Active power adjusting device suitable for low-voltage distribution network

Abstract

The utility model provides an active power adjusting device suitable for a low-voltage distribution network. The active power adjusting device is composed of an energy storage device and a voltage source type converter. The energy storage device is an energy storage type electric energy quality treatment device, and the active power regulation device is connected in parallel to a power grid in a T mode; a main circuit of the active power adjusting device adopts a topological structure of a three-phase voltage source type two-level converter, in the main circuit, an inductor L and a capacitor Cf form an output filter, the inductor L is connected with an IGBT three-phase bridge inverter circuit, and a direct current side of the three-phase bridge inverter circuit is connected with a capacitor C and a storage battery of the energy storage type electric energy quality treatment device; the current transformer and the voltage transformer respectively sample three-phase power grid voltage and three-phase power grid current, send the three-phase power grid voltage and the three-phase power grid current to the double-second-order integrator for positive and negative sequence decomposition, and generate a control signal in the multi-mode control process to drive the energy storage type electric energy quality treatment device of the active power adjusting device. The utility model can overcome the problems of single application scene, poor flexibility and the like in the prior art of the low-voltage power distribution network.

Description

Technical Field

[0001] The utility model relates to the technical field of power grid operation and maintenance, in particular to an active power regulating device suitable for a low-voltage distribution network. Background Art

[0002] With the high proportion of random distributed power sources and impact loads connected, the real-time imbalance of feeder loads in the distribution network has been aggravated. The unbalanced three-phase load will have an adverse effect on the distribution transformer and power quality, increase power loss, and accelerate the aging of heavy-load lines.

[0003] At present, relevant research has mainly solved the problem of load imbalance in different power supply areas by configuring medium and low voltage flexible interconnection devices. As for the problem of load imbalance and balance between three-phase lines in low-voltage distribution networks, there are currently two main solutions. One is to manage by dedicated personnel, reasonably configure the three-phase load, and minimize the imbalance, but this method has large errors. The other is to configure a three-phase imbalance adjustment device and use the device to compensate in real time to ensure the balance of grid current. However, the device has problems such as single applicable scenarios and flexibility, and cannot be applied to complex and changeable operating scenarios. Therefore, it is necessary to explore a new solution. Utility Model Content

[0004] The utility model proposes an active power regulation device suitable for a low-voltage distribution network, which can overcome the problems of the existing low-voltage distribution network related technologies such as single applicable scenario and poor flexibility.

[0005] The utility model adopts the following technical solutions.

[0006] An active power regulation device suitable for a low voltage distribution network, the active power regulation device consists of an energy storage device and a voltage source converter; the energy storage device is an energy storage type power quality management device, and the active power regulation device is connected in parallel to the power grid in a "T" manner.

[0007] The main circuit of the active power regulation device adopts a three-phase voltage source type two-level converter topology. In the main circuit, the inductor L and the capacitor C f The output filter is formed, the inductor L is connected to the IGBT three-phase bridge inverter circuit, and the DC side of the three-phase bridge inverter circuit is connected to the capacitor C and the battery of the energy storage type power quality management device;

[0008] The current transformer and the voltage transformer respectively sample the three-phase grid voltage and the three-phase grid current, and send them to the double second-order integrator for positive and negative sequence decomposition, and generate a control signal in the multi-mode control process to drive the energy storage type power quality management device of the active power regulation device.

[0009] The energy storage type power quality management device includes a battery pack integrated on the DC side of a low voltage distribution network.

[0010] The active power regulation device also includes a wireless data transmission module, and the current transformer and the voltage transformer collect grid port metering device information through the wireless link of the wireless data transmission module to sample the three-phase grid voltage and the three-phase grid current respectively.

[0011] The main advantages of the present invention are:

[0012] (1) The active power regulation device not only has conventional power quality functions, but can also serve as an emergency power supply and participate in grid peak regulation. It has high flexibility and is applicable to a wide range of scenarios.

[0013] (2) The device is equipped with a wireless data transmission module, which can collect information from the metering device at the power grid port by wireless methods, avoiding the need for personnel to connect external cables, shortening equipment deployment time, and promoting quality and efficiency improvements. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments:

[0015] Attached Figure 1 It is a schematic diagram of the main circuit of the active power regulation device of the present invention;

[0016] Attached Figure 2 It is a block diagram of the positive and negative sequence decomposition method of the dual second-order integrator of the present invention;

[0017] Attached Figure 3 is a multi-mode control block diagram of the active power regulation device of the present invention;

[0018] Attached Figure 4 It is a schematic diagram of the connection structure of the active power regulation device. DETAILED DESCRIPTION

[0019] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0020] The main circuit topology of the active power regulation device used in this example adopts a three-phase voltage source two-level converter, and a battery pack is integrated on the DC side, so that the device has the flexible ability to participate in the active power interaction and regulation of the low-voltage distribution network.

[0021] like Figure 1 As shown, an active power regulation device suitable for a low-voltage distribution network is composed of an energy storage device and a voltage source converter; the energy storage device is an energy storage type power quality management device, and the active power regulation device is connected in parallel to the power grid in a "T" manner.

[0022] The main circuit of the active power regulation device adopts a three-phase voltage source type two-level converter topology. In the main circuit, the inductor L and the capacitor Cf The output filter is formed, the inductor L is connected to the IGBT three-phase bridge inverter circuit, and the DC side of the three-phase bridge inverter circuit is connected to the capacitor C and the battery of the energy storage type power quality management device;

[0023] The current transformer and the voltage transformer respectively sample the three-phase grid voltage and the three-phase grid current, and send them to the double second-order integrator for positive and negative sequence decomposition, and generate a control signal in the multi-mode control process to drive the energy storage type power quality management device of the active power regulation device.

[0024] The energy storage type power quality management device includes a battery pack integrated on the DC side of a low voltage distribution network.

[0025] The active power regulation device also includes a wireless data transmission module, and the current transformer and the voltage transformer collect grid port metering device information through the wireless link of the wireless data transmission module to sample the three-phase grid voltage and the three-phase grid current respectively.

[0026] Example:

[0027] like Figure 1 As shown, the active power regulation device in this example is connected in parallel to the power grid in a "T" manner, with the inductor L and the capacitor C f The output filter is composed of an inductor L connected to an IGBT three-phase voltage source type two-level converter, and the DC side of the three-phase voltage source type converter is connected to a capacitor C and a battery. The current transformer and the voltage transformer sample the three-phase grid voltage and the three-phase grid current respectively, and send them to the double second-order integrator for positive and negative sequence decomposition and multi-mode control to generate a control signal to drive the energy storage type power quality management equipment. The main circuit topology of the active power regulation device used in the present invention adopts a three-phase voltage source type two-level converter, and a battery pack is integrated on the DC side, so that the device has the flexible ability to participate in the interaction and regulation of active power of the low-voltage distribution network.

[0028] This example uses a multi-mode control method when deployed and linked with external equipment. The active power regulation device consists of energy storage and voltage source converter.

[0029] The multi-mode control method includes grid-connected and off-grid control modes. During grid-connected operation, due to the unbalanced three-phase load of the low-voltage distribution network, the main control target of the active power regulation device is to compensate for the unbalanced load and ensure the three-phase balance of the grid-side current to avoid problems such as aging of overloaded lines. During off-grid operation, in order to improve the reliability of low-voltage distribution network power supply, the main control target of the active power regulation device is to maintain the stability of the AC bus voltage and frequency.

[0030] This example adopts a power balancing control method during grid-connected operation. First, the wireless data transmission module is used to obtain the grid port voltage and current information. Based on the above information, the positive and negative sequence decomposition method based on a double second-order integrator is used to obtain the positive and negative sequence components of the grid current. In order to ensure the balance of the grid current, the negative sequence current is used as the current instruction of the energy storage type power quality device, and then the current closed-loop control is performed to track the current instruction, thereby eliminating the negative sequence current of the grid and achieving the balance of the three-phase grid current.

[0031] This example adopts constant voltage and constant frequency control method when operating off-grid. When the low-voltage distribution line is under maintenance or the distribution transformer trips, the active power regulation device switches from grid-connected to off-grid control mode. After receiving the off-grid control command, the active power regulation device works in the voltage and current double closed-loop control strategy to ensure the stability of the three-phase voltage and frequency and to ensure continuous power supply to the load.

Claims

1. An active power regulation device suitable for a low voltage distribution network, characterized in that: The active power regulation device is composed of an energy storage device and a voltage source converter; the energy storage device is an energy storage type power quality management device, and the active power regulation device is connected in parallel to the power grid in a "T" manner; The main circuit of the active power regulation device adopts a three-phase voltage source type two-level converter topology. In the main circuit, the inductor L and the capacitor C f The output filter is formed, the inductor L is connected to the IGBT three-phase bridge inverter circuit, and the DC side of the three-phase bridge inverter circuit is connected to the capacitor C and the battery of the energy storage type power quality management device; The current transformer and the voltage transformer of the active power regulation device respectively sample the three-phase grid voltage and the three-phase grid current, and send them to the double second-order integrator for positive and negative sequence decomposition, and generate a control signal in the multi-mode control process to drive the energy storage type power quality management device of the active power regulation device.

2. According to claim 1, an active power regulation device suitable for a low voltage distribution network is characterized in that: The energy storage type power quality management device includes a battery pack integrated on the DC side of a low voltage distribution network.

3. The active power regulation device suitable for a low voltage distribution network according to claim 1, characterized in that: The active power regulation device also includes a wireless data transmission module, and the current transformer and the voltage transformer collect grid port metering device information through the wireless link of the wireless data transmission module to sample the three-phase grid voltage and the three-phase grid current respectively.

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