CN115313496A - Energy storage converter grid-connected control method based on droop control - Google Patents
Energy storage converter grid-connected control method based on droop control Download PDFInfo
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- CN115313496A CN115313496A CN202211079126.3A CN202211079126A CN115313496A CN 115313496 A CN115313496 A CN 115313496A CN 202211079126 A CN202211079126 A CN 202211079126A CN 115313496 A CN115313496 A CN 115313496A
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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
- H02J3/381—Dispersed generators
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
- H02J3/46—Controlling of the sharing of output between the generators, converters, or transformers
- H02J3/48—Controlling the sharing of the in-phase component
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
- H02J3/46—Controlling of the sharing of output between the generators, converters, or transformers
- H02J3/50—Controlling the sharing of the out-of-phase component
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Inverter Devices (AREA)
Abstract
The invention discloses a droop control-based grid-connected control method for an energy storage converter. The method is suitable for grid-connected control of a single converter or multiple converters without a pre-synchronization process, and can avoid the problems of control delay and the like caused by closing delay of a breaker.
Description
Technical Field
The invention relates to the technical field of energy storage converter control, in particular to a droop control-based energy storage converter grid-connected control method.
Background
With the development of economy and the progress of society, the energy demand is increasing day by day, but the traditional fossil energy is rapidly developed in the energy, the problems of grid connection difficulty and consumption difficulty caused by intermittence and fluctuation are more and more prominent, the development of renewable energy power generation is severely restricted, and good development opportunity is brought to the energy storage technology. Droop control enables all distributed power supplies to participate in maintaining the stability of system frequency and voltage together by simulating the power frequency characteristic of the generator set, realizes the non-interconnection control of active power and reactive power, is suitable for a micro-grid peer-to-peer control mode, and can avoid the adverse effect possibly caused by the fault of a single main control unit on the system performance.
Droop control is essentially voltage control, and when a converter is incorporated into a power grid or put into parallel connection, if the frequency, the phase or the voltage amplitude is inconsistent with that of other systems or a large power grid, the forced parallel connection or the grid connection can cause large impact current, so that accidents are caused. Therefore, the droop control is firstly subjected to synchronous control before grid connection, and when the amplitude and the phase of the grid voltage are detected to reach the threshold values, the closing operation is carried out after presynchronization is completed. The method requires that a filter capacitor exists on the alternating current side of the energy storage converter, otherwise, alternating current synchronous control cannot be completed. And secondly, issuing a closing command after the presynchronization is finished, wherein the presynchronization control cannot be accurately stopped due to certain delay of actual circuit breaker closing, so that control delay is caused. Therefore, a reliable and effective grid-connected control method is needed to be provided, and the energy storage converter can be ensured to be quickly connected to the grid without impact.
Disclosure of Invention
The invention aims to provide a droop control-based grid-connected control method for an energy storage converter.
Therefore, the technical scheme of the invention is as follows:
an energy storage converter grid-connected control method based on droop control comprises
Collecting the voltage and current of a power grid;
starting a phase-locked loop control module, taking the voltage of the power grid as the input of the phase-locked loop, and calculating the angle theta of the power grid through the phase-locked loop g The device is used for realizing coordinate transformation and control of voltage and current;
closing a network side breaker, and connecting the converter into a power grid;
will net side three-phase current i a ，i b ，i c Coordinate transformation is carried out to obtain dq axis component i d And i q Setting the dq axis current given value to be 0, and starting a network side current controller to control the network side current;
delay oneSetting the voltage loop to u within a period of time after the grid-connected operation is stable dref And u qref Respectively given as actual voltage dq-axis components u d And u q Ensuring that the voltage loop output is 0;
starting the droop controller, setting the output voltage of the droop controller as a voltage loop, taking the phase of the moment before switching as an initial phase, and integrating the output frequency to obtain a control angle theta c And completing the grid connection of the energy storage converter.
Further, after the droop control is started, the phase-locked loop outputs an angle theta g A phase reference is generated as the initial phase.
Further, the droop control respectively controls the converter to output active power and reactive power by adjusting the voltage frequency and the amplitude, and the droop control expression is
In the formula, omega and U are given values of angular frequency and voltage amplitude of the output of the inverter, P and Q are actual active power and reactive power output by the inverter, and P and Q are actual active power and reactive power output by the inverter 0 And Q 0 Rated output of active and reactive power, omega, for an inverter 0 And U 0 For the inverter to be rated for angular frequency and voltage amplitude, k p And k q The active and reactive droop coefficients are provided, respectively.
Compared with the prior art, the energy storage converter grid-connected control method based on droop control can directly realize converter grid connection without a grid connection presynchronization process, is suitable for single converter grid connection control or multi-converter grid connection control, and can avoid the problems of control lag and the like caused by closing delay of a breaker.
Drawings
Fig. 1 is a schematic diagram of a topology of an energy storage converter.
Fig. 2 is a flowchart of a grid-connected control method for the energy storage converter based on droop control provided by the invention.
Fig. 3 is a schematic diagram of grid-connected control provided by the present invention.
Fig. 4 is a schematic diagram of phase-locked loop control.
Fig. 5 is a schematic diagram of the droop controller control.
Detailed Description
The invention will be further described with reference to the following figures and specific examples, which are not intended to limit the invention in any way.
The energy storage converter topology structure is shown in fig. 1, the alternating-current side circuit breaker is used for breaking connection between the energy storage converter and a power grid, and the controller collects voltage and current of the power grid and is used for achieving converter control.
The invention provides a droop control-based energy storage converter grid-connected control method, the control flow of which is shown in figure 2, and the method comprises the following steps:
the controller collects the voltage and current of the power grid and is used for realizing the control of the converter;
firstly, a phase-locked loop control module is started, the control principle of the phase-locked loop is shown in figure 4, the voltage of a power grid is used as the input of the phase-locked loop, and the angle theta of the power grid is obtained through calculation of the phase-locked loop g The coordinate transformation and control device is used for realizing the coordinate transformation and control of voltage and current;
then closing a network side breaker, and connecting the converter into a power grid;
outputting the grid angle theta through a phase-locked loop g The three-phase current i on the network side a ，i b ，i c Coordinate transformation is carried out to obtain dq axis component i d And i q Setting the dq-axis current given value to be 0, starting a network side current controller to perform network side current control, and outputting control voltage through a PI (proportional-integral) controller after the difference between the dq-axis current given value and feedback current is made as shown in FIG. 3;
delaying for a period of time, and setting a voltage loop u after the grid-connected operation is stable dref And u qref Respectively given as actual voltage dq-axis components u d And u q Ensuring that the voltage loop output is 0;
then, the droop controller is started, as shown in fig. 3-5, the selection switches are all set to be at 2' in fig. 3, the output voltage of the selection switches is given as a voltage loop, the phase at the moment before switching is taken as the initial phase, and the phase-locked loop outputsAngle theta g Generating a phase reference as an initial phase, and integrating the output frequency to obtain a control angle theta c And completing the grid connection of the energy storage converter.
Claims (3)
1. An energy storage converter grid-connected control method based on droop control is characterized by comprising the following steps
Collecting the voltage and current of a power grid;
starting a phase-locked loop control module, taking the voltage of the power grid as the input of the phase-locked loop, and calculating the angle theta of the power grid through the phase-locked loop g The device is used for realizing coordinate transformation and control of voltage and current;
closing a network side breaker, and connecting the converter into a power grid;
will net side three-phase current i a ，i b ，i c Coordinate transformation is carried out to obtain dq axis component i d And i q Setting the dq axis current given value to be 0, and starting a network side current controller to control the network side current;
delaying for a period of time, and setting a voltage loop u after the grid-connected operation is stable dref And u qref Respectively given as actual voltage dq-axis components u d And u q Ensuring that the voltage loop output is 0;
starting the droop controller, giving the output voltage of the droop controller as a voltage ring, taking the phase before switching as an initial phase, and integrating the output frequency to obtain a control angle theta c And completing the grid connection of the energy storage converter.
2. The droop control-based grid-connected control method for the energy storage converter according to claim 1, wherein after the droop control is started, a phase-locked loop is used for outputting an angle theta g A phase reference is generated as the initial phase.
3. The droop control-based grid-connected control method for the energy storage converter according to claim 2, wherein the droop control controls the converter to output active power and reactive power respectively by adjusting voltage frequency and amplitude, and the droop control expression is
In the formula, omega and U are given values of angular frequency and voltage amplitude of the output of the inverter, P and Q are actual active power and reactive power output by the inverter, and P and Q are actual active power and reactive power output by the inverter 0 And Q 0 Rated output of active and reactive power, omega, for an inverter 0 And U 0 For the inverter to be rated for angular frequency and voltage amplitude, k p And k q Active and reactive droop coefficients, respectively.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202211079126.3A CN115313496A (en) | 2022-09-05 | 2022-09-05 | Energy storage converter grid-connected control method based on droop control |
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| CN202211079126.3A CN115313496A (en) | 2022-09-05 | 2022-09-05 | Energy storage converter grid-connected control method based on droop control |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116565916A (en) * | 2023-07-07 | 2023-08-08 | 中国电力科学研究院有限公司 | Response method and device for participation of converter load equipment in power grid balance adjustment |
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2022
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116565916A (en) * | 2023-07-07 | 2023-08-08 | 中国电力科学研究院有限公司 | Response method and device for participation of converter load equipment in power grid balance adjustment |
| CN116565916B (en) * | 2023-07-07 | 2023-12-15 | 中国电力科学研究院有限公司 | Response method and device for participation of converter load equipment in power grid balance adjustment |
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