CN112448412A - Control method for low voltage ride through of photovoltaic inverter - Google Patents
Control method for low voltage ride through of photovoltaic inverter Download PDFInfo
- Publication number
- CN112448412A CN112448412A CN202011169116.XA CN202011169116A CN112448412A CN 112448412 A CN112448412 A CN 112448412A CN 202011169116 A CN202011169116 A CN 202011169116A CN 112448412 A CN112448412 A CN 112448412A
- Authority
- CN
- China
- Prior art keywords
- photovoltaic inverter
- control method
- low voltage
- voltage
- current component
- 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.)
- Pending
Links
- 238000000034 method Methods 0.000 title claims abstract description 24
- 238000005070 sampling Methods 0.000 claims abstract description 20
- 238000000354 decomposition reaction Methods 0.000 claims abstract description 7
- 238000001914 filtration Methods 0.000 claims abstract description 6
- 238000012545 processing Methods 0.000 claims abstract description 5
- 238000007789 sealing Methods 0.000 claims abstract description 5
- 230000004044 response Effects 0.000 description 8
- 238000005516 engineering process Methods 0.000 description 3
- 230000008569 process Effects 0.000 description 3
- 230000008859 change Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000010248 power generation Methods 0.000 description 2
- 230000015556 catabolic process Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000004880 explosion Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
Images
Classifications
-
- 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
- H02J3/381—Dispersed generators
-
- 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
- H02J3/12—Circuit arrangements for ac mains or ac distribution networks for adjusting voltage in ac networks by changing a characteristic of the network load
- H02J3/16—Circuit arrangements for ac mains or ac distribution networks for adjusting voltage in ac networks by changing a characteristic of the network load by adjustment of reactive power
-
- 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
- H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
- H02J2300/20—The dispersed energy generation being of renewable origin
- H02J2300/22—The renewable source being solar energy
- H02J2300/24—The renewable source being solar energy of photovoltaic origin
-
- 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
-
- 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
- Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
- Y02E40/30—Reactive power compensation
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Inverter Devices (AREA)
Abstract
The invention discloses a control method for low voltage ride through of a photovoltaic inverter, which comprises the following steps: A. sampling the voltage of the output side of the photovoltaic inverter in real time; B. extracting a D-axis direct current component of the voltage sampled in the step A through D-Q decomposition; C. b, performing sliding window filtering processing on the D-axis direct-current component extracted in the step B in a power grid period, wherein the length of a sliding window is the number N of sampling points in the power grid period, and when the number of the sliding window points is larger than or equal to N, calculating the average value of the D-axis direct-current component of the N points; d, judging whether the average value is smaller than a set threshold value; when the judgment result is true, judging that the low voltage ride through is met at the moment, and sealing the inversion side of the photovoltaic inverter to drive the photovoltaic inverter to maintain grid connection; and when the judgment result is negative, releasing the inverter drive of the photovoltaic inverter.
Description
Technical Field
The invention belongs to the field of photovoltaic inverters, and relates to a control method for low voltage ride through of a photovoltaic inverter.
Background
In our country, photovoltaic power generation occupies a very important position in the current power production, and through years of exploration and research, the number of construction is continuously increased, the scale is continuously enlarged, and the advantages of reproducibility, high conversion efficiency, environmental protection and the like are paid more attention and supported by the country.
In the practical process, sometimes, a power grid fails, the output voltage and the frequency of the power grid change greatly, and the stability of a power grid system is seriously affected. In order to solve the contradiction, the application of the low voltage ride through technology is very important in the power generation process of various countries.
The low voltage ride through (LVRT for short) refers to a phenomenon that a voltage is greatly reduced in a grid connection process of an inverter, and a certain reactive support can be continuously provided until a power grid recovers normal operation while the grid connection is maintained through a low voltage ride through technology, so that the area ride through in a low voltage time period is finally realized.
The large-amplitude voltage drop can cause the rapid overcurrent of current, and the long-time overcurrent causes the breakdown and explosion of components, so that the LVRT technology is very necessary to maintain the safety and stability of a power grid system.
The existing low-pass processing scheme is characterized in that sudden change of voltage is fed back to a control loop, parameters of a control current loop are adjusted through the feedback quantity, and due to the existence of the response time of the control loop, the response time is required to be in a millisecond level for strict low-pass requirements, and the method cannot meet the requirements frequently. Moreover, for a steady-state system, switching control loop parameters inevitably results in unreliable states.
Disclosure of Invention
In order to solve the above technical problems, an object of the present invention is to provide a method for controlling low voltage ride through of a photovoltaic inverter, which is stable and reliable.
In order to achieve the purpose, the invention adopts the technical scheme that:
a control method for low voltage ride through of a photovoltaic inverter comprises the following steps:
A. sampling the voltage of the output side of the photovoltaic inverter in real time;
B. extracting a D-axis direct current component of the voltage sampled in the step A through D-Q decomposition;
C. b, performing sliding window filtering processing on the D-axis direct-current component extracted in the step B in a power grid period, wherein the length of a sliding window is the number N of sampling points in the power grid period, and when the number of the sliding window points is larger than or equal to N, calculating the average value of the D-axis direct-current component of the N points; and
D. judging whether the average value is smaller than a set threshold value;
when the judgment result is true, judging that the low voltage ride through is met at the moment, and sealing the inversion side of the photovoltaic inverter to drive the photovoltaic inverter to maintain grid connection;
and when the judgment result is negative, releasing the inverter drive of the photovoltaic inverter.
Preferably, the number of sampling points N in the grid period is 20ms/(1/F), where F is the sampling frequency.
Preferably, the D-axis dc component of the voltage sampled in step a is extracted using a phase-locked loop D-Q decomposition. The D-axis component is extracted through the phase-locked loop, the response period only needs one to two mains supply periods, and the front-stage support can be made for the quick response low-penetration function.
More preferably, the D-axis direct current component of the sampled voltage is extracted by D-Q decomposition at the sampling frequency F using the SOGI software phase-lock method.
Preferably, the set threshold is 20-70% of the rated voltage.
Preferably, when the determination result is true, the flag bit is set to 1, and a low voltage ride through mode is entered; if the result is negative, the flag bit is set to 0, and the low voltage ride through mode is exited.
Compared with the prior art, the invention has the following advantages by adopting the scheme:
according to the control method for the low voltage ride through of the photovoltaic inverter, the D-axis component is extracted, the response period only needs one to two mains supply periods, the preceding stage support can be made for the quick response low-ride-through function, meanwhile, the sliding window filtering is arranged, and the reliability of low-ride-through voltage judgment is improved; according to the set conditions, when the low-power-consumption state is judged to be met, in the specified time, the zero-power output is realized by directly adopting the driving of the sealing inversion side, meanwhile, the control loop parameters cannot be reset, and after the low-power-consumption state is quitted, the control loop can be quickly switched in, so that the quick full-power operation of the control loop can be ensured.
Drawings
In order to more clearly illustrate the technical solution of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on the drawings without creative efforts.
FIG. 1 is a flow chart of a control method according to an embodiment of the invention;
FIG. 2a is a graph of nominal voltage waveforms;
FIG. 2b is a schematic diagram of the D-axis component of the rated voltage;
FIG. 3a is a graph of 32V grid voltage waveforms;
fig. 3b is a diagram of the D-axis component of the 32V grid voltage.
Detailed Description
Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings so that the advantages and features of the invention may be more readily understood by those skilled in the art. It should be noted that the description of the embodiments is provided to help understanding of the present invention, but the present invention is not limited thereto. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
According to the control method for the low voltage ride through of the photovoltaic inverter, the low voltage ride through is stably and reliably identified through the design of the MCU with the DSP as the core and the sampling circuit, so that the low voltage ride through of the photovoltaic inverter is controlled. Referring to fig. 1, the control method is embodied as follows.
S100, configuring AD sampling by software, and sampling the voltage of the output side of the photovoltaic inverter in real time, wherein the sampling frequency is set to be F, and the number of sampling points in a power grid period is N-20 ms/(1/F). Fig. 2a and 3a show waveforms of the rated voltage and the 32V voltage, respectively.
S200, under the sampling frequency F, extracting a D-axis direct-current component GRID _ D of the voltage obtained by sampling through D-Q decomposition by utilizing an SOGI (double second order generalized integrator) software phase locking method.
S300, designing software sliding window filtering GRID _ BUFF [ N ], wherein the length of the sliding window is N in the step S100, namely, performing sliding window processing in a power GRID period, and calculating the average value GRID _ D _ AVG of the D-axis component of the N points when the number Count of the sliding window points is more than or equal to the N points. Fig. 2b and 3b show the D-axis dc component of the extracted nominal voltage and 32V voltage, respectively.
S400, judging conditions: it is determined whether the average VALUE Grid _ D _ AVG is less than a set threshold VALUE GRIV _ VALUE.
When the calculated Grid _ D _ AVG is smaller than a set threshold VALUE GRIV _ VALUE, it can be determined that the low voltage ride through is satisfied at this time, and the flag bit uwinvepwrLimiteZeroFlag is set to 1, that is, the low voltage ride through mode is entered; GRIV _ VALUE is typically 20% rated voltage to 70% rated voltage, which refers to a state or region specified ac voltage, for example, china's rated voltage is 220V.
When Grid _ D _ AVG is greater than or equal to GRIV _ VALUE, the flag bit uwinvepwrlimitzolflag is set to 0, i.e., the low voltage ride through mode is exited.
And S500, when uwInvePWrLimitZeroFlag is 1, driving the inverter side to enable the photovoltaic inverter to maintain grid connection.
S600, when the flag bit uwInvePirwrLimiteZeroFlag is 0, the inversion side drive is released.
According to the method, the D-axis component is extracted through the phase-locked loop, the response period only needs one to two mains supply periods, the pre-stage support can be made for the quick response low-pass function, meanwhile, sliding window filtering is arranged under the sampling frequency F, and the reliability of low-pass voltage judgment is improved; according to the set conditions, when the low-power-consumption state is judged to be met, in the specified time, the zero-power output is realized by directly adopting the driving of the sealing inversion side, meanwhile, the control loop parameters cannot be reset, and after the low-power-consumption state is quitted, the control loop can be quickly switched in, so that the quick full-power operation of the control loop can be ensured.
The above embodiments are merely illustrative of the technical ideas and features of the present invention, and are preferred embodiments, which are intended to enable those skilled in the art to understand the contents of the present invention and implement the present invention, and not to limit the scope of the present invention. All equivalent changes or modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.
Claims (6)
1. A control method for low voltage ride through of a photovoltaic inverter is characterized by comprising the following steps:
A. sampling the voltage of the output side of the photovoltaic inverter in real time;
B. extracting a D-axis direct current component of the voltage sampled in the step A through D-Q decomposition;
C. b, performing sliding window filtering processing on the D-axis direct-current component extracted in the step B in a power grid period, wherein the length of a sliding window is the number N of sampling points in the power grid period, and when the number of the sliding window points is larger than or equal to N, calculating the average value of the D-axis direct-current component of the N points; and
D. judging whether the average value is smaller than a set threshold value;
when the judgment result is true, judging that the low voltage ride through is met at the moment, and sealing the inversion side of the photovoltaic inverter to drive the photovoltaic inverter to maintain grid connection;
and when the judgment result is negative, releasing the inverter drive of the photovoltaic inverter.
2. The control method according to claim 1, characterized in that: and the number of sampling points N in the power grid period is 20ms/(1/F), wherein F is the sampling frequency.
3. The control method according to claim 1, characterized in that: and in the step B, D-axis direct current components of the voltage sampled in the step A are decomposed and extracted by utilizing a phase-locked loop through D-Q.
4. The control method according to claim 3, characterized in that: and under the sampling frequency F, the D-axis direct-current component of the sampled voltage is extracted through D-Q decomposition by using an SOGI software phase locking method.
5. The control method according to claim 1, characterized in that: the set threshold is 20-70% of the rated voltage.
6. The control method according to claim 1, characterized in that: when the judgment result is true, setting the flag bit to be 1, and entering a low voltage ride through mode; if the result is negative, the flag bit is set to 0, and the low voltage ride through mode is exited.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011169116.XA CN112448412A (en) | 2020-10-28 | 2020-10-28 | Control method for low voltage ride through of photovoltaic inverter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011169116.XA CN112448412A (en) | 2020-10-28 | 2020-10-28 | Control method for low voltage ride through of photovoltaic inverter |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN112448412A true CN112448412A (en) | 2021-03-05 |
Family
ID=74736509
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202011169116.XA Pending CN112448412A (en) | 2020-10-28 | 2020-10-28 | Control method for low voltage ride through of photovoltaic inverter |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN112448412A (en) |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103269086A (en) * | 2013-04-24 | 2013-08-28 | 西安理工大学 | Positive and negative sequence component separation method of low-voltage ride-through control of photovoltaic grid-connected inverter |
| CN104237711A (en) * | 2014-10-15 | 2014-12-24 | 四川东方电气自动控制工程有限公司 | Fast and reliable low voltage through determination method |
| CN106026094A (en) * | 2016-04-22 | 2016-10-12 | 南京亚派科技股份有限公司 | Imbalance control algorithm applied to active filter |
| US20180166883A1 (en) * | 2015-08-10 | 2018-06-14 | Huawei Technologies Co., Ltd. | Low voltage ride-through control system and method for multi-inverter grid-connected power converter |
| CN110994628A (en) * | 2019-11-14 | 2020-04-10 | 特变电工西安电气科技有限公司 | High voltage ride through control method of two-stage photovoltaic inverter |
| CN111711226A (en) * | 2020-06-05 | 2020-09-25 | 南京南瑞太阳能科技有限公司 | Chopper circuit-based photovoltaic inverter low voltage ride through control method and device |
-
2020
- 2020-10-28 CN CN202011169116.XA patent/CN112448412A/en active Pending
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103269086A (en) * | 2013-04-24 | 2013-08-28 | 西安理工大学 | Positive and negative sequence component separation method of low-voltage ride-through control of photovoltaic grid-connected inverter |
| CN104237711A (en) * | 2014-10-15 | 2014-12-24 | 四川东方电气自动控制工程有限公司 | Fast and reliable low voltage through determination method |
| US20180166883A1 (en) * | 2015-08-10 | 2018-06-14 | Huawei Technologies Co., Ltd. | Low voltage ride-through control system and method for multi-inverter grid-connected power converter |
| CN106026094A (en) * | 2016-04-22 | 2016-10-12 | 南京亚派科技股份有限公司 | Imbalance control algorithm applied to active filter |
| CN110994628A (en) * | 2019-11-14 | 2020-04-10 | 特变电工西安电气科技有限公司 | High voltage ride through control method of two-stage photovoltaic inverter |
| CN111711226A (en) * | 2020-06-05 | 2020-09-25 | 南京南瑞太阳能科技有限公司 | Chopper circuit-based photovoltaic inverter low voltage ride through control method and device |
Non-Patent Citations (1)
| Title |
|---|
| 欧华亚: "光伏并网逆变器的VSG低压穿越控制方法研究及装置研制", 《中国优秀硕士学位论文全文数据库》 * |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN104868766A (en) | Inversion device and AC power supply system applying same | |
| CN103488238B (en) | Adaptive variable-step MPPT (maximum power point tracking) control method for coping with quick change of illumination intensity | |
| CN113193598B (en) | New energy grid-connected inverter transient stability margin evaluation method | |
| CN111049376B (en) | Two-stage type serial photovoltaic power optimizer system communication-free bus modulation method | |
| CN107681688B (en) | Grid-connected converter with VSG (voltage source generator) characteristics and island judgment method and device thereof | |
| WO2023197547A1 (en) | Reliable parallel control system and method for efficient bidirectional power conversion module | |
| CN110336268A (en) | Charge/discharge control method for energy storage reversible transducer | |
| CN202260487U (en) | Control device for single-phase photovoltaic grid-connected power generation system | |
| CN113629771B (en) | Photovoltaic system and photovoltaic turn-off method | |
| WO2023010659A1 (en) | Stability criterion for grid-connected converter control loop under weak grid condition | |
| CN103856045A (en) | Fuzzy PI double-loop control method based on stratification thoughts | |
| CN112448412A (en) | Control method for low voltage ride through of photovoltaic inverter | |
| CN109861287B (en) | Unified control method and system for photovoltaic inverter | |
| CN112968468A (en) | Grid-connected converter negative sequence current control method and system under single dq-PI current control structure | |
| CN109873487B (en) | Master-slave backup method for three-phase three-level VIENNA rectifier | |
| CN201341090Y (en) | Control circuit of non-insulation type bidirectional DC/DC converter | |
| CN113162117B (en) | Method for designing bandwidth of grid-connected inverter controller under weak grid | |
| CN114204789B (en) | Voltage source type AC-DC converter and direct current side fault ride-through method thereof | |
| CN114676573A (en) | Unified mathematical modeling method for open-circuit fault of three-level photovoltaic inverter | |
| Yang et al. | Study of an adaptive fuzzy VDCOL control strategy for coordinated recovery of multi-feed-in HVDC system | |
| Zhao et al. | Design of double loop controller for three-level boost converter | |
| CN110445122B (en) | Direct-current micro-grid distributed autonomous coordination control method capable of remarkably improving bus voltage deviation | |
| CN103633665B (en) | A kind of micro-grid power source based on sinusoidal wave bus | |
| CN112531771A (en) | Off-grid MPPT control device and method for hybrid energy storage inverter | |
| WO2020142890A1 (en) | Method for adjusting bus voltage, and related device |
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 | ||
| RJ01 | Rejection of invention patent application after publication | ||
| RJ01 | Rejection of invention patent application after publication |
Application publication date: 20210305 |