CN114552675A - Grid-connected inverter transient stability control method and device based on virtual synchronous machine - Google Patents

Grid-connected inverter transient stability control method and device based on virtual synchronous machine Download PDF

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CN114552675A
CN114552675A CN202210246882.4A CN202210246882A CN114552675A CN 114552675 A CN114552675 A CN 114552675A CN 202210246882 A CN202210246882 A CN 202210246882A CN 114552675 A CN114552675 A CN 114552675A
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power
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active power
control loop
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程鹏
李孔源
马静
贾利民
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North China Electric Power University
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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
    • 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
    • H02J3/50—Controlling the sharing of the out-of-phase component
    • 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
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy
    • Y02E10/56—Power conversion systems, e.g. maximum power point trackers

Abstract

The invention relates to a grid-connected inverter transient stability control method and device based on a virtual synchronous machinevFinally the compensation power Δ PvAnd the negative feedback is carried out to the front end of the active power control loop. The transient stability of the grid-connected inverter can be effectively improved, and the method is easy to implement.

Description

Grid-connected inverter transient stability control method and device based on virtual synchronous machine
Technical Field
The invention relates to a grid-connected inverter transient stability control method and device based on a virtual synchronous machine.
Background
Voltage Source Inverters (VSIs) are widely used as grid interfaces in renewable energy systems, distributed power generation systems and electric transport systems to convert direct current into alternating current. However, due to short circuit faults and the like, the VSI may operate under severe three-phase voltage drops.
Currently, research on transient stability of grid-connected VSI during voltage sag is mainly focused on more grid-type VSI and grid-connected VSI employing vector control. Because of the small short-circuit ratio (SCR) of weak grids, phase-locked loops in grid-follower VSIs tend to lose stability during grid voltage sags. The networking type VSI does not include a phase-locked loop, and is equivalent to a controlled voltage source, and several networking type VSI control methods have been used in different active power control schemes, including droop control, power synchronization control, virtual oscillator control, and Virtual Synchronous Generator (VSG) control. Of these methods, VSG control is the simplest and most widely used case, where the VSI is controlled to simulate the dynamics of a synchronous generator.
The implementation flexibility of the VSG controller enables corresponding auxiliary control methods to be designed to enhance transient stability on the premise of understanding transient instability mechanisms. In the prior art, a method for improving transient stability by adding a low-pass filter to a reactive power control loop is provided, but the method increases the order of a control system, so that the system analysis is more complicated. In the prior art, a self-adaptive inertia method is also provided, which can reduce frequency deviation during a power grid fault to improve transient stability. However, this method relies on a differentiating element to detect the direction of the frequency change, which is complicated to implement. In the prior art, a method for switching the VSG mode is also provided, which can change the VSG mode when the power grid fails, and can realize fault ride-through even if no balanced operating point exists, thereby improving transient stability. However, this method needs to detect the frequency and active power changes, and also depends on the differential component, and is relatively complex to implement in practice. In the prior art, a method is also proposed, in which a transient damper is designed based on the difference between the grid frequency estimated by the phase-locked loop and the angular frequency in the active power control loop of the VSG. However, this approach relies on a phase-locked loop to acquire the frequency of the grid, which may lose stability during voltage dips.
Disclosure of Invention
The invention aims to provide a grid-connected inverter transient stability control method and device based on a virtual synchronous machine, which can effectively improve the transient stability of a grid-connected inverter and is easy to realize.
Based on the same inventive concept, the invention has two independent technical schemes:
1. a grid-connected inverter transient stability control method based on a virtual synchronous machine controls a grid-connected inverter through an active power control loop, a reactive power control loop and the virtual synchronous machine, when the active power control loop realizes control, a reactive power deviation delta Q and a frequency deviation delta omega are multiplied through a multiplier, and a compensation power delta P is obtained through a proportion linkvFinally the compensation power Δ PvAnd the negative feedback is carried out to the front end of the active power control loop.
Further, the compensation power Δ PvIs obtained by the following formula,
ΔPv＝Kv(Q-Qref)·Δω
in the formula, Δ ω is a frequency deviation, KvIs the proportional coefficient of the proportional link, Q is the reactive power, QrefIs a reactive power reference value.
Furthermore, the control model formula of the active power control loop is as follows,
Figure BDA0003545105750000031
Figure BDA0003545105750000032
in the formula, DpIs the damping coefficient, J is the virtual inertia, Δ ω is the frequency deviation, ω0Is the grid voltage reference frequency, Δ PvIs the compensation power, P is the active power of the grid, PrefIs the grid active power reference value, thetarefThe reference value of the phase angle of the voltage of the power grid is also the output value of the active power control loop.
Further, the proportionality coefficient KvIs obtained by a process which comprises the steps of,
step 2.1: setting a proportionality coefficient KvA reference value of (d);
step 2.2: based on the proportionality coefficient KvCalculating to obtain a current virtual power angle delta;
step 2.3: judging the current virtual power angle deltapWhether greater than δm，δmIs referred to as KvWhen the value is equal to 0, the virtual power angle corresponding to the unstable balance point of the system is obtained; if yes, entering step 4, otherwise entering step 5;
step 2.4: kv＝Kv- Δ K, Δ K being KvStep 2 is returned to;
step 2.5: the current proportionality coefficient KvAs an output value.
Further, in step 2.2, the virtual power angle δ is calculated by the following formula,
Figure BDA0003545105750000033
in the formula, DpIs the damping coefficient, J is the virtual inertia, Δ ω is the frequency deviation, ω0Is the grid voltage reference frequency, omegagIs the current grid voltage frequency, Δ PvIs the compensation power, P is the active power of the grid, PrefIs the grid active power reference value, KvIs the proportionality coefficient of the proportional link, Q is the reactive power, QrefIs a reactive power reference value.
Further, in step 2.3, δmThe value of (d) is pi.
Further, in step 2.4, the value of the iteration step Δ k is 0.1p.u.
Further, the method comprises the following steps:
step 1: three-phase current I output by grid-connected inverter is acquired through sensorfThree-phase current instantaneous value I of grid-connected pointpccAnd three-phase voltage instantaneous value UpccCalculating three-phase instantaneous active power P and reactive power Q;
step 2: the active power P calculates the reference value theta of the phase angle of the grid voltage through an active power control loopref；
And step 3: the reactive power Q is calculated to obtain a reference voltage amplitude U through a reactive power control loopref；
And 4, step 4: will If、Ipcc、Upcc、θrefAnd UrefThe PMW signal is output by the virtual synchronous machine through pulse width modulation, and the grid-connected inverter is controlled.
2. A control device for improving transient stability of a grid-connected inverter comprises an active power control loop, a reactive power control loop and a virtual synchronous machine, wherein the virtual synchronous machine is based on a grid voltage phase angle reference value theta output by the active power control loop and the reactive power control looprefAnd a reference voltage amplitude UrefThe PMW signal is output through pulse width modulation to control a grid-connected inverter, an active power control loop is provided with a control branch, and the control branch comprises a proportion module and a multiplier; the control branch performs the following control,
when the active power control loop realizes control, the reactive power deviation delta Q and the frequency deviation delta omega are multiplied by a multiplier, and then a proportion link is carried out to obtain the compensation power delta PvFinally the compensation power Δ PvAnd the negative feedback is carried out to the front end of the active power control loop.
Furthermore, the control model formula of the active power control loop is as follows,
Figure BDA0003545105750000041
Figure BDA0003545105750000051
in the formula, DpIs the damping coefficient, J is the virtual inertia, Δ ω is the frequency deviation, ω0Is the grid voltage reference frequency, Δ PvIs the compensation power, P is the active power of the grid, PrefIs the grid active power reference value, thetarefThe reference value of the phase angle of the voltage of the power grid is also the output value of the active power control loop.
The invention has the following beneficial effects:
when the VSI is unstable in the transient process, the reactive power Q of the power grid side and the reactive power reference value Q in the reactive power controllerrefIs greater than 0, i.e. Q-Qref＝ΔQ>0; while the angular frequency deviation in the active power controller is always larger than 0, i.e. Δ ω>0 and the angular frequency deviation Δ ω is equal to 0 at steady state. The invention utilizes the constant delta Q of the existing virtual synchronous machine control type VSI in transient instability>When the active power control loop realizes control, an auxiliary control branch is added on the basis of the existing control method, the reactive power deviation delta Q and the frequency deviation delta omega are multiplied by a multiplier, and then a proportional link is carried out to obtain the compensation power delta PvFinally the compensation power Δ PvThe negative feedback is carried out to the front end of the active power control loop, so that the stability of the control type VSI of the virtual synchronous machine is improved, the operation is simple, and the realization is easy.
The invention compensates the power Delta PvIs obtained by the following formula,
ΔPv＝Kv(Q-Qref)·Δω
in the formula, Δ ω is a frequency deviation, KvIs the proportionality coefficient of the proportional link, Q is the reactive power, QrefIs a reactive power reference value.
The control model formula of the active power control loop is as follows,
Figure BDA0003545105750000052
Figure BDA0003545105750000053
in the formula, DpIs the damping coefficient, J is the virtual inertia, Δ ω is the frequency deviation, ω0Is the grid voltage reference frequency, Δ PvIs the compensation power, P is the active power of the grid, PrefIs the grid active power reference value, thetarefIs the grid voltage phaseThe angle reference is also the output value of the active power control loop.
Coefficient of proportionality KvIs obtained by a process which comprises the steps of,
step 2.1: setting a proportionality coefficient KvA reference value of (d);
step 2.2: based on the proportionality coefficient KvCalculating to obtain a current virtual power angle delta;
step 2.3: judging the current virtual power angle deltapWhether greater than δm，δmIs referred to as KvWhen the value is equal to 0, the virtual power angle corresponding to the unstable balance point of the system is obtained; if yes, entering step 4, otherwise entering step 5;
step 2.4: kv＝Kv- Δ K, Δ K being KvStep 2 is returned to;
step 2.5: the current proportionality coefficient KvAs an output value.
In step 2.2, the virtual power angle delta is calculated and obtained by the following formula,
Figure BDA0003545105750000061
in the formula, DpIs the damping coefficient, J is the virtual inertia, Δ ω is the frequency deviation, ω0Is the grid voltage reference frequency, omegagIs the current grid voltage frequency, Δ PvIs the compensation power, P is the active power of the grid, PrefIs the grid active power reference value, KvIs the proportional coefficient of the proportional link, Q is the reactive power, QrefIs a reactive power reference value.
δmThe value of (d) is pi.
The value of the iteration step length delta k is 0.1p.u.
The invention obtains the proportionality coefficient K through the method and the specific parametersvAnd the calculation accuracy and the calculation efficiency of the feedback power delta P are further ensured, and the transient stability of the grid-connected inverter is effectively improved.
Drawings
FIG. 1 is a control schematic of a prior art control method of the present invention;
FIG. 2 is a control schematic of the control method of the present invention;
FIG. 3 is a scale factor K of the present inventionvA calculation flowchart of (1);
FIG. 4 is KvWhen the voltage is 0, the simulation oscillogram when the voltage of the power grid drops;
FIG. 5 is Kv2.6p.u., simulation oscillogram when the voltage of the power grid drops.
Detailed Description
The present invention is described in detail with reference to the embodiments shown in the drawings, but it should be understood that these embodiments are not intended to limit the present invention, and those skilled in the art should understand that functional, methodological, or structural equivalents or substitutions made by these embodiments are within the scope of the present invention.
The first embodiment is as follows:
grid-connected inverter transient stability control method based on virtual synchronous machine
As shown in fig. 1, a grid-connected inverter is controlled by an active power control loop, a reactive power control loop, and a current-voltage control loop, which is a conventional technique.
As shown in fig. 2, the present invention adds an auxiliary control branch based on the existing control method. When the active power control loop realizes control, the reactive power deviation delta Q and the frequency deviation delta omega are multiplied by a multiplier, and then a proportion link is carried out to obtain the compensation power delta PvFinally the compensation power Δ PvAnd the negative feedback is carried out to the front end of the active power control loop.
Compensating power Δ PvIs obtained by the following formula,
ΔPv＝Kv(Q-Qref)·Δω (1)
in the formula, Δ ω is a frequency deviation, KvIs the proportionality coefficient of the proportional link, Q is the reactive power, QrefIs a reactive power reference value. Delta PvRepresenting the transient compensation power. Since the frequency deviation Δ ω is 0 at the steady state, Δ P is present at the steady state v0, the auxiliary control branch in the invention does not affectThe steady state characteristics of the VSI are affected.
The control model formula of the active power control loop is as follows,
Figure BDA0003545105750000081
Figure BDA0003545105750000082
in the formula DpIs the damping coefficient, J is the virtual inertia, Δ ω is the frequency deviation, ω0Is the grid voltage reference frequency, Δ PvIs the compensation power, P is the active power of the grid, PrefIs the grid active power reference value, thetarefThe reference value of the phase angle of the voltage of the power grid is also the output value of the active power control loop.
Defining a virtual power angle δ ═ θref-θgAnd assuming that the grid voltage frequency is maintained at the reference frequency ω0Then equation (3) can be rewritten as follows:
Figure BDA0003545105750000083
from the reactive power controller, we can get:
Uref＝U0+Kq(Qref-Q) (5)
Kqis the Q-V sag coefficient, U0Is the reference peak value, Q, of the network phase voltagerefIs the reactive power reference value of the power grid. The above analysis is performed in the power control loop, and in order to build a large signal model that can be used for transient stability analysis, the relationship of the actual circuit and the power controller must also be considered. Generally, the bandwidth of the voltage-current inner loop is higher than that of the outer loop power controller, which means that the inner loop has a faster response speed. According to time scale decoupling, when mathematical model analysis is established, the inner loop control can be considered to be capable of accurately tracking the voltage reference UrefAnd phase reference thetarefThereby simplifying VSITo satisfy Vpcc＝VrefThe transient stability of the controlled voltage source is mainly determined by the outer loop power controller. Therefore, from fig. 2, the P and Q on the grid side can be derived:
Figure BDA0003545105750000091
Figure BDA0003545105750000092
wherein, UgRepresenting the grid voltage, ZgRepresenting the grid side line impedance magnitude, jgRepresenting the grid side line impedance angle. Substituting (7) into (5) can solve Uref，
Figure BDA0003545105750000093
Wherein
Figure BDA0003545105750000096
Due to the fact that formula (8) is longer, use ZtRepresenting intermediate variables, i.e.
Therefore, a large signal model of the control method provided by the invention can be obtained, as shown in formula (9).
Figure BDA0003545105750000095
In the formula, DpIs the damping coefficient, J is the virtual inertia, Δ ω is the frequency deviation, ω0Is the grid voltage reference frequency, omegagIs the current grid voltage frequency, Δ PvIs the compensation power, P is the active power of the grid, PrefIs the grid active power reference value, KvIs the proportionality coefficient of the proportional link, Q is the reactive power, QrefIs a reactive power reference value.
As shown in fig. 3, the proportionality coefficient KvIs obtained by a process which comprises the steps of,
step 2.1: setting a proportionality coefficient KvA reference value of (d); kvIs 1U0/Pmax，PmaxIs the rated capacity of the VSI.
Step 2.2: based on the proportionality coefficient KvCalculating to obtain a current virtual power angle delta;
in step 2.2, the virtual power angle delta is obtained by the calculation of the formula (9),
Figure BDA0003545105750000101
in the formula, DpIs the damping coefficient, J is the virtual inertia, Δ ω is the frequency deviation, ω0Is the grid voltage reference frequency, omegagIs the current grid voltage frequency, Δ PvIs the compensation power, P is the active power of the grid, PrefIs the grid active power reference value, KvIs the proportionality coefficient of the proportional link, Q is the reactive power, QrefIs a reactive power reference value.
Step 2.3: judging the current virtual power angle deltapWhether greater than δm，δmIs referred to as KvWhen the value is equal to 0, the virtual power angle corresponding to the unstable balance point of the system is obtained; if yes, go to step 4, otherwise go to step 5. In this embodiment, δmIs pi because the virtual power angle at transient instability must exceed pi when the integration time is long enough.
Step 2.4: kv＝Kv- Δ K, Δ K being KvStep 2 is returned to; in this embodiment, the value of the iteration step Δ K is 0.1p.u., so that the inner loop pair K can be reducedvThe influence of errors can also speed up the iterative computation.
Step 2.5: the current proportionality coefficient KvAs an output value.
The control method comprises the following steps:
step 1: three-phase current I output by grid-connected inverter is acquired through sensorfThree-phase current instantaneous value I of grid-connected pointpccAnd three-phase voltage instantaneous value UpccCalculating three-phase instantaneous active power P and reactive power Q;
step 2: the active power P calculates the reference value theta of the phase angle of the grid voltage through an active power control loopref；
And step 3: the reactive power Q is calculated to obtain a reference voltage amplitude U through a reactive power control loopref；
And 4, step 4: will If、Ipcc、Upcc、θrefAnd UrefThe PMW signal is input into a virtual synchronous machine, and the PMW signal is output by the virtual synchronous machine through pulse width modulation to control a grid-connected inverter (VSI).
In order to evaluate the transient performance of the virtual synchronous machine control type VSI control method provided by the invention, a simulation model shown in FIG. 2 is built by utilizing Matlab/Simulink for verification. Setting grid reference frequency to omega050Hz, active power reference value Pref40kW, VSI rated capacity Pmax40kW, reference value of reactive power Qref＝0，J＝Dp＝10Pref/ω0.，Dq0.0001V/W, 380V of power line voltage and line impedance Zg3.288 omega, impedance angle of
Figure BDA0003545105750000111
The voltage source on the VSI DC side is 1.2 kV. FIG. 4 shows that when KvWhen the three-phase voltage of the power grid suddenly drops from 1p.u. to 0.56p.u. (namely the VSI controlled by the existing virtual synchronous machine), the simulation waveforms are respectively the three-phase voltage V of the power grid from top to bottomgabcThree-phase current I of power gridgabcThe active power P of the power grid side, the frequency deviation delta omega and the virtual power angle delta. As can be seen from fig. 4, the grid voltage drops to 0.56p.u. at time t ═ 0, the system is transient unstable, at IgabcLow frequency oscillations can be observed in the waveforms of P, Δ ω, and δ. FIG. 5 shows that when KvWhen t is 0, the three-phase voltage of the power grid suddenly drops from 1p.u. to 0.56p.u. time. In fig. 5, it can be seen that the system can still maintain stable operation when the three-phase voltage of the power grid drops; when the steady state is reached, the output power P is 40kW,it can be seen that the control method proposed by the present invention does not change the steady state output power of the VSI. Therefore, the VSI control method of the virtual synchronous machine control type provided by the invention is combined with KvDetermining the critical KvAs long as K is selectedvGreater than critical KvThe transient stability of the virtual synchronous machine control type grid-connected inverter can be greatly enhanced.
The second embodiment:
control device for improving transient stability of grid-connected inverter
As shown in fig. 2, the system comprises an active power control loop, a reactive power control loop and a virtual synchronous machine, wherein the virtual synchronous machine is based on the grid voltage phase angle reference value theta output by the active power control loop and the reactive power control looprefAnd a reference voltage amplitude UrefThe PMW signal is output through pulse width modulation to control a grid-connected inverter, an active power control loop is provided with a control branch, and the control branch comprises a proportion module and a multiplier; the control branch performs the following control,
when the active power control loop realizes control, the reactive power deviation delta Q and the frequency deviation delta omega are multiplied by a multiplier, and then compensation power delta P is obtained through a proportion linkvFinally the compensation power Δ PvAnd the negative feedback is carried out to the front end of the active power control loop.
The control model formula of the active power control loop is as follows,
Figure BDA0003545105750000121
Figure BDA0003545105750000122
in the formula, DpIs the damping coefficient, J is the virtual inertia, Δ ω is the frequency deviation, ω0Is the grid voltage reference frequency, Δ PvIs the compensation power, P is the active power of the grid, PrefIs the grid active power reference value, thetarefThe reference value of the phase angle of the voltage of the power grid is also the output value of the active power control loop.
The above-listed detailed description is only a specific description of a possible embodiment of the present invention, and they are not intended to limit the scope of the present invention, and equivalent embodiments or modifications made without departing from the technical spirit of the present invention should be included in the scope of the present invention.
It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

Claims (10)

1. A grid-connected inverter transient stability control method based on a virtual synchronous machine controls a grid-connected inverter through an active power control loop, a reactive power control loop and the virtual synchronous machine, and is characterized in that: when the active power control loop realizes control, the reactive power deviation delta Q and the frequency deviation delta omega are multiplied by a multiplier, and then a proportion link is carried out to obtain the compensation power delta PvFinally the compensation power Δ PvAnd the negative feedback is carried out to the front end of the active power control loop.
2. The method for controlling transient stability of the grid-connected inverter based on the virtual synchronous machine according to claim 1, wherein: compensating power Δ PvIs obtained by the following formula,
ΔPv＝Kv(Q-Qref)·Δω
in the formula, Δ ω is a frequency deviation, KvIs the proportionality coefficient of the proportional link, Q is the reactive power, QrefIs a reactive power reference value.
3. The method for controlling transient stability of the grid-connected inverter based on the virtual synchronous machine according to claim 2, wherein: the control model formula of the active power control loop is as follows,
Figure FDA0003545105740000011
Figure FDA0003545105740000012
in the formula, DpIs the damping coefficient, J is the virtual inertia, Δ ω is the frequency deviation, ω0Is the grid voltage reference frequency, Δ PvIs the compensation power, P is the active power of the grid, PrefIs the grid active power reference value, thetarefThe reference value of the phase angle of the voltage of the power grid is also the output value of the active power control loop.
4. The method for controlling transient stability of the grid-connected inverter based on the virtual synchronous machine according to claim 2, wherein: coefficient of proportionality KvIs obtained by a process which comprises the steps of,
step 2.1: setting a proportionality coefficient KvA reference value of (d);
step 2.2: based on the proportionality coefficient KvCalculating to obtain a current virtual power angle delta;
step 2.3: judging the current virtual power angle deltapWhether greater than δm，δmIs referred to as KvWhen the value is equal to 0, the virtual power angle corresponding to the unstable balance point of the system is obtained; if yes, entering step 4, otherwise entering step 5;
step 2.4: kv＝Kv- Δ K, Δ K being KvStep 2 is returned to;
step 2.5: the current proportionality coefficient KvAs an output value.
5. The virtual synchronous machine-based grid-connected inverter transient stability control method according to claim 4, characterized in that: in step 2.2, the virtual power angle delta is calculated and obtained by the following formula,
Figure FDA0003545105740000021
in the formula, DpIs the damping coefficient, J is the virtual inertia, Δ ω is the frequency deviation, ω0Is the grid voltage reference frequency, omegagIs the current grid voltage frequency, Δ PvIs the compensation power, P is the active power of the grid, PrefIs the grid active power reference value, KvIs the proportionality coefficient of the proportional link, Q is the reactive power, QrefIs a reactive power reference value.
6. The virtual synchronous machine-based grid-connected inverter transient stability control method according to claim 4, characterized in that: in step 2.3, δmThe value of (d) is pi.
7. The virtual synchronous machine-based grid-connected inverter transient stability control method according to claim 4, characterized in that: in step 2.4, the value of the iteration step Δ k is 0.1p.u.
8. The virtual synchronous machine-based grid-connected inverter transient stability control method according to claims 1 to 7, characterized by comprising the following steps:
step 1: three-phase current I output by grid-connected inverter is acquired through sensorfThree-phase current instantaneous value I of grid-connected pointpccAnd three-phase voltage instantaneous value UpccCalculating three-phase instantaneous active power P and reactive power Q;
and 2, step: the active power P calculates the reference value theta of the phase angle of the grid voltage through an active power control loopref；
And step 3: the reactive power Q is calculated to obtain a reference voltage amplitude U through a reactive power control loopref；
And 4, step 4:will If、Ipcc、Upcc、θrefAnd UrefThe PMW signal is output by the virtual synchronous machine through pulse width modulation, and the grid-connected inverter is controlled.
9. A control device for improving transient stability of a grid-connected inverter comprises an active power control loop, a reactive power control loop and a virtual synchronous machine, wherein the virtual synchronous machine is based on a grid voltage phase angle reference value theta output by the active power control loop and the reactive power control looprefAnd a reference voltage amplitude UrefThe PMW signal is output through pulse width modulation to control the grid-connected inverter, and the PMW signal is characterized in that an active power control loop is provided with a control branch, and the control branch comprises a proportion module and a multiplier; the control branch performs the following control,
when the active power control loop realizes control, the reactive power deviation delta Q and the frequency deviation delta omega are multiplied by a multiplier, and then a proportion link is carried out to obtain the compensation power delta PvFinally the compensation power Δ PvAnd the negative feedback is carried out to the front end of the active power control loop.
10. The apparatus of claim 9, wherein: the control model formula of the active power control loop is as follows,
Figure FDA0003545105740000041
Figure FDA0003545105740000042
in the formula, DpIs the damping coefficient, J is the virtual inertia, Δ ω is the frequency deviation, ω0Is the grid voltage reference frequency, Δ PvIs the compensation power, P is the active power of the grid, PrefIs the grid active power reference value, thetarefIs a reference value of the phase angle of the voltage of the power grid and is also the active powerThe output value of the rate control loop.
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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116614019A (en) * 2023-06-07 2023-08-18 广东电网有限责任公司广州供电局 Bandwidth improving method under direct-current voltage stabilizing framework of bidirectional charging pile virtual synchronous machine
JP7355265B1 (en) 2023-05-23 2023-10-03 富士電機株式会社 power converter

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP7355265B1 (en) 2023-05-23 2023-10-03 富士電機株式会社 power converter
CN116614019A (en) * 2023-06-07 2023-08-18 广东电网有限责任公司广州供电局 Bandwidth improving method under direct-current voltage stabilizing framework of bidirectional charging pile virtual synchronous machine
CN116614019B (en) * 2023-06-07 2024-01-23 广东电网有限责任公司广州供电局 Bandwidth improving method under direct-current voltage stabilizing framework of bidirectional charging pile virtual synchronous machine

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