Industrial and commercial energy storage grid-connected system and reactive power regulation control method thereof

Abstract

According to the industrial and commercial energy storage grid-connected system and the reactive power regulation control method thereof, the primary side of a distribution transformer of the industrial and commercial energy storage grid-connected system is connected with a high-voltage switch cabinet and is used for being connected with a distribution network; the secondary side is connected to the power distribution secondary main cabinet; a first end of a secondary main switch of the power distribution secondary main cabinet is connected with a secondary side of the power distribution transformer, and a second end is connected with an industrial and commercial user bus through a cable; the first CT is arranged on a cable connected between the second end and the industrial and commercial user bus; the first end of each energy storage and current collection switch of the energy storage outdoor current collection cabinet is connected with the energy storage and current collection bus, and the second end of each energy storage and current collection switch is connected with one liquid cooling energy storage and current conversion all-in-one machine. The energy storage current collection bus is connected to the energy storage grid-connected cabinet; the energy storage grid-connected cabinet is connected to the power distribution secondary main cabinet; and the parallel capacitor reactive power regulation subsystem is connected to an industrial and commercial user bus. The size of the liquid cooling energy storage and conversion all-in-one machine is reduced, and it is guaranteed that the power factor meets the requirement of a power grid under the control of the reactive power adjusting device during energy storage and discharging.

Description

Technical Field

[0001] This invention belongs to the field of industrial and commercial energy storage technology, and more specifically, relates to an industrial and commercial energy storage grid-connected system and its reactive power regulation and control method. Background Technology

[0002] With the vigorous development of new energy sources, there are more and more industrial and commercial energy storage grid-connected projects. Liquid-cooled energy storage converters are the core equipment for industrial and commercial energy storage. This equipment needs to integrate energy storage batteries, converters, fire protection systems and other equipment, and is relatively large in size. Therefore, moving some of the equipment inside the liquid-cooled energy storage converter will greatly reduce its size.

[0003] When constructing industrial and commercial energy storage grid-connected systems, users' 400V distribution systems are usually already in operation. The user's existing parallel capacitor reactive power regulation system collects current from the low-voltage side of the distribution transformer to achieve reactive power control. If the energy storage grid-connection cabinet is directly connected to the user's existing 400V bus or directly connected to an existing feeder switch, this output will not be controlled by the reactive power regulation system when the energy storage discharges. Summary of the Invention

[0004] To address the shortcomings of existing technologies, reduce the size of liquid-cooled energy storage converters, and solve the problem of energy storage being uncontrolled by the reactive power regulation system during discharge, this invention provides a grid connection scheme for industrial and commercial energy storage.

[0005] The present invention adopts the following technical solution. The first aspect of the present invention provides an industrial and commercial energy storage grid-connected system, comprising: a distribution transformer, a secondary distribution cabinet, an industrial and commercial user busbar, an energy storage grid-connected cabinet, an outdoor energy storage collector cabinet, a parallel capacitor reactive power regulation subsystem, and a liquid-cooled energy storage converter integrated unit; the primary side of the distribution transformer is connected to a high-voltage switchgear for connection to the distribution network; the secondary side of the distribution transformer is connected to the secondary distribution cabinet; the secondary distribution cabinet includes: a secondary main switch and a first current transformer (CT); the first terminal of the secondary main switch is connected to the secondary side of the distribution transformer, and the secondary main switch... The second end is connected to the industrial and commercial user bus via a cable; the first CT is installed on the cable connecting the second end and the industrial and commercial user bus; the outdoor energy storage collector cabinet includes: an energy storage collector bus and multiple energy storage collector switches; the first end of each energy storage collector switch is connected to the energy storage collector bus, and the second end of each energy storage collector switch is connected to a liquid-cooled energy storage converter; the energy storage collector bus is connected to the energy storage grid-connected cabinet; the energy storage grid-connected cabinet is connected to the secondary distribution cabinet; the parallel capacitor reactive power regulation subsystem is connected to the industrial and commercial user bus.

[0006] Preferably, the industrial and commercial user bus is connected to the industrial and commercial user load, and the industrial and commercial user load is connected in parallel with the parallel capacitor reactive power regulation subsystem; the parallel capacitor reactive power regulation subsystem includes: multiple sets of parallel capacitors, parallel capacitor grid-connected switches and reactive power compensation controllers; the reactive power compensation controller controls the parallel capacitor grid-connected switches to switch multiple sets of parallel capacitors in groups.

[0007] Preferably, the reactive power compensation controller is connected to the first current transformer (CT). The reactive power compensation controller calculates the power factor based on the bus voltage and current of industrial and commercial users and sends a reactive power adjustment command to the grid-connected switch of the parallel capacitor.

[0008] Preferably, the energy storage grid-connected cabinet includes: an energy storage grid-connected switch and a second current transformer (CT); the first end of the energy storage grid-connected switch is connected to the secondary main distribution cabinet via an energy storage grid-connected cable, with the connection point located between the secondary main switch and the first CT; the second end of the energy storage grid-connected switch is connected to the energy storage collector bus via a cable; the second CT is installed on the cable connecting the second end of the energy storage grid-connected switch and the energy storage collector bus.

[0009] Preferably, the energy storage grid-connected cable is a four-core cable.

[0010] A second aspect of the present invention provides a reactive power regulation and control method for an industrial and commercial energy storage grid-connected system. Based on the industrial and commercial energy storage grid-connected system described in the first aspect, the reactive power regulation and control method includes the following steps:

[0011] Step 1: Collect the incoming current of the busbar for industrial and commercial users and send it to the parallel capacitor reactive power regulation subsystem;

[0012] Step 2: The parallel capacitor reactive power regulation subsystem calculates the power factor based on the bus voltage and incoming current of industrial and commercial users, and generates and executes reactive power regulation commands.

[0013] Step 3: The parallel capacitor reactive power regulation subsystem determines whether the current power factor meets the grid requirements; if it does, it exits reactive power regulation control; if it does not, it returns to step 1.

[0014] Preferably, in step 1, the energy storage grid-connected cable is connected between the secondary main switch and the first CT in the secondary main switch cabinet of the power distribution transformer. The first CT in the secondary main switch cabinet of the power distribution transformer collects the incoming current of the bus of industrial and commercial users and sends it to the reactive power compensation controller.

[0015] Preferably, in step 2, the liquid-cooled energy storage converter is in a discharge state;

[0016] The energy storage section operates as follows: when the grid-connected switch on the AC side of the converter of the liquid-cooled energy storage converter is closed, the liquid-cooled energy storage converter operates in grid-connected mode.

[0017] Preferably, in step 2, in the parallel capacitor reactive power regulation subsystem, the relevant actions of the parallel capacitor are: the parallel capacitor grid connection switch is closed, and the capacitors are switched in groups according to the instructions of the reactive power compensation controller.

[0018] Preferably, in step 2, the relevant actions of the secondary distribution cabinet are: the secondary main switch is closed, connecting to the power grid.

[0019] Compared with the prior art, the beneficial effects of the present invention include at least the following:

[0020] 1. Reduce the size of the liquid-cooled energy storage converter.

[0021] 2. During energy storage and discharge, the power factor is controlled by the reactive power regulation device to ensure that it meets the grid requirements. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of a commercial and industrial energy storage grid-connected system according to the present invention;

[0023] Figure 2 This is a flowchart of a reactive power regulation method for an industrial and commercial energy storage grid-connected system according to the present invention. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of this invention. The described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the spirit of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this invention.

[0025] like Figure 1 As shown, Embodiment 1 of the present invention provides an industrial and commercial energy storage grid-connected system, including: a distribution transformer, a secondary distribution cabinet, an industrial and commercial user busbar, an energy storage grid-connected cabinet, an outdoor energy storage collector cabinet, and a liquid-cooled energy storage converter integrated unit.

[0026] The primary side of the distribution transformer is connected to the high-voltage switchgear for connection to the distribution network; the secondary side of the distribution transformer is connected to the secondary distribution main cabinet.

[0027] The secondary distribution cabinet includes a secondary main switch and a first CT (Current Transformer). The first terminal of the secondary main switch is connected to the secondary side of the distribution transformer, and the second terminal of the secondary main switch is connected to the industrial and commercial user bus via a cable. The first CT is installed on the cable connecting the second terminal to the industrial and commercial user bus to collect current.

[0028] The industrial and commercial user busbar is connected to the industrial and commercial user loads, as well as the parallel capacitor reactive power regulation subsystem connected in parallel with the industrial and commercial user loads. The parallel capacitor reactive power regulation subsystem includes: multiple sets of parallel capacitors, parallel capacitor grid-connected switches, and reactive power compensation controllers. The reactive power compensation controllers are connected to the first CT, receive the current collected by the first CT, and implement reactive power control by controlling the parallel capacitor grid-connected switches to switch multiple sets of parallel capacitors in groups.

[0029] The outdoor energy storage collector cabinet includes: an energy storage collector bus and multiple energy storage collector switches; the first end of each energy storage collector switch is connected to the energy storage collector bus, and the second end of each energy storage collector switch is connected to a liquid-cooled energy storage converter; the energy storage collector bus is connected to the energy storage grid-connected cabinet.

[0030] It is worth noting that the energy storage collector switch is installed inside the outdoor energy storage collector cabinet, thus eliminating the need for an AC switch in the liquid-cooled energy storage converter. This achieves two beneficial technical effects simultaneously: firstly, it effectively reduces the size of the liquid-cooled energy storage converter; secondly, it centralizes the AC switches, previously distributed across multiple liquid-cooled energy storage converters, into a single outdoor energy storage collector cabinet, enabling centralized control. This eliminates the need for individual communication with each liquid-cooled energy storage converter to send AC switch control commands, reducing control complexity and improving reliability. This overcomes the technical bias of over-integration in existing liquid-cooled energy storage converter technologies, significantly reducing the manufacturing and control difficulties of liquid-cooled energy storage converters.

[0031] The energy storage grid-connected cabinet includes: an energy storage grid-connected switch and a second current collector (CT); the first end of the energy storage grid-connected switch is connected to the secondary main distribution cabinet via an energy storage grid-connected cable, specifically, the connection point is located between the secondary main switch and the first CT; the second end of the energy storage grid-connected switch is connected to the energy storage collector bus via a cable; the second CT is installed on the cable connecting the second end of the energy storage grid-connected switch and the energy storage collector bus to collect current.

[0032] Preferably, the energy storage grid-connected cable is a four-core cable.

[0033] It is worth noting that, as another prominent substantive feature of this invention and a significant advancement over the prior art, the energy storage grid-connected cable is connected between the switch and the CT in the secondary distribution cabinet, which effectively prevents the energy storage from being controlled by the reactive power regulation of the parallel capacitor when discharging into the system. The reactive power regulation control method is described in detail in Embodiment 2 below.

[0034] like Figure 2 As shown, Embodiment 2 of the present invention provides a reactive power regulation and control method for an industrial and commercial energy storage grid-connected system, comprising the following steps:

[0035] Step 1: Collect the incoming bus current of industrial and commercial users and send it to the reactive power compensation controller.

[0036] It is worth noting that the current of the incoming line of industrial and commercial users is collected, including the current output of the distribution network to industrial and commercial users and the current output of energy storage to industrial and commercial users, thereby incorporating energy storage into reactive power regulation and control.

[0037] Preferably, in step 1, the energy storage grid-connected cable is connected between the secondary main switch and the first CT in the secondary main switch cabinet of the power distribution transformer. The first CT in the secondary main switch cabinet of the power distribution transformer collects the incoming current of the bus of industrial and commercial users and sends it to the reactive power compensation controller.

[0038] Step 2: The parallel capacitor reactive power regulation subsystem calculates the power factor based on the bus voltage and incoming current of industrial and commercial users, and generates and executes reactive power regulation commands.

[0039] Preferably, in step 2, the reactive power compensation controller calculates the power factor based on the collected bus voltage and incoming current of the industrial and commercial users, and issues a reactive power adjustment command.

[0040] Among them, the liquid-cooled energy storage converter is in a discharging state;

[0041] The operation mode of the energy storage equipment is as follows: when the grid-connected energy storage switch on the AC side of the converter is closed, the energy storage system is connected to the grid and operates.

[0042] The relevant actions of parallel capacitors are as follows: the grid connection switch of the parallel capacitors is closed, and the capacitors are switched on and off in groups according to the instructions of the reactive power compensation controller;

[0043] The relevant actions of the secondary main distribution cabinet are: the secondary main switch is closed, connecting to the power grid;

[0044] Step 3: Determine whether the current power factor meets the grid requirements; if it does, exit reactive power regulation control; if it does not, return to step 1.

[0045] It is worth noting that because the energy storage grid-connected cable is connected between the secondary main switch and the first current transformer (CT) in the secondary distribution cabinet, during step 2, the output of the energy storage device is controlled in the reactive power regulation control, thus coordinating and completing the reactive power regulation control. Otherwise, if the reactive power compensation controller only detects the output of the power grid and does not perform unified reactive power control on the energy storage output, it will cause sampling deviation of the reactive power compensation controller, and the power factor on the grid side will be lower than the allowable value.

[0046] This disclosure can be a system, method, and / or computer program product. A computer program product may include a computer-readable storage medium having computer-readable program instructions loaded thereon for causing a processor to implement various aspects of this disclosure.

[0047] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not 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 modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the protection scope of the claims of the present invention.

Claims

1. A commercial and industrial energy storage grid-connected system, comprising: Distribution transformers, secondary distribution cabinets, industrial and commercial user busbars, energy storage grid-connected cabinets, outdoor energy storage collector cabinets, parallel capacitor reactive power regulation subsystems, and liquid-cooled energy storage converter integrated units; characterized in that: The primary side of the distribution transformer is connected to the high-voltage switchgear for connection to the distribution network; the secondary side of the distribution transformer is connected to the secondary main distribution cabinet. The secondary distribution cabinet includes a secondary main switch and a first current transformer (CT). The first terminal of the secondary main switch is connected to the secondary side of the distribution transformer, and the second terminal of the secondary main switch is connected to the industrial and commercial user busbar via a cable. The first CT is installed on the cable connecting the second terminal to the industrial and commercial user busbar. The outdoor energy storage collector cabinet includes: an energy storage collector bus and multiple energy storage collector switches; the first terminal of each energy storage collector switch is connected to the energy storage collector bus, and the second terminal of each energy storage collector switch is connected to a liquid-cooled energy storage converter; the energy storage collector bus is connected to the energy storage grid-connected cabinet; the energy storage grid-connected cabinet is connected to the secondary distribution cabinet. The parallel capacitor reactive power regulation subsystem is connected to the industrial and commercial user bus.

2. The industrial and commercial energy storage grid-connected system according to claim 1, characterized in that: The industrial and commercial user bus is connected to the industrial and commercial user loads, which are connected in parallel with the parallel capacitor reactive power regulation subsystem. The parallel capacitor reactive power regulation subsystem includes: multiple sets of parallel capacitors, parallel capacitor grid-connected switches, and reactive power compensation controllers. The reactive power compensation controller controls the parallel capacitor grid-connected switches to switch multiple sets of parallel capacitors in groups.

3. The industrial and commercial energy storage grid-connected system according to claim 1, characterized in that: The reactive power compensation controller is connected to the first current transformer (CT). The reactive power compensation controller calculates the power factor based on the bus voltage and current of industrial and commercial users and sends reactive power adjustment commands to the grid-connected capacitor switch.

4. The industrial and commercial energy storage grid-connected system according to claim 1, characterized in that: The energy storage grid-connected cabinet includes: an energy storage grid-connected switch and a second current transformer (CT); the first end of the energy storage grid-connected switch is connected to the secondary main distribution cabinet via an energy storage grid-connected cable, with the connection point located between the secondary main switch and the first CT; the second end of the energy storage grid-connected switch is connected to the energy storage collector bus via a cable; the second CT is installed on the cable connecting the second end of the energy storage grid-connected switch and the energy storage collector bus.

5. The industrial and commercial energy storage grid-connected system according to claim 3, characterized in that: The energy storage grid-connected cable is a four-core cable.

6. A reactive power regulation and control method for an industrial and commercial energy storage grid-connected system, wherein the industrial and commercial energy storage grid-connected system is the industrial and commercial energy storage grid-connected system as described in any one of claims 1 to 5, characterized in that, The reactive power regulation and control method includes the following steps: Step 1: Collect the incoming current of the busbar for industrial and commercial users and send it to the parallel capacitor reactive power regulation subsystem; Step 2: The parallel capacitor reactive power regulation subsystem calculates the power factor based on the bus voltage and incoming current of industrial and commercial users, and generates and executes reactive power regulation commands. Step 3: The parallel capacitor reactive power regulation subsystem determines whether the current power factor meets the grid requirements; if it does, it exits reactive power regulation control; if it does not, it returns to step 1.

7. The reactive power regulation and control method for an industrial and commercial energy storage grid-connected system according to claim 6, characterized in that: In step 1, the energy storage grid-connected cable is connected between the secondary main switch and the first CT in the secondary main switch cabinet of the power distribution transformer. The first CT in the secondary main switch cabinet of the power distribution transformer collects the incoming current of the bus of industrial and commercial users and sends it to the reactive power compensation controller.

8. The reactive power regulation and control method for an industrial and commercial energy storage grid-connected system according to claim 6, characterized in that: In step 2, the liquid-cooled energy storage converter is in a discharging state; The energy storage section operates as follows: when the grid-connected switch on the AC side of the converter of the liquid-cooled energy storage converter is closed, the liquid-cooled energy storage converter operates in grid-connected mode.

9. The reactive power regulation and control method for an industrial and commercial energy storage grid-connected system according to claim 6, characterized in that: In step 2, in the parallel capacitor reactive power regulation subsystem, the relevant actions of the parallel capacitor are as follows: the parallel capacitor grid connection switch is closed, and the capacitors are switched in groups according to the instructions of the reactive power compensation controller.

10. The reactive power regulation and control method for an industrial and commercial energy storage grid-connected system according to claim 6, characterized in that: In step 2, the relevant actions of the secondary distribution cabinet are: the secondary main switch is closed, connecting to the power grid.

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