CN110212546B - Control method and controller for suppressing torsional oscillator terminal STATCOM output current - Google Patents

Control method and controller for suppressing torsional oscillator terminal STATCOM output current Download PDF

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CN110212546B
CN110212546B CN201910249771.7A CN201910249771A CN110212546B CN 110212546 B CN110212546 B CN 110212546B CN 201910249771 A CN201910249771 A CN 201910249771A CN 110212546 B CN110212546 B CN 110212546B
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statcom
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CN110212546A (en
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张琦雪
吴小丹
王辉
王凯
马志恒
朱信舜
孙胜洪
盛晓东
王新宝
王光
陈俊
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NR Electric Co Ltd
NR Engineering Co Ltd
State Grid Electric Power Research Institute
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/18—Arrangements for adjusting, eliminating or compensating reactive power in networks
    • H02J3/1885—Arrangements for adjusting, eliminating or compensating reactive power in networks using rotating means, e.g. synchronous generators
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/24—Arrangements for preventing or reducing oscillations of power in networks
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
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    • Y02E40/10—Flexible AC transmission systems [FACTS]

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Abstract

A control method of terminal STATCOM output current for restraining torsional vibration comprises a power frequency current compensation calculation link, a signal quantity measurement link, a modal current compensation calculation link, a current control inner loop link, a direct current voltage control outer loop link and a pulse generation link; the method comprises the steps of firstly calculating a power frequency current compensation value, a modal control value and a direct current compensation value, then obtaining a modulated wave voltage reference value by the three through a PIR controller of a current control inner ring, finally generating a trigger pulse through a pulse generation module, controlling the on-off of an IGBT in the STATCOM, generating required subsynchronous/supersynchronous current, injecting the required subsynchronous/supersynchronous current into a stator winding of a generator, and generating an electromagnetic torque for restraining torsional vibration. The invention also correspondingly provides a terminal STATCOM controller for inhibiting torsional vibration. According to the scheme, the STATCOM not only participates in power frequency fundamental wave reactive current regulation, but also improves the characteristics of the original PR controller, improves the torsional vibration suppression effect and is easy to implement.

Description

Control method and controller for suppressing torsional oscillator terminal STATCOM output current
Technical Field
The invention belongs to the technical field of control of power electronic equipment of a power system, and particularly relates to a control method and a controller for an output current of a terminal STATCOM (static synchronous compensator) for restraining torsional vibration.
Background
When the power of a large-capacity steam turbine generator unit is sent out, if a point-to-grid long-distance power transmission mode is adopted, in order to improve the transmission power, the power grid sometimes adopts capacitor series compensation, and sometimes adopts high-voltage direct-current power transmission. Theory and practice show that the power transmission mode is easy to cause subsynchronous oscillation of a power grid and shafting torsional vibration of a steam turbine generator unit. When the power grid has subsynchronous oscillation, under the interaction of the power grid, each rotor of a shaft system of the steam turbine generator unit comprises a steam turbine high-pressure cylinder rotor, a medium-pressure cylinder rotor, a low-pressure cylinder rotor, a generator rotor and an exciter rotor, and the torsional oscillation phenomenon of mutual torsional oscillation can occur. The subsynchronous oscillation and torsional oscillation are harmful greatly, which not only affects the safety and stability of the power grid, but also can cause the fatigue damage of the shafting of the turbo generator set, reduce the service life of the set, and even lead to the crack of the large shaft in serious cases, thereby causing huge loss. For example, in the 70 s of the 20 th century, due to the fact that the capacitor series compensation on the power transmission line fails, the American Mohave power plant continuously generates two serious torsional vibration accidents, and the shafting is damaged; after 2000 years, the coupler between the low-pressure cylinder rotor and the generator rotor of a generator set has cracks due to long-time torsional vibration of 2 sets of a certain power plant in China. These accidents cause significant losses. In addition, in recent years, oscillation events of power systems also show that large-scale wind power can cause subsynchronous or supersynchronous oscillation of power grids, so that torsional oscillation of turbo generator units of nearby thermal power plants is caused.
In order to ensure the safe operation of the turbo generator unit, the torsional vibration suppression of the power plant with subsynchronous oscillation and torsional vibration risks is realized by various technical means. Such as:
(1) a Static Block Filter (SBF) is adopted, and a passive Filter loop consisting of a reactor and a capacitor is connected in series at the neutral point side of a main transformer to Block specific subsynchronous harmonics;
(2) adopting additional excitation damping control (SEDC), and injecting specific subsynchronous mode current into the excitation winding of the generator by the method to enable the generator to generate electromagnetic torque for counteracting torsional vibration;
(3) adopting a Static Var Compensator (SVC), installing a thyristor control-based reactor TCR at the high-voltage side or the low-voltage side of a main transformer, namely at the end of a generator, and injecting specific subsynchronous/supersynchronous modal current into a stator winding of the generator by controlling the on and off of a thyristor to generate electromagnetic torque for counteracting torsional vibration;
(4) a static synchronous compensator (STATCOM) is adopted, the STATCOM is installed on the low-voltage side of a factory transformer of a generator, or on the high-voltage side of a factory, namely the generator end, or on the high-voltage side of a main transformer, and specific subsynchronous/supersynchronous modal current is injected into a stator winding of the generator by controlling the on-off of an IGBT in the STATCOM to generate electromagnetic torque for counteracting torsional vibration.
The methods (4) are called as 'terminal STATCOM', the method uses a fully-controlled power device IGBT, is more flexible in control than an SVC scheme, can design rated capacity according to engineering requirements, is not limited by the capacity of an excitation system by an SEDC scheme, is not high in manufacturing cost like an SBF scheme, and is therefore valued.
The current terminal STATCOM for torsional vibration suppression only controls specific subsynchronous/supersynchronous modal current output, and the basic method is to measure the rotating speed omega of a large shaft of a generator set through a rotating speed sensor, perform multi-mode filtering processing, adjust the amplitude and phase of each modal component to obtain a comprehensive current control signal, and then obtain Pulse Width Modulation (PWM) through current closed-loop control to control the STATCOM to output the required subsynchronous/supersynchronous modal current. Because the current machine end STATCOM for suppressing the torsional vibration does not consider the adjustment of power frequency fundamental wave reactive current, only the suppression of specific inherent torsional vibration modal frequency with the largest harm to a machine set shafting is considered. Therefore, when the power grid system does not have subsynchronous/hypersynchronous oscillation but has disturbance conditions such as low-frequency oscillation and the like, the STATCOM of the method is in an approximately no-load running state, does not participate in power frequency fundamental wave reactive current regulation, and does not exert the potential capability of the STATCOM in improving the power grid stability and the disturbance-resistant capability of the power grid. The disturbance is reduced, and the torsional vibration of the turbo generator set can be relieved to a certain degree.
In addition, a proportional resonant controller (PR) is often adopted in a conventional STATCOM, but as is well known, a resonant controller (R) in the PR controller only has better gain control for a set frequency point, usually power frequency, so that the R controller cannot effectively control a wide-range subsynchronous/supersynchronous oscillation component; the control of the subsynchronous/supersynchronous oscillation component only depends on a proportional controller P controller in the PR controller, which is differential regulation, so that the STATCOM in the PR control has poor effect of suppressing the torsional vibration of a shaft system.
Disclosure of Invention
The purpose of the invention is: the method and the controller for controlling the output current of the machine-end STATCOM for suppressing the torsional vibration solve the problem that the existing STATCOM for suppressing the torsional vibration does not participate in power frequency fundamental wave reactive current regulation, and improve the problem that the effect of suppressing the torsional vibration of a shafting of a proportional resonance controller in a control link is poor.
In order to achieve the purpose, the invention adopts the technical scheme that:
a power frequency current compensation calculating link is added in the control of the machine-end STATCOM, the power frequency current compensation calculating link calculates to obtain a power frequency current compensation value according to a reactive power given reference value, and the power frequency current compensation value participates in the calculation of a modulated wave voltage reference value under the action of a current control inner ring link.
Further, the method further comprises: a signal quantity measuring link, a modal current compensation calculating link, a current control inner ring link, a direct current voltage control outer ring link and a pulse generating link; the power frequency current compensation value obtained by the power frequency current compensation calculation link, the modal control value obtained by the modal current compensation calculation link and the direct current compensation value obtained by the direct current voltage control outer ring link are used for obtaining a modulated wave voltage reference value under the action of the current control inner ring link, and finally a trigger pulse is generated by the pulse generation link to control the on-off of an IGBT in the STATCOM so as to generate the required subsynchronous/supersynchronous current which is injected into a generator stator winding to generate an electromagnetic torque for restraining torsional vibration.
Furthermore, in the above method, the function of the signal measurement unit is to measure the rotation speed ω of the steam turbine generator unit and the generator terminal voltage ugGenerator terminal current igSTATCOM output current isSTATCOM direct-current side voltage udc(ii) a Where ω is the rotational speed of the rotor on the steam turbine side or the generator side of the steam turbine generator unit, ugIs the three-phase voltage or the three-phase voltage of the generator igIs the three-phase current of the generator isIs the three-phase current of the STATCOM output, udcIs the three-phase voltage on the dc side of the STATCOM.
Further, in the above method, the reactive power is given a reference value Q*Through a power frequency current compensation calculation link, a power frequency current compensation value is obtained through calculation
Figure BDA0002012060720000031
The power frequency current compensation calculation link adopts open loop calculation, firstly, the generator terminal voltage u is calculatedgObtaining d-axis component u through dq0 transformationdReuse Q*Divided by udTo obtain the desired
Figure BDA0002012060720000032
Further, in the method, the rotation speed omega of the steam turbine generator unit is calculated to obtain each modal control value delta lambda through a modal current compensation calculation linkjThe subscript j is 1,2, 3., N indicates that the turbo-generator unit has N inherent subsynchronous torsional vibration modes; the modal current compensation calculation method is to convert the rotation speed omega per unit, separate each torsional vibration modal quantity through a band-pass filter, and obtain each modal control value delta lambda through respective proportional amplification and phase shiftj，j＝1,2,3,...,N。
Further, in the above method, the reference value of the DC voltage
Figure BDA0002012060720000041
STATCOM DC-side voltage udcThe DC voltage is used for controlling an outer ring link to calculate and obtain a DC compensation value
Figure BDA0002012060720000042
The compensation value of the three-phase direct current is specifically calculated according to the following formula:
Figure BDA0002012060720000043
wherein, thetaaIs the reference phase, C, of the A-phase voltage at the generator terminal calculated by the phase-locked loop PLL33(θa) Is a 3 x 3 diagonal matrix, C33(θa)＝diag(cos(θa)cos(θa-2π/3)cos(θa+2π/3))，
Figure BDA0002012060720000044
Is a proportional integral transfer function, KP1Is the proportionality coefficient, KI1Is an integral coefficient.
Further, in the method, the STATCOM output current i is obtained according to the semaphore measurement linksPower frequency current compensation value output by power frequency current compensation calculation link
Figure BDA0002012060720000045
Modal control value delta lambda output by modal current compensation calculation linkjDC voltage control of DC current compensation value output by outer ring link
Figure BDA0002012060720000046
Through the inner loop link of current control, the reference value u of the modulated wave voltage is obtained by calculationref(ii) a The calculation step of the current control inner ring element comprises the following steps:
(1) firstly, the following formula is adopted for calculation to obtainModal current control value
Figure BDA0002012060720000047
Figure BDA0002012060720000048
(2) Then the current control deviation value delta i is calculated by adopting the following formulas：
Figure BDA0002012060720000049
(3) Finally Δ isObtaining a modulated wave voltage reference value u through a transfer function H(s)ref：
uref＝H(s)·ΔisFormula 4
C in formula 213(θj) And C13(θ0) Are all 3 × 1 matrices, respectively:
C13(θj)＝-[sin(θj)sin(θj-2π/3)sin(θj+2π/3)]T，
C13(θ0)＝-[sin(θ0)sin(θ0-2π/3)sin(θ0+2π/3)]T，
wherein theta isj＝θa+σj，θ0＝θa，θaIs the reference phase, sigma, of the generator terminal A phase voltage calculated by the phase-locked loop PLLjThe compensation phase of the set jth mode is shown, and subscript j is 1,2,3, N indicates that the turbo-generator unit has N inherent subsynchronous torsional vibration modes; formula 2 is to convert the modal control signal and the power frequency current compensation value into a three-phase modal current control value i after being superposeds *。
Further, in the above method, in the step (3) of calculating the current control inner loop element, the transfer function h(s) is in the form of a proportional-integral resonant regulator, as shown in the following formula:
Figure BDA0002012060720000051
wherein, KPIs the proportionality coefficient, KIIs the integral coefficient, KRIs the resonance coefficient, ζ is the resonance damping coefficient, ω0Is the power frequency angular frequency.
Further, in the above method, the pulse generation link adopts a nearest level approximation modulation or a carrier phase shift pulse width modulation.
Further, in the method, the body of the STATCOM adopts a star connection mode or a triangle connection mode.
The invention also provides an engine-end STATCOM controller for restraining torsional vibration, which comprises a power frequency current compensation calculation module and a current control inner ring module, wherein the power frequency current compensation calculation module calculates a power frequency current compensation value according to a reactive power given reference value, and the power frequency current compensation value is input into the current control inner ring module to participate in the calculation of the modulated wave voltage reference value.
Furthermore, the controller also comprises a signal quantity measuring module, a modal current compensation calculating module, a direct current voltage control outer ring module and a pulse generating module; the power frequency current compensation value obtained by the power frequency current compensation calculation module, the modal control value obtained by the modal current compensation calculation module and the direct current compensation value obtained by the direct current voltage control outer ring module are used for obtaining a modulated wave voltage reference value under the action of the current control inner ring module, and finally a trigger pulse is generated by the pulse generation module to control the on-off of an IGBT in the STATCOM, so that the required subsynchronous/supersynchronous current is generated and injected into a stator winding of the generator, and the electromagnetic torque for restraining torsional vibration is generated.
Furthermore, in the controller, the function of the signal quantity measuring module is to measure the rotation speed ω of the steam turbine generator unit and the generator terminal voltage ugGenerator terminal current igSTATCOM output current isSTATCOM direct-current side voltage udc(ii) a Where ω is the steam side of the steam turbine unit orRotational speed of generator-side rotor, ugIs the three-phase voltage or three-phase voltage of the generator igIs the three-phase current of the generator isIs the three-phase current of the STATCOM output, udcIs the three-phase voltage on the dc side of the STATCOM.
Further, in the above controller, the reactive power gives the reference value Q*Through the power frequency current compensation calculation module, the power frequency current compensation value is obtained through calculation
Figure BDA0002012060720000061
The power frequency current compensation calculation module adopts open loop calculation, and firstly, the voltage u at the generator terminal is calculatedgD-axis component u is obtained by dq0 transformationdReuse Q*Divided by udTo obtain the desired
Figure BDA0002012060720000062
Further, in the controller, the rotation speed ω of the steam turbine generator unit is calculated by the modal current compensation calculation module to obtain each modal control value Δ λjThe subscript j is 1,2,3, the. The modal current compensation calculation method is to unify the rotation speed omega, separate each torsional vibration modal quantity through a band-pass filter, and obtain each modal control value delta lambda through respective proportional amplification and phase shiftj，j＝1,2,3,...,N。
Further, in the above controller, the dc voltage reference value
Figure BDA0002012060720000063
STATCOM DC-SIDE VOLTAGE udcThe DC voltage controls the outer ring module to calculate and obtain the DC compensation value
Figure BDA0002012060720000064
The compensation value of the three-phase direct current is specifically calculated according to the following formula:
Figure BDA0002012060720000065
wherein, thetaaIs the reference phase, C, of the voltage of A phase at the generator terminal calculated by a phase-locked loop PLL33(θa) Is a 3 x 3 diagonal matrix, C33(θa)＝diag(cos(θa)cos(θa-2π/3)cos(θa+2π/3))，
Figure BDA0002012060720000066
Is a proportional-integral transfer function, KP1Is the proportionality coefficient, KI1Is an integral coefficient.
Furthermore, in the controller, the STATCOM output current i obtained according to the semaphore measurement modulesAnd a power frequency current compensation value output by the power frequency current compensation calculation module
Figure BDA0002012060720000067
Modal control value delta lambda output by modal current compensation calculation modulejDC voltage control of DC current compensation value output by outer ring module
Figure BDA0002012060720000071
The reference value u of the voltage of the modulated wave is obtained by calculation through a current control inner loop moduleref(ii) a The current control inner loop module comprises the following sub-modules:
(1) a modal current control value operator module for calculating modal current control value according to the following formula
Figure BDA0002012060720000072
Figure BDA0002012060720000073
(2) The current control deviation value calculation submodule is used for calculating to obtain a current control deviation value delta i according to the following formulas：
Figure BDA0002012060720000074
(3) A modulation wave voltage reference value operator module for calculating the reference value according to Δ isObtaining a modulated wave voltage reference value u through a transfer function H(s)ref：
uref＝H(s)·ΔisFormula 4
C in formula 213(θj) And C13(θ0) Are all 3 × 1 matrices, respectively:
C13(θj)＝-[sin(θj)sin(θj-2π/3)sin(θj+2π/3)]T，
C13(θ0)＝-[sin(θ0)sin(θ0-2π/3)sin(θ0+2π/3)]T，
wherein theta isj＝θa+σj，θ0＝θa，θaIs the reference phase, sigma, of the A-phase voltage at the generator terminal calculated by the phase-locked loop PLLjThe compensation phase of the set jth mode is shown, and subscript j is 1,2,3, N indicates that the turbo-generator unit has N inherent subsynchronous torsional vibration modes; formula 2 converts the superimposed modal control signal and power frequency current compensation value into a three-phase modal current control value
Figure BDA0002012060720000075
Further, in the above controller, the transfer function h(s) in the modulation wave voltage reference value operator module is in the form of a proportional integral resonant regulator, as shown in the following formula:
Figure BDA0002012060720000076
wherein, KPIs the proportionality coefficient, KIIs the integral coefficient, KRIs the resonance coefficient, ζ is the resonance damping coefficient, ω0Is the power frequency angular frequency.
Further, in the controller, the pulse generating module adopts nearest level approximation modulation or carrier phase shift pulse width modulation.
Further, in the controller, the body of the STATCOM adopts a star connection mode or a triangle connection mode.
The invention has the beneficial effects that: (1) a power frequency current compensation module is added, so that a machine terminal STATCOM participates in the regulation of power frequency reactive current, the stability of a power grid is improved, the disturbance of the power grid is reduced, and the torsional vibration of a steam turbine generator unit is relieved; (2) in the STATCOM control link, a proportional integral resonant controller (PIR controller) is used, so that gain control of output power frequency current is guaranteed, high gain output in a wide frequency range is achieved, control of sub-synchronous/super-synchronous oscillation components is changed into error-free control, and the effect of torsional vibration suppression is improved.
Drawings
FIG. 1 is a schematic wiring diagram of the electrical apparatus of the method of the present invention;
FIG. 2 is a schematic diagram of the relationship between external signal acquisition and internal calculation links in the method of the present invention;
FIG. 3 is a schematic diagram of the internal calculation method of the present invention;
FIG. 4 is a schematic diagram of the internal calculation of a PIR module according to the method of the present invention;
FIG. 5 is a schematic diagram illustrating the suppression effect of each modal rotation speed of the turbo generator unit under the condition of disturbance of the interphase short circuit fault of the power grid system in the embodiment of the present invention;
FIG. 6 is a schematic diagram of the relationship between the external signal acquisition and internal calculation modules of the controller according to the present invention.
Detailed Description
For the purpose of illustrating the methods of the invention, there is shown in the drawings embodiments which are presently preferred.
Example 1:
as shown in FIG. 1, the wiring diagram of the electrical equipment in the invention is shown, the STATCOM primary equipment is connected with a generator terminal bus through an isolation transformer, and the STATCOM controller is connected with a turbo generator unit rotating speed omega and a generator terminal voltage ugGenerator terminal current igSTATCOM output current isSTATCOM direct current side currentPress udcAnd the like; meanwhile, the STATCOM controller also receives an external reactive power instruction Q*. In the figure, CT1 is a terminal current transformer, PT is a terminal voltage transformer, CT2 is a STATCOM output current transformer, the equivalent of the power grid system is two return lines and an infinite power supply system, wherein one return line has capacitor series compensation, and the other return line does not have capacitor series compensation.
FIG. 2 is a schematic diagram showing the relationship between external signal acquisition and internal calculation links in the method of the present invention; as shown in fig. 2, in the method for controlling output current of the machine-side STATCOM for suppressing torsional oscillation according to the present invention, a power frequency current compensation calculation link is added in the control of the machine-side STATCOM, the power frequency current compensation calculation link calculates a power frequency current compensation value according to a reference value given by reactive power, and the power frequency current compensation value participates in the calculation of the reference value of the modulated wave voltage under the action of the current control inner loop link.
The method further comprises the following steps: a signal quantity measuring link, a modal current compensation calculating link, a current control inner ring link, a direct current voltage control outer ring link and a pulse generating link; the power frequency current compensation value obtained by the power frequency current compensation calculation link, the modal control value obtained by the modal current compensation calculation link and the direct current compensation value obtained by the direct current voltage control outer ring link are used for obtaining a modulated wave voltage reference value under the action of the current control inner ring link, and finally, a trigger pulse is generated by a pulse generation link to control the on-off of an IGBT in the STATCOM so as to generate required subsynchronous/supersynchronous current which is injected into a generator stator winding to generate electromagnetic torque for inhibiting torsional vibration.
In the method, the signal quantity measuring link has the function of measuring the rotation speed omega of the steam turbine generator unit and the generator terminal voltage ugGenerator terminal current igSTATCOM output current isSTATCOM direct-current side voltage udc(ii) a Where ω is the rotational speed of the rotor on the steam turbine side or the generator side of the steam turbine generator unit, ugIs the three-phase voltage or three-phase voltage of the generator igIs the three-phase current of the generator isIs the three-phase current of the STATCOM output, udcIs the three-phase voltage on the dc side of the STATCOM.
In the above method, the reactive power is given a reference value Q*Through a power frequency current compensation calculation link, a power frequency current compensation value is calculated and obtained
Figure BDA0002012060720000091
The power frequency current compensation calculation link adopts open loop calculation, and firstly, the generator terminal voltage u is measuredgObtaining d-axis component u through dq0 transformationdReuse Q*Divided by udTo obtain the desired
Figure BDA0002012060720000092
In the method, the rotating speed omega of the steam turbine generator unit is calculated to obtain each modal control value delta lambda through a modal current compensation calculation linkjThe subscript j is 1,2,3, the. The modal current compensation calculation method is to unify the rotation speed omega, separate each torsional vibration modal quantity through a band-pass filter, and obtain each modal control value delta lambda through respective proportional amplification and phase shiftj，j＝1,2,3,...,N。
In the above method, the reference value of the DC voltage
Figure BDA0002012060720000101
STATCOM DC-side voltage udcThe DC voltage is used to control the outer ring link, and the DC compensation value is calculated
Figure BDA0002012060720000102
Figure BDA0002012060720000103
The compensation value of the three-phase direct current is specifically calculated according to the following formula:
Figure BDA0002012060720000104
wherein, thetaaIs the generator terminal A phase voltage reference phase calculated by a phase-locked loop PLL，C33(θa) Is a 3 x 3 diagonal matrix, C33(θa)＝diag(cos(θa)cos(θa-2π/3)cos(θa+2π/3))，
Figure BDA0002012060720000105
Is a proportional-integral transfer function, KP1Is the proportionality coefficient, KI1Is the integral coefficient.
In the method, the STATCOM output current i is obtained according to the semaphore measurement linksAnd a power frequency current compensation value output by the power frequency current compensation calculation link
Figure BDA0002012060720000106
Modal control value delta lambda output by modal current compensation calculation linkjDC voltage control of DC current compensation value output by outer ring link
Figure BDA0002012060720000107
The reference value u of the modulated wave voltage is obtained by calculation through the inner loop link of current controlref(ii) a The calculation step of the current control inner ring link comprises the following steps:
(1) firstly, the modal current control value is obtained by calculation by adopting the following formula
Figure BDA0002012060720000108
Figure BDA0002012060720000109
(2) Then the current control deviation value delta i is calculated by adopting the following formulas：
Figure BDA00020120607200001010
(3) Finally Δ isObtaining a reference value u of the modulated wave voltage through a transfer function H(s)ref：
uref＝H(s)·Δis Formula 4
C in formula 213(θj) And C13(θ0) Are all 3 × 1 matrices, respectively:
C13(θj)＝-[sin(θj)sin(θj-2π/3)sin(θj+2π/3)]T，
C13(θ0)＝-[sin(θ0)sin(θ0-2π/3)sin(θ0+2π/3)]T，
wherein theta isj＝θa+σj，θ0＝θa，θaIs the reference phase, sigma, of the A-phase voltage at the generator terminal calculated by the phase-locked loop PLLjThe compensation phase of the set jth mode is shown, and subscript j is 1,2,3, N indicates that the turbo-generator unit has N inherent subsynchronous torsional vibration modes; formula 2 converts the superimposed modal control signal and power frequency current compensation value into a three-phase modal current control value
Figure BDA0002012060720000111
In the above method, in the step (3) of calculating the current control inner loop element, the transfer function h(s) is in the form of a proportional-integral resonant regulator, as shown in the following formula:
Figure BDA0002012060720000112
wherein, KPIs the proportionality coefficient, KIIs the integral coefficient, KRIs the resonance coefficient, ζ is the resonance damping coefficient, ω0Is the power frequency angular frequency.
In the method, the pulse generation link adopts the nearest level approximation modulation or adopts the carrier phase-shifting pulse width modulation.
In the method, the STATCOM body adopts a star connection mode or a triangular connection mode.
Example 2:
the electrical equipment wiring of the method of the invention is shown in figure 1The STATCOM primary equipment is connected to a generator terminal bus through an isolation transformer, and the STATCOM controller is connected to the rotating speed omega of the steam turbine generator unit and the generator terminal voltage ugGenerator terminal current igSTATCOM output current isSTATCOM direct-current side voltage udcAnd the like; meanwhile, the STATCOM controller also receives an external reactive power instruction Q*. In the figure, CT1 is a terminal current transformer, PT is a terminal voltage transformer, CT2 is a STATCOM output current transformer, the equivalent of the power grid system is two return lines and an infinite power supply system, wherein one return line has capacitor series compensation, and the other return line does not have capacitor series compensation.
In this embodiment, the rated capacity of the generator is 667MVA, the rated voltage is 20kV, the rated power factor is 0.9, and the per unit value of each reactance parameter of the generator is Xd＝2.16,Xd'＝0.269,Xd"＝0.21,Xq＝2.11,Xq"═ 0.206; the rated capacity of a main transformer is 720MVA, and the voltage transformation ratio is 500kV/20 kV; this unit shafting includes high intermediate pressure jar rotor (HIP), low pressure jar A rotor (LPA), low pressure jar B rotor (LPB), generator rotor (GEN), and their inertia is respectively:
Figure BDA0002012060720000113
Figure BDA0002012060720000121
the equivalent torsional stiffness between each rotor is:
serial number Rotor Torsional rigidity (N.m/rad)
1 HIP-LPA 6.237E+07
2 LPA-LPB 1.074E+08
3 LPB-GEN 1.135E+08
The natural mode frequencies of the shafting are 10.71Hz of the mode 1 frequency, 18.47Hz of the mode 2 frequency and 19.92Hz of the mode 3 frequency.
For the embodiment, the primary equipment rated capacity of the STATCOM body is 18MVA, and the rated voltage is 10 kV; the rated capacity of the isolation transformer is 20MVA, and the rated voltage transformation ratio is 22kV/10 kV. The STATCOM body can adopt a star connection mode or a triangle connection mode, and preferably adopts a triangle connection mode. The STATCOM in this example uses a three-phase angle type wiring scheme.
The method for controlling the output current of the machine-end STATCOM for suppressing the torsional vibration adopted by the embodiment is characterized in that a power frequency current compensation calculation link, a semaphore measurement link, a modal current compensation calculation link, a current control inner loop link, a direct-current voltage control outer loop link and a pulse generation link are added in the control of the machine-end STATCOM; the power frequency current compensation value obtained by the power frequency current compensation calculation link, the modal control value obtained by the modal current compensation calculation link and the direct current compensation value obtained by the direct current voltage control outer ring link are used for obtaining a modulated wave voltage reference value under the action of the current control inner ring link, and finally a trigger pulse is generated by the pulse generation link to control the on-off of an IGBT in the STATCOM so as to generate the required subsynchronous/supersynchronous current which is injected into a generator stator winding to generate an electromagnetic torque for restraining torsional vibration.
The method is implemented by the following steps:
step (1): measuring the rotation speed omega of the steam turbine generator unit and the generator terminal voltage u in the signal quantity measuring linkgGenerator terminal current igSTATCOM output current isSTATCOM direct-current side voltage udc(ii) a Where ω is the rotational speed of the rotor on the steam turbine side or the generator side of the steam turbine generator unit, ugIs the three-phase voltage or three-phase voltage of the generator igIs the three-phase current of the generator isIs the three-phase current of the STATCOM output, udcIs the three-phase voltage on the dc side of the STATCOM. If the slash and the number 3 are marked on each analog quantity signal line in fig. 2, the signal is a three-phase signal, and the description is omitted below.
Step (2): as shown in fig. 3, the reactive power gives a reference value Q*Through a power frequency current compensation calculation link, a power frequency current compensation value is calculated and obtained
Figure BDA0002012060720000131
The power frequency current compensation calculation link adopts open loop calculation, firstly, the generator terminal voltage u is calculatedgD-axis component u is obtained by dq0 transformationdReuse Q*Divided by udTo obtain the desired
Figure BDA0002012060720000132
In which the reactive power gives a reference value Q*The STATCOM controller may be sent by a power plant automatic voltage regulation system (AVC system) via a communication link.
And (3): as shown in fig. 3, the rotation speed ω of the turbo generator unit is calculated to obtain each modal control value Δ λ through a modal current compensation calculation procedurejThe subscript j is 1,2, 3., N indicates that the turbo-generator unit has N inherent subsynchronous torsional vibration modes; the modal current compensation calculation method is to convert the rotation speed omega per unit, separate each torsional vibration modal quantity through a band-pass filter, and obtain each modal control value delta lambda through respective proportional amplification and phase shiftjJ ═ 1,2, 3. For the present embodiment, there are 3 modes in total, N is 3, the mode 1 frequency is 10.71Hz, and the mode 2 frequency is 18.47Hz, modal 3 frequency 19.92 Hz.
And (4): as shown in fig. 3, the dc voltage reference value
Figure BDA0002012060720000133
STATCOM DC-side voltage udcThe DC voltage is used for controlling an outer ring link to calculate and obtain a DC compensation value
Figure BDA0002012060720000134
The compensation value is a three-phase direct current compensation value, and is specifically calculated according to the following formula:
Figure BDA0002012060720000135
wherein, thetaaIs the reference phase, C, of the voltage of A phase at the generator terminal calculated by a phase-locked loop PLL33(θa) Is a 3 x 3 diagonal matrix, C33(θa)＝diag(cos(θa)cos(θa-2π/3)cos(θa+2π/3))，
Figure BDA0002012060720000136
Is a proportional integral transfer function, KP1Is the proportionality coefficient, KI1Is the integral coefficient. For this example, KP1＝0.8，KI1＝10。
And (5): STATCOM output Current i, as shown in FIG. 3sPower frequency current compensation value
Figure BDA0002012060720000137
Mode control signal delta lambdajDC current compensation value
Figure BDA0002012060720000138
Through the inner loop link of current control, the reference value u of the modulated wave voltage is obtained by calculationref(ii) a The calculation step of the current control inner ring link comprises the following steps:
(a) firstly, the modal current control value is obtained by calculation by adopting the following formula
Figure BDA0002012060720000139
Figure BDA0002012060720000141
(b) Calculating to obtain a current control deviation value delta i by adopting the following formulas：
Figure BDA0002012060720000142
(c) Finally Δ isObtaining a reference value u of the modulated wave voltage through a transfer function H(s)ref：
uref＝H(s)·ΔisFormula 4
C in formula 213(θj) And C13(θ0) Are all 3 × 1 matrices, respectively:
C13(θj)＝-[sin(θj)sin(θj-2π/3)sin(θj+2π/3)]T，
C13(θ0)＝-[sin(θ0)sin(θ0-2π/3)sin(θ0+2π/3)]T，
wherein theta isj＝θa+σj，θ0＝θa，θaIs the reference phase, sigma, of the A-phase voltage at the generator terminal calculated by the phase-locked loop PLLjThe compensation phase of the set jth mode is represented by subscript j which is 1,2,3, N, and indicates that the steam turbine generator unit has N inherent subsynchronous torsional vibration modes; formula 2 is to convert the modal control signal and the power frequency current compensation value into a three-phase modal current control value after being superposed
Figure BDA0002012060720000143
For this embodiment, there are 3 modes, and the compensation phases are σ1＝85.35deg，σ2＝80.14deg，σ374.90 deg. These compensated phases are modeled by the systemAnd (4) true presetting, and finally determining after on-site actual measurement and correction.
The transfer function h(s) in equation 4 takes the form of a proportional integral resonant regulator, which, as shown in fig. 4, can be represented by the following equation:
Figure BDA0002012060720000144
wherein, KPIs the proportionality coefficient, KIIs the integral coefficient, KRIs the resonance coefficient, ζ is the resonance damping coefficient, ω0Is the power frequency angular frequency. For this example, KP＝0.42，KI＝11，KR＝0.11，ζ＝0.01，ω0＝100πrad/s。
In this example, fig. 5 shows one result of the application of the method of the invention: the method comprises the following steps that an interphase short circuit fault occurs at the far end of a power grid system at the moment of 2s, the fault is removed after 100ms, a steam turbine generator unit generates torsional vibration under the condition of system disturbance, each modal component in the rotating speed rises, each modal component in the rotating speed is obviously attenuated after a few tenths of a second under the inhibiting action of a machine-end STATCOM, and the torsional vibration is effectively inhibited. The safety of the unit is guaranteed. In addition, in the implementation process, the pulse generation link adopts the nearest level approximation modulation or carrier phase shift pulse width modulation. The embodiment employs the nearest level approximation modulation.
Example 3:
fig. 6 is a schematic diagram showing the relationship between the external signal acquisition module and the internal calculation module of the controller according to the present invention. The specific embodiment of the terminal STATCOM controller for suppressing torsional vibration comprises a power frequency current compensation calculation module and a current control inner ring module, wherein the power frequency current compensation calculation module calculates a power frequency current compensation value according to a reactive power given reference value, and the power frequency current compensation value is input into the current control inner ring module to participate in the calculation of a modulated wave voltage reference value.
The controller also comprises a signal quantity measuring module, a modal current compensation calculating module, a direct current voltage control outer ring module and a pulse generating module; the power frequency current compensation value obtained by the power frequency current compensation calculation module, the modal control value obtained by the modal current compensation calculation module and the direct current compensation value obtained by the direct current voltage control outer ring module are used for obtaining a modulated wave voltage reference value under the action of the current control inner ring module, and finally, a trigger pulse is generated by the pulse generation module to control the on-off of an IGBT in the STATCOM, so that the required subsynchronous/supersynchronous current is generated and injected into a generator stator winding, and the electromagnetic torque for inhibiting torsional vibration is generated.
In the controller, the signal quantity measuring module has the function of measuring the rotation speed omega of the steam turbine generator unit and the generator terminal voltage ugGenerator terminal current igSTATCOM output current isSTATCOM direct-current side voltage udc(ii) a Where ω is the rotational speed of the rotor on the steam turbine side or the generator side of the turbo generator unit, ugIs the three-phase voltage or the three-phase voltage of the generator igIs the three-phase current of the generator isIs the three-phase current of the STATCOM output, udcIs the three-phase voltage on the dc side of the STATCOM.
In the above controller, the reactive power is given a reference value Q*Through the power frequency current compensation calculation module, the power frequency current compensation value is obtained through calculation
Figure BDA0002012060720000151
The power frequency current compensation calculation module adopts open loop calculation, and firstly, the voltage u at the generator terminal is calculatedgD-axis component u is obtained by dq0 transformationdReuse Q*Divided by udTo obtain the desired
Figure BDA0002012060720000152
In the controller, the rotation speed omega of the steam turbine generator unit is calculated through the modal current compensation calculation module to obtain each modal control value delta lambdajThe subscript j is 1,2, 3., N indicates that the turbo-generator unit has N inherent subsynchronous torsional vibration modes; the modal current compensation calculation method is to convert the rotation speed omega per unit, separate each torsional vibration modal quantity through a band-pass filter, and amplify and phase-convert each torsional vibration modal quantity through respective proportionShifting to obtain control value delta lambda of each modej，j＝1,2,3,...,N。
In the above controller, the DC voltage reference value
Figure BDA0002012060720000161
STATCOM DC-side voltage udcThe DC voltage controls the outer ring module to calculate and obtain the DC compensation value
Figure BDA0002012060720000162
The compensation value is a three-phase direct current compensation value, and is specifically calculated according to the following formula:
Figure BDA0002012060720000163
wherein, thetaaIs the reference phase, C, of the voltage of A phase at the generator terminal calculated by a phase-locked loop PLL33(θa) Is a 3 x 3 diagonal matrix, C33(θa)＝diag(cos(θa) cos(θa-2π/3) cos(θa+2π/3))，
Figure BDA0002012060720000164
Is a proportional integral transfer function, KP1Is the proportionality coefficient, KI1Is an integral coefficient.
In the controller, the STATCOM output current i obtained according to the signal quantity measuring modulesAnd a power frequency current compensation value output by the power frequency current compensation calculation module
Figure BDA0002012060720000165
Modal control value delta lambda output by modal current compensation calculation modulejDC voltage control DC current compensation value output by outer ring module
Figure BDA0002012060720000166
The reference value u of the modulated wave voltage is obtained by calculation through a current control inner loop moduleref(ii) a The current control inner loop module comprises the following sub-modules:
(1) a modal current control value operator module for calculating modal current control value according to the following formula
Figure BDA0002012060720000167
Figure BDA0002012060720000168
(2) A current control deviation value calculating submodule for calculating the current control deviation value delta i according to the following formulas：
Figure BDA0002012060720000169
(3) A modulation wave voltage reference value calculation operator module for calculating the reference value according to the delta isObtaining a reference value u of the modulated wave voltage through a transfer function H(s)ref：
uref＝H(s)·ΔisFormula 4
C in formula 213(θj) And C13(θ0) Are all 3 × 1 matrices, respectively:
C13(θj)＝-[sin(θj)sin(θj-2π/3)sin(θj+2π/3)]T，
C13(θ0)＝-[sin(θ0)sin(θ0-2π/3)sin(θ0+2π/3)]T，
wherein theta isj＝θa+σj，θ0＝θa，θaIs the reference phase, sigma, of the A-phase voltage at the generator terminal calculated by the phase-locked loop PLLjThe compensation phase of the set jth mode is shown, and subscript j is 1,2,3, N indicates that the turbo-generator unit has N inherent subsynchronous torsional vibration modes; formula 2 converts the superimposed modal control signal and power frequency current compensation value into a three-phase modal current control value is *。
In the above controller, the transfer function h(s) in the modulation wave voltage reference value operator module is in the form of a proportional-integral resonant regulator, as shown in the following formula:
Figure BDA0002012060720000171
wherein, KPIs the proportionality coefficient, KIIs the integral coefficient, KRIs the resonance coefficient, ζ is the resonance damping coefficient, ω0Is the power frequency angular frequency.
In the controller, the pulse generation module adopts nearest level approximation modulation or carrier phase-shifting pulse width modulation.
In the controller, the STATCOM body adopts a star connection mode or a triangle connection mode.
Thus, the description of the specific embodiments has been completed.
The above examples are merely illustrative of the technical idea of the present invention, and the scope of the present invention is not limited thereto. Any equivalent replacement or modification made on the basis of the technical scheme according to the technical idea provided by the invention does not exceed the protection scope of the invention.

Claims (18)

1. A control method of an output current of an engine-end STATCOM for restraining torsional vibration is characterized in that a power frequency current compensation calculating link is added in the control of the engine-end STATCOM, the power frequency current compensation calculating link calculates a power frequency current compensation value according to a reactive power given reference value, and the power frequency current compensation value participates in the calculation of a modulated wave voltage reference value under the action of a current control inner ring link;
further comprising: a signal quantity measuring link, a modal current compensation calculating link, a current control inner loop link, a direct current voltage control outer loop link and a pulse generating link; the power frequency current compensation value obtained by the power frequency current compensation calculation link, the modal control value obtained by the modal current compensation calculation link and the direct current compensation value obtained by the direct current voltage control outer ring link are used for obtaining a modulated wave voltage reference value under the action of the current control inner ring link, and finally, a trigger pulse is generated by a pulse generation link to control the on-off of an IGBT in the STATCOM so as to generate required subsynchronous/supersynchronous current which is injected into a generator stator winding to generate electromagnetic torque for inhibiting torsional vibration.
2. The method as claimed in claim 1, wherein the signal measurement unit is configured to measure a rotation speed ω of the steam turbine generator and a generator-side voltage ugGenerator terminal current igSTATCOM output current isSTATCOM direct-current side voltage udc(ii) a Where ω is the rotational speed of the rotor on the steam turbine side or the generator side of the steam turbine generator unit, ugIs the three-phase voltage or three-phase voltage of the generator igIs the three-phase current of the generator, isIs the three-phase current of the STATCOM output, udcIs the three-phase voltage on the dc side of the STATCOM.
3. A method as claimed in claim 1, wherein the reactive power is given a reference Q, and the method comprises the step of controlling the output current of a terminal STATCOM for suppressing torsional oscillations*Through a power frequency current compensation calculation link, a power frequency current compensation value is obtained through calculation
Figure FDA0003640187220000011
The power frequency current compensation calculation link adopts open loop calculation, and firstly, the generator terminal voltage u is measuredgD-axis component u is obtained by dq0 transformationdReuse Q*Divided by udTo obtain the desired
Figure FDA0003640187220000012
4. The method as claimed in claim 1, wherein the rotation speed ω of the turbo generator set is calculated to obtain each modal control value Δ λ by a modal current compensation calculation procedurejThe subscript j ═ 1,2, 3., N denotes a turbineThe generator set has N inherent subsynchronous torsional vibration modes; the modal current compensation calculation method is to convert the rotation speed omega per unit, separate each torsional vibration modal quantity through a band-pass filter, and obtain each modal control value delta lambda through respective proportional amplification and phase shiftj，j＝1,2,3,...,N。
5. The method as claimed in claim 1, wherein the dc voltage reference is a dc voltage reference
Figure FDA0003640187220000021
STATCOM DC-SIDE VOLTAGE udcThe DC voltage is used for controlling an outer ring link to calculate and obtain a DC compensation value
Figure FDA0003640187220000022
Figure FDA0003640187220000023
The compensation value of the three-phase direct current is specifically calculated according to the following formula:
Figure FDA0003640187220000024
wherein, thetaaIs the reference phase, C, of the voltage of A phase at the generator terminal calculated by a phase-locked loop PLL33(θa) Is a 3 x 3 diagonal matrix, C33(θa)＝diag(cos(θa)cos(θa-2π/3)cos(θa+2π/3))，
Figure FDA0003640187220000025
Is a proportional integral transfer function, KP1Is the proportionality coefficient, KI1Is the integral coefficient.
6. The method as claimed in claim 1, wherein the loop is measured according to the signal quantityNode-derived STATCOM output current isPower frequency current compensation value output by power frequency current compensation calculation link
Figure FDA0003640187220000026
Modal control value delta lambda output by modal current compensation calculation linkjDC voltage control of DC current compensation value output by outer ring link
Figure FDA0003640187220000027
Through the inner loop link of current control, the reference value u of the modulated wave voltage is obtained by calculationref(ii) a The calculation step of the current control inner ring link comprises the following steps:
(1) firstly, the modal current control value is obtained by calculation by adopting the following formula
Figure FDA0003640187220000028
Figure FDA0003640187220000029
(2) Calculating to obtain a current control deviation value delta i by adopting the following formulas：
Figure FDA00036401872200000210
(3) Finally Δ isObtaining a modulated wave voltage reference value u through a transfer function H(s)ref：
uref＝H(s)·ΔisFormula 4
C in formula 213(θj) And C13(θ0) Are all 3 × 1 matrices, respectively:
C13(θj)＝-[sin(θj) sin(θj-2π/3) sin(θj+2π/3)]T，
C13(θ0)＝-[sin(θ0) sin(θ0-2π/3) sin(θ0+2π/3)]T，
wherein theta isj＝θa+σj，θ0＝θa，θaIs the reference phase, sigma, of the generator terminal A phase voltage calculated by the phase-locked loop PLLjThe compensation phase of the set jth mode is represented by subscript j which is 1,2,3, N, and indicates that the steam turbine generator unit has N inherent subsynchronous torsional vibration modes; formula 2 is to convert the modal control signal and the power frequency current compensation value into a three-phase modal current control value after being superposed
Figure FDA0003640187220000031
7. The method as claimed in claim 6, wherein in the step (3) of calculating the current control inner loop element, the transfer function h(s) is in the form of a proportional-integral resonant regulator, as shown in the following equation:
Figure FDA0003640187220000032
wherein, KPIs the proportionality coefficient, KIIs the integral coefficient, KRIs the resonance coefficient, ζ is the resonance damping coefficient, ω0Is the power frequency angular frequency.
8. The method as claimed in claim 1, wherein the pulse generation unit is implemented by using nearest level approximation modulation or carrier phase-shift pulse width modulation.
9. The method as claimed in claim 1, wherein the body of the STATCOM is star-connected or delta-connected.
10. An engine-end STATCOM controller for restraining torsional vibration is characterized in that the controller comprises a power frequency current compensation calculation module and a current control inner ring module, the power frequency current compensation calculation module calculates a power frequency current compensation value according to a reactive power given reference value, and the power frequency current compensation value is input into the current control inner ring module to participate in the calculation of a modulated wave voltage reference value; the device also comprises a signal quantity measuring module, a modal current compensation calculating module, a direct current voltage control outer ring module and a pulse generating module; the power frequency current compensation value obtained by the power frequency current compensation calculation module, the modal control value obtained by the modal current compensation calculation module and the direct current compensation value obtained by the direct current voltage control outer ring module are used for obtaining a modulated wave voltage reference value under the action of the current control inner ring module, and finally, a trigger pulse is generated by the pulse generation module to control the on-off of an IGBT in the STATCOM, so that the required subsynchronous/supersynchronous current is generated and injected into a generator stator winding, and the electromagnetic torque for inhibiting torsional vibration is generated.
11. The STATCOM controller as claimed in claim 10, wherein the signal measurement module is for measuring the speed ω of the turbo generator and the voltage u at the generator endgGenerator terminal current igSTATCOM output current isSTATCOM direct-current side voltage udc(ii) a Where ω is the rotational speed of the rotor on the steam turbine side or the generator side of the steam turbine generator unit, ugIs the three-phase voltage or three-phase voltage of the generator igIs the three-phase current of the generator isIs the three-phase current of the STATCOM output, udcIs the three-phase voltage on the dc side of the STATCOM.
12. A torsional vibration damping space-terminal STATCOM controller as claimed in claim 10, wherein the reactive power is given a reference Q*Through the power frequency current compensation calculation module, the power frequency current compensation value is obtained through calculation
Figure FDA0003640187220000041
Power frequency current compensation calculating modelThe block adopts open loop calculation, and the generator terminal voltage u is calculated firstlygObtaining d-axis component u through dq0 transformationdReuse Q*Divided by udTo obtain the desired
Figure FDA0003640187220000042
13. The terminal STATCOM controller for suppressing torsional vibration as claimed in claim 10, wherein the rotation speed ω of the turbo generator set is calculated by the modal current compensation calculation module to obtain the control value Δ λ of each modejThe subscript j is 1,2, 3., N indicates that the turbo-generator unit has N inherent subsynchronous torsional vibration modes; the modal current compensation calculation method is to unify the rotation speed omega, separate each torsional vibration modal quantity through a band-pass filter, and obtain each modal control value delta lambda through respective proportional amplification and phase shiftj，j＝1,2,3,...,N。
14. A torsional vibration damping dead-end STATCOM controller as claimed in claim 10, wherein the dc voltage reference is a dc voltage reference
Figure FDA0003640187220000043
STATCOM DC-side voltage udcThe DC voltage is used for controlling an outer ring module, and a DC compensation value is obtained through calculation
Figure FDA0003640187220000044
Figure FDA0003640187220000045
The compensation value is a three-phase direct current compensation value, and is specifically calculated according to the following formula:
Figure FDA0003640187220000046
wherein, thetaaIs the reference phase of the A phase voltage at the generator terminal calculated by the phase-locked loop PLL,C33(θa) Is a 3 x 3 diagonal matrix, C33(θa)＝diag(cos(θa) cos(θa-2π/3) cos(θa+2π/3))，
Figure FDA0003640187220000047
Is a proportional-integral transfer function, KP1Is the proportionality coefficient, KI1Is the integral coefficient.
15. A torsional vibration suppressing terminal STATCOM controller as claimed in claim 10, wherein the STATCOM output current i is obtained from the semaphore measurement modulesPower frequency current compensation value output by power frequency current compensation calculation module
Figure FDA0003640187220000051
Modal control value delta lambda output by modal current compensation calculation modulejDC voltage control of DC current compensation value output by outer ring module
Figure FDA0003640187220000052
The reference value u of the modulated wave voltage is obtained by calculation through a current control inner loop moduleref(ii) a The current control inner loop module comprises the following sub-modules:
(1) a modal current control value operator module for calculating the modal current control value according to the following formula
Figure FDA0003640187220000053
Figure FDA0003640187220000054
(2) The current control deviation value calculation submodule is used for calculating to obtain a current control deviation value delta i according to the following formulas：
Figure FDA0003640187220000055
(3) A modulation wave voltage reference value calculation operator module for calculating the reference value according to the delta isObtaining a modulated wave voltage reference value u through a transfer function H(s)ref：
uref＝H(s)·ΔisFormula 4
C in formula 213(θj) And C13(θ0) Are all 3 × 1 matrices, respectively:
C13(θj)＝-[sin(θj) sin(θj-2π/3) sin(θj+2π/3)]T，
C13(θ0)＝-[sin(θ0) sin(θ0-2π/3) sin(θ0+2π/3)]T，
wherein theta isj＝θa+σj，θ0＝θa，θaIs the reference phase, sigma, of the generator terminal A phase voltage calculated by the phase-locked loop PLLjThe compensation phase of the set jth mode is shown, and subscript j is 1,2,3, N indicates that the turbo-generator unit has N inherent subsynchronous torsional vibration modes; formula 2 is to convert the modal control signal and the power frequency current compensation value into a three-phase modal current control value after being superposed
Figure FDA0003640187220000056
16. A torsional-oscillation-suppressing terminal STATCOM controller as claimed in claim 10, wherein the transfer function h(s) in said modulation-wave voltage reference value operator module is in the form of a proportional-integral resonant regulator, as shown in the following equation:
Figure FDA0003640187220000061
wherein, KPIs the proportionality coefficient, KIIs the integral coefficient, KRIs the resonance coefficient, ζ is the resonanceDamping coefficient, ω0Is the power frequency angular frequency.
17. A torsional-oscillation-suppressing terminal STATCOM controller as claimed in claim 10, wherein said pulse generating module employs nearest-level-approximation modulation or carrier-phase-shifted pulse-width modulation.
18. A torsional vibration damping space-terminal STATCOM controller as claimed in claim 10, wherein said STATCOM body is star-wired or delta-wired.
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