[0002] The static synchronous compensator (SSC: Static Self-Synchronous Compensator, hereinafter referred to as SSC) is a new type of power grid voltage and frequency support equipment based on power electronic technology. It is realized based on network construction type control technology through a super capacitor and a high-voltage power electronic converter. When the power grid voltage fluctuates, the SSC can quickly respond to provide necessary voltage support and maintain the stability of the power grid voltage. As a relatively independent synchronous voltage source, the SSC cannot suddenly change the potential amplitude when a system fault occurs, and provides fast reactive power support instantaneously. After the fault is removed, there is no reactive power reverse adjustment, and the reactive power response characteristics can completely match the transient reactive power response of the traditional compensator during system fault. In addition to the excellent reactive power and voltage regulation characteristics, the SSC also has high inertia and high damping characteristics, which enhances the stability of the power system. Based on the excellent characteristics of the SSC, domestic new energy stations have begun to gradually pilot and promote the construction and application of the SSC.

[0003] The wind farm AVC (Automatic Voltage Control) substation is generally installed in a new energy station, receives the instructions issued by the AVC master station system of the power grid control center, and then controls the reactive power equipment (mainly including wind turbines, static synchronous compensators and SVG equipment) in the station to make the grid-connected point voltage / reactive power meet the requirements of the power grid. After the SSC is built and put into operation, it also needs to be included in the control of the AVC substation.

[0004] At present, the AVC substation generally takes the SSC as a "reactive power source" device similar to SVG to calculate the control strategy, and controls according to the reactive power voltage comprehensive control mode to issue the reactive power setting instruction and the voltage upper and lower limit constraint condition. This control mode can play the voltage regulating role when the wind farm voltage fluctuation rate is small, but cannot fully exert the role of the SSC "voltage source" to quickly suppress the farm station voltage fluctuation. In order to fully exert the role of the SSC "voltage source", some manufacturers propose to control all SSCs in the farm station as "voltage sources". The AVC substation estimates the outlet end voltage change of the SSC in each control period, and issues the voltage setting value (or increment value) instruction to the SSC. This mode can fully exert the characteristics of the SSC "voltage source", but in the control calculation, in order to reserve the dynamic reactive power regulation margin of the SSC, the reactive power setting calculation value is set near 0, which is easy to cause the reactive power circulating current of the SSC and other devices, and when the system operating condition changes greatly, the multiple "voltage source" characteristics of the SSC devices may cause the repeated adjustment and oscillation of the reactive power, cannot dynamically adjust the operation mode of the SSC, needs artificial intervention, increases the problem processing time, and is not conducive to the rapid problem processing. SUMMARY

[0005] The purpose of the present application is to overcome the deficiencies of the prior art, and to provide a method for wind farm static synchronous compensator participating in AVC control. The present application anchors the static synchronous compensator SSC reactive power voltage operating point through the secondary distribution of reactive power, avoids or reduces the circulating current of each reactive power device; and the present application also realizes the automatic switching of the voltage source and reactive power source control modes of the SSC device.

[0006] The embodiment of the present application provides a method for wind farm static synchronous compensator participating in AVC control, which comprises the following steps:

[0007] When each control period arrives, the wind farm AVC substation judges the voltage of the booster station bus to eliminate voltage over-limit and complete voltage regulation;

[0008] After the voltage regulation is completed, the reactive power calculation iteration value of each reactive power device of the wind farm is calculated, wherein the reactive power device comprises a wind turbine cluster, an SVG and a static synchronous compensator;

[0009] The reactive power of the reactive power device is judged to be in the capacitive interval or the inductive interval, and the reactive power calculation iteration value of each reactive power device is combined to adjust the reactive power calculation iteration value of the static synchronous compensator through the secondary distribution of reactive power, so as to obtain the reactive power setting value of the static synchronous compensator;

[0010] The AVC substation sends the corresponding control mode, output voltage setting value, reactive power setting value, and voltage upper and lower limit setting value to the stationary synchronous condenser, wherein the control mode includes voltage source control mode and reactive power source control mode.

[0011] In one specific embodiment of the present invention, it further includes:

[0012] Set the initial reactive voltage oscillation flag S of the AVC substation wave =0;

[0013] At the arrival of each control cycle, if the AVC substation acquires a reactive voltage oscillation signal sent by any stationary synchronous condenser, then set S... wave The flag is set to 1; otherwise, keep S. wave The logo remains unchanged;

[0014] If S wave The flag is 1 and the AVC substations are consecutive N c If the reactive voltage oscillation signal sent by the stationary synchronous condenser is not collected in a control cycle, then S will be... wave The flag is reset to 0.

[0015] In one specific embodiment of the present invention, it further includes:

[0016] When the AVC substation determines the bus voltage of the booster station:

[0017] 1) If the voltage of any busbar exceeds the voltage safety limit, an emergency control mode is activated to regulate the voltage back to the normal range; wherein, if the voltage U of the high-voltage side busbar exceeds the limit... pcc ≥U sup U sup To meet the upper limit of voltage safety, the target voltage value of the AVC substation is adjusted to U. sup -U dead Calculate the voltage difference ΔU = U sup -U dead -U pcc U dead This is the dead zone for wind farm voltage control; if the high-voltage side bus voltage U pcc ≤U sdn U sdn To set the voltage safety lower limit, the voltage target value of the AVC substation is adjusted to U. sdn +U dead ΔU=U sdn +U dead -U pcc If the voltage on the low-voltage side bus exceeds the limit, then the voltage is converted to the high-voltage side according to the transformer turns ratio to calculate ΔU.

[0018] Then it enters the correction control mode to correct the voltage difference;

[0019] 2) If the voltage of each bus is within the normal range, then calculate the voltage difference ΔU = U set -U pcc ,in:

[0020] If |ΔU|≥U dead Then, it enters the correction control mode to correct the voltage difference;

[0021] If |ΔU|<U bal U bal To establish a dead zone for voltage balance control in the wind farm, let ΔU = 0. Once voltage regulation is complete, reactive power will be redistributed.

[0022] If U bal ≤|ΔU|<U dead Then the AVC substation sends control commands according to the level control mode.

[0023] In a specific embodiment of the present invention, entering the correction control mode to correct the voltage difference includes:

[0024] Let U step For each round of voltage adjustment step size, determine:

[0025] If |ΔU|>U step Then update Otherwise, keep the value of ΔU unchanged.

[0026] In one specific embodiment of the present invention, the reactive power calculation iteration value of each reactive power device in the wind farm is calculated using any one of the following strategies: equal margin, equal proportion, or wind turbine priority.

[0027] In a specific embodiment of the present invention, adjusting the reactive power calculation iteration value of the static synchronous condenser through reactive power secondary allocation includes:

[0028] If the reactive power generated by the reactive power equipment is in the inductive range, the reactive power calculation iteration value of the static synchronous condenser is adjusted to the inductive reactive power operating point through secondary reactive power allocation; if the reactive power generated by the reactive power equipment is in the capacitive range, the reactive power calculation iteration value of the static synchronous condenser is adjusted to the capacitive reactive power operating point through secondary reactive power allocation.

[0029] In one specific embodiment of the present invention, it further includes:

[0030] 1) For a wind farm with K wind turbine clusters, let P be the current active power of the i-th wind turbine cluster. iPVC The unproductive value is Q. iPVC The reactive power limit is QLmtUp iPVCThe lower limit of reactive power is QLmtDn iPVC The total reactive power of the wind turbine cluster is obtained by summing the reactive power of each wind turbine cluster.

[0031] For M SVG devices in a wind farm, let Q be the current reactive power of the j-th SVG device. jSVG This can increase reactive power to QUp. jSVG The reactive power can be reduced to QDn. jSVG The inherent dead zone of reactive power regulation at 0 is QDead. jSVG The total reactive power of the SVG device is obtained by accumulating these values.

[0032] For N SSC devices in a wind farm, let Q be the current reactive power of the x-th SVG device. xSSC This can increase reactive power to QUp. xSSC The reactive power can be reduced to QDn. xSSC The static synchronous condenser uses grid technology, and its reactive power can be adjusted to 0. The reactive power capacitive operating point is QCP. xSSC The reactive inductive operating point is QRL. xSSC The total reactive power of the stationary synchronous condenser is obtained by summing the current values. The total reactive power at the capacitive operating point of the static synchronous condenser is obtained by summing up the reactive power. The total reactive power inductive operating point of the static synchronous condenser is:

[0033] 2) Judgment:

[0034] 2-1) If Q sumPVC >0 and Q sumSVG >0 and Q sumSSC <Q CPSSC If all reactive power equipment in the wind farm is operating in the capacitive reactive power range and the stationary synchronous condenser has not reached the capacitive operating point, proceed to step 3).

[0035] 2-2) If Q sumPVC <0 at the same time Q sumSVG <0 and Q sumSSC >Q RLSSC If all reactive power equipment in the wind farm is operating in the inductive reactive power range and the stationary synchronous condenser has not reached the inductive reactive power operating point, proceed to step 6).

[0036] 2-3) If the conditions in steps 2-1) and 2-2) are not met, then no secondary allocation of reactive power will be performed;

[0037] 3) Calculate the reactive power regulation replacement amount, specifically including:

[0038] For K wind turbine clusters, let Q be the current reactive power of the i-th wind turbine cluster.iPVC ;

[0039] Decision: If Q iPVC When the value is greater than 0, the reactive power replacement capacity Qd of the i-th wind turbine cluster is reduced. iPVC =Q iPVC Otherwise, let Qd iPVC =0;

[0040] After traversing all wind turbine clusters, the reactive power reduction and replacement capacity of the K wind turbine clusters is accumulated to obtain the total reactive power reduction and replacement capacity of the wind turbine clusters.

[0041] For M SVG devices, let Q be the current reactive power of the j-th SVG device. jSVG ;

[0042] Judgment: If Q jSVG >QDead jSVG Then the reactive power replacement capacity Qd of the j-th SVG device is reduced. jSVG =Q jSVG -QDead jSVG Otherwise, let Qd jSVG =0;

[0043] After all SVG devices have been traversed, the total reactive power reduction and replacement capacity of the SVG is obtained. Calculate the total reactive power reduction replacement capacity of the wind turbine cluster and SVG, Qd = Qd PVC +Qd SVG ;

[0044] For N stationary synchronous condensers, let Q be the current reactive power of the x-th stationary synchronous condenser. xSSC ;

[0045] Decision: If Q xSSC <QCP xSSC Then, the reactive power demand Qu of the xth stationary synchronous condenser will be increased. xSSC =QCP xSSC -Q xSSC Otherwise, let Qu xSSC =0;

[0046] After all static synchronous condensers have been traversed, the total reactive power upward adjustment demand of the static synchronous condensers is obtained.

[0047] Let the reactive power adjustment displacement Qadj = Qu SSC Then determine: if Qadj > Qd, then update Qadj = Qd; otherwise, Qadj remains unchanged.

[0048] 4) Based on the results of step 3), make a judgment:

[0049] If Qadj < Q thre If the reactive power is not redistributed, then no secondary allocation of reactive power is performed; otherwise, proceed to step 5) to perform secondary allocation calculation of reactive power.

[0050] Among them, Q thre This is a preset threshold for reactive power replacement;

[0051] 5) Obtain the reactive power calculation iteration value after reactive power replacement for each reactive power device;

[0052] Here, the reactive power calculation iteration value of the i-th wind turbine cluster is denoted as Qest. iPVC After reactive power substitution calculation, update

[0053] Let the reactive power calculation iteration value of the j-th SVG be Qest. jSVG After reactive power substitution calculation, update

[0054] Let Qest be the reactive power calculation iteration value of the x-th stationary synchronous condenser. xSSC After reactive power substitution calculation, update

[0055] 6) Calculate the reactive power regulation replacement amount, specifically including:

[0056] For a cluster of K wind turbines, the current reactive power of the i-th wind turbine cluster is Q. iPVC ;

[0057] Decision: If Q iPVC If the value is less than 0, then the reactive power replacement capacity Qu of the i-th wind turbine cluster is increased. iPVC =Q iPVC ×-1.0, otherwise let Qu iPVC =0;

[0058] After traversing all wind turbine clusters, the reactive power adjustment and replacement capacity of the K wind turbine clusters is summed to obtain the total reactive power adjustment and replacement capacity of the wind turbine clusters.

[0059] For M SVG devices, let Q be the current reactive power of the j-th SVG device. jSVG ;

[0060] Decision: If Q jSVG <QDead jSVG If the value is ×-1.0, then the reactive power replacement capacity Qu of the j-th SVG device is increased. jSVG = -1.0 × QDead jSVG -Q jSVG Otherwise, let Qu jSVG =0;

[0061] After all SVG devices have been traversed, the total reactive power upswing and replacement capacity of the SVG is obtained.

[0062] Calculate the total reactive power upsampling capacity Qu = Qu of the wind turbine cluster and SVG. PVC +Qu SVG ;

[0063] For N stationary synchronous condensers, let Q be the current reactive power of the x-th stationary synchronous condenser. xSSC ;

[0064] Decision: If Q xSSC >QRL xSSC Then, the reactive power demand Qd of the xth stationary synchronous condenser is reduced. xSSC =Q xSSC -QRL xSSC Otherwise, let Qd xSSC =0;

[0065] After all stationary synchronous condensers have been traversed, the total reactive power reduction demand of the stationary synchronous condensers is obtained.

[0066] Let the reactive power regulation displacement Qadj = Qd SSC Then determine: if Qadj > Qu, then update Qadj = Qu; otherwise, Qadj remains unchanged.

[0067] 7) Based on the results of step 6), make a judgment:

[0068] If Qadj < Q thre If the reactive power is not redistributed, then no secondary allocation of reactive power will be performed; otherwise, proceed to step 8) to perform secondary allocation of reactive power.

[0069] 8) Obtain the reactive power calculation iteration value after reactive power replacement for each reactive power device;

[0070] Here, the reactive power calculation iteration value of the i-th wind turbine cluster is denoted as Qest. iPVC After reactive power substitution calculation, update

[0071] Let the reactive power calculation iteration value of the j-th SVG be Qest. jSVG After reactive power substitution calculation, update

[0072] Let Qest be the reactive power calculation iteration value of the x-th stationary synchronous condenser. xSSC After reactive power substitution calculation, update

[0073] In one specific embodiment of the present invention, it further includes:

[0074] When the reactive voltage oscillation flag S wave When the value is 0, for static synchronous condensers in voltage source control mode, the AVC substation issues a control mode setting of voltage source control mode, and issues the corresponding output voltage setting, reactive power recommendation, voltage upper limit setting, and voltage lower limit setting for that device. For static synchronous condensers in reactive power source control mode, one static synchronous condenser is randomly selected and designated as the z-th static synchronous condenser. Then, the control mode setting is issued to this static synchronous condenser as voltage source control mode, and the corresponding output voltage setting Uset is issued. zSSC Recommended reactive power value Qset zSSC The control mode setting for the remaining static synchronous condensers in reactive power source control mode during the current control cycle is set to reactive power source control mode, and the corresponding reactive power setting, suggested output voltage value, upper voltage limit setting, and lower voltage limit setting are issued to the device.

[0075] When the reactive voltage oscillation flag S wave When the value is 1, for all static synchronous condensers in reactive power source control mode, the control mode setting is issued as reactive power source control mode, and the corresponding reactive power setting value, suggested output voltage value, upper voltage setting value, and lower voltage setting value are issued for that device. For static synchronous condensers in voltage source control mode that send reactive voltage oscillation signals in the current control cycle, one static synchronous condenser is randomly selected and designated as the a-th static synchronous condenser. Then, the reactive power source control mode is issued to this static synchronous condenser, and the corresponding reactive power setting value Qset is issued for that device. aSSC Recommended output voltage value Uset aSSC Voltage upper limit setting value Ulmtup aSSC and voltage lower limit setting value Ulmtdn aSSC For stationary synchronous condensers that are in voltage source control mode and have not sent reactive voltage oscillation signals in the current control cycle, maintain the current state of the equipment, send the control mode setting to voltage source control mode, and send the corresponding output voltage setting, reactive power suggestion value, voltage upper limit setting, and voltage lower limit setting for the equipment.

[0076] Features and beneficial effects of the present invention:

[0077] Most current SSCs (Solution Controllers) adopt a "reactive power source" control mode, which cannot fully utilize their autonomous voltage regulation function. SSCs, implemented using grid technology, can be controlled as a "voltage source." In this invention, when the wind farm AVC substation performs reactive power distribution, after completing the initial distribution, it performs internal iterative calculations. Through secondary reactive power distribution, it anchors the reactive voltage operating point of the SSC, thereby avoiding or reducing circulating currents between reactive power devices. Each control cycle, the AVC substation sends control mode suggestions to the SSC. The SSC, based on the received suggestions and its own circumstances, autonomously selects the control mode and transmits the current control mode to the AVC substation in real time, thus enabling flexible switching between "voltage source" and "reactive power source" for the SSC equipment.

[0078] This invention can fully utilize the autonomous voltage regulation function of SSC, reduce voltage fluctuations, make the voltage of wind farms more stable, indirectly promote the consumption of new energy, avoid or reduce voltage assessment, and improve the operating efficiency of wind farms. Attached Figure Description

[0079] Figure 1 This is an overall flowchart of a method for a wind farm static synchronous condenser to participate in AVC control according to an embodiment of the present invention. Detailed Implementation

[0080] This invention proposes a method for wind farm static synchronous condensers to participate in AVC control, which is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0081] This invention provides a method for wind farm static synchronous condensers to participate in AVC control, comprising:

[0082] At the arrival of each control cycle, the wind farm AVC substation determines the voltage of the booster station bus to eliminate voltage over-limit and complete voltage regulation;

[0083] After the voltage regulation is completed, the reactive power calculation iteration value of each reactive power device in the wind farm is calculated. The reactive power device includes: wind turbine cluster, SVG and static synchronous condenser.

[0084] It is determined that the reactive power generated by the reactive power equipment is in the capacitive or inductive range. Based on the reactive power calculation iteration value of each reactive power equipment, the reactive power calculation iteration value of the static synchronous condenser is adjusted through the secondary allocation of reactive power, thereby obtaining the reactive power setting value of the static synchronous condenser.

[0085] The AVC substation sends the corresponding control mode, output voltage setting value, reactive power setting value, and voltage upper and lower limit setting value to the stationary synchronous condenser, wherein the control mode includes voltage source control mode and reactive power source control mode.

[0086] In a specific embodiment of the present invention, the method for a wind farm static synchronous condenser to participate in AVC control is as follows: Figure 1 As shown, it includes the following steps:

[0087] 1) Initialize the reactive voltage oscillation flag S of the AVC substation wave It is 0.

[0088] 2) At the arrival of each control cycle, the AVC substation collects the active power P at the wind farm's grid connection point. pcc reactive Q pcc Voltage U pcc And the voltage control command U issued by the dispatcher set Simultaneously, information from various equipment in the wind farm's booster station is collected, including: status information of switches and disconnectors, voltage information of each busbar, tap position information of the main transformer, and active and reactive power information on the high, medium, and low voltage sides of the main transformer; active power, reactive power, adjustable upper limit of reactive power, and adjustable lower limit of reactive power for each wind turbine cluster; active power, reactive power, reactive power increase / decrease, operating status, and fault lockout status for each SVG device; and active power, reactive power, reactive power increase / decrease, operating status, fault lockout status, current control mode, and whether reactive voltage oscillation occurs for each SSC device. For SSC devices connected to the low-voltage side busbar of the wind farm via the booster transformer, active and reactive power information on the high and low voltage sides of the SSC booster transformer is also collected.

[0089] 3) Based on the result of step 2), determine:

[0090] If the information collected by the AVC substation includes reactive voltage oscillation signals transmitted from any SSC device, then set S... wave The flag is set to 1; otherwise, keep S. wave The logo remains unchanged.

[0091] If S wave The flag is 1 and the AVC substations are consecutive N c If the information collected in each control cycle does not include the reactive voltage oscillation signal sent by the SSC device, then S... wave The flag is reset to 0.

[0092] In this embodiment, N c The value can generally be set between 10 and 20.

[0093] 4) The AVC substation determines whether the voltage of each busbar in the substation exceeds the voltage safety limit:

[0094] 4-1) If the voltage of any busbar exceeds the voltage safety limit, the emergency control mode is activated to adjust the voltage of the busbar that exceeds the limit back to the normal range; among which, if the voltage U of the high-voltage side busbar... pcc ≥Usup (U sup If the voltage safety upper limit is used, then the voltage target value of the AVC substation is adjusted to U. sup -U dead Calculate the voltage difference ΔU = U sup -U dead -U pcc U dead This is the dead zone for wind farm voltage control; if the high-voltage side bus voltage U pcc ≤U sdn (U sdn If the voltage safety lower limit is used, then the voltage target value of the AVC substation is adjusted to U. sdn +U dead ΔU=U sdn +U dead -U pcc If the voltage on the low-voltage side bus exceeds the limit, then the voltage is converted to the high-voltage side according to the transformer turns ratio to calculate ΔU.

[0095] Then proceed to step 5).

[0096] 4-2) If the voltage of each bus is within the normal range, then calculate the voltage difference ΔU = U set -U pcc ,in:

[0097] If |ΔU|≥U dead If so, then enter the correction control mode and proceed to step 5);

[0098] If |ΔU|<U bal U bal If the voltage balance control dead zone of the wind farm is reached, the optimized control mode is entered and ΔU = 0 is set. At this time, it is not necessary to adjust the voltage of the high-voltage side bus, but to optimize the reactive power distribution of each device and proceed to step 6).

[0099] If U bal ≤|ΔU|<U dead Then, the AVC substation issues control commands according to the leveling control mode (leveling commands generally use the current reactive power value of each reactive power device; for some reactive power devices with poor response performance, the command value calculated in the previous control cycle can be used. At the same time, the reactive power leveling command is directly assigned to the reactive power calculation iteration value of each device), and proceeds to step 8).

[0100] 5) Correct the voltage difference and calculate the reactive power regulation.

[0101] Let U step For each round of voltage adjustment step size, determine:

[0102] If |ΔU|>U step Then update Otherwise, keep the value of ΔU unchanged.

[0103] Furthermore, in this embodiment, the reactive power regulation is obtained based on ΔU. in This refers to the reactive power sensitivity of the grid connection point voltage.

[0104] Then proceed to step 6).

[0105] 6) Calculate the reactive power calculation iteration value of each reactive power device according to strategies such as equal margin, equal proportion or wind turbine priority.

[0106] In this embodiment, the reactive power equipment includes: wind turbine clusters, SVG equipment, and SSC equipment.

[0107] For any reactive power device D, let its reactive power calculation iteration value be Qest. D The reactive power value is Qreal D At the start of policy computation, let Qest... D =Qreal D After strategy calculation, if reactive power device D needs to participate in reactive power regulation, then update the corresponding Qest value for that device. D Then proceed to step 7).

[0108] 7) Determine the range of reactive power generated by each reactive power device, and then adjust the reactive power calculation iteration value of each controlled SSC through secondary allocation of reactive power.

[0109] In this embodiment, if the reactive power generated by the reactive power equipment is in the inductive range, the reactive power calculation iteration value of each controlled SSC is adjusted as close as possible to the inductive reactive power operating point through secondary reactive power allocation; if the reactive power generated by the reactive power equipment is in the capacitive range, the reactive power calculation iteration value of each controlled SSC is adjusted as close as possible to the capacitive reactive power operating point through secondary reactive power allocation; the specific steps are as follows:

[0110] 7-1) For a wind farm with K wind turbine clusters, let P be the current active power of the i-th wind turbine cluster. iPVC The unproductive value is Q. iPVC The reactive power limit is QLmtUp iPVC The lower limit of reactive power is QLmtDn iPVC The total reactive power of the wind turbine cluster is obtained by summing the reactive power of each wind turbine cluster.

[0111] For M SVG devices in a wind farm, let Q be the current reactive power of the j-th SVG device. jSVG This can increase reactive power to QUp. jSVG The reactive power can be reduced to QDn. jSVG The inherent dead zone of reactive power regulation at 0 is QDead. jSVGThe total reactive power of the SVG device is obtained by accumulating these values.

[0112] For N SSC devices in a wind farm, let Q be the current reactive power of the x-th SVG device. xSSC This can increase reactive power to QUp. xSSC The reactive power can be reduced to QDn. xSSC The SSC equipment uses network technology, and its reactive power can be adjusted to 0. The reactive power capacitive operating point is QCP. xSSC The reactive inductive operating point is QRL. xSSC The total reactive power of the SSC device is obtained by summing the values. The total reactive power at the capacitive operating point of the SSC equipment is obtained by summing up the reactive power. The total reactive power inductive operating point of the SSC equipment is

[0113] In this embodiment, QCP xSSC Generally set to 10% to 15% of the reactive power capacity of the xth SSC device, QRL xSSC It is generally set to -15% to -10% of the reactive capacity of the xth SSC device.

[0114] 7-2) Judgment:

[0115] 7-2-1) If Q sumPVC >0 and Q sumSVG >0 and Q sumSSC <Q CPSSC If the reactive power equipment in the wind farm is operating in the capacitive reactive power range and the SSC has not reached the capacitive operating point, then proceed to step 7-3.

[0116] 7-2-2) If Q sumPVC <0 at the same time Q sumSVG <0 and Q sumSSC >Q RLSSC If the reactive power equipment in the wind farm is operating in the inductive reactive power range and the SSC has not reached the inductive reactive power operating point, then proceed to step 7-6.

[0117] 7-2-3) If the conditions in steps 7-2-1) and 7-2-2) are not met, it is assumed that the reactive power equipment in the wind farm does not have clear capacitive characteristics. In this case, no secondary distribution of reactive power is performed, and the process proceeds to step 8), where the voltage prediction and command issuance are executed. The reactive power iteration value in step 8) is the result calculated in step 6).

[0118] 7-3) Calculate the reactive power regulation replacement amount, specifically including:

[0119] For K wind turbine clusters, let Q be the current reactive power of the i-th wind turbine cluster. iPVC .

[0120] Decision: If Q iPVC When the value is greater than 0, the reactive power replacement capacity Qd of the i-th wind turbine cluster is reduced. iPVC =Q iPVC Otherwise, let Qd iPVC =0.

[0121] After traversing all wind turbine clusters, the reactive power reduction and replacement capacity of the K wind turbine clusters is accumulated to obtain the total reactive power reduction and replacement capacity of the wind turbine clusters.

[0122] For M SVG devices, let Q be the current reactive power of the j-th SVG device. jSVG .

[0123] Judgment: If Q jSVG >QDead jSVG Then the reactive power replacement capacity Qd of the j-th SVG device is reduced. jSVG =Q jSVG -QDead jSVG Otherwise, let Qd jSVG =0.

[0124] After all SVG devices have been traversed, the total reactive power reduction and replacement capacity of the SVG is obtained. Furthermore, calculate the total reactive power reduction replacement capacity of the wind turbine cluster and SVG, Qd = Qd PVC +Qd SVG .

[0125] For N SSC devices, let Q be the current reactive power of the x-th SSC device. xSSC .

[0126] Judgment: If 0Q xSSC <QCP xSSC Then the reactive power demand Qu of the xth SSC device will be increased. xSSC =QCP xSSC -Q xSSC Otherwise, let Qu xSSC =0.

[0127] After all SSC devices have been traversed, the total reactive power demand adjustment of the SSCs is calculated.

[0128] Let the reactive power adjustment displacement Qadj = Qu SSC Then determine: if Qadj > Qd, then update Qadj = Qd; otherwise, Qadj remains unchanged.

[0129] 7-4) Based on the results of step 7-3), make a judgment:

[0130] If Qadj < Qthre If the result is positive, then no secondary allocation of reactive power is performed, and proceed to step 8); otherwise, proceed to step 7-5) to perform secondary allocation calculation of reactive power.

[0131] Among them, Q thre Q is the preset reactive power replacement threshold. thre The value is generally between 0.2 and 0.5.

[0132] 7-5) Based on the results of step 6), obtain the reactive power calculation iteration value after reactive power replacement for each reactive power device.

[0133] In this embodiment, the reactive power calculation iteration value of the i-th wind turbine cluster is denoted as Qest. iPVC After reactive power substitution calculation, update

[0134] Let the reactive power calculation iteration value of the j-th SVG be Qest. jSVG After reactive power substitution calculation, update

[0135] Let the reactive power calculation iteration value of the x-th SSC be Qest. xSSC After reactive power substitution calculation, update

[0136] Then proceed to step 8).

[0137] 7-6) Calculate the reactive power regulation replacement amount, specifically including:

[0138] For a cluster of K wind turbines, the current reactive power of the i-th wind turbine cluster is Q. iPVC .

[0139] Decision: If Q iPVC If the value is less than 0, then the reactive power replacement capacity Qu of the i-th wind turbine cluster is increased. iPVC =Q iPVC ×-1.0, otherwise let Qu iPVC =0.

[0140] After traversing all wind turbine clusters, the reactive power adjustment and replacement capacity of the K wind turbine clusters is summed to obtain the total reactive power adjustment and replacement capacity of the wind turbine clusters.

[0141] For M SVG devices, let Q be the current reactive power of the j-th SVG device. jSVG .

[0142] Decision: If Q jSVG <QDead jSVG If the value is ×-1.0, then the reactive power replacement capacity Qu of the j-th SVG device is increased. jSVG = -1.0 × QDead jSVG -QjSVG Otherwise, let Qu jSVG =0.

[0143] After all SVG devices have been traversed, the total reactive power upswing and replacement capacity of the SVG is obtained.

[0144] Furthermore, calculate the total reactive power up-compensation capacity Qu = Qu of the wind turbine cluster and SVG. PVC +Qu SVG .

[0145] For N SSC devices, let Q be the current reactive power of the x-th SSC device. xSSC .

[0146] Decision: If Q xSSC >QRL xSSC Then, the reactive power demand Qd of the x-th SSC device will be reduced. xSSC =Q xSSC -QRL xSSC Otherwise, let Qd xSSC =0.

[0147] After all SSC devices have been traversed, the total reactive power demand reduction of the SSCs is calculated.

[0148] Let the reactive power regulation displacement Qadj = Qd SSC Then determine: if Qadj > Qu, then update Qadj = Qu; otherwise, Qadj remains unchanged.

[0149] 7-7) Based on the results of step 7-6), make a judgment:

[0150] If Qadj < Q thre If the result is positive, then no secondary allocation of reactive power is performed, and proceed to step 8); otherwise, proceed to steps 7-8) to perform secondary allocation calculation of reactive power.

[0151] 7-8) Based on the results of step 6), obtain the reactive power calculation iteration value after reactive power replacement for each reactive power device.

[0152] In this embodiment, the reactive power calculation iteration value of the i-th wind turbine cluster is denoted as Qest. iPVC After reactive power substitution calculation, update

[0153] Let the reactive power calculation iteration value of the j-th SVG be Qest. jSVG After reactive power substitution calculation, update

[0154] Let the reactive power calculation iteration value of the x-th SSC device be Qest. xSSCAfter reactive power substitution calculation, update

[0155] Then proceed to step 8).

[0156] 8) Calculate the estimated iterative value of the output voltage of SSC equipment in the wind farm.

[0157] In this embodiment, the final SSC output voltage value can be estimated by using compensation coefficients and conversion coefficients; or by using power flow calculation, the iterative value of the high-voltage side bus voltage of the main transformer of the wind farm can be estimated first, and then the iterative value of the low-voltage side bus voltage of the main transformer can be estimated, and the estimated iterative value of the SSC equipment output voltage can be further predicted.

[0158] For the x-th SSC device, its estimated output voltage iterative value Uest can be obtained. xSSC After verifying the voltage adjustment step size and voltage upper and lower limits, the output voltage setting value (recommended value) for the x-th SSC device can be obtained as Uset. xSSC Similarly, the reactive power calculation iteration value Qest for the x-th SSC device is... xSSC After verifying the reactive power adjustment step size and upper and lower limits of reactive power capacity, the reactive power setpoint (recommended value) Qset is obtained. xSSC The voltage upper and lower limit constraints for the x-th SSC device are obtained by taking the intersection of the locally set parameters and the voltage upper and lower limit values ​​issued by the dispatcher. The upper voltage limit setting for the x-th SSC is Ulmtup. xSSC The lower voltage limit setting is Ulmtdn xSSC .

[0159] 9) Based on the results of step 8), the AVC substation sends control mode, voltage setpoint, and reactive power recommendation value to the SSC device.

[0160] Among them, when the reactive voltage oscillation flag S wave When the value is 0, the AVC substation, for SSC devices in "voltage source" control mode, issues the control mode setting value as "voltage source" control mode, and issues the corresponding output voltage setting value, reactive power suggestion value, voltage upper limit setting value, and voltage lower limit setting value for that device; for SSC devices in "reactive power source" control mode, one SSC device is randomly selected and designated as the z-th SSC device, and then the control mode setting value as "voltage source" control mode is issued to that SSC device, and the corresponding output voltage setting value Uset for that device is issued. zSSC Recommended reactive power value Qset zSSC(In this embodiment, in the next control cycle, another device in the "reactive power source" mode will be selected and switched to the "voltage source" control mode until all SSC devices are in the "voltage source" control mode); in the current control cycle, the remaining SSC devices in the "reactive power source" control mode will issue the control mode setting value as the "reactive power source" control mode, and issue their corresponding reactive power setting value, output voltage recommendation value, voltage upper limit setting value and voltage lower limit setting value.

[0161] When the reactive voltage oscillation flag S wave When the value is 1, for all SSC devices in "reactive power source" control mode, the control mode setting is set to "reactive power source" control mode, and the corresponding reactive power setting value, suggested output voltage value, upper voltage limit setting value, and lower voltage limit setting value are issued. For SSC devices in "voltage source" control mode that have sent reactive power voltage oscillation signals in the current control cycle, one SSC device is randomly selected and designated as the a-th SSC device. Then, the "reactive power source" control mode is set for this SSC device, and the corresponding reactive power setting value Qset is issued. aSSC Recommended output voltage value Uset aSSC Voltage upper limit setting value Ulmtup aSSC and voltage lower limit setting value Ulmtdn aSSC For SSC devices in "voltage source" control mode and which have not sent reactive voltage oscillation signals in the current control cycle, maintain the current state of the device, send the control mode setting to "voltage source" control mode, and send the corresponding output voltage setting, reactive power suggestion value, voltage upper limit setting value, and voltage lower limit setting value for the device.

[0162] Furthermore, the method described in this embodiment also includes:

[0163] For SSC equipment in "voltage source" control mode, when reactive voltage oscillation is detected, the reactive power recommendation value issued by the AVC substation can be used as the reactive power setting control target of the equipment, and the equipment can be automatically switched to "reactive power source" control mode for control. Alternatively, the "voltage source" to "reactive power source" switch can be performed after receiving the "reactive power source" control mode command issued by the AVC substation.

[0164] For SSC devices in "reactive power source" control mode, when the device receives a "voltage source" control command from the AVC substation, it can switch from "reactive power source" to "voltage source" based on its own situation (whether it has just experienced reactive power voltage oscillation). If a switch is made, control is performed according to the voltage setpoint command, and the current control mode switching information is sent to the AVC substation; if no switch is made, control continues in "reactive power source" control mode according to the reactive power recommendation value issued by the AVC substation.

Claims

1. A method for participating a stationary synchronous condenser in a wind farm in AVC control, characterized in that, include: At the arrival of each control cycle, the wind farm AVC substation determines the voltage of the booster station bus to eliminate voltage over-limit and complete voltage regulation; After the voltage regulation is completed, the reactive power calculation iteration value of each reactive power device in the wind farm is calculated. The reactive power device includes: wind turbine cluster, SVG and static synchronous condenser. It is determined that the reactive power generated by the reactive power equipment is in the capacitive or inductive range. Based on the reactive power calculation iteration value of each reactive power equipment, the reactive power calculation iteration value of the static synchronous condenser is adjusted through the secondary allocation of reactive power, thereby obtaining the reactive power setting value of the static synchronous condenser. The AVC substation sends the corresponding control mode, output voltage setting value, reactive power setting value, and voltage upper and lower limit setting value to the stationary synchronous condenser, wherein the control mode includes voltage source control mode and reactive power source control mode.

2. The method according to claim 1, characterized in that, Also includes: Set the initial reactive voltage oscillation flag S of the AVC substation wave =0; At the arrival of each control cycle, if the AVC substation acquires a reactive voltage oscillation signal sent by any stationary synchronous condenser, then set S... wave The flag is set to 1; otherwise, keep S. wave The logo remains unchanged; If S wave The flag is 1 and the AVC substations are consecutive N c If the reactive voltage oscillation signal sent by the stationary synchronous condenser is not collected in a control cycle, then S will be... wave The flag is reset to 0.

3. The method according to claim 2, characterized in that, Also includes: When the AVC substation determines the bus voltage of the booster station: 1) If the voltage of any busbar exceeds the voltage safety limit, an emergency control mode is activated to regulate the voltage back to the normal range; wherein, if the voltage U of the high-voltage side busbar exceeds the limit... pcc ≥U sup U sup To meet the upper limit of voltage safety, the target voltage value of the AVC substation is adjusted to U. sup -U dead Calculate the voltage difference ΔU = U sup -U dead -U pcc U dead This is the dead zone for wind farm voltage control; if the high-voltage side bus voltage U pcc ≤U sdn U sdn To set the voltage safety lower limit, the voltage target value of the AVC substation is adjusted to U. sdn +U dead ΔU=U sdn +U dead -U pcc If the voltage on the low-voltage side bus exceeds the limit, then the voltage is converted to the high-voltage side according to the transformer turns ratio to calculate ΔU. Then it enters the correction control mode to correct the voltage difference; 2) If the voltage of each bus is within the normal range, then calculate the voltage difference ΔU = U set -U pcc ,in: If |ΔU|≥U dead Then, it enters the correction control mode to correct the voltage difference; If |ΔU|<U bal U bal To establish a dead zone for voltage balance control in the wind farm, let ΔU = 0. Once voltage regulation is complete, reactive power will be redistributed. If U bal ≤|ΔU|<U dead Then the AVC substation sends control commands according to the level control mode.

4. The method according to claim 3, characterized in that, The entry into the correction control mode, which corrects the voltage difference, includes: Let U step For each round of voltage adjustment step size, determine: If |ΔU|>U step Then update Otherwise, keep the value of ΔU unchanged.

5. The method according to claim 4, characterized in that, The reactive power calculation iteration value of each reactive power device in the wind farm is calculated using any one of the following strategies: equal margin, equal proportion, or wind turbine priority.

6. The method according to claim 4, characterized in that, The step of adjusting the reactive power calculation iteration value of the static synchronous condenser through reactive power secondary allocation includes: If the reactive power generated by the reactive power equipment is in the inductive range, the reactive power calculation iteration value of the static synchronous condenser is adjusted to the inductive reactive power operating point through secondary reactive power allocation; if the reactive power generated by the reactive power equipment is in the capacitive range, the reactive power calculation iteration value of the static synchronous condenser is adjusted to the capacitive reactive power operating point through secondary reactive power allocation.

7. The method according to claim 6, characterized in that, Also includes: 1) For a wind farm with K wind turbine clusters, let P be the current active power of the i-th wind turbine cluster. iPVC The unproductive value is Q. iPVC The maximum reactive power is QLmtUp iPVC The lower limit of reactive power is QLmtDn iPVC The total reactive power of the wind turbine cluster is obtained by summing the reactive power of each wind turbine cluster. For M SVG devices in a wind farm, let Q be the current reactive power of the j-th SVG device. jSVG This can increase reactive power to QUp. jSVG The reactive power can be reduced to QDn. jSVG The inherent dead zone of reactive power regulation at 0 is QDead. jSVG The total reactive power of the SVG device is obtained by accumulating these values. For N SSC devices in a wind farm, let Q be the current reactive power of the x-th SVG device. xSSC This can increase reactive power to QUp. xSSC The reactive power can be reduced to QDn. xSSC The static synchronous condenser uses grid technology, and its reactive power can be adjusted to 0. The reactive power capacitive operating point is QCP. xSSC The reactive inductive operating point is QRL. xSSC The total reactive power of the stationary synchronous condenser is obtained by summing the current values. The total reactive power at the capacitive operating point of the static synchronous condenser is obtained by summing up the reactive power. The total reactive power inductive operating point of the static synchronous condenser is: 2) Judgment: 2-1) If Q sumPVC >0 and Q sumSVG >0 and Q sumSSC <Q CPSSC If all reactive power equipment in the wind farm is operating in the capacitive reactive power range and the stationary synchronous condenser has not reached the capacitive operating point, proceed to step 3). 2-2) If Q sumPVC <0 at the same time Q sumSVG <0 and Q sumSSC >Q RLSSC If all reactive power equipment in the wind farm is operating in the inductive reactive power range and the stationary synchronous condenser has not reached the inductive reactive power operating point, proceed to step 6). 2-3) If the conditions in steps 2-1) and 2-2) are not met, then no secondary allocation of reactive power will be performed; 3) Calculate the reactive power regulation replacement amount, specifically including: For K wind turbine clusters, let Q be the current reactive power of the i-th wind turbine cluster. iPVC ; Decision: If Q iPVC When the value is greater than 0, the reactive power replacement capacity Qd of the i-th wind turbine cluster is reduced. iPVC =Q iPVC Otherwise, let Qd iPVC =0; After traversing all wind turbine clusters, the reactive power reduction and replacement capacity of the K wind turbine clusters is accumulated to obtain the total reactive power reduction and replacement capacity of the wind turbine clusters. For M SVG devices, let Q be the current reactive power of the j-th SVG device. jSVG ; Judgment: If Q jSVG >QDead jSVG Then the reactive power replacement capacity Qd of the j-th SVG device is reduced. jSVG =Q jSVG -QDead jSVG Otherwise, let Qd jSVG =0; After all SVG devices have been traversed, the total reactive power reduction and replacement capacity of the SVG is obtained. Calculate the total reactive power reduction replacement capacity of the wind turbine cluster and SVG, Qd = Qd PVC +Qd SVG ; For N stationary synchronous condensers, let Q be the current reactive power of the x-th stationary synchronous condenser. xSSC ; Decision: If Q xSSC <QCP xSSC Then, the reactive power demand Qu of the xth stationary synchronous condenser will be increased. xSSC =QCP xSSC -Q xSSC Otherwise, let Qu xSSC =0; After all static synchronous condensers have been traversed, the total reactive power upward adjustment demand of the static synchronous condensers is obtained. Let the reactive power adjustment displacement Qadj = Qu SSC Then determine: if Qadj > Qd, then update Qadj = Qd; otherwise, Qadj remains unchanged. 4) Based on the results of step 3), make a judgment: If Qadj < Q thre If the reactive power is not redistributed, then no secondary allocation of reactive power is performed; otherwise, proceed to step 5) to perform secondary allocation calculation of reactive power. Among them, Q thre This is a preset threshold for reactive power replacement; 5) Obtain the reactive power calculation iteration value after reactive power replacement for each reactive power device; Here, the reactive power calculation iteration value of the i-th wind turbine cluster is denoted as Qest. iPVC After reactive power substitution calculation, update Let the reactive power calculation iteration value of the j-th SVG be Qest. jSVG After reactive power substitution calculation, update Let Qest be the reactive power calculation iteration value of the x-th stationary synchronous condenser. xSSC After reactive power substitution calculation, update 6) Calculate the reactive power regulation replacement amount, specifically including: For a cluster of K wind turbines, the current reactive power of the i-th wind turbine cluster is Q. iPVC ; Decision: If Q iPVC If the value is less than 0, then the reactive power replacement capacity Qu of the i-th wind turbine cluster is increased. iPVC =Q iPVC ×-1.0, otherwise let Qu iPVC =0; After traversing all wind turbine clusters, the reactive power adjustment and replacement capacity of the K wind turbine clusters is summed to obtain the total reactive power adjustment and replacement capacity of the wind turbine clusters. For M SVG devices, let Q be the current reactive power of the j-th SVG device. jSVG ; Decision: If Q jSVG <QDead jSVG If the value is ×-1.0, then the reactive power replacement capacity Qu of the j-th SVG device is increased. jSVG = -1.0 × QDead jSVG -Q jSVG Otherwise, let Qu jSVG =0; After all SVG devices have been traversed, the total reactive power upswing and replacement capacity of the SVG is obtained. Calculate the total reactive power upsampling capacity Qu = Qu of the wind turbine cluster and SVG. PVC +Qu SVG ; For N stationary synchronous condensers, let Q be the current reactive power of the x-th stationary synchronous condenser. xSSC ; Decision: If Q xSSC >QRL xSSC Then, the reactive power demand Qd of the xth stationary synchronous condenser is reduced. xSSC =Q xSSC -QRL xSSC Otherwise, let Qd xSSC =0; After all stationary synchronous condensers have been traversed, the total reactive power reduction demand of the stationary synchronous condensers is obtained. Let the reactive power regulation displacement Qadj = Qd SSC Then determine: if Qadj > Qu, then update Qadj = Qu; otherwise, Qadj remains unchanged. 7) Based on the results of step 6), make a judgment: If Qadj < Q thre If the reactive power is not redistributed, then no secondary allocation of reactive power is performed; otherwise, proceed to step 8) to perform secondary allocation calculation of reactive power. 8) Obtain the reactive power calculation iteration value after reactive power replacement for each reactive power device; Here, the reactive power calculation iteration value of the i-th wind turbine cluster is denoted as Qest. iPVC After reactive power substitution calculation, update Let the reactive power calculation iteration value of the j-th SVG be Qest. jSVG After reactive power substitution calculation, update Let Qest be the reactive power calculation iteration value of the x-th stationary synchronous condenser. xSSC After reactive power substitution calculation, update 8. The method according to claim 7, characterized in that, Also includes: When the reactive voltage oscillation flag S wave When the value is 0, for static synchronous condensers in voltage source control mode, the AVC substation issues a control mode setting of voltage source control mode, and issues the corresponding output voltage setting, reactive power recommendation, voltage upper limit setting, and voltage lower limit setting for that device. For static synchronous condensers in reactive power source control mode, one static synchronous condenser is randomly selected and designated as the z-th static synchronous condenser. Then, the control mode setting is issued to this static synchronous condenser as voltage source control mode, and the corresponding output voltage setting Uset is issued. zSSC Recommended reactive power value Qset zSSC The control mode setting for the remaining static synchronous condensers in reactive power source control mode during the current control cycle is set to reactive power source control mode, and the corresponding reactive power setting, suggested output voltage value, upper voltage limit setting, and lower voltage limit setting are issued to the device. When the reactive voltage oscillation flag S wave When the value is 1, for all static synchronous condensers in reactive power source control mode, the control mode setting is issued as reactive power source control mode, and the corresponding reactive power setting value, suggested output voltage value, upper voltage setting value, and lower voltage setting value are issued for that device. For static synchronous condensers in voltage source control mode that send reactive voltage oscillation signals in the current control cycle, one static synchronous condenser is randomly selected and designated as the a-th static synchronous condenser. Then, the reactive power source control mode is issued to this static synchronous condenser, and the corresponding reactive power setting value Qset is issued for that device. aSSC Recommended output voltage value Uset aSSC Voltage upper limit setting value Ulmtup aSSC and voltage lower limit setting value Ulmtdn aSSC For stationary synchronous condensers that are in voltage source control mode and have not sent reactive voltage oscillation signals in the current control cycle, maintain the current state of the equipment, send the control mode setting to voltage source control mode, and send the corresponding output voltage setting, reactive power suggestion value, voltage upper limit setting, and voltage lower limit setting for the equipment.

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