SVG multi-machine parallel grouping control method

Abstract

The application discloses an SVG multi-machine parallel grouping control method, provides multiple parallelly connected SVG devices and a controller, the parallelly connected SVG devices are provided with multiple power grid current sampling points, the controller adopts a parallel grouping control strategy to perform parallel control on the multiple parallelly connected SVG devices; the parallel grouping control strategy comprises a multi-layer grouping logic strategy, a master selection logic strategy and a parallel following logic strategy; the multi-layer grouping logic strategy comprises: dividing the parallel SVG devices into N SVG device large groups; the master selection logic strategy comprises: an SVG device small group master selection logic strategy and an SVG device large group master selection logic strategy; the SVG multi-machine parallel grouping control method supports multiple point power grid current sampling under the premise of guaranteeing the function performance of the multi-machine parallel system, can realize multiple point parallel control, and greatly improves the flexibility of the SVG multi-machine parallel application.

Description

Technical Field

[0001] This invention relates to a control method for reactive power compensation devices in new energy grid connection, and more particularly to a SVG multi-machine parallel group control method. Background Technology

[0002] When two or more SVG reactive power compensation devices are configured in the same station, and the control target of each SVG is the same electrical quantity (voltage, power factor, reactive power, etc.) at the same connection point, the SVG needs to have coordinated control capability to meet the control accuracy, response speed and power distribution index requirements of the control target.

[0003] Currently, master-slave control systems for multi-unit parallel SVG group all group all parallel SVGs, and all parallel SVGs sample the same grid current. If there are multiple main transformers in the plant, and only the high-voltage side current of each main transformer is sampled, and it is necessary to control reactive power, power factor, etc. under each main transformer separately, the multi-unit parallel SVG method that only supports sampling the grid current at the same point cannot meet the control requirements.

[0004] There is an urgent need for an SVG multi-machine parallel group control method that, while ensuring the functional performance of the multi-machine parallel system, supports multi-point grid current sampling, enables multi-point parallel control, and greatly improves the flexibility of SVG multi-machine parallel applications. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to propose an SVG multi-machine parallel group control method. This SVG multi-machine parallel group control method supports multi-point grid current sampling while ensuring the functional performance of the multi-machine parallel system, and can realize multi-point parallel control, which greatly improves the flexibility of SVG multi-machine parallel application.

[0006] To solve the above technical problems, the present invention provides a parallel grouping control method for multiple SVG devices, which provides multiple SVG devices connected in parallel and a controller. The SVG devices connected in parallel are equipped with multiple grid current sampling points. The controller adopts a parallel grouping control strategy to perform parallel control on the multiple SVG devices connected in parallel.

[0007] The parallel grouping control strategy includes a multi-level grouping logic strategy, a host selection logic strategy, and a parallel following logic strategy.

[0008] The multi-layer grouping logic strategy includes: dividing the parallel SVG devices into N large groups of SVG devices;

[0009] Each SVG device group comprises M SVG device subgroups, and each SVG device subgroup comprises several SVG devices connected in parallel. The grid current sampling points of the SVG devices in the same subgroup are the same grid current sampling points.

[0010] The host selection logic strategy includes: SVG device group host selection logic strategy and SVG device large group host selection logic strategy. The SVG device group host selection logic strategy includes selecting a group host among SVGs with parallel function enabled and in operation. The SVG device large group host selection logic strategy includes determining whether there is an SVG device group host in each SVG device group. If there is no SVG device group host in any SVG device group, it is determined that there is no SVG device large group host. If there is a group host in an SVG device group, it is determined whether there was an SVG device large group host in the previous control cycle. If there was no SVG device large group host in the previous control cycle, the SVG device group host with the smallest group number is selected as the large group host.

[0011] The parallel following logic strategy includes an SVG device working mode following logic strategy, which includes: the working mode of each parallel SVG device is consistent with the working mode of the SVG device group host, and when the working mode of the SVG device group host is switched, the working mode of each parallel SVG device group is also switched in the same way.

[0012] Preferably, the SVG device group host selection logic strategy further includes: determining whether there is an SVG device with parallel function enabled and in operation; if there is no SVG device with parallel function enabled and in operation, then determining that there is no SVG device group host in the current SVG device.

[0013] If there are SVG devices with parallel function enabled and in operation, then determine whether there is an SVG device group master in the previous control cycle. If there is no SVG device group master in the previous control cycle, then select the SVG device with the smallest group number among the SVG devices with parallel function enabled and in operation as the SVG device group master.

[0014] If there are SVG devices with parallel operation enabled and in operation, determine whether there is an SVG device group master in the previous control cycle. If there is an SVG device group master in the previous control cycle, and the SVG device group master in the previous control cycle has parallel operation enabled and is in operation in this cycle, then keep the SVG device group master unchanged. If the SVG device group master in the previous control cycle does not meet the condition of parallel operation enabled and in operation in this control cycle, then select the SVG device with the smallest group number among the SVG devices with parallel operation enabled and in operation as the SVG device group master.

[0015] Preferably, the SVG device group host selection logic strategy further includes: if there is an SVG device subgroup host, determine whether there is an SVG device group host in the previous control cycle; if there is an SVG device group host in the previous control cycle and the SVG device group host in the previous control cycle is a subgroup host in the current control cycle, then keep the SVG device group host unchanged; if the SVG device group host in the previous control cycle is not a subgroup host in the current control cycle, then select the SVG device subgroup host with the smallest group number as the SVG device group host.

[0016] Preferably, the parallel following logic strategy further includes a parallel SVG device current setting following logic strategy, and the working modes of the SVG device include user reactive power setting working mode, power factor compensation working mode, grid constant reactive power working mode, voltage stabilization working mode, and grid voltage range control working mode.

[0017] Preferably, when the SVG device operates in voltage regulation mode, the current setting logic strategy of the parallel SVG device is specifically as follows: the current setting of the parallel SVG device follows the current setting I of the main SVG device group. qrefBigTeam The current given I of the SVG device group host qrefBigTeam It originates from the outer loop controller of the voltage regulator, specifically:

[0018] I qrefSmallTeam =(U RMSRef -U RMSAct )*(K p +K i / s)

[0019] Among them, U RMSRef U is the voltage regulation setpoint. RMSAct K represents the actual effective value of the voltage. p For the voltage regulator outer loop controller P coefficient, K i is the coefficient of the voltage regulator outer loop controller i, and s is the Laplace factor.

[0020] Preferably, when the SVG device is operating in power factor compensation mode, the current setting follow-up logic strategy of the parallel SVG device is specifically as follows: the current setting of the parallel SVG device follows the current setting I of the SVG device group host. qrefSmallTeam The current given I of the SVG device group host qrefSmallTeam It originates from the power factor outer loop controller, specifically:

[0021] I qrefSmallTeam =(S*sinθ-Q)*(K) pfactor +K ifactor / s)

[0022] Where S is the apparent power of the power grid, θ is the power angle corresponding to the set power factor, Q is the actual reactive power of the power grid, and K pfactor K represents the power factor loop outer loop controller P coefficient. ifactor is the power factor loop outer loop controller i coefficient, and s is the Laplace factor.

[0023] Preferably, when the SVG device operates in the grid constant reactive power compensation mode, the current setting following logic strategy of the parallel SVG device is specifically as follows: the current setting of the parallel SVG device follows the current setting of the SVG device group host, and the current setting I of the SVG device group host... qrefSmallTeam It originates from the power grid constant reactive power outer loop controller, specifically:

[0024] I qrefSmallTeam =(Q gref -Q)*(K ppower +K ipower / s)

[0025] Among them, Q ref K represents the constant reactive power setpoint of the power grid, Q represents the actual reactive power of the power grid, and K represents the reactive power of the power grid. ppower K represents the coefficient P of the outer loop controller for the constant reactive power of the power grid. ipower is the i-coefficient of the outer loop controller for the constant reactive power of the power grid, and s is the Laplace factor.

[0026] Preferably, when the SVG device operates in the grid voltage range control mode, the current setting following logic strategy of the parallel SVG device is as follows: within the grid voltage range, the SVG device is subjected to power factor compensation control, and the current setting of the SVG device is consistent with the current setting method of the power factor compensation mode; outside the grid voltage range, the SVG device is subjected to voltage regulation control, and the current setting of the SVG device is consistent with the current setting method of the voltage regulation mode.

[0027] After adopting the above method, the controller uses a parallel grouping control strategy to control multiple SVG devices connected in parallel. The parallel grouping control strategy includes a multi-level grouping logic strategy, a master selection logic strategy, and a parallel following logic strategy. The multi-level grouping logic strategy includes: dividing the parallel SVG devices into N large SVG device groups; each large SVG device group includes M small SVG device subgroups; each small SVG device subgroup includes several parallel SVG devices; the grid current sampling points of the SVG devices in the same subgroup are the same grid current sampling points. The master selection logic strategy includes: a master selection logic strategy for SVG device subgroups and a master selection logic strategy for SVG device groups. The master selection logic strategy for SVG device subgroups includes selecting a subgroup master from SVG devices that are enabled in parallel operation and are in running state. The master selection logic strategy for SVG device groups includes determining whether there are SVG devices in each SVG device subgroup. If no SVG device group host exists in any of the SVG device groups, then it is determined that no SVG device group host exists. If a group host exists in any of the SVG device groups, then it is determined whether an SVG device group host existed in the previous control cycle. If no SVG device group host existed in the previous control cycle, then the SVG device group host with the smallest group number is selected as the group host. The parallel following logic strategy includes an SVG device operating mode following logic strategy, which includes: the operating mode of each parallel SVG device is consistent with the operating mode of the SVG device group host. When the operating mode of the SVG device group host changes, the operating mode of each parallel SVG device group also changes in the same way. This SVG multi-machine parallel group control method supports multi-point grid current sampling while ensuring the functional performance of the multi-machine parallel system, and can realize multi-point parallel control, greatly improving the flexibility of SVG multi-machine parallel applications. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of multi-point power grid current sampling and parallel SVG grouping in the SVG multi-machine parallel grouping control method of the present invention;

[0029] Figure 2 This is a flowchart illustrating the logic strategy for selecting the host device in the SVG device group of the SVG multi-machine parallel group control method of the present invention.

[0030] Figure 3 This is the logic strategy for selecting the main host of the SVG device group in the SVG multi-machine parallel group control method of the present invention;

[0031] Figure 4 This is a control block diagram of the current setting following logic strategy of the parallel SVG devices when the SVG devices are operating in the voltage-stabilized working mode, which is the SVG multi-machine parallel group control method of the present invention.

[0032] Figure 5 This is a control block diagram of the current setting following logic strategy for parallel SVG devices when the SVG devices are operating in power factor compensation mode, according to the SVG multi-machine parallel group control method of the present invention.

[0033] Figure 6 This is a control block diagram of the current setting following logic strategy of the parallel SVG devices in the SVG multi-machine parallel group control method of the present invention when the SVG devices are operating in the constant reactive power mode of the power grid. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0035] Example 1

[0036] Please see Figure 1 , Figure 1 This is a schematic diagram of multi-point power grid current sampling and parallel SVG grouping in the SVG multi-machine parallel grouping control method of the present invention;

[0037] This embodiment discloses a parallel grouping control method for multiple SVG devices, providing multiple SVG devices connected in parallel and a controller. The SVG devices connected in parallel are equipped with multiple grid current sampling points, and the controller adopts a parallel grouping control strategy to perform parallel control on the multiple SVG devices connected in parallel.

[0038] The parallel grouping control strategy includes a multi-level grouping logic strategy, a host selection logic strategy, and a parallel following logic strategy.

[0039] The multi-layer grouping logic strategy includes: dividing the parallel SVG devices into N large groups of SVG devices;

[0040] Each SVG device group comprises M SVG device subgroups, and each SVG device subgroup comprises several SVG devices connected in parallel. The grid current sampling points of the SVG devices in the same subgroup are the same grid current sampling points.

[0041] The host selection logic strategy includes: SVG device group host selection logic strategy and SVG device large group host selection logic strategy. The SVG device group host selection logic strategy includes selecting a group host among SVGs with parallel function enabled and in operation. The SVG device large group host selection logic strategy includes determining whether there is an SVG device group host in each SVG device group. If there is no SVG device group host in any SVG device group, it is determined that there is no SVG device large group host. If there is a group host in an SVG device group, it is determined whether there was an SVG device large group host in the previous control cycle. If there was no SVG device large group host in the previous control cycle, the SVG device group host with the smallest group number is selected as the large group host.

[0042] The parallel following logic strategy includes an SVG device working mode following logic strategy, which includes: the working mode of each parallel SVG device is consistent with the working mode of the SVG device group host, and when the working mode of the SVG device group host is switched, the working mode of each parallel SVG device group is also switched in the same way.

[0043] Example 2

[0044] Please see Figure 2 , Figure 2 This is a flowchart illustrating the logic strategy for selecting the host device in the SVG device group of the SVG multi-machine parallel group control method of the present invention.

[0045] In this embodiment, the SVG device group host selection logic strategy specifically includes: selecting a group host among SVGs with parallel function enabled and in operation, determining whether there are SVG devices with parallel function enabled and in operation, and if there are no SVG devices with parallel function enabled and in operation, then determining that there is no SVG device group host in the current SVG device.

[0046] If there are SVG devices with parallel function enabled and in operation, then determine whether there is an SVG device group master in the previous control cycle. If there is no SVG device group master in the previous control cycle, then select the SVG device with the smallest group number among the SVG devices with parallel function enabled and in operation as the SVG device group master.

[0047] If there are SVG devices with parallel operation enabled and in operation, determine whether there is an SVG device group master in the previous control cycle. If there is an SVG device group master in the previous control cycle, and the SVG device group master in the previous control cycle has parallel operation enabled and is in operation in this cycle, then keep the SVG device group master unchanged. If the SVG device group master in the previous control cycle does not meet the condition of parallel operation enabled and in operation in this control cycle, then select the SVG device with the smallest group number among the SVG devices with parallel operation enabled and in operation as the SVG device group master.

[0048] Example 3

[0049] Please see Figure 3 , Figure 3 This is a flowchart illustrating the logic strategy for selecting the main host of a large group of SVG devices in the SVG multi-machine parallel group control method of the present invention.

[0050] The logic strategy for selecting the SVG device group host specifically includes: determining whether there is an SVG device group host in each SVG device group; if there is no SVG device group host in any SVG device group, then determining that there is no SVG device group host; if there is a group host in the SVG device group, then determining whether there was an SVG device group host in the previous control cycle; if there was no SVG device group host in the previous control cycle, then selecting the SVG device group host with the smallest group number as the group host.

[0051] If each SVG device group has an SVG device group host, determine if an SVG device master group host existed in the previous control cycle. If an SVG device master group host existed in the previous control cycle and the SVG device master group host of the previous control cycle is a group host in this control cycle, then keep the SVG device master group host unchanged. If the SVG device master group host of the previous control cycle is not an SVG device group host in the current control cycle, then select the SVG device group host with the smallest group number as the SVG device master group host.

[0052] Example 4

[0053] This embodiment is based on Embodiment 1. In this embodiment, the parallel following logic strategy also includes the parallel SVG device current given following logic strategy. The working modes of the SVG device include user reactive power setting working mode, power factor compensation working mode, grid constant reactive power working mode, voltage stabilization working mode, and grid voltage range control working mode.

[0054] Please see Figure 4 When the SVG device is operating in voltage regulation mode, the current setting logic strategy for the parallel SVG device is specifically as follows: the current setting of the parallel SVG device follows the current setting I of the main SVG device group.qrefBigTeam The current given I of the SVG device group host qrefBigTeam It originates from the outer loop controller of the voltage regulator, specifically:

[0055] I qrefSmallTeam =(U RMSRef -U RMSAct )*(K p +K i / s)

[0056] Among them, U RMSRef U is the voltage regulation setpoint. RMSAct K represents the actual effective value of the voltage. p For the voltage regulator outer loop controller P coefficient, K i is the coefficient of the voltage regulator outer loop controller i, and s is the Laplace factor.

[0057] Please see Figure 5 When the SVG device operates in power factor compensation mode, the current setting follow logic strategy for the parallel SVG device is specifically as follows: the current setting of the parallel SVG device follows the current setting I of the SVG device group host. qrefSmallTeam The current given I of the SVG device group host qrefSmallTeam It originates from the power factor outer loop controller, specifically:

[0058] I qrefSmallTeam =(S*sinθ-Q)*(K) pfactor +K ifactor / s)

[0059] Where S is the apparent power of the power grid, θ is the power angle corresponding to the set power factor, Q is the actual reactive power of the power grid, and K pfactor K is the power factor coefficient of the outer loop controller P. ifactor is the power factor of the outer loop controller i, and s is the Laplace factor.

[0060] Please see Figure 6 When the SVG device operates in the grid constant reactive power compensation mode, the current setting following logic strategy of the parallel SVG device is specifically as follows: the current setting of the parallel SVG device follows the current setting of the SVG device group host, and the current setting I of the SVG device group host... qrefSmallTeam It originates from the power grid constant reactive power outer loop controller, specifically:

[0061] I qrefSmallTeam =(Q gref -Q)*(K ppower +K ipower / s)

[0062] Among them, Q refK represents the constant reactive power setpoint of the power grid, Q represents the actual reactive power of the power grid, and K represents the reactive power of the power grid. ppower K represents the coefficient P of the outer loop controller for the constant reactive power of the power grid. ipower is the i-coefficient of the outer loop controller for the constant reactive power of the power grid, and s is the Laplace factor.

[0063] When the SVG device operates in the grid voltage range control mode, the current setting following logic strategy of the parallel SVG device is as follows: within the grid voltage range, the SVG device is subjected to power factor compensation control, and the current setting of the SVG device is consistent with the current setting method of the power factor compensation mode; outside the grid voltage range, the SVG device is subjected to voltage regulation control, and the current setting of the SVG device is consistent with the current setting method of the voltage regulation mode.

[0064] This SVG multi-machine parallel group control method, while ensuring the functional performance of the multi-machine parallel system, supports multi-point grid current sampling and can realize multi-point parallel control, greatly improving the flexibility of SVG multi-machine parallel applications.

[0065] It should be understood that the above are merely preferred embodiments of the present invention and should not be construed as limiting the scope of the patent. Any equivalent structural or procedural transformations made based on the description and drawings of the present invention, or direct or indirect applications in other related technical fields, are similarly included within the scope of patent protection of the present invention.

Claims

1. A method for parallel group control of multiple SVG machines, characterized in that, The system provides multiple SVG devices connected in parallel and a controller. The SVG devices connected in parallel are equipped with multiple grid current sampling points. The controller adopts a parallel group control strategy to control the multiple SVG devices connected in parallel. The parallel grouping control strategy includes a multi-level grouping logic strategy, a host selection logic strategy, and a parallel following logic strategy. The multi-layer grouping logic strategy includes: dividing the parallel SVG devices into N large groups of SVG devices; Each SVG device group comprises M SVG device subgroups, and each SVG device subgroup comprises several SVG devices connected in parallel. The grid current sampling points of the SVG devices in the same subgroup are the same grid current sampling points. The host selection logic strategy includes: SVG device group host selection logic strategy and SVG device large group host selection logic strategy. The SVG device group host selection logic strategy includes selecting a group host among SVGs with parallel function enabled and in operation. The SVG device large group host selection logic strategy includes determining whether there is an SVG device group host in each SVG device group. If there is no SVG device group host in any SVG device group, it is determined that there is no SVG device large group host. If there is a group host in an SVG device group, it is determined whether there was an SVG device large group host in the previous control cycle. If there was no SVG device large group host in the previous control cycle, the SVG device group host with the smallest group number is selected as the large group host. The parallel following logic strategy includes an SVG device working mode following logic strategy, which includes: the working mode of each parallel SVG device is consistent with the working mode of the SVG device group host, and when the working mode of the SVG device group host is switched, the working mode of each parallel SVG device group is also switched in the same way.

2. The SVG multi-machine parallel group control method according to claim 1, characterized in that, The SVG device group host selection logic strategy also includes: determining whether there is an SVG device with parallel function enabled and in operation; if there is no SVG device with parallel function enabled and in operation, then determining that there is no SVG device group host in the current SVG device. If there are SVG devices with parallel function enabled and in operation, then determine whether there is an SVG device group master in the previous control cycle. If there is no SVG device group master in the previous control cycle, then select the SVG device with the smallest group number among the SVG devices with parallel function enabled and in operation as the SVG device group master. If there are SVG devices with parallel operation enabled and in operation, determine whether there is an SVG device group master in the previous control cycle. If there is an SVG device group master in the previous control cycle, and the SVG device group master in the previous control cycle has parallel operation enabled and is in operation in this cycle, then keep the SVG device group master unchanged. If the SVG device group master in the previous control cycle does not meet the condition of parallel operation enabled and in operation in this control cycle, then select the SVG device with the smallest group number among the SVG devices with parallel operation enabled and in operation as the SVG device group master.

3. The SVG multi-machine parallel group control method according to claim 1, characterized in that, The logic strategy for selecting the SVG device group host also includes: if there is an SVG device subgroup host, determine whether there is an SVG device group host in the previous control cycle. If there is an SVG device group host in the previous control cycle and the SVG device group host in the previous control cycle is a subgroup host in the current control cycle, then keep the SVG device group host unchanged. If the SVG device group host in the previous control cycle is not a subgroup host in the current control cycle, then select the SVG device subgroup host with the smallest group number as the SVG device group host.

4. The SVG multi-machine parallel group control method according to claim 1, characterized in that, The parallel following logic strategy also includes a parallel SVG device current setting following logic strategy. The operating modes of the SVG device include user reactive power setting operating mode, power factor compensation operating mode, grid constant reactive power operating mode, voltage stabilization operating mode, and grid voltage range control operating mode.

5. The SVG multi-machine parallel group control method according to claim 4, characterized in that, When the SVG device operates in voltage regulation mode, the current setting logic strategy for the parallel SVG device is specifically as follows: the current setting of the parallel SVG device follows the current setting I of the main SVG device group. qrefBigTeam The current given I of the SVG device group host qrefBigTeam It originates from the voltage regulator outer loop controller, specifically: I qrefSmallTeam =(U RMSRef -U RMSAct )*(K p +K i / s) where U RMSRef U is the voltage regulation setpoint. RMSAct K represents the actual effective value of the voltage. p For the voltage regulator outer loop controller P coefficient, K i is the coefficient of the voltage regulator outer loop controller i, and s is the Laplace factor.

6. The SVG multi-machine parallel group control method according to claim 4, characterized in that, When the SVG device operates in power factor compensation mode, the current setting logic strategy for the parallel SVG device is specifically as follows: the current setting of the parallel SVG device follows the current setting I of the SVG device group host. qrefSmallTeam The current given I of the SVG device group host qrefSmallTeam It originates from the power factor outer loop controller, specifically: I qrefSmallTeam =(S*sinθ-Q)*(K pfactor +K ifactor / s) Where S is the apparent power of the power grid, θ is the power angle corresponding to the set power factor, Q is the actual reactive power of the power grid, and K pfactor K represents the power factor loop outer loop controller P coefficient. ifactor is the power factor loop outer loop controller i coefficient, and s is the Laplace factor.

7. The SVG multi-machine parallel group control method according to claim 4, characterized in that, When the SVG device operates in the grid constant reactive power compensation mode, the current setting following logic strategy of the parallel SVG device is specifically as follows: the current setting of the parallel SVG device follows the current setting of the SVG device group host, and the current setting I of the SVG device group host... qrefSmallTeam It originates from the power grid constant reactive power outer loop controller, specifically: I qrefSmallTeam =(Q gref -Q)*(K ppower +K ipower / s) Among them, Q ref K represents the constant reactive power setpoint of the power grid, Q represents the actual reactive power of the power grid, and K represents the reactive power of the power grid. ppower K represents the coefficient P of the outer loop controller for the constant reactive power of the power grid. ipower is the i-coefficient of the outer loop controller for the constant reactive power of the power grid, and s is the Laplace factor.

8. The SVG multi-machine parallel group control method according to claim 4, characterized in that, When the SVG device operates in the grid voltage range control mode, the current setting following logic strategy of the parallel SVG device is as follows: within the grid voltage range, the SVG device is subjected to power factor compensation control, and the current setting of the SVG device is consistent with the current setting method of the power factor compensation mode; outside the grid voltage range, the SVG device is subjected to voltage regulation control, and the current setting of the SVG device is consistent with the current setting method of the voltage regulation mode.

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