Method for repairing power three-phase imbalance of base station and energy storage system

Abstract

The invention discloses a method for repairing power three-phase imbalance of a base station and an energy storage system. The system comprises an energy storage battery, an energy management system (EMS) used for controlling the energy storage battery, an energy storage converter (PCS) used for current conversion of the energy storage battery, a first current transformer used for collecting Ia, Ib and Ic, a second current transformer used for collecting Ia1, Ib1 and Ic1, a load and a third current transformer used for collecting Ia2, Ib2 and Ic2. And the non-energy storage power supply and the energy storage battery are used for supplying electric energy to the load. The maximum charging and discharging power is directly limited through the energy management system, the charging and discharging electric power of each phase of the PCS is automatically adjusted through three-phase imbalance, self-adaptive load tracking and countercurrent prevention are achieved, and the response speed is high.

Description

Technical Field

[0001] The present invention relates to a method for repairing three-phase power imbalance of a base station, in particular to a method for repairing three-phase power imbalance of a base station and an energy storage system. Background Art

[0002] The impact of energy storage grid connection on the power grid and the situation of power waste due to inadequate control have always existed. In order to reduce power consumption and achieve a green computer room, many communication base stations have begun to consider connecting to an energy storage system. However, before the energy storage is connected, due to various electrical loads in many communication base stations, some are three-phase power supply and some are single-phase power supply, resulting in a very unbalanced three-phase power output. At the same time, adding the power consumption of the energy storage will cause problems such as overloading of the cable lines at some sites. Currently, the anti-counterflow regulation of the energy storage is carried out by the electric meter to measure the power grid and then adjust the PCS through communication with the EMS. Such multiple communication conversions increase the adjustment time, and the response speed may also slow down in case of frequent fluctuations of the electrical equipment. Summary of the Invention

[0003] To solve the above problems, the present application provides a method for repairing three-phase power imbalance of a base station and an energy storage system.

[0004] The present invention provides the following technical solutions: A method for repairing three-phase power imbalance of a base station is as follows: Collect the three-phase output currents Ia, Ib, and Ic of the non-energy storage power supply, collect the three-phase output currents Ia1, Ib1, and Ic1 of the energy storage converter, and collect the three-phase input currents Ia2, Ib2, and Ic2 of the load; During discharging, the maximum discharging power of the energy storage battery is P1, and the calculation formula is as follows: P1 = energy storage battery power * depth of discharge * depth of charge * discharge efficiency / peak power discharge duration in the region; When the load power is less than or equal to P1: Control Ia = Ib = Ic = 0, Ia1 = Ia2, Ib1 = Ib2, Ic1 = Ic2; When the load power is greater than P1: Control Ia1 = Ia / (Ia + Ib + Ic) * (P1 / 220), Ib1 = Ib / (Ia + Ib + Ic) * (P1 / 220); Ic1 = Ic / (Ia + Ib + Ic) * (P1 / 220); During charging, the maximum charging power of the energy storage battery is P2, and the calculation formula is as follows: P2 = P1 * charge rate; Control Ia1 = 1 - Ia / (Ia + Ib + Ic) * (P2 / 220); Ib1 = 1 - Ib / (Ia + Ib + Ic) * (P2 / 220); Ic1 = 1 - Ic / (Ia + Ib + Ic) * (P2 / 220); and Ia = Ia2 + Ia1, Ib = Ib2 + Ib1, Ic = Ic2 + Ic1; During the discharge or charge process of the energy storage battery, Ia1 < Ia2, Ib1 < Ib2, Ic1 < Ic2, and while Ia, Ib, and Ic are greater than 0, the differences between them are less than the threshold value.

[0005] Furthermore, the depth of discharge is 70%, the depth of charge is 0.95, and the discharge efficiency is 0.93.

[0006] Furthermore, the charge rate is 1.5.

[0007] Furthermore, the threshold value is 0.1%.

[0008] An energy storage system for implementing the method for repairing the three - phase power imbalance of the base station described above, including an energy storage battery, an energy management system for controlling the energy storage battery, a power conversion device for the energy storage battery, a first current transformer for collecting Ia, Ib, Ic, a second current transformer for collecting Ia1, Ib1, Ic1, a load, and a third current transformer for collecting Ia2, Ib2, Ic2. The non - energy - storage power supply and the energy storage battery are used to supply electrical energy to the load.

[0009] Furthermore, it also includes a thermal management system for monitoring the temperature of the energy storage battery.

[0010] Furthermore, the non - energy - storage power supply includes at least one of mains power or diesel - engine power generation.

[0011] The beneficial effects of the present invention are as follows: In this application, the energy management system directly limits the maximum charge - discharge power, and the three - phase imbalance automatically adjusts the charge - discharge electric power of each phase of the PCS, adapts to the load tracking and prevents reverse current, with a fast response speed. Description of the Drawings

[0012] Figure 1 It is a module schematic diagram of the energy storage system of the present invention; Among them, A, B, and C respectively represent one phase in the three - phase. Detailed Embodiments

[0013] To further elaborate on the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the following combines the drawings and preferred embodiments to describe in detail the specific embodiments, structures, features, and their effects of the present invention as follows.

[0014] In this application, the maximum charge and discharge power is directly limited by the energy management system. The power conversion system (PCS) for three-phase imbalance automatic adjustment adjusts the charge and discharge electric power of each phase, adapts to load tracking and prevents reverse current, with a fast response speed.

[0015] The embodiments of the present invention will be further described in multiple embodiments below.

[0016] Embodiment 1 A method for repairing three-phase power imbalance of a base station is as follows: Collect the three-phase output currents Ia, Ib, and Ic of the non-energy storage power supply, the three-phase output currents Ia1, Ib1, and Ic1 of the energy storage converter, and the three-phase input currents Ia2, Ib2, and Ic2 of the load; As Figure 1 , in this embodiment, the non-energy storage power supply can be mains power or a diesel generator. The mains power and the diesel generator use interlocked circuit breakers 1 and 2. When circuit breaker 1 is closed and the mains power is running, the PCS can both discharge and charge; when circuit breaker 2 is closed and the diesel generator is running, the PCS can charge but cannot discharge. If it discharges, it will cause damage to the diesel generator. Therefore, this embodiment also has a diesel generator operation detection device so that the energy management system cannot issue a discharge command.

[0017] During discharge, the maximum discharge power of the energy storage battery is P1, and the calculation formula is as follows: P1 = energy storage battery power * discharge depth * charge depth * discharge efficiency / peak power discharge duration in the region; the discharge depth is 70%, the charge depth is 0.95, and the discharge efficiency is 0.93; When the load power is less than or equal to P1: Control Ia = Ib = Ic = 0, Ia1 = Ia2, Ib1 = Ib2, Ic1 = Ic2; When the load power is greater than P1: Control Ia1 = Ia / (Ia + Ib + Ic) * (P1 / 220), Ib1 = Ib / (Ia + Ib + Ic) * (P1 / 220); Ic1 = Ic / (Ia + Ib + Ic) * (P1 / 220); During charging, the maximum charging power of the energy storage battery is P2, and the calculation formula is as follows: P2 = P1 * charge rate; the charge rate is 1.5; Control Ia1 = 1 - Ia / (Ia + Ib + Ic) * (P2 / 220); Ib1 = 1 - Ib / (Ia + Ib + Ic) * (P2 / 220); Ic1 = 1 - Ic / (Ia + Ib + Ic) * (P2 / 220); and Ia = Ia2 + Ia1, Ib = Ib2 + Ib1, Ic = Ic2 + Ic1; During the discharge or charge process of the energy storage battery, Ia1 < Ia2, Ib1 < Ib2, Ic1 < Ic2, and while Ia, Ib, and Ic are greater than 0, the differences between them are less than the threshold value, and the threshold value is 0.1%.

[0018] The fast anti-backflow control forward algorithm ensures that the mains power is all forward output without reverse current output: during energy storage discharge, the PCS performs fast load tracking through CT current detection and output. The current fast operation adjustment speed can be completed within 10 ms, which is at least 10 times faster than the traditional electricity meter anti-backflow detection method, better solving the calculation error of load fluctuations, the issued control accuracy, and the time difference. Initialize the settings Ia1 = Ia, Ib1 = Ib, Ic1 = Ic. According to the CT current direction, the PCS adjusts the magnitudes of Ia1, Ib1, and Ic1 in real time to ensure anti-backflow Ia1 < Ia2, Ib1 < Ib2, Ic1 < Ic2, and Ia, Ib, and Ic are infinitely close to being equal and greater than 0. It solves the problem that after the fast battery is connected to the grid, it instead wastes battery capacity when fed back to the grid.

[0019] Such as Figure 1 , an energy storage system for implementing the method for repairing the three-phase imbalance of the base station power as described above, including an energy storage battery, an energy management system for controlling the energy storage battery, an energy storage converter for current conversion of the energy storage battery, a first current transformer for collecting Ia, Ib, and Ic, a second current transformer for collecting Ia1, Ib1, and Ic1, a load, and a third current transformer for collecting Ia2, Ib2, and Ic2. The non-energy storage power supply and the energy storage battery are used to supply electrical energy to the load.

[0020] In this embodiment, it further includes a thermal management system for monitoring the temperature of the energy storage battery.

[0021] This system can directly use the first current transformer for three-phase anti-backflow detection and judgment. When the current of any one phase of the first current transformer is greater than 0 (Ia > 0 or Ib > 0 or Ic > 0), in the standby state after the PCS passes the self-check, it proves that the mains power is connected and the energy storage can be normally charged and discharged. When the three phases of the current of the first current transformer are basically close to 0, the PCS can also pass the self-check and be in the standby state, proving that the generator is connected. At this time, the EMS issues an instruction for the PCS to protect and simultaneously shuts down the energy storage, which can ensure that after the base station power outage, when the maintenance personnel connect the generator, the energy storage is still running, resulting in equipment damage or fault protection.

[0022] By adopting the solution of this application, the following purposes can be achieved: (1) Low-voltage energy storage grid connection access, maximum discharge power limit, automatic adjustment of the discharge electric power of each phase of the PCS for three-phase imbalance, and adaptive load tracking for anti-backflow.

[0023] (2)Power detection of the energy storage three-phase unbalance device to ensure three-phase power balance. While not reducing the total charging power, adjust the power of each phase of the PCS for charging balance.

[0024] (3)Fast anti-counterflow control forward algorithm to ensure that the mains power is all forward output and there is no reverse current output.

[0025] (4)Self-identification of mains power access and generator power access for power supply, and self-adjustment of operation strategies.

[0026] The above are only the preferred embodiments of the present invention, and do not impose any form of limitation on the present invention. Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some changes or modifications to equivalent embodiments by using the disclosed technical content within the scope of the technical solution of the present invention. However, as long as it does not depart from the content of the technical solution of the present invention, any brief modifications, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A method for repairing the three-phase imbalance of the base station power, characterized in that The details are as follows: Collect the three-phase output currents Ia, Ib, and Ic of the non-energy storage power supply, the three-phase input and output currents Ia1, Ib1, and Ic1 of the energy storage converter, and the three-phase input currents Ia2, Ib2, and Ic2 of the load; During discharging, the maximum discharging power of the energy storage battery is P1, and the calculation formula is as follows: P1 = energy storage battery power * depth of discharge * depth of charge * discharge efficiency / peak power discharge duration in the region; When the load power is less than or equal to P1: Control Ia = Ib = Ic = 0, Ia1 = Ia2, Ib1 = Ib2, Ic1 = Ic2; When the load power is greater than P1: Control Ia1 = Ia / (Ia + Ib + Ic) * (P1 / 220), Ib1 = Ib / (Ia + Ib + Ic) * (P1 / 220); Ic1 = Ic / (Ia + Ib + Ic) * (P1 / 220); During charging, the maximum charging power of the energy storage battery is P2, and the calculation formula is as follows: P2 = P1 * charge rate; Control Ia1 = 1 - Ia / (Ia + Ib + Ic) * (P2 / 220); Ib1 = 1 - Ib / (Ia + Ib + Ic) * (P2 / 220); Ic1 = 1 - Ic / (Ia + Ib + Ic) * (P2 / 220); and Ia = Ia2 + Ia1, Ib = Ib2 + Ib1, Ic = Ic2 + Ic1; During the discharging or charging process of the energy storage battery, Ia1 < Ia2, Ib1 < Ib2, Ic1 < Ic2, and when Ia, Ib, and Ic are greater than 0, the difference between them is less than the threshold value.

2. The method according to claim 1, wherein The depth of discharge is 70%, the depth of charge is 0.95, and the discharge efficiency is 0.

93.

3. The method according to claim 1, wherein The charge rate is 1.

5.

4. The method according to claim 1, wherein The threshold value is 0.1%.

5. An energy storage system for implementing the method for repairing the three-phase imbalance of the base station power according to claim 1, characterized in that, It includes an energy storage battery, an energy management system (EMS) for controlling the energy storage battery, a power conversion system (PCS) for current conversion of the energy storage battery, a first current transformer for collecting Ia, Ib, and Ic, a second current transformer for collecting Ia1, Ib1, and Ic1, a load, and a third current transformer for collecting Ia2, Ib2, and Ic2. The non-energy storage power supply and the energy storage battery are used to supply electrical energy to the load.

6. The energy storage system according to claim 5, wherein It also includes a thermal management system for monitoring the temperature of the energy storage battery.

7. The energy storage system according to claim 5, characterized in that, The non-energy storage power supply includes at least one of mains power or diesel generator power.

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