CN105576707A - Microgrid converter phase-locking method for switching from off-network to grid-connection - Google Patents
Microgrid converter phase-locking method for switching from off-network to grid-connection Download PDFInfo
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- CN105576707A CN105576707A CN201610029859.4A CN201610029859A CN105576707A CN 105576707 A CN105576707 A CN 105576707A CN 201610029859 A CN201610029859 A CN 201610029859A CN 105576707 A CN105576707 A CN 105576707A
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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
- H02J3/40—Synchronising a generator for connection to a network or to another generator
- H02J3/42—Synchronising a generator for connection to a network or to another generator with automatic parallel connection when synchronisation is achieved
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- Inverter Devices (AREA)
Abstract
The invention discloses a microgrid converter phase-locking method for switching from off-network to grid-connection. Phase pre-synchronization is carried out firstly in switching from off-network to grid-connection; the phase pre-synchronization process is implemented as follows: after a three-phase voltage Uabc_converter output from the converter is subjected to CLARK conversion, the three-voltage voltage is subjected to PARK conversion by feedback power grid voltage phase theta g; and then after the output voltage passes through a loop filter, the voltage is subjected to a voltage-controlled oscillator link to obtain theta c. According to the microgrid converter phase-locking method for switching from off-network to grid-connection provided by the invention, a phase pre-synchronization module is added when the off-network mode is switched into the grid-connection mode, so that the power grid phase can be tracked.
Description
Technical field
The present invention relates to microgrid inverter control field, particularly relating to the phase-lock technique that a kind of microgrid current transformer takes over seamlessly when turning grid-connected from net.
Background technology
Along with increasingly sharpening of world energy sources crisis and problem of environmental pollution, and the continuous exposure of traditional bulk power grid problem, various countries turn one's attention to environmental protection more, reliably distributed generation technology one after another.Microgrid is that the one proposed on distributed power generation basis is in recent years more advanced, novel supply power mode flexibly, is one and the small intelligent that photovoltaic, wind-powered electricity generation distributed power supply, energy storage device, power electronic equipment, local load and monitoring and protecting device merge is transported to electric system.Microgrid both can be incorporated into the power networks with outside bulk power grid, also can from net islet operation, and independent powers for local load, thus has higher Supply Security and reliability.
In microgrid, the current transformer be connected with energy storage device that capacity generally can be adopted larger is as networking power supply.When grid-connected, this current transformer runs on P/Q pattern, directly controls grid-connected current; When from net, this current transformer runs on V/F pattern, for other distributed power sources provide voltage and frequency reference.
Under grid-connect mode, 3-phase power converter adopts conventional soft phase-lock technique, and as shown in Figure 1, i.e. lockable grid phase, realizes being incorporated into the power networks; From under net pattern, grid-connected converter independently need generate reference phase.When being incorporated into the power networks from net turn, phase place need take over seamlessly current transformer from master phase from grid phase, can not cause SPA sudden phase anomalies.When being incorporated into the power networks from net turn, because current transformer exists phase difference between master phase and line voltage, therefore need realize grid phase in current transformer Phase Tracking, after both are identical, can close grid-connected switch, realizes the seamless switching from net pattern to grid-connect mode.
In GB GB/T15945-2008 " quality of power supply power system frequency deviation ", regulation electric power system normal running (operation) conditions lower frequency deviation limit value is ± 0.2Hz.When power system capacity is less, deviation limit value can be loosened to ± 0.5Hz.Therefore grid-connected, mutually switch from net pattern time, need guarantee that current transformer output frequency can not exceed the requirement of GB.
Summary of the invention
The object of this invention is to provide a kind of microgrid current transformer and turn a grid-connected phase-lock technique from net, in order to solve in prior art the nonsynchronous problem of phase place when micro-capacitance sensor realizes turning grid-connected from net.
For achieving the above object, the solution of the present invention comprises:
Microgrid current transformer turns a grid-connected phase-lock technique from net, first carries out phase place presynchronization when carrying out from net to grid-connected conversion, and the process of described phase place presynchronization is the three-phase voltage U exported from current transformer
abc_converterwith the electric network voltage phase θ of feedback after CLARK conversion
gcarry out PARK conversion, after output ring path filter, after voltage-controlled oscillator (VCO) link, obtain θ
c.
Further, what export after described PARK conversion is value on q axle.
Preferably, the proportional integral that described voltage carries out is transformed to the integral transformation of amplitude limit ratio.
Preferably, the amplitude that the integral transformation of described amplitude limit ratio is limit is [-π, π].
Microgrid current transformer turns a grid-connected phase-locking device from net, comprises presynchronization module, and for first carrying out phase place presynchronization when carrying out from net to grid-connected conversion, the process of described phase place presynchronization is the three-phase voltage U exported from current transformer
abc_converterwith the electric network voltage phase θ of feedback after CLARK conversion
gcarry out PARK conversion, export and after voltage-controlled oscillator (VCO) link, obtain θ after loop filter
c.
Further, what export after PARK conversion in described presynchronization module is value on q axle.
Preferably, in described presynchronization module, voltage loop filter is the integral transformation of limit ratio example.
Preferably, the amplitude that in described presynchronization module, the integral transformation of amplitude limit ratio is limit is [-π, π].
A kind of microgrid current transformer provided by the invention turns grid-connected phase-lock technique from net, from when switching to grid-connect mode from net pattern, increases phase place presynchronization module, thus can follow the tracks of grid phase.
In phase place presynchronization process, module is exported and carries out amplitude limit, make the frequency of current transformer output voltage to meet Standard by amplitude limit value, can not work the mischief to load.
Accompanying drawing explanation
Fig. 1 is three-phase grid-connected converter Method of Software Phase Lock;
Fig. 2 is microgrid current transformer of the present invention and switches phase-lock technique from net.
Embodiment
Below in conjunction with accompanying drawing, the present invention will be further described in detail.
Current transformer in micro-capacitance sensor needs when grid-connect mode runs to carry out phase-locked to line voltage, obtains grid phase θ
g; From the phase theta then using self-service generation during net mode operation
c.Micro-capacitance sensor from when switching from net pattern to grid-connect mode, due to θ
gand θ
cbetween will inevitably there is phase difference, therefore need to adopt phase place presynchronization, make θ
cθ can be got caught up in
g, thus guarantee can not have phase difference and cause excessive combined floodgate impulse current due to load voltage and line voltage when grid-connected combined floodgate.But in the process of phase place presynchronization, in order to make θ
cθ can be got caught up in
g, θ
cfrequency will inevitably change, therefore, need herein ensure θ
cfrequency can not exceed GB limit scope, namely its frequency ensures within the scope of 50 ± 0.5Hz.
Concrete, its phase-lock technique as shown in Figure 2, the basis of traditional three-phase grid-connected converter Method of Software Phase Lock increases presynchronization module.As can be seen from Figure 2, from the three-phase voltage U that current transformer exports
abcConverteragain with the θ fed back after CLARK conversion
gcarry out PARK conversion together, the Q shaft voltage U of output
qccarrying out amplitude limit is after three selector switches, add 2 π f after the proportional integral conversion of [-π, π] to regulate, and obtains θ after carrying out integration with after 2 π phase MOD
c.
Concrete adjustment process is as follows:
1. under grid-connect mode, switch S gets to position 1, and the phase theta c that now current transformer is used is electric network voltage phase θ g.
2. under net pattern, switch S gets to position 2, the phase place that the phase place that now current transformer is used generates for itself.
3. grid-connected to when switching from net, switch is got to 2 by 1.Due at steady state, the value of 1 is substantially close to 0, therefore switch gets to 2 by 1, can guarantee smoothing pseudorange transition, can not produce SPA sudden phase anomalies.
4., time from net to grid-connected switching, increase a phase place presynchronization module, as shown in shade in Fig. 2.Current transformer receive turn grid-connect mode instruction from net pattern time, first phase place presynchronization is carried out, switch S is switched to position 3, the PARK translation-angle adopted due to Uabc_converter is θ g, therefore output Uqc must have value, control this value by PI and be transitioned into 0 gradually, θ g in θ c tracking can be realized.Because θ c is when following the tracks of θ g, frequency can uprise or step-down, therefore needs to export PI to carry out amplitude limit, to guarantee the scope that its output frequency can not exceed load and can normally work.Amplitude limit value is defined as π (2* π * 0.5) according to GB 50 ± 0.5Hz herein.After phase place presynchronization completes, current transformer phase theta c is identical with grid phase θ g, and switch S is switched to position 1, completes Phase synchronization, and in the process, the frequency of current transformer output voltage can not exceed Standard, and can follow the tracks of and be transitioned into electric network voltage phase.
It should be noted that, each module in said method is all in the concrete steps of method when specifically implementing, instead of actual corresponding module.
Be presented above the execution mode that the present invention is concrete, but the present invention is not limited to described execution mode.Under the thinking that the present invention provides; the mode easily expected to those skilled in the art is adopted to convert the technological means in above-described embodiment, replace, revise; and the effect played goal of the invention that is substantially identical with the relevant art means in the present invention, that realize is also substantially identical; the technical scheme of such formation is carried out fine setting to above-described embodiment and is formed, and this technical scheme still falls within the scope of protection of the present invention.
Claims (8)
1. microgrid current transformer turns a grid-connected phase-lock technique from net, it is characterized in that, first carrying out phase place presynchronization when carrying out from net to grid-connected conversion, and the process of described phase place presynchronization is the three-phase voltage U exported from current transformer
abc_converterwith the electric network voltage phase θ of feedback after CLARK conversion
gcarry out PARK conversion, after output ring path filter, after voltage-controlled oscillator (VCO) link, obtain θ
c.
2. a kind of microgrid current transformer turns a grid-connected phase-lock technique from net according to claim 1, it is characterized in that, what export after described PARK conversion is value on q axle.
3. a kind of microgrid current transformer turns grid-connected phase-lock technique from net according to claim 1, and it is characterized in that, the proportional integral that described voltage carries out is transformed to the integral transformation of amplitude limit ratio.
4. a kind of microgrid current transformer turns grid-connected phase-lock technique from net according to claim 3, it is characterized in that, the amplitude that the integral transformation of described amplitude limit ratio is limit is [-π, π].
5. microgrid current transformer turns a grid-connected phase-locking device from net, it is characterized in that, comprises presynchronization module, and for first carrying out phase place presynchronization when carrying out from net to grid-connected conversion, the process of described phase place presynchronization is the three-phase voltage U exported from current transformer
abc_converterwith the electric network voltage phase θ of feedback after CLARK conversion
gcarry out PARK conversion, export and after voltage-controlled oscillator (VCO) link, obtain θ after loop filter
c.
6. a kind of microgrid current transformer turns a grid-connected phase-locking device from net according to claim 5, it is characterized in that, what export after PARK conversion in described presynchronization module is value on q axle.
7. a kind of microgrid current transformer turns grid-connected phase-locking device from net according to claim 5, it is characterized in that, in described presynchronization module, voltage loop filter is the integral transformation of limit ratio example.
8. a kind of microgrid current transformer turns grid-connected phase-locking device from net according to claim 7, and it is characterized in that, the amplitude that in described presynchronization module, the integral transformation of amplitude limit ratio is limit is [-π, π].
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108226588A (en) * | 2017-11-01 | 2018-06-29 | 中国矿业大学(北京) | It is a kind of to be suitable for single-phase and three-phase electrical power system Method of Software Phase Lock |
| CN110994688A (en) * | 2019-12-31 | 2020-04-10 | 国家电网有限公司 | Photovoltaic energy storage grid-connected and off-grid coordination control method and system |
| CN112583024A (en) * | 2021-03-01 | 2021-03-30 | 四川华泰电气股份有限公司 | Rapid grid-connected and grid-disconnected switching method and system of energy storage grid-connected converter |
| CN116316728A (en) * | 2023-03-14 | 2023-06-23 | 上海正泰电源***有限公司 | Automatic off-grid-to-grid phase tracking method based on bilateral phase locking |
| CN116454958A (en) * | 2022-08-08 | 2023-07-18 | 深圳闻储创新科技有限公司 | Inverter grid-connection and presynchronization control method, inverter system and photovoltaic power supply system |
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| WO2005067120A1 (en) * | 2003-12-19 | 2005-07-21 | Square D Company | Method and apparatus for power inverter synchronization |
| CN102832698A (en) * | 2012-09-05 | 2012-12-19 | 南京航空航天大学 | Novel software phaselock technique applicable to micro-grid master-slave control |
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Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108226588A (en) * | 2017-11-01 | 2018-06-29 | 中国矿业大学(北京) | It is a kind of to be suitable for single-phase and three-phase electrical power system Method of Software Phase Lock |
| CN110994688A (en) * | 2019-12-31 | 2020-04-10 | 国家电网有限公司 | Photovoltaic energy storage grid-connected and off-grid coordination control method and system |
| CN110994688B (en) * | 2019-12-31 | 2021-09-10 | 国家电网有限公司 | Photovoltaic energy storage grid-connected and off-grid coordination control method and system |
| CN112583024A (en) * | 2021-03-01 | 2021-03-30 | 四川华泰电气股份有限公司 | Rapid grid-connected and grid-disconnected switching method and system of energy storage grid-connected converter |
| CN116454958A (en) * | 2022-08-08 | 2023-07-18 | 深圳闻储创新科技有限公司 | Inverter grid-connection and presynchronization control method, inverter system and photovoltaic power supply system |
| CN116454958B (en) * | 2022-08-08 | 2024-01-30 | 深圳闻储创新科技有限公司 | Inverter grid-connection and presynchronization control method, inverter system and photovoltaic power supply system |
| CN116316728A (en) * | 2023-03-14 | 2023-06-23 | 上海正泰电源***有限公司 | Automatic off-grid-to-grid phase tracking method based on bilateral phase locking |
| CN116316728B (en) * | 2023-03-14 | 2024-03-29 | 上海正泰电源***有限公司 | Automatic off-grid-to-grid phase tracking method based on bilateral phase locking |
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