CN109802433A - A kind of gird-connected inverter oscillation of power inhibition system and method - Google Patents
A kind of gird-connected inverter oscillation of power inhibition system and method Download PDFInfo
- Publication number
- CN109802433A CN109802433A CN201910022829.4A CN201910022829A CN109802433A CN 109802433 A CN109802433 A CN 109802433A CN 201910022829 A CN201910022829 A CN 201910022829A CN 109802433 A CN109802433 A CN 109802433A
- Authority
- CN
- China
- Prior art keywords
- voltage
- oscillation
- feedback
- power
- resistance
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Landscapes
- Inverter Devices (AREA)
Abstract
The present invention relates to electricity fields, inhibit system and method more particularly to a kind of gird-connected inverter oscillation of power, the present invention passes through feedback DC voltage micro component to corresponding controlling unit, and carry out corresponding feedback parameter configuration, realize the inhibition to grid-connected system oscillation of power, greatly promotion grid adaptability range and control parameter domain.The invention not only significant effect, and structure is simple, does not increase other external hardware costs, is applicable in the weak grid in larger range, and have stronger robustness for control ring parameter perturbation.
Description
Technical field
The present invention relates to electricity fields, and in particular to a kind of gird-connected inverter oscillation of power inhibition system and method.
Background technique
Restrainable algorithms common for grid-connected inverters system oscillation at present include: lead-lag penalty method, virtual impedance
Method, self adaptive control etc..Lead-lag penalty method is to pass through design by the way that lead-lag compensator is added in inverter current ring
The time constant of lead-lag promotes closed-loop system Phase margin, to achieve the effect that improving stability inhibits oscillation.This
The kind most important problem of method is that parameter designing is too complicated, and lead-lag calculating will unavoidably reduce control response speed, only
It works for a certain specific power grid；Virtual impedance rule is by feedback communication voltage and current to form virtual resistance
It is anti-, Phase margin is promoted to inhibit to vibrate.The problem of this method, is also that parameter designing is too complicated, and just for a certain specific electricity
Net works；Self adaptive control is to be used to generate alternating voltage by real-time measurement electric network impedance and by its parameter, thus sharp
Feedovered the influence for weakening electric network impedance variation to inverter control with alternating voltage, is inhibited by electric network impedance variation bring oscillation
Problem.The problem of this method is to need to introduce additional Current Voltage sensor, increases the hardware cost of inverter, secondly
Computing impedance will also decrease control response speed etc..
Summary of the invention
Control algolithm proposed by the present invention is the gird-connected inverter oscillation of power based on inverter direct-current voltage Derivative Feedback
Inhibit strategy.
A kind of gird-connected inverter oscillation of power inhibition system, which is characterized in that a Voltage Feedback dress is added in DC side
It sets, the voltage feedback device is for measuring DC voltage instantaneous value and feeding back to Voltage loop and electric current loop input.
Inhibit system in a kind of above-mentioned gird-connected inverter oscillation of power, the voltage feedback device includes:
Resistance pressure-dividing network is made of resistance and measuring probe, for measuring DC voltage instantaneous value；
Sampling filter module, is made of filter circuit, for carrying out low pass sampling filter to the DC voltage of measurement；
Scale operation module is made of two voltage followers, for carrying out scale operation to the signal after sampling, and is divided
Voltage loop and electric current loop input are not fed back to；
It differentiates module, is made of amplifier circuit, for two-way feedback signal to be differentiated, obtains to the end
Feedback signal.
A kind of gird-connected inverter oscillation of power suppressing method, which is characterized in that
Step 1, selection feedback DC voltage micro component to Voltage loop input, and analyze Physical Mechanism, are equivalent in DC side
It connects a resistance, oscillation energy is consumed by virtual resistance.
DC capacitor voltage differential is fed back to electric current loop input by step 2 again, and effect is by DC current by differential ring
DC voltage instruction value is fed back to again after section and proportional component are in parallel, is equivalent to and is connected a resistance and inductance in DC side, one
Aspect changes the frequency of oscillation of system, reduces oscillation risks；On the other hand, oscillation energy is by series connection virtual resistance " consumption ".
In a kind of above-mentioned gird-connected inverter oscillation of power suppressing method, the specific method of feedback is:
Step 1, selection feedback variable；
According to instantaneous power theory, inverter alternating current-direct current side meets instantaneous power equilibrium relation:
Pin+Pdc=Pout (1)
Small signalling processing is carried out to formula (1):
The essence of oscillation of power is that the increase of electric network impedance reduces the damping action of grid-connected inverter system, so that system
Inverter input-output power deviation is difficult to balance in a short time after being disturbed.By formula (2) it is found that under microvariations,
Inverter input-output power deviation and DC voltage micro component are proportional, and the essence of active damping is to system oscillation frequency
The feedback control of corresponding scale variable.To sum up, system power oscillation is carried out inhibiting to select DC voltage micro component as feedback
Variable.
Step 2, selection feedback introduction point, including Voltage loop input and electric current loop input.
In oscillatory process, it is believed that phaselocked loop can track exchange side phase always and grid-connected current can follow grid-connected electricity always
Instruction value is flowed, tracking process is equivalent with Proportional coefficient K eqi, while ignoring dq axis coupling effect, only considers d axis active power.
Feedback variable can be fed back to Voltage loop input, by attached drawing 3 it is found that by changing control block diagram interior joint position, it was therefore concluded that
DC side reference voltage after feedback is that a value composition is subtracted on the basis of former reference voltage, which can be multiplied by DC current
One coefficient composition relevant with feedback factor and DC capacitor, this coefficient is virtual resistance.Therefore, the physics of feedback effect
Mechanism is equivalent in DC side one resistance of series connection, and the energy of oscillation is by virtual resistance " consumption ".
Feedback variable is fed back into electric current loop input, passes through successively concept transfer position and summing junction position, it was therefore concluded that
DC side reference voltage after feedback is that a value composition is subtracted on the basis of former reference voltage, which can be multiplied by DC current
One coefficient composition relevant to the PI parameter of DC voltage control, DC capacitor, feedback factor, further carries out the coefficient
Fortran, it is concluded that the coefficient is composed in parallel by a proportional component and a differentiation element, proportional component and differential ring
The i.e. corresponding virtual resistance of section and virtual inductor.Therefore, the Physical Mechanism of feedback effect is in one resistance of DC side series connection and electricity
On the one hand sense changes the frequency of oscillation of system, reduce oscillation risks；On the other hand, oscillation energy " is disappeared by concatenated virtual resistance
Consumption ".
The present invention is carried out corresponding feedback parameter and is matched by feedback DC voltage micro component to corresponding controlling unit
It sets, realizes the inhibition to grid-connected system oscillation of power, greatly promotion grid adaptability range and control parameter domain.The invention is not
Only significant effect, and structure is simple, does not increase other external hardware costs, is applicable in the weak grid in larger range, and right
There is stronger robustness in control ring parameter perturbation.
Detailed description of the invention:
Fig. 1 is inverter topology of the present invention and traditional control algorithm.
Fig. 2 is that oscillation of power of the present invention inhibits policy control block diagram.
Fig. 3 is the block diagram conversion process that feedback variable to Voltage loop inputs.
Fig. 4 is the block diagram conversion process that feedback variable to electric current loop inputs.
Fig. 5 is that oscillation of power of the present invention inhibits policy control block diagram.
Fig. 6 is experimental prototype figure of the present invention.
Experimental result when Fig. 7 is power grid inductance 2.5mH under Traditional control of the present invention.
Fig. 8 is using the experimental result after inventive control algorithm when power grid inductance 2.5mH.
Fig. 9 is using the experimental result after inventive control algorithm when power grid inductance 10mH.
Specific embodiment
The present invention is understood and implemented for the ease of those of ordinary skill in the art, and with reference to the accompanying drawing and example is to the present invention
It is described in further detail, it should be understood that implementation example described herein is merely to illustrate and explain the present invention, and is not had to
It is of the invention in limiting.
One, system of the present invention under introducing first.
Mainly a voltage feedback device is added in DC side in the present invention, and the voltage feedback device is for measuring DC side
Instantaneous voltage simultaneously feeds back to Voltage loop and electric current loop input.
Voltage feedback device includes:
Resistance pressure-dividing network is made of resistance and measuring probe, for measuring DC voltage instantaneous value；
Sampling filter module, is made of filter circuit, for carrying out low pass sampling filter to the DC voltage of measurement；
Scale operation module is made of two voltage followers, for carrying out scale operation to the signal after sampling, and is divided
Voltage loop and electric current loop input are not fed back to；
It differentiates module, is made of amplifier circuit, for two-way feedback signal to be differentiated, obtains to the end
Feedback signal.
Two, the invention further relates to a kind of gird-connected inverter oscillation of power suppressing methods, including
Selection feedback DC voltage micro component to Voltage loop inputs, and analyzes its Physical Mechanism, is equivalent to and connects in DC side
One resistance, oscillation energy is by virtual resistance " consumption ".
DC capacitor voltage differential is fed back into electric current loop input again, effect be by DC current by differentiation element and
DC voltage instruction value is fed back to again after proportional component is in parallel, this is equivalent in one resistance of DC side series connection and inductance, a side
Face changes the frequency of oscillation of system, reduces oscillation risks；On the other hand, oscillation energy is by series connection virtual resistance " consumption ".
The specific method of feedback is:
Step 1, selection feedback variable；
According to instantaneous power theory, inverter alternating current-direct current side meets instantaneous power equilibrium relation:
Pin+Pdc=Pout (1)
Small signalling processing is carried out to formula (1):
The essence of oscillation of power is that the increase of electric network impedance reduces the damping action of grid-connected inverter system, so that system
Inverter input-output power deviation is difficult to balance in a short time after being disturbed.By formula (2) it is found that under microvariations,
Inverter input-output power deviation and DC voltage micro component are proportional, and the essence of active damping is to system oscillation frequency
The feedback control of corresponding scale variable.To sum up, system power oscillation is carried out inhibiting to select DC voltage micro component as feedback
Variable.
Step 2, selection feedback introduction point
Inverter topology and traditional control algorithm of the present invention are available as shown in Figure 1, in the control algolithm
Introduction point have Voltage loop input and electric current loop input.In oscillatory process, it is believed that phaselocked loop can track exchange side phase always
And grid-connected current can follow grid-connected current instruction value, tracking process Proportional coefficient K alwayseqiIt is equivalent, while ignoring dq axis coupling
Effect is closed, only considers d axis active power.It is as shown in Figure 2 that the small signal diagram of inverter control structures can be derived.
Feedback variable is fed back into Voltage loop input, is converted by simple block diagram, its available Physical Mechanism, Fig. 3
For block diagram conversion process, which is that DC current is fed back to DC voltage instruction value by proportional component, is equivalent to
In DC side one resistance of series connection, the energy of oscillation is by virtual resistance " consumption ".
Feedback variable is fed back into electric current loop input, is converted by block diagram, its Physical Mechanism is obtained, Fig. 4 is corresponding frame
Figure conversion process.The feedback effect is that DC current is fed back to DC voltage after differentiation element and proportional component are in parallel again
Instruction value is equivalent in one resistance of DC side series connection and inductance, on the one hand changes the frequency of oscillation of system, reduces and vibrate wind
Danger；On the other hand, oscillation energy is by concatenated virtual resistance " consumption ".
To sum up, the present invention proposes while inputting the oscillation of power of two kinds of feedbacks comprising being introduced into Voltage loop input and electric current loop
Inhibit strategy.Control block diagram is as shown in Figure 5.
It three, is the concrete case for using the systems and methods below.
A 20kW three-phase grid-connected inverter principle prototype has been built herein, as shown in Figure 6.Model machine is with TMS320F28335
As control chip, model machine DC voltage is 800V, and alternating voltage virtual value is 380V.Power tube uses Vishay
The NPT module VS-GB100TH120U of Semiconductor company, is sampled using voltage-current sensor.It is straight in experiment
It connects using alternating current and inductance and simulates weak grid situation, power grid inductance changes between 2.5mH-10mH.Inverter control algorithm is such as
Fig. 1, shown in 5.
Performance analysis:
Biggish power grid inductance Lg=2.5mH is chosen, as control waveform.Obtain experimental result DC voltage and alternating current
It is as shown in Figure 7 to flow waveform.Since power grid inductance is sufficiently large, the inverter control parameter based on strong electrical reticulation design and it is not suitable at this time
In weak grid, system will generate oscillation of power, and it is about 5Hz that be reacted to DC voltage waveform, which be frequency, amplitude be about 150V etc.
Width oscillation.
When power grid inductance is continued to increase, if maintaining traditional control method constant, inverter alternating current-direct current side electricity will be produced
Raw oscillation and divergence, leads to system unstability, will cause irremediable damage to experimental prototype, therefore do not carry out this part
Experiment.When using oscillation of power active damping strategy proposed by the invention, experimental results are shown in figure 8, DC voltage with simultaneously
The oscillation of net electric current decays rapidly, and the fast quick-recovery of system is stablized, and adjustment time is about ts=0.6s.This shows that the present invention proposes
Oscillation of power active damping strategy restriction weak grid under system oscillation of power.Fig. 9 is to have selected bulk power grid inductance Lg=
The DC voltage and grid-connected current waveform that 10mH is tested.The oscillation of DC voltage and grid-connected current as time goes by and by
Degradation subtracts, adjustment time ts=1.6s.This shows that the present invention proposes that control algolithm can significantly promote inverter and adapt to light current
Net range.
Specific embodiment described herein is only an example for the spirit of the invention.The neck of technology belonging to the present invention
The technical staff in domain can make various modifications or additions to the described embodiments or replace by a similar method
In generation, however, it does not deviate from the spirit of the invention or beyond the scope of the appended claims.
Claims (4)
1. a kind of gird-connected inverter oscillation of power inhibits system, which is characterized in that a voltage feedback device is added in DC side,
The voltage feedback device is for measuring DC voltage instantaneous value and feeding back to Voltage loop and electric current loop input.
2. a kind of gird-connected inverter oscillation of power according to claim 1 inhibits system, which is characterized in that the voltage is anti-
Presenting device includes:
Resistance pressure-dividing network is made of resistance and measuring probe, for measuring DC voltage instantaneous value；
Sampling filter module, is made of filter circuit, for carrying out low pass sampling filter to the DC voltage of measurement；
Scale operation module is made of two voltage followers, for carrying out scale operation to the signal after sampling, and it is anti-respectively
It is fed to Voltage loop and electric current loop input；
It differentiates module, is made of amplifier circuit, for two-way feedback signal to be differentiated, obtain to the end anti-
Feedback signal.
3. a kind of gird-connected inverter oscillation of power suppressing method, which is characterized in that
Step 1, selection feedback DC voltage micro component to Voltage loop input, and analyze Physical Mechanism, are equivalent to and connect in DC side
One resistance, oscillation energy are consumed by virtual resistance；
DC capacitor voltage differential is fed back to electric current loop input by step 2 again, effect be by DC current by differentiation element and
DC voltage instruction value is fed back to again after proportional component is in parallel, is equivalent in one resistance of DC side series connection and inductance, on the one hand
The frequency of oscillation of change system reduces oscillation risks；On the other hand, oscillation energy is by series connection virtual resistance " consumption ".
4. a kind of gird-connected inverter oscillation of power suppressing method according to claim 3, which is characterized in that feedback it is specific
Method is:
Step 1, selection feedback variable；
According to instantaneous power theory, inverter alternating current-direct current side meets instantaneous power equilibrium relation:
Pin+Pdc=Pout (1)
Small signalling processing is carried out to formula (1):
The essence of oscillation of power is that the increase of electric network impedance reduces the damping action of grid-connected inverter system so that system by
Inverter input-output power deviation is difficult to balance in a short time after to disturbance, by formula (2) it is found that under microvariations, inversion
Device input-output power deviation and DC voltage micro component are proportional, and the essence of active damping is corresponding to system oscillation frequency
The feedback control of scale variable to sum up carries out inhibiting to select DC voltage micro component as feedback variable to system power oscillation；
Step 2, selection feedback introduction point, including Voltage loop input and electric current loop input；
In oscillatory process, it is believed that phaselocked loop can track exchange side phase always and grid-connected current can follow grid-connected current to refer to always
Value is enabled, tracking process is equivalent with Proportional coefficient K eqi, while ignoring dq axis coupling effect, only considers d axis active power, can incite somebody to action
Feedback variable feeds back to Voltage loop input, by attached drawing 3 it is found that by changing control block diagram interior joint position, it was therefore concluded that feedback
DC side reference voltage afterwards is that a value composition is subtracted on the basis of former reference voltage, which can be multiplied one by DC current
Coefficient composition relevant with feedback factor and DC capacitor, this coefficient is virtual resistance, therefore, the Physical Mechanism of feedback effect
It is to be equivalent in DC side one resistance of series connection, the energy of oscillation is by virtual resistance " consumption "；
Feedback variable is fed back into electric current loop input, passes through successively concept transfer position and summing junction position, it was therefore concluded that feedback
DC side reference voltage afterwards is that a value composition is subtracted on the basis of former reference voltage, which can be multiplied one by DC current
Coefficient composition relevant to the PI parameter of DC voltage control, DC capacitor, feedback factor, further carries out formula to the coefficient
Transformation, it is concluded that the coefficient is composed in parallel by a proportional component and a differentiation element, proportional component and differentiation element are
Corresponding virtual resistance and virtual inductor, therefore, the Physical Mechanism of feedback effect are connected a resistance and inductance in DC side, one
Aspect changes the frequency of oscillation of system, reduces oscillation risks；On the other hand, oscillation energy is by concatenated virtual resistance " consumption ".
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910022829.4A CN109802433B (en) | 2019-01-10 | 2019-01-10 | Grid-connected inverter power oscillation suppression system and method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910022829.4A CN109802433B (en) | 2019-01-10 | 2019-01-10 | Grid-connected inverter power oscillation suppression system and method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN109802433A true CN109802433A (en) | 2019-05-24 |
| CN109802433B CN109802433B (en) | 2022-10-14 |
Family
ID=66557085
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201910022829.4A Active CN109802433B (en) | 2019-01-10 | 2019-01-10 | Grid-connected inverter power oscillation suppression system and method |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN109802433B (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110797915A (en) * | 2019-11-13 | 2020-02-14 | 国网安徽省电力有限公司 | Photovoltaic power station active frequency control method based on energy storage |
| CN111769582A (en) * | 2020-06-24 | 2020-10-13 | 南京航空航天大学 | Alternating current feedback additional damping control method based on multi-terminal direct current distribution system |
| CN112014631A (en) * | 2020-08-24 | 2020-12-01 | 武汉大学 | Oscillation power acquisition method and device under transient fault of power grid |
| CN112379153A (en) * | 2020-10-30 | 2021-02-19 | 阳光电源股份有限公司 | Direct current oscillation detection circuit, direct current arc detection circuit and inverter |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102710165A (en) * | 2012-03-19 | 2012-10-03 | 天津大学 | Improved method for controlling direct current (DC) bus voltage of two-stage converter |
| CN107612027A (en) * | 2017-09-18 | 2018-01-19 | 西安许继电力电子技术有限公司 | A kind of photovoltaic DC-to-AC converter DC voltage transient state falls suppressing method |
-
2019
- 2019-01-10 CN CN201910022829.4A patent/CN109802433B/en active Active
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102710165A (en) * | 2012-03-19 | 2012-10-03 | 天津大学 | Improved method for controlling direct current (DC) bus voltage of two-stage converter |
| CN107612027A (en) * | 2017-09-18 | 2018-01-19 | 西安许继电力电子技术有限公司 | A kind of photovoltaic DC-to-AC converter DC voltage transient state falls suppressing method |
Non-Patent Citations (1)
| Title |
|---|
| YUNHUI HUANG等: "DC-Bus Voltage Control Stability Affected by", 《IEEE JOURNAL OF EMERGING AND SELECTED TOPICS IN POWER ELECTRONICS》 * |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110797915A (en) * | 2019-11-13 | 2020-02-14 | 国网安徽省电力有限公司 | Photovoltaic power station active frequency control method based on energy storage |
| CN110797915B (en) * | 2019-11-13 | 2021-01-08 | 国网安徽省电力有限公司 | Photovoltaic power station active frequency control method based on energy storage |
| CN111769582A (en) * | 2020-06-24 | 2020-10-13 | 南京航空航天大学 | Alternating current feedback additional damping control method based on multi-terminal direct current distribution system |
| CN111769582B (en) * | 2020-06-24 | 2021-11-23 | 南京航空航天大学 | Alternating current feedback additional damping control method based on multi-terminal direct current distribution system |
| CN112014631A (en) * | 2020-08-24 | 2020-12-01 | 武汉大学 | Oscillation power acquisition method and device under transient fault of power grid |
| CN112014631B (en) * | 2020-08-24 | 2022-03-22 | 武汉大学 | Oscillation power acquisition method and device under transient fault of power grid |
| CN112379153A (en) * | 2020-10-30 | 2021-02-19 | 阳光电源股份有限公司 | Direct current oscillation detection circuit, direct current arc detection circuit and inverter |
Also Published As
| Publication number | Publication date |
|---|---|
| CN109802433B (en) | 2022-10-14 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN109802433A (en) | A kind of gird-connected inverter oscillation of power inhibition system and method | |
| Escobar et al. | An adaptive control for UPS to compensate unbalance and harmonic distortion using a combined capacitor/load current sensing | |
| Pan et al. | A highly robust single-loop current control scheme for grid-connected inverter with an improved LCCL filter configuration | |
| CN104716668B (en) | Improve feed forward control method of the LCL type combining inverter to grid adaptability | |
| CN106532702B (en) | A kind of Active Power Filter-APF improvement adaptive repetitive control of wideband | |
| CN106786639B (en) | A kind of Active Power Filter-APF improvement wideband self-adapting resonance control method | |
| Xiao et al. | Virtual flux direct power control for PWM rectifiers based on an adaptive sliding mode observer | |
| CN106936157B (en) | The control method and control device of grid-connected converter system | |
| CN104333002B (en) | A kind of based on ip-iq detection method with the hybrid active filter of Hysteresis control | |
| CN112165271B (en) | Grid-connected converter system and model prediction control method thereof | |
| Rong et al. | Output feedback control of single-phase UPQC based on a novel model | |
| CN103780107A (en) | Current control method for three-phase voltage source type PWM rectifier | |
| CN112886647B (en) | Load virtual synchronous machine coordination optimization control method based on impedance remodeling | |
| CN112260279A (en) | Improved passive control system and method based on LCL filtering grid-connected inverter under complex power grid impedance | |
| CN105406741B (en) | PWM rectifier Fuzzy Sliding Mode Control Approach during a kind of three-phase power grid voltage imbalance | |
| CN106451573B (en) | A kind of the three-phase LCL type networking converter and method of multivariable feedback controller | |
| CN110429835B (en) | LCL filtering-based RBFNN segmented online optimization passive control system and method | |
| CN107124092A (en) | A kind of electric automobile single phase bidirectional DC/AC converters self-adaptation control method and its device | |
| CN104795836B (en) | A kind of single-phase photovoltaic grid-connected generating detecting system and its non-linear current control method | |
| CN106230015B (en) | Single-phase LCL type gird-connected inverter resonance suppressing method based on output current on line side estimation | |
| CN207442691U (en) | A kind of electric vehicle single phase bidirectional DC/AC converter adaptive controllers | |
| Chittora et al. | Performance evaluation of a new Kalman filter based least mean square algorithm for power quality improvement | |
| Liu et al. | An adaptive multi‐mode switching control strategy to improve the stability of virtual synchronous generator with wide power grid strengths variation | |
| CN115241912A (en) | Model mismatch compensation method for model predictive control three-phase grid-connected inverter | |
| CN106300355B (en) | A kind of resonance control method that Active Power Filter-APF calculation amount simplifies |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |