CN108462209B - Frequency-voltage integrated robust optimization control method based on virtual synchronous generator - Google Patents

Frequency-voltage integrated robust optimization control method based on virtual synchronous generator Download PDF

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CN108462209B
CN108462209B CN201810319278.3A CN201810319278A CN108462209B CN 108462209 B CN108462209 B CN 108462209B CN 201810319278 A CN201810319278 A CN 201810319278A CN 108462209 B CN108462209 B CN 108462209B
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frequency
voltage
virtual synchronous
synchronous generator
control
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窦晓波
张从越
王小红
侯凯
葛浦东
汤晓晨
伍小刚
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Southeast University
NARI Group Corp
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H02J3/381—Dispersed generators
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
    • H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A30/00—Adapting or protecting infrastructure or their operation
    • Y02A30/60—Planning or developing urban green infrastructure

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  • Power Engineering (AREA)
  • Control Of Eletrric Generators (AREA)

Abstract

The invention discloses a frequency voltage based on a virtual synchronous generatorAn integrated robust optimization control method is characterized in that on the basis of a traditional virtual synchronous generator control strategy, the actual operation state of a system is considered, modeling is carried out on the variables of the integrated system and the disturbance variables, and robust H is introduced∞The control theory realizes the feedback control of frequency and voltage, and further introduces the sliding mode control theory to realize the tracking control of frequency and voltage on the basis of stable feedback control. The optimization control method fully considers the active and reactive power in the system and the change of load current, and establishes a state space equation for the frequency and the voltage on the basis. The model fully considers the condition of incomplete decoupling of current and voltage decoupling, so the method is suitable for a high-voltage power grid of an inductive line and a low-voltage power distribution network of a resistive line; meanwhile, the feedback is a feedback control method with a fixed structure, the dynamic adjustment of parameters is not needed, and the operation reliability and stability are high.

Description

Frequency-voltage integrated robust optimization control method based on virtual synchronous generator
Technical Field
The invention belongs to the technical field of generator control, relates to an inverter control and optimization technology, and particularly relates to a frequency-voltage integrated robust optimization control method based on a virtual synchronous generator.
Background
When the distributed power supply is connected to a power distribution network in a large quantity, the conventional inverter control method can generate instantaneous overload due to the fact that no damping and inertia characteristic support exists, and therefore damage to power electronic equipment can be caused. Although the virtual synchronous generator control method can provide certain inertia and damping support for the system by adding virtual inertia and damping characteristics in the aspect of control, the operation state of the operation system cannot be considered actually, and the system is easy to lose stability when being influenced by internal and external disturbances.
Disclosure of Invention
In order to solve the problems, the invention discloses a frequency-voltage integrated robust optimization control method based on a virtual synchronous generator, which is characterized in that a system state space equation is established to solve by considering the actual running state of the system to obtain a robust H∞And the feedback controller minimizes the influence of internal and external disturbance on the output of the system, and ensures the stability of the system after being disturbed by external disturbance input and internal load to the maximum extent.
In order to achieve the purpose, the invention provides the following technical scheme:
a frequency and voltage integrated robust optimization control method based on a virtual synchronous generator comprises the following steps:
step 1, robust control of virtual synchronous generator frequency
Based on active-frequency control of traditional virtual synchronous generator, robust H is adopted∞The theory method introduces the disturbance of the input of the external and internal active power of the system to realize the fast feedback and the stable operation of the active power-frequency;
step 2, robust control of virtual synchronous generator voltage
Based on the reactive-voltage control of the traditional virtual synchronous generator, the robust H is adopted∞The theoretical method introduces load current disturbance and system reactive disturbance to realize the rapid feedback and stable operation of system reactive-voltage;
step 3, feedback control integration based on sliding mode control method
On the basis of frequency and voltage robust control in the steps 1 and 2, a sliding mode control theory is introduced, and the state space equation is expanded by integrating the state space equation in the steps 1 and 2 and adding integral of frequency and voltage, so that stable tracking control optimization control of the system frequency and voltage is realized.
Further, the robust control equation of the virtual synchronous generator frequency in step 1 is as follows:
Figure GDA0002952267020000021
in the formula: omeganIs the rated frequency value of the system, omega is the frequency value of the actual operation of the system, P is the output active power of the inverter, PrefIs the system gives the reference active power, PloadIs the active value of the equivalent external system input, mpIs the active power droop coefficient.
Further, in step 2, introducing a virtual ground capacitor into the grid-connected node to realize the introduction of a grid-connected point voltage state variable, wherein a virtual synchronous generator voltage robust control equation is as follows:
Figure GDA0002952267020000022
in the formula: u. ofd,uqIs the voltage value, i, across the dq axis of the grid connection point1d,i1qIs the current, omega, output by the virtual synchronous generatornIs the rated frequency value of the system, Q is the output reactive power of the inverter, QrefIs the system gives the reference reactive power, i2d,i2qIs the current input from an external system, ild,ilqIs the value of the current of the internal load of the system, QloadIs the reactive power of the external system input, R L is the line impedance value, C is the virtual earth capacitance value, mqIs the reactive power droop coefficient, u1du1qIs the virtual synchronous generator output voltage value.
Further, based on a sliding mode control theory in the step 3, in combination with the equations in the steps 1 and 2, the robust control state equation of the frequency and the voltage of the virtual synchronous generator is obtained as follows:
Figure GDA0002952267020000023
in the formula: a B1 B2 BrefC is coefficient equation of system, x is system state variable, xrefFeeding back a reference variable for the system, wherein w is system disturbance, u is system controllable input, and z is an evaluation variable; setting robust H according to system state space equation∞The feedback controller is K, and the robust H is realized by establishing the relation u ═ Kx between the controllable input and the state variable∞Solving a theoretical feedback controller; after the feedback controller is obtained by solving, the acquired state variable is multiplied by a feedback matrix K to obtain a controllable input variable Pref、QrefAnd the feedback optimization control of the frequency voltage is realized through the input of the controllable input variable to the system.
Further, the feedback controller solves through a linear matrix inequality method to obtain a feedback control matrix K, and the control matrix establishes disturbance variables in the virtual synchronous generator: active power P, reactive power Q, internal load current ild,ilqExternal input current i2d,i2q(ii) a And a controllable input variable Pref、QrefThe equation connection of the method realizes that the system can dynamically change the controllable input according to the disturbance variable, thereby realizing the stable and optimized control of the frequency and the voltage.
Compared with the prior art, the invention has the following advantages and beneficial effects:
1. by adding robust H on the basis of virtual synchronous generator control in consideration of disturbance input possibly suffered by the system during actual operation and change disturbance of internal load∞Feedback, robust H∞The control theory can obtain a feedback controller which enables the influence of the internal and external disturbances of the system on the output of the system to be minimum through the analysis and calculation of the overall state of the system, and the minimization from the internal and external disturbances to the output influence is realized, so that the stable operation of the system under the disturbance is ensured to the maximum extent.
2. A sliding mode control theory is introduced, and tracking control of frequency and voltage is realized on the basis of stable feedback control.
3. The method is suitable for a high-voltage power grid of an inductive line and a low-voltage power distribution network of a resistive line.
4. The method belongs to a feedback control mode with a fixed structure, does not need to dynamically adjust inertia and damping parameters according to the actual running state in the running process, reduces errors caused by data analysis and judgment, and has relatively high stability and reliability of the system.
Drawings
Fig. 1 is a diagram of a robust feedback control principle.
FIG. 2 is a schematic view of the structure of the present invention.
Fig. 3 is a schematic diagram of active and reactive power regulation of a virtual synchronous generator.
Detailed Description
The technical solutions provided by the present invention will be described in detail below with reference to specific examples, and it should be understood that the following specific embodiments are only illustrative of the present invention and are not intended to limit the scope of the present invention.
The frequency-voltage integrated robust optimization control method based on the virtual synchronous generator is realized based on the control framework shown in the figures 2 and 3 by combining the core idea of the robust feedback control principle shown in figure 1, and introduces the robust H through modeling the whole system variable and the disturbance variable on the basis of the traditional virtual synchronous generator control strategy∞The control theory realizes the optimal control of the frequency voltage. Specifically, the method comprises the following steps:
(1) virtual synchronous generator frequency robust control
On the basis of active-frequency control of a traditional virtual synchronous generator, disturbance of external and internal active power input of a system is considered. By robust H∞The theoretical method minimizes the influence of active disturbance on the output frequency of the system, thereby realizing that the system can maximally cope with the change of active input, reducing the active output and the frequency change of the system, and realizing the rapid feedback and the stable operation of the active-frequency of the system.
In this step, the robust control equation of the virtual synchronous generator frequency is as follows:
Figure GDA0002952267020000041
in the formula: omeganIs the rated frequency value of the system, omega is the frequency value of the actual operation of the system, P is the output active power of the inverter, PrefIs the system gives the reference active power, PloadIs the active value of the equivalent external system input, mpIs the active power droop coefficient.
In robust H∞In control theory, (P + P)load) As a disturbance value of the system, PrefAs a controllable input of the system, omega is used as a system state variable, so that H can be solved∞Relation of feedback controller
Pref＝Kω (8)
In the formula: k is a robust feedback controller.
(2) Virtual synchronous generator voltage robust control
On the basis of the reactive-voltage control of the traditional virtual synchronous generator, the load current disturbance and the system reactive disturbance are considered. By robust H∞The theoretical method minimizes the influence of load current disturbance and system reactive change on the voltage of a grid-connected point, thereby realizing that the system can maximally respond to the change of the load and realizing the rapid feedback and stable operation of the system reactive-voltage.
The introduction of a voltage state variable of a grid-connected point is realized by introducing a virtual ground capacitor into a grid-connected node, and a voltage robust control state equation of a virtual synchronous generator is as follows:
Figure GDA0002952267020000042
in the formula: u. ofd,uqIs the voltage value, i, across the dq axis of the grid connection point1d,i1qIs a virtual synchronous generator outputCurrent drawn, ωnIs the rated frequency value of the system, Q is the output reactive power of the inverter, QrefIs the system gives the reference reactive power, i2d,i2qIs the current input from an external system, ild,ilqIs the value of the current of the internal load of the system, QloadIs the reactive power input by the external system, RL is the line impedance value, C is the virtual earth capacitance value, mqIs the reactive power droop coefficient, u1du1qIs the virtual synchronous generator output voltage value.
In robust H∞In control theory, (Q + Q)load) And ild,ilqAs a disturbance value of the system, QrefFor controllable input of the system, [ u ]d uq i1d i1q]TIs a system state variable. So that H can be solved∞Relation of feedback controller
Qref＝K[ud uq i1d i1q]T (10)
In the formula: k is a robust feedback controller.
(3) On the basis of frequency and voltage robust control, a sliding mode control theory is introduced, the state space equation of the two steps is integrated, and the integral of frequency and voltage is added, so that the state space equation is expanded, and the stable tracking control optimization control of the system frequency and voltage is realized.
Based on a sliding mode control theory, combining the equations in the steps (1) and (2), obtaining a frequency-voltage robust control state equation of the virtual synchronous generator as follows:
Figure GDA0002952267020000051
in the formula: a B1 B2 BrefC is coefficient equation of system, x is system state variable, xrefFeeding back a reference variable for the system, wherein w is system disturbance, u is system controllable input, and z is an evaluation variable; setting robust H according to system state space equation∞FeedbackThe controller is K, the relation u of the controllable input and the state variable is established as Kx, and the implementation is based on the robust H∞The theoretical feedback controller solves.
By integrating the state space equations of the steps (1) and (2) and combining the state equations in the form of the step (3), the state space equation of the whole system can be obtained as the following formula.
Figure GDA0002952267020000052
Setting robust H according to system state space equation∞The feedback controller is K, by establishing the relationship between the controllable inputs and the state variables as follows:
Figure GDA0002952267020000061
the controller can be solved by a linear matrix inequality method to obtain a frequency-voltage integrated robust optimization control method based on the virtual synchronous generator. That is, the controllable input variable P is obtained by multiplying the acquired state variable by the feedback matrix Kref、QrefAnd the feedback optimization control of the frequency voltage is realized through the input of the controllable input variable to the system.
The technical means disclosed in the invention scheme are not limited to the technical means disclosed in the above embodiments, but also include the technical scheme formed by any combination of the above technical features. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principle of the present invention, and such improvements and modifications are also considered to be within the scope of the present invention.

Claims (5)

1. The frequency-voltage integrated robust optimization control method based on the virtual synchronous generator is characterized by comprising the following steps of:
step 1, robust control of virtual synchronous generator frequency
Active-frequency control in traditional virtual synchronous generatorBased on system, by robust H∞The theory method introduces the disturbance of the input of the external and internal active power of the system to realize the fast feedback and the stable operation of the active power-frequency;
step 2, robust control of virtual synchronous generator voltage
Based on the reactive-voltage control of the traditional virtual synchronous generator, the robust H is adopted∞The theoretical method introduces load current disturbance and system reactive disturbance to realize the rapid feedback and stable operation of system reactive-voltage;
step 3, feedback control integration based on sliding mode control method
On the basis of robust control of the frequency of the virtual synchronous generator in the step 1 and robust control of the voltage of the virtual synchronous generator in the step 2, a sliding mode control theory is introduced, and the state space equation is expanded by integrating the state space equation in the steps 1 and 2 and adding integral of the frequency and the voltage, so that stable tracking control optimization control of the frequency and the voltage of the system is realized.
2. The virtual synchronous generator-based frequency-voltage integrated robust optimization control method according to claim 1, wherein the virtual synchronous generator frequency robust control equation in step 1 is as follows:
Figure FDA0002952267010000011
in the formula: omeganIs the rated frequency value of the system, omega is the frequency value of the actual operation of the system, P is the output active power of the inverter, PrefIs the system gives the reference active power, PloadIs the active value of the equivalent external system input, mpIs the active power droop coefficient.
3. The virtual synchronous generator-based frequency-voltage integrated robust optimization control method according to claim 2, wherein in the step 2, the introduction of the grid-connected point voltage state variable is realized by introducing a virtual ground capacitor into the grid-connected node, and the virtual synchronous generator voltage robust control equation is as follows:
Figure FDA0002952267010000012
in the formula: u. ofd,uqIs the voltage value, i, across the dq axis of the grid connection point1d,i1qIs the current, omega, output by the virtual synchronous generatornIs the rated frequency value of the system, Q is the output reactive power of the inverter, QrefIs the system gives the reference reactive power, i2d,i2qIs the current input from an external system, ild,ilqIs the value of the current of the internal load of the system, QloadIs the reactive power input by the external system, R is the line resistance value, L is the line inductance value, C is the virtual capacitance to ground value, mqIs the reactive power droop coefficient, u1d,u1qIs the virtual synchronous generator output voltage value.
4. The virtual synchronous generator frequency and voltage integrated robust optimization control method according to claim 3, wherein the virtual synchronous generator frequency and voltage integrated robust control state equation obtained in step 3 based on the sliding mode control theory and combined with the equations in steps 1 and 2 is as follows:
Figure FDA0002952267010000021
in the formula: a, B1,B2,BrefC is the coefficient equation of the system, x is the system state variable, xrefFeeding back a reference variable for the system, wherein w is system disturbance, u is system controllable input, and z is an evaluation variable; setting robust H according to system state space equation∞The feedback matrix of the feedback controller is K, and the robust H is realized by establishing the relation u of the controllable input and the state variable as Kx∞Solving a theoretical feedback controller; after solving to obtain a feedback controller, multiplying the acquired state variable byObtaining a controllable input variable P by a feedback matrix Kref、QrefAnd the feedback optimization control of the frequency voltage is realized through the input of the controllable input variable to the system.
5. The virtual synchronous generator-based frequency-voltage integrated robust optimization control method according to claim 4, characterized in that: the feedback controller is solved through a linear matrix inequality method to obtain a feedback matrix K, and the feedback matrix K establishes a disturbance variable and a controllable input variable P in the virtual synchronous generatorref、QrefIn relation to the disturbance variable in the virtual synchronous generator: active power P, reactive power Q, internal load current ild,ilqExternal input current i2d,i2q(ii) a The system can dynamically change the controllable input according to the disturbance variable, so that the stable and optimized control of the frequency voltage is realized.
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