CN102780414A - Device and method for inhibiting inrush starting current for large-power grid-connected inverter - Google Patents
Device and method for inhibiting inrush starting current for large-power grid-connected inverter Download PDFInfo
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- CN102780414A CN102780414A CN2012100099855A CN201210009985A CN102780414A CN 102780414 A CN102780414 A CN 102780414A CN 2012100099855 A CN2012100099855 A CN 2012100099855A CN 201210009985 A CN201210009985 A CN 201210009985A CN 102780414 A CN102780414 A CN 102780414A
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Abstract
The invention discloses a digitized method for inhibiting the impulse current of a large-power grid-connected inverter. The grid-connected inverter consists of a direct-current voltage source, a three-phase inverter, a filtering inductor, a filtering capacitor and a digital current controller. When the grid-connected inverter responds a starting command, the amplitude and the phase of the three-phase mains voltage are detected; a modulating wave value is calculated according to the mains voltage; if direct-current side voltage satisfies the lowest grid-connected voltage of the inverter, an inverter alternating-current contactor is closed; the modulating wave value at the moment is used as an initial value of the output of a digital controller, and the digital controller begins to work; the grid-connected inverter achieves a steady-state value at the beginning moment; and grid-connected impulse-free can be realized without a transition process. The digitized method for inhibiting the impulse current of the big-power grid-connected inverter is suitable for PWM (pulse-width modulation)-type grid-connected inverters of various forms, grid-connected current can directly enter the steady state when grid connection is carried out at any moment, and smooth impulse-free grid connection is realized.
Description
Technical field
The present invention relates to the digitizing solution that a kind of combining inverter suppresses to start impulse current, belong to the field of combining inverter control method.
Background technology
Three-phase PWM type combining inverter can be realized presenting energy with any power factor to electrical network, and along with the development of the regenerative resource technology of generating electricity by way of merging two or more grid systems, the control technology of the high-power combining inverter of three-phase has become one of focus of research.
Combining inverter is in actual motion, because the existence of closed loop current FEEDBACK CONTROL, the electric current of common Control current digitial controller is given, and the initial value of output is made as 0.Constantly difference and the influence of DSP control hysteresis owing to be incorporated into the power networks, the output voltage of combining inverter and line voltage exist amplitude and phase difference in the moment of being incorporated into the power networks, and equivalent circuit diagram is as shown in Figure 3, can cause the moment inductance impulse current of being incorporated into the power networks excessive.In addition, grid-connected current is excessive to be prone to cause inductance saturated, thereby can make that electric current increases sharply in the circuit, and then causes the protective device action, even damages switching device.
Fig. 1 and Fig. 2 are common three-phase grid-connected inverter topological circuit figure; The startup method that is incorporated into the power networks commonly used at present has following several kinds: first method is through impulse current and the relation that drops into the moment of being incorporated into the power networks; Select optimum that combining inverter is cut electrical network, this method is to suppress single-phase inverter one of the effective ways of impulse current that are incorporated into the power networks, but for three-phase grid-connected inverter; Three-phase differs 120 °; Can not reach the best time point simultaneously, being incorporated into the power networks constantly still can make at least one impulse current that exists mutually, can impact inverter and electrical network; Second method is to be incorporated into the power networks before the relay closes, makes inverter be in independent operation mode, with the output voltage of inverter and line voltage with frequently with after the identical amplitude; The closure switch that is incorporated into the power networks again, this method can effectively reduce the startup impulse current, but inverter is worked before being incorporated into the power networks; Can cause the waste of portion of energy; And inverter is carried out the transition to when being incorporated into the power networks pattern by stand-alone mode, and process is comparatively complicated, and the possibility that produces impulse current is arranged.
Summary of the invention
The present invention is exactly the deficiency to conventional art; A kind of device that is used to suppress the startup impulse current of high-power combining inverter that proposes; Solved in the high-power grid-connected system owing to start the existence of impulse current; Harmful effect to switching device and electrical network cause has proposed a kind of being incorporated into the power networks at any time simultaneously and all can suppress the effective ways of impulse current.
The device that high-power combining inverter of the present invention suppresses the startup impulse current is: the AC side at the alternating current-direct current inverter disposes filter inductance, current sensor, AC voltage sensor, interchange slow-operating relay and AC relay successively; DC side at the alternating current-direct current inverter disposes PWM unit (Pulse Width Modulation; Pulse width modulation), DSP control unit (Digital Signal Processing; Digital Signal Processing) and the electric current and voltage sampling unit, also dispose voltage measurement unit at the DC side of alternating current-direct current inverter simultaneously.
In the described DSP control unit current digital controller and period register are arranged.
Three current digital controllers are arranged in the described DSP control unit, and described three current digital controllers are controlled the three-phase grid electric current respectively.
Further, described current digital controller is the PI controller.
The device that utilizes described high-power combining inverter to suppress the startup impulse current realizes that the method that digitlization suppresses is:
The first step: before the inverter startup; The DSP control unit blocks PWM unit pulse; After passing to the DSP control unit under the starting command of host computer, the DSP control unit detects three-phase mains voltage, obtain line voltage through the phase-locked loop joint phase place and frequency, the instantaneous value through voltage, current sampling unit acquisition three-phase mains voltage
u a(k),
u b(k),
u c(k);
Second step: according to the sampled value of three-phase mains voltage
u a(k),
u b(k),
u c(k) and the voltage sample value V of inverter direct-flow side voltage measurement unit
DcAnd the T1PR value of period register in the task manager of DSP control unit, obtain
Moment three-phase mains modulating wave
,
,
Value:
When three-phase mains voltage satisfies when being incorporated into the power networks standard; The DSP control unit is given the PWM unit with value
,
,
assignment of three-phase modulations ripple, makes inverter output voltage and civil power same frequently with identical amplitude;
The 3rd step: the voltage measurement unit of the DC side configuration of alternating current-direct current inverter is measured the voltage of alternating current-direct current inverter; When this voltage satisfies minimum being incorporated into the power networks during voltage; The closed slow-operating relay that exchanges; Delay time after 1 second; Closed AC relay; Be the k+n moment this moment; And k+n modulating wave
,
,
assignment constantly given the current digital controller of DSP control unit; This assignment is as current digital controller k+n-1 initial value constantly simultaneously; The current digital controller of DSP control unit is started working, and opens pwm pulse, realizes the output of grid-connected current.
Beneficial effect of the present invention is: the present invention is not increasing hardware cost, is not wasting under the prerequisite of energy; Propose to suppress the digitizing solution that high-power combining inverter starts impulse current; Through above-mentioned control algolithm, can realize inscribing when any not having to impact and be incorporated into the power networks, reduce even eliminates of the influence of startup moment impact electric current switching device and electrical network; Control is convenient, and effect is obvious.
Description of drawings
Fig. 1 is the three-phase grid-connected inverter main circuit diagram
Fig. 2 is another layout circuit diagram of three-phase grid-connected inverter main circuit
Fig. 3 is the device simplified electrical circuit diagram that high-power combining inverter suppresses to start impulse current
Fig. 4 is grid-connected current ring control sketch
Fig. 5 is C phase line voltage and inductive current oscillogram when not using the present invention program
Fig. 6 is C phase line voltage and an inductive current oscillogram when using the present invention program
Among the figure: 1, inverter; 2, filter inductance; 3, current sensor; 4, AC voltage sensor; 5, exchange slow-operating relay; 6, AC relay; 7, utility grid; 8, voltage electricity sampling unit; 9, DSP control unit; 10, three-phase modulations ripple; 11, PWM unit; 12, dc voltage measuring unit.
Embodiment
Like Fig. 3; The device that high-power combining inverter of the present invention suppresses the startup impulse current is: the AC side at alternating current-direct current inverter 1 disposes filter inductance 2, current sensor 3, AC voltage sensor 4 successively, exchanges slow-operating relay 5 and AC relay 6; Exchanging slow-operating relay 5 links to each other with utility grid 7; DC side at alternating current-direct current inverter 1 disposes PWM unit 11, DSP control unit 9 and electric current and voltage sampling unit 8, and the DC side at alternating current-direct current inverter 1 also disposes voltage measurement unit 12 simultaneously.
In the described DSP control unit 9 current digital controller and period register are arranged.
Three current digital controllers are arranged in the described DSP control unit 9, and described three current digital controllers are controlled the phase in the three-phase grid electric current respectively.
In the system standby process; After passing to DSP control unit 9 under the starting command of host computer; DSP control unit 9 blocks PWM unit 11 pulses, detect three-phase mains voltage, obtain line voltage mutually through lock phase place with frequency, pass through electric current and voltage sampling unit 8 acquisition three-phase mains voltage magnitudes; If three-phase mains voltage satisfies the standard that is incorporated into the power networks; According to inverter 1 output voltage and utility grid with frequently with the principle of identical amplitude; Calculate three-phase modulations ripple 10
, the size of
,
, give PWM unit 11 with three-phase modulations ripple 10 assignment that calculate.
The computational methods of said three-phase modulations ripple 10 are: according to the sampled value of three-phase mains voltage
u a(k),
u b(k),
u c(k) and the voltage sample value V of the dc voltage measuring unit of alternating current-direct current inverter
DcAnd the T1PR value of period register in the task manager of DSP control unit, can obtain
Moment three-phase modulations ripple
,
,
Value:
Further, the voltage measurement unit 12 of the DC side of alternating current-direct current inverter configuration is measured the voltage of alternating current-direct current inverters 1, when this voltage satisfies minimum being incorporated into the power networks during voltage, and the closed slow-operating relay 5 and will of exchanging
kThe value of moment modulating wave
,
,
Assignment PWM control unit is opened pwm pulse, realizes the output of grid-connected current, and at this moment, the current digital controller in the DSP control unit 9 does not put into operation.Afterwards, every separated fixed cycle is sampled three-phase mains voltage, calculating three-phase modulations ripple and assignment to the PWM unit.This cycle is by the T1PR value decision of period register.
Delay time after 1 second, closed AC relay 6, the operation node time of current digital controller is closed AC relay 6.
As shown in Figure 4, the detailed process that the grid-connected current digitial controller puts into operation is:
If the moment of putting into operation is
;
constantly the current digital controller be input as
; The current digital controller is output as
, and then the difference formula of current digital controller is:
K in the above-mentioned formula
pBe proportionality coefficient, k
iBe integral coefficient.
Further, the difference that obtains for the electric current of current sensor 3 and given current subtraction of
input
of current digital controller constantly.
Further, described given electric current refers to the sinusoidal current command value that is incorporated into the power networks.
With the three-phase modulations ripple at
constantly value
,
,
simultaneously assignment give three-phase current corresponding digitial controller, as initial value
,
,
of current digital controller:
Simultaneously;
be the starting current digitial controller constantly;
is through the current digital controller; By the difference formula of current digital controller calculate the value of three-phase modulations ripple
,
,
; And they are loaded in the PWM unit as value
,
,
of three-phase modulations ripple again; Acquisition is used to drive the drive signal of IGBT switching tube, the output of beginning grid-connected current.
Further; The value of the three-phase modulations ripple that
is later is calculated decision by the difference equation of current digital controller, and no longer the calculating by the civil power sampled value decides.
Scheme of the present invention is through to modulating wave and current digital controller initialize; Make combining inverter directly get into another kind of stable state by a kind of stable state; No transient process; Reduced the impulse current that causes because of voltage phase difference and difference in magnitude, realized that combining inverter starts the moment non-impact current, can not impact switching device and electrical network.
For verifying practicality of the present invention, adopt the topological structure of three-phase six brachium pontis composite type combining inverters, be to test on the model machine of 500KVA at power.
Experiment shows that A phase zero crossing starts constantly is incorporated into the power networks, and BC has bigger impulse current mutually, and Fig. 5 is a C phase inductance electric current and C line voltage waveform mutually, can find out that the impulse current peak value is up to 350A; Fig. 6 is C phase voltage and the C phase inductance current waveform after the inventive method is handled, and can find out that from oscillogram this method realizes that basically non-impact current is incorporated into the power networks.
Claims (11)
1. high-power combining inverter suppresses to start the device of impulse current; It is characterized in that; AC side at the alternating current-direct current inverter disposes filter inductance, current sensor, AC voltage sensor, interchange slow-operating relay and AC relay successively; DC side at the alternating current-direct current inverter disposes PWM unit, DSP control unit and electric current and voltage sampling unit, and the DC side at the alternating current-direct current inverter also disposes voltage measurement unit simultaneously.
2. high-power combining inverter as claimed in claim 1 suppresses to start the device of impulse current, it is characterized in that in the described DSP control unit current digital controller and period register being arranged.
3. high-power combining inverter as claimed in claim 1 suppresses to start the device of impulse current, it is characterized in that three current digital controllers are arranged in the described DSP control unit, and described three current digital controllers are controlled the three-phase grid electric current respectively.
4. high-power combining inverter as claimed in claim 2 suppresses to start the device of impulse current, it is characterized in that described current digital controller is the PI controller.
5. the device that utilizes high-power combining inverter as claimed in claim 1 to suppress the startup impulse current realizes that the method that digitlization suppresses is:
The first step: before the inverter startup; The DSP control unit blocks PWM unit pulse; After passing to the DSP control unit under the starting command of host computer, the DSP control unit detects three-phase mains voltage, obtain line voltage through the phase-locked loop joint phase place and frequency, the instantaneous value through voltage, current sampling unit acquisition three-phase mains voltage
u a(k),
u b(k),
u c(k);
Second step: according to the sampled value of three-phase mains voltage
u a(k),
u b(k),
u c(k) and the voltage sample value V of inverter direct-flow side voltage measurement unit
DcAnd the T1PR value of period register in the task manager of DSP control unit, obtain
Moment three-phase mains modulating wave
,
,
Value;
The 3rd step: the voltage measurement unit of the DC side configuration of alternating current-direct current inverter is measured the voltage of alternating current-direct current inverter; When this voltage satisfies minimum being incorporated into the power networks during voltage; The closed slow-operating relay that exchanges; Delay time after 1 second; Closed AC relay; Be the k+n moment this moment; And k+n modulating wave
,
,
assignment constantly given the current digital controller of DSP control unit; This assignment is as current digital controller k+n-1 initial value constantly simultaneously; The current digital controller of DSP control unit is started working; Open pwm pulse, realize the output of grid-connected current.
6. high-power combining inverter as claimed in claim 5 suppresses to start the method that the digitlization of impulse current suppresses, it is characterized by, when three-phase mains voltage satisfies when being incorporated into the power networks standard, inverter output voltage and civil power with frequency with identical amplitude.
7. high-power combining inverter as claimed in claim 5 suppresses the method for the digitlization inhibition of startup impulse current, it is characterized by, and the condition that the current digital controller of said DSP control unit is started working is closed AC relay.
8. high-power combining inverter as claimed in claim 5 suppresses the method for the digitlization inhibition of startup impulse current; It is characterized by; When the current digital controller puts into operation at
constantly; Give three-phase current corresponding digitial controller with the three-phase modulations ripple value
in the moment,
,
while assignment, as current digital controller k+n-1 initial value
,
,
constantly at
.
9. high-power combining inverter as claimed in claim 5 suppresses the method for the digitlization inhibition of startup impulse current; It is characterized by; After the current digital controller puts into operation at
constantly; The value of the three-phase modulations ripple that
is constantly later is confirmed by the output valve that the difference equation of current digital controller calculates, is no longer confirmed by the calculating of civil power sampled value.
10. high-power combining inverter as claimed in claim 9 suppresses the method for the digitlization inhibition of startup impulse current, it is characterized by, and the difference equation of described current digital controller is:
Wherein:
Divide ik
pBe proportionality coefficient;
k
iBe integral coefficient;
The difference that
obtains for the electric current of current sensor and given current subtraction.
11. high-power combining inverter as claimed in claim 10 suppresses the method that the digitlization of startup impulse current suppresses, and it is characterized by, described given electric current refers to the simple sinusoidal alternating current instruction.
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|---|---|---|---|
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|---|---|---|---|
| CN201210009985.5A CN102780414B (en) | 2012-01-13 | 2012-01-13 | Device and method for inhibiting inrush starting current for large-power grid-connected inverter |
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103312139A (en) * | 2012-03-09 | 2013-09-18 | 台达电子工业股份有限公司 | Starting device of grid-connected inverter and control method thereof |
| CN103368199A (en) * | 2013-04-10 | 2013-10-23 | 万洲电气股份有限公司 | Parallelable large energy feedback device electricity-saving device |
| CN104300774A (en) * | 2014-09-02 | 2015-01-21 | 中国东方电气集团有限公司 | Starting device of single-phase grid-connected inverter and control method |
| WO2019174331A1 (en) * | 2018-03-12 | 2019-09-19 | 江苏固德威电源科技股份有限公司 | Impact-current-free grid-connected control method for three-phase photovoltaic grid-connected inverter |
| CN113078806A (en) * | 2021-05-11 | 2021-07-06 | 江苏固德威电源科技股份有限公司 | Method and device for inhibiting pull-in impact current of inverter output relay |
| CN117955047A (en) * | 2024-03-26 | 2024-04-30 | 锦浪科技股份有限公司 | Leakage current suppression method in relay self-test |
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Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103312139A (en) * | 2012-03-09 | 2013-09-18 | 台达电子工业股份有限公司 | Starting device of grid-connected inverter and control method thereof |
| CN103312139B (en) * | 2012-03-09 | 2016-05-11 | 台达电子工业股份有限公司 | A kind of starting drive of combining inverter and control method thereof |
| CN103368199A (en) * | 2013-04-10 | 2013-10-23 | 万洲电气股份有限公司 | Parallelable large energy feedback device electricity-saving device |
| CN103368199B (en) * | 2013-04-10 | 2015-03-11 | 万洲电气股份有限公司 | Parallelable large energy feedback device electricity-saving device |
| CN104300774A (en) * | 2014-09-02 | 2015-01-21 | 中国东方电气集团有限公司 | Starting device of single-phase grid-connected inverter and control method |
| WO2019174331A1 (en) * | 2018-03-12 | 2019-09-19 | 江苏固德威电源科技股份有限公司 | Impact-current-free grid-connected control method for three-phase photovoltaic grid-connected inverter |
| CN113078806A (en) * | 2021-05-11 | 2021-07-06 | 江苏固德威电源科技股份有限公司 | Method and device for inhibiting pull-in impact current of inverter output relay |
| CN117955047A (en) * | 2024-03-26 | 2024-04-30 | 锦浪科技股份有限公司 | Leakage current suppression method in relay self-test |
| CN117955047B (en) * | 2024-03-26 | 2024-05-31 | 锦浪科技股份有限公司 | Leakage current suppression method in relay self-test |
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| CN102780414B (en) | 2014-12-24 |
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