Photovoltaic station multi-element equipment fault ride-through coordination control method, system, equipment and medium
By obtaining the rated current of the grid-connected equipment in the photovoltaic field station, determining the reactive current requirements during the failure, and setting fault crossing parameters, coordinating the dynamic reactive current injection strategy of photovoltaic converters and static reactive generators, the photovoltaic field is solved The problem of transient instability caused by lack of active support during a failure improves the stability and efficiency of the system.
Patent Information
- Application Number
- CN202411488996.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-24
- Publication Date
- 2025-02-18
AI Technical Summary
When a photovoltaic field station fails, it lacks effective support and is prone to transient instability.
By obtaining the rated current of the photovoltaic converter and static reactive generator running in the photovoltaic site, determine the reactive current requirements during a fault, and set corresponding fault crossing parameters to coordinate the photovoltaic converter and static reactive generator. The dynamic reactive current injection strategy of the device is to ensure the stability of the system during failure.
It effectively solves the problem of transient instability caused by the lack of active support during the photovoltaic field station during the failure, and improves the stability and efficiency of the system.
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Figure CN119482374A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of fault ride-through coordinated control, and in particular to a method, system, device and medium for coordinated control of fault ride-through of multiple devices in a photovoltaic station. Background Art
[0002] In the field of new energy technology, photovoltaic power generation is an environmentally friendly and renewable energy form. The photovoltaic system consists of solar panels, inverters, etc., among which the inverter is one of the core devices that converts the direct current generated by the solar panel into alternating current. With the continuous development of technology, the low voltage ride-through technology of photovoltaic inverters has become one of the important technologies to improve the efficiency and stability of photovoltaic systems.
[0003] In the prior art, when a voltage failure occurs, the voltage at the photovoltaic station grid connection point drops. When the voltage is higher than a certain threshold, the photovoltaic maintains normal control; when the voltage drops below the threshold, the photovoltaic enters a low voltage ride-through state. Since photovoltaics need to first meet the dynamic reactive power injection requirements and the total capacity of the equipment is limited, the active power output of the equipment is often limited during low voltage periods, and the system is prone to transient instability problems when it lacks active power support.
[0004] In view of this, a method, system, device and medium for coordinated control of fault ride-through of multiple devices in a photovoltaic station are needed. Summary of the invention
[0005] The embodiments of the present application provide a method, system, device and medium for coordinated control of fault ride-through of multiple devices in a photovoltaic station, which are used to solve the problem of transient instability that easily occurs when the system lacks active support.
[0006] A first aspect of an embodiment of the present application provides a photovoltaic station multi-device fault ride-through coordination control method, comprising:
[0007] Obtain the rated current of the photovoltaic converter and the rated current of the static VAR generator connected to the grid in the photovoltaic station;
[0008] When a fault occurs in the photovoltaic station, determining whether the injected reactive current of the photovoltaic station as a whole meets the demand according to the rated current of the photovoltaic converter;
[0009] When the reactive current injected by the photovoltaic station as a whole meets the demand, the fault ride-through parameter of the photovoltaic converter is set, and the fault ride-through parameter of the static reactive generator is calculated at the same time;
[0010] The fault ride-through parameters of the photovoltaic inverter and the fault ride-through parameters of the static VAR generator are transmitted to the photovoltaic inverter and the static VAR generator respectively through network communication, so that the photovoltaic inverter generates a corresponding reactive current injection strategy and an active current injection strategy, and the static VAR generator generates a corresponding reactive current injection strategy.
[0011] Furthermore, when the photovoltaic station fails, determining whether the injected reactive current of the photovoltaic station as a whole meets the demand according to the rated current of the photovoltaic converter includes:
[0012] Determining the extent of the failure of the photovoltaic station, the extent including a medium-depth failure and a deep failure;
[0013] When a fault occurs at a medium depth, it is determined whether the injected reactive current of the entire photovoltaic station meets the demand according to the rated current of the photovoltaic converter.
[0014] Furthermore, when the photovoltaic station fails, determining whether the injected reactive current of the photovoltaic station as a whole meets the demand according to the rated current of the photovoltaic converter includes:
[0015] Determine whether the injected reactive current of the photovoltaic station as a whole meets the following conditions:
[0016]
[0017] Where: I qtot is the reactive current injected by the PV station during the fault, K tot is the dynamic reactive current proportional coefficient of the photovoltaic station as a whole, U t is the voltage amplitude of the photovoltaic station grid connection point, I N,h is the rated current of the hth grid-connected PV converter.
[0018] Furthermore, the setting of the fault ride-through parameters of the photovoltaic converter includes:
[0019] The fault ride-through parameters of the photovoltaic converter include the dynamic reactive current proportional coefficient K of the photovoltaic converter pv and the threshold voltage U Lpv , K pv Set up with K tot Consistent, U Lpv Set to 0.8 to 0.4.
[0020] Furthermore, the calculating of the fault ride-through parameter of the static VAR generator includes:
[0021] The fault ride-through parameters of the static VAR generator include the dynamic reactive current proportional coefficient K of the static VAR generator. 1sta , K 2sta and the threshold voltage U Lsta :
[0022]
[0023] Where: I N,i is the rated current of the i-th static VAR generator.
[0024] Furthermore, the step of causing the photovoltaic converter to generate a corresponding reactive current injection strategy and an active current injection strategy includes:
[0025] Reactive current injection strategy I qpv,h :
[0026]
[0027] Active current injection strategy I dpv,h :
[0028]
[0029] Among them: U t,h is the AC voltage amplitude of the photovoltaic inverter grid connection point, I dpv0,h is the active current before the fault.
[0030] Furthermore, the static VAR generator generates a corresponding reactive current injection strategy, including:
[0031] Reactive current injection strategy:
[0032]
[0033] Among them: U t,i is the AC voltage amplitude of the static VAR generator grid connection point, I N,i is the rated current of the i-th static VAR generator.
[0034] A second aspect of the embodiment of the present application provides a photovoltaic station multi-device fault ride-through coordination control system, including:
[0035] A rated current acquisition unit is used to acquire the rated current of a photovoltaic converter and a static VAR generator connected to the grid in a photovoltaic station;
[0036] A rated current judgment unit, used to determine whether the injected reactive current of the photovoltaic station as a whole meets the demand according to the rated current of the photovoltaic converter when a fault occurs in the photovoltaic station;
[0037] A unit for setting and calculating a fault ride-through parameter is used to set the fault ride-through parameter of the photovoltaic converter and calculate the fault ride-through parameter of the static reactive generator when the reactive current injected by the photovoltaic station as a whole meets the demand;
[0038] A strategy generation unit is used to transmit the fault ride-through parameters of the photovoltaic converter and the fault ride-through parameters of the static VAR generator to the photovoltaic converter and the static VAR generator respectively through network communication, so that the photovoltaic converter generates a corresponding reactive current injection strategy and an active current injection strategy, and the static VAR generator generates a corresponding reactive current injection strategy.
[0039] A third aspect of the embodiments of the present application provides a computer device, including:
[0040] memories, transceivers, processors, and bus systems;
[0041] Wherein, the memory is used to store programs;
[0042] The processor is used to execute the program in the memory, including the steps of executing the coordinated control method for fault ride-through of multiple devices in a photovoltaic station as described in any one of the above items;
[0043] The bus system is used to connect the memory and the processor so that the memory and the processor can communicate with each other.
[0044] A fourth aspect of an embodiment of the present application provides a readable storage medium, including instructions, which, when executed on a computer, enables the computer to execute the coordinated control method for fault ride-through of multiple devices in a photovoltaic station as described in any one of the above.
[0045] It can be seen from the above technical solutions that the embodiments of the present application have the following advantages:
[0046] After obtaining the rated current of the photovoltaic inverter and static VAR generator connected to the grid, the present application determines that the fault ride-through coefficients of the photovoltaic inverter and the static VAR generator are set respectively, under the premise that the overall injected reactive current meets the demand when a fault occurs; the ride-through system of the photovoltaic inverter and the static VAR generator is calculated by the fault ride-through coefficient, so as to coordinate the dynamic reactive power injected into the photovoltaic inverter and the static VAR generator system under different voltage drop depths, thereby solving the problem of transient instability that is prone to occur when the system lacks active support. BRIEF DESCRIPTION OF THE DRAWINGS
[0047] Figure 1 It is a schematic diagram of an embodiment of a coordinated control method for fault ride-through of multiple equipment in a photovoltaic station in the present invention;
[0048] Figure 2It is a structural diagram of the coordinated control process of fault ride-through of multiple equipment in a photovoltaic station in the present invention. DETAILED DESCRIPTION
[0049] The embodiments of the present application provide a method, system, device and medium for coordinated control of fault ride-through of multiple devices in a photovoltaic station, which are used to solve the problem of transient instability that easily occurs when the system lacks active support.
[0050] The terms "first", "second", "third", "fourth", etc. (if any) in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein, for example. In addition, the terms "including" and "corresponding to" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.
[0051] Embodiment 1
[0052] The implementation method in this embodiment can be implemented in the system, in the server, or in the terminal, and there is no specific limitation. The following will introduce the coordinated control method for fault ride-through of multiple equipment in the photovoltaic station in this application from the perspective of system implementation. Figure 1 , the method provided in the embodiment of the present application comprises the following steps:
[0053] S11. Obtain the rated current of the photovoltaic converter and the rated current of the static VAR generator connected to the grid in the photovoltaic station;
[0054] S12. When a fault occurs in a photovoltaic station, determine whether the injected reactive current of the photovoltaic station as a whole meets the demand based on the rated current of the photovoltaic converter;
[0055] See also Figure 2 , this embodiment mainly includes the control algorithm of the transient voltage collaborative controller at the station level, the low voltage ride-through algorithm in the SVG controller and the photovoltaic converter controller, and the collaborative control strategy between them. In addition to the photovoltaic power converter, the photovoltaic station will also be equipped with a static VAR generator (SVG), which is used to adjust the overall voltage performance of the station. Specifically, the national standard GB / T19964 requires that in the event of a symmetrical fault, the overall dynamic reactive power support capacity of the photovoltaic power station should meet the following requirements:
[0056] 1. When a three-phase short circuit fault occurs in the power system and the positive sequence component of the grid connection point voltage is lower than 90% of the nominal voltage, the photovoltaic power station should have dynamic reactive power support capability.
[0057] 2. The dynamic reactive current increment of the photovoltaic power station should respond to the voltage change at the grid connection point and should meet the following requirements:
[0058] ΔI t ≥K1×(0.9―U t )×I N (0≤U t ≤0.9);
[0059] Where: ΔI t U is the dynamic reactive current increment injected by the photovoltaic power station, in ampere (A). K1 is the dynamic reactive current proportional coefficient of the photovoltaic power station. The value of K1 should be no less than 1.5 and preferably no more than 3. t The voltage per unit value of the photovoltaic power station grid connection point, I N It is the rated current of the photovoltaic power station, in ampere (A).
[0060] 3. During the voltage drop, the reactive current injected by the photovoltaic power station into the grid should be the reactive current output value I0 before the voltage drop and the dynamic reactive current increment ΔI t The maximum output capacity of the reactive current of the photovoltaic power station should not be less than the rated current I N 1.05 times of.
[0061] 4. From the moment the grid-connected point voltage drops, the dynamic reactive current response time of the photovoltaic power station should be no more than 30ms. From the moment the grid-connected point voltage recovers to more than 90% of the nominal voltage, the photovoltaic power station should exit the dynamic reactive current increment within 20ms.
[0062] Based on the above requirements, after obtaining the rated current of the photovoltaic inverter and the rated current of the static VAR generator connected to the grid in the photovoltaic station, when a photovoltaic station fails, it is necessary to determine the degree of the failure of the photovoltaic station, which includes medium-depth failure and deep failure; specifically, in the case of medium-depth failure (0.4 t <0.9), allowing SVG to bear most of the dynamic reactive power demand of the station, reducing the dynamic reactive power of the PV converter. The remaining capacity allows the PV converter to inject more dynamic active power to support the transient recovery of the system. t <0.4), SVG and PV converter jointly bear the reactive power demand of the station. Therefore, when it is a medium-depth fault, it is necessary to determine whether the injected reactive current of the PV station as a whole meets the demand based on the rated current of the PV converter. Specifically, it is necessary to determine whether the injected reactive current of the PV station as a whole meets the following conditions:
[0063]
[0064] Where: I qtot is the reactive current injected by the PV station during the fault, K tot is the dynamic reactive current proportional coefficient of the photovoltaic station as a whole. The international recommendation is K tot The value should be no less than 1.5 and preferably no more than 3. t is the voltage amplitude of the photovoltaic station grid connection point, I N,h is the rated current of the hth grid-connected PV converter.
[0065] It should be noted that the rated current of the PV inverter and the SVG connected to the grid in the station refers to all the grid-connected equipment. If a PV inverter or SVG is in a state such as maintenance and cannot be connected to the grid normally, there is no need to obtain its rated current information.
[0066] S13. When the injected reactive current of the photovoltaic station as a whole meets the demand, the fault ride-through parameters of the photovoltaic converter are set, and the fault ride-through parameters of the static reactive generator are calculated at the same time;
[0067] In this embodiment, the fault ride-through parameters of the photovoltaic converter include the dynamic reactive current proportional coefficient K of the photovoltaic converter. pv and the threshold voltage U Lpv , K pv Set up with K tot Consistent, U Lpv Set to 0.8 to 0.4.
[0068] The fault ride-through parameters of the static VAR generator SVG include the dynamic reactive current proportional coefficient K of the static VAR generator 1sta , K 2sta and the threshold voltage U Lsta :
[0069]
[0070] Where: I N,i is the rated current of the i-th static VAR generator.
[0071] S14. The fault ride-through parameters of the photovoltaic converter and the fault ride-through parameters of the static VAR generator are transmitted to the photovoltaic converter and the static VAR generator respectively through network communication, so that the photovoltaic converter generates corresponding reactive current injection strategy and active current injection strategy, and the static VAR generator generates corresponding reactive current injection strategy.
[0072] In this embodiment, U Lpv and K pvTransmit to the photovoltaic inverter through network communication; 1sta , K 2sta and U Lsta The information is transmitted to the static VAR generator SVG through network communication, so that the photovoltaic converter generates corresponding reactive current injection strategy and active current injection strategy, and the static VAR generator generates corresponding reactive current injection strategy.
[0073] Specifically, the reactive current injection strategy I qpv,h :
[0074]
[0075] Active current injection strategy for photovoltaic converters dpv,h :
[0076]
[0077] Among them: U t,h is the AC voltage amplitude of the photovoltaic inverter grid connection point, I dpv0,h is the active current before the fault.
[0078] Reactive current injection strategy for static VAR generator:
[0079]
[0080] Among them: U t,i is the AC voltage amplitude of the static VAR generator grid connection point, I N,i is the rated current of the i-th static VAR generator.
[0081] Finally, after a certain period of time, such as 1 second, step S11 is repeated to update the capacity information of the grid-connected equipment in the station, that is, the rated current of the grid-connected photovoltaic converter and the rated current of the grid-connected static VAR generator, and complete a series of subsequent steps.
[0082] The above embodiment adjusts the reactive current injection strategy of SVG by appropriately reducing the voltage threshold for the photovoltaic converter to enter low-breakdown, under the premise of meeting the reactive injection demand of the entire station. In the case of medium-depth faults, SVG is allowed to bear most of the dynamic reactive power demand of the station, reducing the dynamic reactive power of the photovoltaic converter, and freeing up capacity so that the photovoltaic converter can inject dynamic active power to support the transient recovery of the system. In the case of deep faults, SVG and photovoltaic converters jointly bear the reactive power demand of the station. This effectively solves the problem of transient instability that is prone to occur when the system lacks active power support.
[0083] Embodiment 2
[0084] An embodiment of a photovoltaic station multi-device fault ride-through coordinated control system of the present invention comprises the following steps:
[0085] A rated current acquisition unit is used to acquire the rated current of a photovoltaic converter and a static VAR generator connected to the grid in a photovoltaic station;
[0086] A rated current judgment unit is used to determine whether the injected reactive current of the photovoltaic station as a whole meets the demand according to the rated current of the photovoltaic converter when a photovoltaic station fails;
[0087] The unit for setting and calculating fault ride-through parameters is used to set the fault ride-through parameters of the photovoltaic converter and calculate the fault ride-through parameters of the static reactive generator when the reactive current injected by the photovoltaic station as a whole meets the demand;
[0088] The strategy generation unit is used to transmit the fault ride-through parameters of the photovoltaic converter and the fault ride-through parameters of the static VAR generator to the photovoltaic converter and the static VAR generator respectively through network communication, so that the photovoltaic converter generates the corresponding reactive current injection strategy and active current injection strategy, and the static VAR generator generates the corresponding reactive current injection strategy.
[0089] Embodiment 3
[0090] The present invention provides a computer device, comprising a memory, a processor, and computer-readable instructions stored in the memory and executable on the processor. When the processor executes the computer-readable instructions, the steps of the above method are implemented.
[0091] Those of ordinary skill in the art will appreciate that the units of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition of each example has been generally described in terms of function in the above description. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.
[0092] In the embodiments provided by the present invention, it should be understood that the division of units is only a logical function division, and there may be other division methods in actual implementation, such as multiple units can be combined into one unit, one unit can be split into multiple units, or some features can be ignored. In addition, each functional unit in each embodiment of the present invention can be integrated into a processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of software functional units.
[0093] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product, which is stored in a storage medium and includes several instructions for a computer device (which can be a personal computer, a server or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, read-only memory (ROM, Read-0nlyMemory), random access memory (RAM, RandomAccessMemory), mobile hard disk, magnetic disk or optical disk, etc., which can store program code.
[0094] It can be understood that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein by equivalents. These modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and specification of the present invention.
Claims
1. A coordinated control method for fault ride-through of multiple devices in a photovoltaic station, characterized in that: include: Obtain the rated current of the photovoltaic converter and the rated current of the static VAR generator connected to the grid in the photovoltaic station; When a fault occurs in the photovoltaic station, determining whether the injected reactive current of the photovoltaic station as a whole meets the demand according to the rated current of the photovoltaic converter; When the reactive current injected by the photovoltaic station as a whole meets the demand, the fault ride-through parameter of the photovoltaic converter is set, and the fault ride-through parameter of the static VAR generator is calculated at the same time; The fault ride-through parameters of the photovoltaic inverter and the fault ride-through parameters of the static VAR generator are transmitted to the photovoltaic inverter and the static VAR generator respectively through network communication, so that the photovoltaic inverter generates a corresponding reactive current injection strategy and an active current injection strategy, and the static VAR generator generates a corresponding reactive current injection strategy.
2. The photovoltaic station multi-device fault ride-through coordination control method according to claim 1 is characterized in that: When the photovoltaic station fails, determining whether the injected reactive current of the photovoltaic station as a whole meets the demand according to the rated current of the photovoltaic converter includes: Determining the extent of the failure of the photovoltaic station, the extent including a medium-depth failure and a deep failure; When a fault occurs at a medium depth, it is determined whether the injected reactive current of the entire photovoltaic station meets the demand according to the rated current of the photovoltaic converter.
3. The photovoltaic station multi-device fault ride-through coordination control method according to claim 2 is characterized in that: When the photovoltaic station fails, determining whether the injected reactive current of the photovoltaic station as a whole meets the demand according to the rated current of the photovoltaic converter includes: Determine whether the injected reactive current of the photovoltaic station as a whole meets the following conditions: Where: I qtot is the reactive current injected by the PV station during the fault, K tot is the dynamic reactive current proportional coefficient of the photovoltaic station as a whole, U t is the voltage amplitude of the photovoltaic station grid connection point, I N，h is the rated current of the hth grid-connected PV converter.
4. The photovoltaic station multi-device fault ride-through coordination control method according to claim 3 is characterized in that: The step of setting the fault ride-through parameters of the photovoltaic converter includes: The fault ride-through parameters of the photovoltaic converter include the dynamic reactive current proportional coefficient K of the photovoltaic converter pv and the threshold voltage U Lpv , K pv Set up with K tot Consistent, U Lpv Set to 0.8 to 0.
4.
5. The photovoltaic station multi-device fault ride-through coordination control method according to claim 4 is characterized in that: The calculating the fault ride-through parameter of the static VAR generator includes: The fault ride-through parameters of the static VAR generator include the dynamic reactive current proportional coefficient K of the static VAR generator. 1sta , K 2sta and the threshold voltage U Lsta : Where: I N，i is the rated current of the i-th static VAR generator.
6. The photovoltaic station multi-device fault ride-through coordination control method according to any one of claims 1 to 5, characterized in that: The step of causing the photovoltaic converter to generate a corresponding reactive current injection strategy and an active current injection strategy includes: Reactive current injection strategy I qpv，h : Active current injection strategy I dpv，h : Among them: U t,h is the AC voltage amplitude of the photovoltaic inverter grid connection point, I dpv0,h is the active current before the fault.
7. The photovoltaic station multi-device fault ride-through coordination control method according to any one of claims 1 to 5, characterized in that: The static VAR generator generates a corresponding reactive current injection strategy, including: Reactive current injection strategy: Among them: U t,i is the AC voltage amplitude of the static VAR generator grid connection point, I N,i is the rated current of the i-th static VAR generator.
8. A photovoltaic station multi-device fault ride-through coordination control system, characterized in that: include: A rated current acquisition unit is used to acquire the rated current of a photovoltaic converter and a static VAR generator connected to the grid in a photovoltaic station; A rated current judgment unit, used to determine whether the injected reactive current of the photovoltaic station as a whole meets the demand according to the rated current of the photovoltaic converter when a fault occurs in the photovoltaic station; A unit for setting and calculating a fault ride-through parameter is used to set the fault ride-through parameter of the photovoltaic converter and calculate the fault ride-through parameter of the static reactive generator when the reactive current injected by the photovoltaic station as a whole meets the demand; A strategy generation unit is used to transmit the fault ride-through parameters of the photovoltaic converter and the fault ride-through parameters of the static VAR generator to the photovoltaic converter and the static VAR generator respectively through network communication, so that the photovoltaic converter generates a corresponding reactive current injection strategy and an active current injection strategy, and the static VAR generator generates a corresponding reactive current injection strategy.
9. A computer device, characterized in that: include: memories, transceivers, processors, and bus systems; Wherein, the memory is used to store programs; The processor is used to execute the program in the memory, including executing the photovoltaic field station multi-device fault ride-through coordination control method according to any one of claims 1 to 7; The bus system is used to connect the memory and the processor so that the memory and the processor can communicate with each other.
10. A readable storage medium, characterized in that: The method comprises instructions, which, when executed on a computer, enable the computer to execute the photovoltaic station multi-device fault ride-through coordination control method as described in any one of claims 1 to 7.