CN115021317A - Low voltage ride through control method for new energy self-synchronizing grid-connected inverter - Google Patents
Low voltage ride through control method for new energy self-synchronizing grid-connected inverter Download PDFInfo
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- H—ELECTRICITY
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- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
- H02J3/46—Controlling of the sharing of output between the generators, converters, or transformers
- H02J3/48—Controlling the sharing of the in-phase component
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
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- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
- H02J3/46—Controlling of the sharing of output between the generators, converters, or transformers
- H02J3/50—Controlling the sharing of the out-of-phase component
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- 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
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Abstract
The invention discloses a low voltage ride through control method for a new energy self-synchronizing grid-connected inverter, and belongs to the field of power control. The control method comprises the following steps: the system operates in a self-synchronizing control mode under a steady-state operation condition, has the capability of actively supporting the voltage and the frequency of a power grid, and can also take the current performance into consideration; when the voltage of the power grid drops, the power grid is switched to a constant current control mode, reactive compensation is provided for the system, and the power grid has good low-voltage ride through capability; the automatic switching is realized through the voltage drop depth D of the grid-connected point, and the switching time is shortened; meanwhile, phase adjustment is carried out at the voltage drop ending moment, the phase angle mutation of a grid-connected point caused by the voltage drop is prevented, the grid-connected point is ensured to operate within a rated range under the transient and steady state condition of the current of the grid-connected point, the off-grid times of the new energy are reduced, and the stability of a new energy grid-connected system is improved.
Description
Technical Field
The invention relates to a low voltage ride through control method of a new energy self-synchronizing grid-connected inverter, in particular to a transient and steady state dual-mode switching control method of a new energy grid-connected system under a weak power grid, and belongs to the field of power control.
Background
Under the double-carbon background of 'carbon peak reaching and carbon neutralization', the development of a new energy power generation technology is particularly important. Compared with the traditional power grid, the power generation system taking new energy as a main body can greatly improve the carbon reduction capability. However, the new energy power generation is greatly influenced by weather, and the frequency and the voltage of a power grid are difficult to actively support. Therefore, further research on an active support technology and a system stable operation control method under high-proportion penetration of new energy has important significance for a new energy power system.
In recent years, experts and scholars at home and abroad research the control problem of high-proportion new energy to be accessed into a power grid from various angles, and new energy power generation technologies such as virtual synchronous generator control and the like are continuously applied. However, there are many challenges in the stable operation of the current new energy power generation, and especially for island micro-grids in island reefs and remote areas, there are problems of low inertia, poor stability and the like. In addition, when the voltage of the power grid drops, how to help the system to quickly recover the voltage and ensure that the system realizes low voltage ride through is also a problem which needs to be solved urgently at present.
In order to solve the problems, experts and scholars at home and abroad provide methods which mainly comprise the following steps:
chinese patent application specification (CN112821445A) entitled "virtual synchronous generator control method based on inertia and damping adaptation" provides a control method capable of adapting between inertia and damping and angular frequency change rate. The method reduces the overshoot and the oscillation time of the system in the transient process, effectively enhances the inertia of the system, has better voltage and frequency supporting capacity, but lacks the current control capacity, and is difficult to ensure that the system has good stability under the condition of power grid faults.
The technical scheme disclosed in the Chinese patent application (CN114069709A) entitled "comprehensive control method for low voltage ride through of virtual synchronous machine" provides a comprehensive control method for power grid voltage feedforward, power and current instruction change during voltage drop and virtual resistance addition. The control method improves the low voltage ride through capability of the VSG to a certain extent, improves the output power quality of the VSG when the voltage of the power grid fails, but the control method is complex, serious in interaction condition under weak power grid and not strong in adaptability to the power grid.
The Chinese patent application (CN108092308A) entitled "a distributed virtual synchronous generator low voltage ride through control method" improves a reactive power loop, changes an instruction when the voltage drops so that a system preferentially sends out reactive power, and the control method has certain low voltage ride through capability, but the system still has certain overcurrent condition.
In a word, the existing self-synchronization control strategy of the new energy grid-connected inverter is difficult to ensure that the system has good voltage current control capability, active support capability and good low voltage ride through capability under a fault under the condition of weak power grid.
Disclosure of Invention
The invention provides a low-voltage ride-through control method of a new energy self-synchronizing grid-connected inverter, aiming at solving the problems of poor current performance, overvoltage and overcurrent under grid voltage drop, low system stability under a weak grid and the like of conventional self-synchronizing control.
According to the inventionThe object is achieved in this way. The invention provides a low voltage ride through control method of a new energy self-synchronizing grid-connected inverter, wherein the topology of the new energy self-synchronizing grid-connected inverter comprises a direct-current power supply U dc DC side filter capacitor C dc Three-phase full-bridge inverter circuit, filter inductor L and filter capacitor C 1 And a grid-connected equivalent resistor R g Grid-connected equivalent inductor L g And a three-phase network e a 、e b 、e c Filter capacitor C on the DC side dc Connected in parallel to a direct current source U dc And a three-phase full-bridge inverter circuit connected in series with the DC side power supply U dc A filter capacitor C between the filter inductor L and the filter capacitor 1 First series passive damping resistor R C And then connected in parallel with the filter inductor L and the grid-connected equivalent resistor R g Equivalent inductance L between and connected to grid g Serially connected with a grid-connected equivalent resistor R g And a three-phase network e a 、e b 、e c To (c) to (d);
the control method comprises the following steps:
recording the new energy self-synchronizing grid-connected inverter as a grid-connected inverter, wherein the sampling comprises the following data acquisition: the voltage of the grid-connected point of the grid-connected inverter is recorded as grid-connected voltage u oa ,u ob ,u oc And the current of the grid-connected point of the grid-connected inverter is recorded as grid-connected current i oa ,i ob ,i oc And the current at the filter inductor L of the grid-connected inverter is recorded as bridge arm side inductor current i La ,i Lb ,i Lc Grid voltage of grid-connected inverter and recorded as grid voltage u ga ,u gb ,u gc ；
The coordinate transformation includes coordinate transformation of: to grid-connected voltage u oa ,u ob ,u oc Grid-connected current i oa ,i ob ,i oc Bridge arm side inductive current i La ,i Lb ,i Lc Grid voltage u ga ,u gb ,u gc Respectively carrying out single synchronous rotation coordinate transformation to obtain grid-connected voltage dq component U od ,U oq Grid-connected currentdq component I od ,I oq Bridge arm side inductor current dq component I Ld ,I Lq Grid voltage dq component U gd ,U gq ；
P＝1.5(U oq I oq +U od I od )
Q＝1.5(U od I oq -U oq I od )
wherein, ω is 0 Active power command P given for grid-connected inverter 0 The method comprises the following steps that (1) the rated angular frequency of time, m is a power angle control droop coefficient, J is the virtual rotational inertia of a simulation synchronous generator set, and s is a Laplace operator;
carrying out phase adjustment at the voltage drop ending moment, and meanwhile, integrating the angular frequency omega of the self-synchronization control to obtain an output phase angle theta of the self-synchronization control; the phase adjustment at the voltage drop ending time is the compensation of an output phase difference delta theta which is theta g0 -θ 0 Wherein theta g0 For the output phase angle, theta, of the network voltage at the end of the voltage sag 0 For the output phase angle of the self-synchronization control at the voltage drop ending time, the expression of the output phase angle θ of the self-synchronization control is as follows:
The expressions of the reactive power control equation and the instruction synthesis equation are respectively as follows:
E * ＝U 0 +n(Q 0 -Q)
wherein, U 0 Reactive power instruction Q given for new energy self-synchronizing grid-connected inverter 0 The rated voltage of the transformer, n is a reactive-voltage droop coefficient;
wherein R is v Is a virtual resistance, L v Is a virtual inductor;
for current command signal
Performing single synchronous rotation coordinate transformation to obtain a current command signal dq component
the expressions of the power grid voltage amplitude calculation equation and the voltage drop calculation equation are respectively as follows:
step 7, obtaining a q-axis instruction of a current loop when the voltage of the power grid drops according to a reactive compensation control equation in the low voltage ride through standard
Obtaining a d-axis instruction of a current loop when the voltage of a power grid drops through a limiting control equation of the current stress of a power device
The reactive compensation control equation and the limiting control equation of the current stress of the power device are respectively as follows:
wherein, K m Is a reactive compensation coefficient, I N The rated current amplitude of the grid-connected inverter is obtained;
step 8, obtaining a D-axis instruction signal of the current inner ring according to the voltage drop depth D of the grid-connected point
And current inner loop q-axis command signal
The method comprises the following specific steps:
let the voltage of the grid-connected point be t 0 Falling off at time t 1 Ending the time drop and beginning to recover, recording t as the current time, and d-axis instruction signal of the current loop
And current inner loop q-axis command signal
Switching is performed in the following manner:
(1)t＜t 0 in the stable operation stage of the system, D is more than or equal to 0.9 and less than or equal to 1,
(2)t 0 ≤t＜t 1 in the stage of grid voltage drop, D is less than 0.9,
(3)t 1 t is less than or equal to t, in the power grid voltage recovery stage,
step 9, according to the instruction value of the dq axis of the current loop obtained in the step 8
And bridge arm side inductor current dq component I Ld ,I Lq Obtaining a control signal U by a current control equation d ,U q The current control equation is:
wherein, K pi As a current loop proportional control coefficient, K ii Is a current loop integral control coefficient;
the obtained control signal U d ,U q Control signal U of grid-connected inverter is obtained through single synchronous rotation coordinate inverse transformation a ,U b ,U c Then according to the control signal U a ,U b ,U c And generating PWM control signals for the three-phase full-bridge inverter circuit.
Compared with the prior art, the invention has the following advantages for the new energy power generation system:
1. the active support of the voltage and the frequency of the power grid can be realized, and the current control capability is realized.
2. The phase adjustment at the voltage drop ending moment can effectively avoid the sudden change of the phase angle of the grid-connected point caused by the voltage drop, and the power angle stability of the system is improved.
3. The low-voltage ride through capability is good when the voltage of the power grid drops, and the voltage and the current of the grid-connected point are guaranteed to operate within a rated range.
4. The system can stably operate under a strong power grid and a weak power grid, and improves the adaptability to the power grid.
Drawings
Fig. 1 is a topology of a new energy grid-connected inverter according to the present invention.
Fig. 2 is a control block diagram of the low voltage ride through control method of the new energy self-synchronous grid-connected inverter of the invention.
Fig. 3 is a waveform diagram of grid-connected voltage simulation when the grid voltage drops by 50% in the embodiment of the invention.
Fig. 4 is a waveform diagram of grid-connected current simulation when the grid voltage drops by 50% in the embodiment of the invention.
Fig. 5 is a simulation waveform diagram of the d-axis component of the bridge arm side inductive current when the grid voltage drops by 50% in the embodiment of the invention.
Fig. 6 is a waveform diagram of simulation of q-axis components of bridge arm side inductor current when the grid voltage drops by 50% in the embodiment of the invention.
Detailed Description
Preferred embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.
Fig. 1 is a topology structure of a new energy grid-connected inverter in an embodiment of the present invention. As can be seen from the figure, the topology of the new energy self-synchronizing grid-connected inverter comprises a direct-current power supply U dc DC side filter capacitor C dc Three-phase full-bridge inverter circuit, filter inductor L and filter capacitor C 1 Grid-connected equivalent resistor R g Grid-connected equivalent inductor L g And a three-phase network e a 、e b 、e c Filter capacitor C on the DC side dc Connected in parallel to a direct current source U dc And a three-phase full-bridge inverter circuit connected in series with the DC side power supply U dc And a filter capacitor C between the filter inductor L 1 First series passive resistorDamping resistance R C And then connected in parallel with the filter inductor L and the grid-connected equivalent resistor R g Equivalent inductance L of grid connection g Connected in series with a grid-connected equivalent resistor R g And a three-phase network e a 、e b 、e c In the meantime. In addition, PCC on fig. 1 is a point of grid connection.
Specifically, the parameters in this embodiment are as follows: the effective value of the output alternating current line voltage is 380V/50Hz, the rated capacity is 100kW, the inductance value of the filter inductor L is 0.3mH, the resistance value of the filter capacitor C is 150 muF, and the sampling frequency F of the new energy grid-connected inverter s Is 10kHz, so the sampling period T s ＝100μs。
Fig. 2 is a control block diagram of the control method of the present invention, and as can be seen from fig. 2, the steps of the control method of the low voltage ride through of the new energy self-synchronization grid-connected inverter of the present invention are as follows:
recording the new energy self-synchronizing grid-connected inverter as a grid-connected inverter, wherein the sampling comprises the following data acquisition: the voltage of the grid-connected point of the grid-connected inverter is recorded as grid-connected voltage u oa ,u ob ,u oc And the current of the grid-connected point of the grid-connected inverter is recorded as grid-connected current i oa ,i ob ,i oc And the current at the filter inductor L of the grid-connected inverter is recorded as bridge arm side inductor current i La ,i Lb ,i Lc Grid voltage of grid-connected inverter and recorded as grid voltage u ga ,u gb ,u gc ；
The coordinate transformation includes coordinate transformation of: to grid-connected voltage u oa ,u ob ,u oc And a grid-connected current i oa ,i ob ,i oc Bridge arm side induction current i La ,i Lb ,i Lc Grid voltage u ga ,u gb ,u gc Respectively carrying out single synchronous rotation coordinate transformation to obtain grid-connected voltage dq component U od ,U oq Grid-connected current dq component I od ,I oq Bridge arm side inductor current dq component I Ld ,I Lq Grid voltage dq component U gd ,U gq 。
P＝1.5(U oq I oq +U od I od )
Q＝1.5(U od I oq -U oq I od )
wherein, ω is 0 Active power command P given for grid-connected inverter 0 And m is a power angle control droop coefficient, J is the virtual moment of inertia of the simulation synchronous generator set, and s is a Laplace operator.
Carrying out phase adjustment at the voltage drop ending moment, and meanwhile, integrating the angular frequency omega of the self-synchronization control to obtain an output phase angle theta of the self-synchronization control; the phase adjustment at the voltage drop ending time is the compensation of the output phase difference delta theta which is theta g0 -θ 0 Wherein theta g0 For the output phase angle, theta, of the network voltage at the end of the voltage sag 0 For the output phase angle of the self-synchronization control at the voltage drop ending time, the expression of the output phase angle θ of the self-synchronization control is as follows:
the power angle control equation shows the droop curve relation and the virtual inertia of the active power of the grid-connected inverter. The virtual inertia marks the change rate of the system frequency, and a larger virtual inertia is needed to ensure that the system frequency changes stably; however, the virtual inertia is equivalent to adding a first order to the systemIn the inertial link, too large virtual inertia may cause instability of the system. Thus, the parameter selection requires a compromise process. In order to ensure the stability of the system, the inertia time constant is in a range of tau virtual ＝Jω 0 m≤2e -3 And s. The active power droop curve relation in the power angle control equation comprises three coefficients, the power angle control droop coefficient m represents the slope of the droop curve, and the value principle is that when the active power changes by 100%, the frequency changes within 0.5 Hz; given active power command P 0 And corresponding nominal angular frequency omega 0 The position relation of a droop curve is represented, and the active power output by the new energy grid-connected inverter is mainly considered to be P 0 Its output frequency is large or small.
In this embodiment, the droop coefficient of power angle control takes the value of
Taking tau according to the principle of inertia time constant value virtual ＝Jω 0 m＝1.5e -3 s, can obtain J equal to 0.154kg m 2 In order to ensure that the energy does not flow to the direct current side during the control operation, the value of the active power instruction is given as P 0 100kW, the corresponding rated angular frequency is omega 0 ＝314.16rad/s。
The expressions of the reactive power control equation and the instruction synthesis equation are respectively as follows:
E * ＝U 0 +n(Q 0 -Q)
wherein, U 0 Giving reactive power instruction Q for new energy self-synchronization grid-connected inverter 0 The rated voltage of the time, n, is the reactive-voltage droop coefficient.
In the present embodiment, it is preferred that,
Q 0 when it is 0, the corresponding U 0 ＝380V。
wherein R is v Is a virtual resistance, L v Is a virtual inductor;
for current command signal
Performing single synchronous rotation coordinate transformation to obtain a current command signal dq component
In this embodiment, R v ＝0.05Ω,L v ＝0.52mH。
the expressions of the power grid voltage amplitude calculation equation and the voltage drop calculation equation are respectively as follows:
in the present embodiment, it is preferred that,
step 7, obtaining a q-axis instruction of a current loop when the voltage of the power grid drops according to a reactive compensation control equation in the low voltage ride through standard
Obtaining a d-axis instruction of a current loop when the voltage of a power grid drops through a limiting control equation of the current stress of a power device
The reactive compensation control equation and the limiting control equation of the current stress of the power device are respectively as follows:
wherein, K m Is a reactive compensation coefficient, I N The rated current amplitude of the grid-connected inverter.
In this embodiment, K m ＝-1.5，
Step 8, obtaining a D-axis instruction signal of the current inner ring according to the voltage drop depth D of the grid-connected point
And current inner loop q-axis command signal
The method comprises the following specific steps:
let the voltage of the grid-connected point be t 0 Falling off at time t 1 Ending the time drop and beginning to recover, recording t as the current time, and d-axis instruction signal of the current loop
And current inner loop q-axis command signal
Switching is performed in the following manner:
(1)t＜t 0 in the stable operation stage of the system, D is more than or equal to 0.9 and less than or equal to 1,
(2)t 0 ≤t＜t 1 in the stage of grid voltage drop, D is less than 0.9,
(3)t 1 t is less than or equal to t, in the power grid voltage recovery stage,
step 9, according to the instruction value of the dq axis of the current loop obtained in the step 8
And bridge arm side inductor current dq component I Ld ,I Lq Obtaining the control signal U by a current control equation d ,U q The current control equation is:
wherein, K pi As a current loop proportional control coefficient, K ii Is a current loop integral control coefficient;
the obtained control signal U d ,U q Control signal U of grid-connected inverter is obtained through single synchronous rotation coordinate inverse transformation a ,U b ,U c Then according to the control signal U a ,U b ,U c And generating PWM control signals for the three-phase full-bridge inverter circuit.
In this embodiment, K pi ＝1.0，K ii ＝15。
In order to prove the technical effect of the invention, the invention is simulated.
Fig. 3, 4, 5, and 6 are a grid-connected voltage waveform, a grid-connected current waveform, a bridge arm side inductive current d-axis component waveform, and a bridge arm side inductive current q-axis component waveform of the new energy power generation unit when the grid voltage drops by 50% in a weak grid (short-circuit ratio SCR is 2.0), respectively, where the upper half of fig. 3 and 4 is an overall waveform, and the lower half is a waveform after being pulled away. As can be seen from fig. 3 and 4, the low voltage ride through control method for the new energy self-synchronizing grid-connected inverter provided by the invention can ensure rated operation of grid-connected voltage and grid-connected current during normal operation, can ensure that the grid-connected voltage and the grid-connected current operate within a rated range during a voltage drop stage, and can recover to a rated operation state after undergoing transient oscillation during a voltage recovery stage. As can be seen from fig. 5 and 6, according to the low voltage ride through control method for the new energy self-synchronizing grid-connected inverter provided by the invention, when the voltage of the power grid drops, the system is switched from the self-synchronizing control mode to the constant current control mode, and the system preferentially sends out reactive power to help the voltage of the power grid recover, so that low voltage ride through is realized, and the stability is improved.
Claims (1)
1. A low voltage ride through control method for a new energy self-synchronizing grid-connected inverter is disclosed, wherein the topology of the new energy self-synchronizing grid-connected inverter comprises a direct current power supply U dc DC side filter capacitor C dc Three-phase full-bridge inverter circuit, filter inductor L and filter capacitor C 1 Grid-connected equivalent resistor R g Grid-connected equivalent inductor L g And a three-phase network e a 、e b 、e c Filter capacitor C on the DC side dc Connected in parallel to a direct current source U dc And a three-phase full-bridge inverter circuit connected in series with the DC side power supply U dc A filter capacitor C between the filter inductor L and the filter capacitor 1 First series passive damping resistor R C And then connected in parallel with the filter inductor L and the grid-connected equivalent resistor R g Equivalent inductance L of grid connection g Connected in series with a grid-connected equivalent resistor R g And a three-phase network e a 、e b 、e c In the middle of;
the control method is characterized by comprising the following steps:
step 1, sampling and coordinate transformation;
recording the new energy self-synchronizing grid-connected inverter as a grid-connected inverter, wherein the sampling comprises the following data acquisition: the voltage of the grid-connected point of the grid-connected inverter is recorded as grid-connected voltage u oa ,u ob ,u oc And the current of the grid-connected point of the grid-connected inverter is recorded as grid-connected current i oa ,i ob ,i oc And the current at the filter inductor L of the grid-connected inverter is recorded as bridge arm side inductor current i La ,i Lb ,i Lc Grid voltage of grid-connected inverter and recorded as grid voltage u ga ,u gb ,u gc ；
The coordinate transformation includes coordinate transformation of: to grid-connected voltage u oa ,u ob ,u oc Grid-connected current i oa ,i ob ,i oc Bridge arm side inductive current i La ,i Lb ,i Lc Grid voltage u ga ,u gb ,u gc Respectively carrying out single synchronous rotation coordinate transformation to obtain grid-connected voltage dq component U od ,U oq Grid-connected current dq component I od ,I oq Bridge arm side inductor current dq component I Ld ,I Lq Grid voltage dq component U gd ,U gq ；
Step 2, obtaining an average active power P and an average reactive power Q by using an active power calculation equation and a reactive power calculation equation, wherein the active power calculation equation and the reactive power calculation equation are respectively as follows:
P＝1.5(U oq I oq +U od I od )
Q＝1.5(U od I oq -U oq I od )
step 3, according to the average active power P obtained in the step 2 and an active power instruction P given by the grid-connected inverter 0 Obtaining the angular frequency omega of the self-synchronization control through a power angle control equation, wherein the expression of the power angle control equation is as follows:
wherein, ω is 0 Active power command P given for grid-connected inverter 0 The method comprises the following steps that (1) the rated angular frequency of time, m is a power angle control droop coefficient, J is the virtual rotational inertia of a simulation synchronous generator set, and s is a Laplace operator;
carrying out phase adjustment at the voltage drop ending moment, and meanwhile, integrating the angular frequency omega of the self-synchronization control to obtain an output phase angle theta of the self-synchronization control; the phase adjustment at the voltage drop ending time is the compensation of the output phase difference delta theta which is theta g0 -θ 0 Wherein θ g0 For the output phase angle, theta, of the network voltage at the end of the voltage sag 0 For the output phase angle of the self-synchronization control at the voltage drop ending time, the expression of the output phase angle θ of the self-synchronization control is as follows:
step 4, according to the average reactive power Q obtained in the step 2 and a reactive power instruction Q given by the grid-connected inverter 0 Obtaining a self-synchronous control terminal voltage amplitude instruction E through a reactive power control equation * And then according to the self-synchronous control output phase angle theta and the terminal voltage amplitude instruction E obtained in the step 3 * Obtaining self-synchronization control three-phase terminal voltage instruction through instruction synthesis equation
The expressions of the reactive power control equation and the instruction synthesis equation are respectively as follows:
E * ＝U 0 +n(Q 0 -Q)
wherein, U 0 Giving reactive power instruction Q for new energy self-synchronization grid-connected inverter 0 Rated voltage of the time, n is a reactive-voltage droop coefficient;
step 5, according to the three-phase terminal voltage instruction obtained in the step 4
And the grid-connected voltage u obtained in the step 1 oa ,u ob ,u oc Obtaining a current command signal by a virtual impedance control equation
The expression of the virtual impedance control equation is as follows:
wherein R is v Is a virtual resistance, L v Is a virtual inductor;
for current command signal
Performing single synchronous rotation coordinate transformation to obtain a current command signal dq component
Step 6, obtaining the grid voltage dq component U according to the step 1 gd ,U gq Obtaining the grid voltage amplitude U through a grid voltage amplitude calculation equation g According to the obtained voltage amplitude U of the power grid g With a given grid voltage amplitude command U ref Determining the voltage drop depth D of the grid-connected point through a voltage drop calculation equation;
the expressions of the power grid voltage amplitude calculation equation and the voltage drop calculation equation are respectively as follows:
step 7, obtaining a q-axis instruction of a current loop when the voltage of the power grid drops according to a reactive compensation control equation in the low voltage ride through standard
Obtaining a d-axis instruction of a current loop when the voltage of a power grid drops through a limiting control equation of the current stress of a power device
The reactive compensation control equation and the limiting control equation of the current stress of the power device are respectively as follows:
wherein, K m For compensating for reactive powerCoefficient of compensation, I N The rated current amplitude of the grid-connected inverter is obtained;
step 8, obtaining a current inner ring D-axis instruction signal according to the voltage drop depth D of the grid-connected point
And current inner loop q-axis command signal
The method comprises the following specific steps:
let the voltage of the grid-connected point be t 0 Falling off at time t 1 Ending the time drop and beginning to recover, recording t as the current time, and d-axis instruction signal of the current loop
And current inner loop q-axis command signal
Switching is performed in the following manner:
(1)t＜t 0 in the stable operation stage of the system, D is more than or equal to 0.9 and less than or equal to 1,
(2)t 0 ≤t＜t 1 in the stage of grid voltage drop, D is less than 0.9,
(3)t 1 t is less than or equal to t, in the power grid voltage recovery stage,
step 9, according to the instruction value of the dq axis of the current loop obtained in the step 8
Current dq of bridge arm side inductorQuantity I Ld ,I Lq Obtaining the control signal U by a current control equation d ,U q The current control equation is:
wherein, K pi Is a current loop proportional control coefficient, K ii Is a current loop integral control coefficient;
the obtained control signal U d ,U q Control signal U of grid-connected inverter is obtained through single synchronous rotation coordinate inverse transformation a ,U b ,U c Then according to the control signal U a ,U b ,U c And generating PWM control signals for the three-phase full-bridge inverter circuit.
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101860043A (en) * | 2010-05-17 | 2010-10-13 | 东南大学 | Low voltage traversing control device and method for serial connection wind power generator set |
| CN113346559A (en) * | 2021-05-31 | 2021-09-03 | 合肥工业大学 | Low-voltage ride-through power switching control method for direct-drive wind power system under extremely weak grid |
| WO2021233190A1 (en) * | 2020-05-21 | 2021-11-25 | 合肥工业大学 | Dual-mode combined control method for multi-inverter system based on double split transformer |
| CN113964879A (en) * | 2021-11-23 | 2022-01-21 | 合肥工业大学 | New energy grid-connected inverter self-synchronizing voltage source control method |
| CN113991755A (en) * | 2021-10-20 | 2022-01-28 | 国网湖北省电力有限公司电力科学研究院 | Self-synchronizing voltage source control method for new energy power generation unit |
-
2022
- 2022-06-24 CN CN202210738510.3A patent/CN115021317B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101860043A (en) * | 2010-05-17 | 2010-10-13 | 东南大学 | Low voltage traversing control device and method for serial connection wind power generator set |
| WO2021233190A1 (en) * | 2020-05-21 | 2021-11-25 | 合肥工业大学 | Dual-mode combined control method for multi-inverter system based on double split transformer |
| CN113346559A (en) * | 2021-05-31 | 2021-09-03 | 合肥工业大学 | Low-voltage ride-through power switching control method for direct-drive wind power system under extremely weak grid |
| CN113991755A (en) * | 2021-10-20 | 2022-01-28 | 国网湖北省电力有限公司电力科学研究院 | Self-synchronizing voltage source control method for new energy power generation unit |
| CN113964879A (en) * | 2021-11-23 | 2022-01-21 | 合肥工业大学 | New energy grid-connected inverter self-synchronizing voltage source control method |
Non-Patent Citations (1)
| Title |
|---|
| 周皓;童朝南;李江昀;景鹏;: "三电平光伏并网逆变器低电压穿越的控制策略", 太阳能学报, no. 07, 31 July 2016 (2016-07-31), pages 1788 - 1796 * |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115473273A (en) * | 2022-09-21 | 2022-12-13 | 合肥工业大学 | Self-synchronization low-voltage ride-through control method for new energy power generation unit under extremely weak grid |
| CN115473273B (en) * | 2022-09-21 | 2024-03-19 | 合肥工业大学 | New energy power generation unit self-synchronizing low voltage ride through control method under extremely weak network |
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