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Unbalanced load based flying capacitor type modular multi-level reactive compensation device

A modular multi-level, flying capacitor technology, applied in reactive power compensation, reactive power adjustment/elimination/compensation, circuit devices, etc., can solve problems such as deterioration of power quality, increased line loss, and low power factor. Achieve the effect of scalability, good compensation effect and low switching frequency

Inactive Publication Date: 2019-03-12
HARBIN UNIV OF SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Detrimental effects of unbalanced loads include low power factor, increased line losses, and heating effects in the power system
[0003] Static compensation is an effective technique for unbalance compensation, they are able to actively compensate unbalanced loads, but their connection to the unbalanced network causes second harmonic components to appear on the DC side of the converter
If not eliminated, this will generate low order harmonic currents on the AC side, leading to further deterioration of power quality
The situation becomes especially complicated when the imbalance is continuously changing

Method used

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  • Unbalanced load based flying capacitor type modular multi-level reactive compensation device
  • Unbalanced load based flying capacitor type modular multi-level reactive compensation device
  • Unbalanced load based flying capacitor type modular multi-level reactive compensation device

Examples

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Comparison scheme
Effect test

Embodiment 1

[0039] A flying-span capacitive modular multi-level reactive power compensation device based on unbalanced loads, which consists of: a main circuit, a detection circuit, a control circuit and a drive circuit, the main circuit includes an inductance connected to the power grid, and the The inductance is connected with the flying-span capacitive modular multi-level cascaded inverter 1, and the flying-span capacitive modular multi-level cascaded inverter is connected with the DC voltage sampling circuit 2, and the inductance is connected with the DC voltage sampling circuit 2. The inverter AC current sampling circuit 3 is connected, and the DSP chip 4 is respectively connected with the described DC voltage sampling circuit, the described inverter AC current sampling circuit, the grid voltage detection circuit 5, the grid load AC current sampling circuit 6, and the FPGA chip 7 is connected, and described FPGA chip is connected with driving circuit 8.

Embodiment 2

[0041] According to the unbalanced load-based flying-span capacitor type modular multi-level reactive power compensation device described in Embodiment 1, the main circuit topology is a flying-span capacitor type cascaded topology, and each phase includes three modules 9. Each module includes two H-bridge structures connected in parallel;

[0042] The module includes 8 power switch tubes, two flying capacitors and a DC capacitor, the power switch tube The emitter and power switch tube The collectors are connected together, the power switch tube The emitter and power switch tube The collectors are connected together, the power switch tube The emitter and power switch tube The collectors of the flying capacitors are connected together, The positive electrode and the power switch tube , power switch tube Connected to the connection point between the negative pole and the power switch tube , power switch tube The connection points between them are connected to ...

Embodiment 3

[0045] According to the unbalanced load-based flying-span capacitive modular multilevel reactive power compensation device described in Embodiment 1 or 2, the DC voltage value of each module is The voltage value of the flying capacitor is half of the DC voltage as , each module has a total of 16 effective switching states, and synthesizes 5 voltage levels, namely 0, ±0.5 、± , A total of nine basic modules are cascaded in three phases, three modules are cascaded in each phase, and 13 voltage levels are output for each phase voltage: 0, ±0.5 , ± , ±1.5 , ±2 , ±2.5 , ±3 .

[0046] The device features a flying-span capacitive modular multilevel cascade topology as figure 2 , each phase bridge arm of the inverter is formed by cascading three basic modules. Each module consists of 8 IGBTs and a DC link capacitor and two flying capacitors and composition. The voltage on the module defines the DC voltage as , is twice the value of the voltage across the...

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Abstract

The invention discloses an unbalanced load based flying capacitor type modular multi-level reactive compensation device. A traditional control strategy is to detect reactive component to serve as reference of compensating current; and the compensation precision greatly depends on a voltage and current sampling and detection scheme. The unbalanced load based flying capacitor type modular multi-level reactive compensation device comprises a primary circuit which comprises an inductor connected with an electric grid; the inductor is connected with a flying capacitor type modular multi-level cascade inverter (1); the flying capacitor type modular multi-level cascade inverter is connected with a DC voltage sampling circuit (2); the inductor is connected with an inverter AC sampling circuit (3);the DSP chip (4) is respectively connected with the DC voltage sampling circuit, the inverter AC sampling circuit, an electric grid voltage detection circuit (5), an electric grid load AC sampling circuit (6) and an FPGA chip (7); and the FPGA chip is connected with a drive circuit (8). The unbalanced load based flying capacitor type modular multi-level reactive compensation device is applied tothe unbalanced load based flying capacitor type modular multi-level reactive compensation device.

Description

Technical field: [0001] The invention relates to the field of power quality control, in particular to a flying-span capacitive modular multi-level reactive power compensation device based on unbalanced loads, which is suitable for solving unbalance problems caused by uneven single-phase loads. Background technique: [0002] With the development of power systems, high-voltage and high-power converters play an increasingly important role in the field of electric energy conversion. At the same time, single-phase loads caused by commercial facility loads, single-phase electric traction systems, and rural power systems Uneven distribution as well as power system failures can lead to large short-term imbalances, exacerbated by the recent unprecedented growth of power electronics energy-saving solutions and switch-mode power supplies, and the trend to use renewable energy generators, especially photovoltaic panels. question. The adverse effects of load imbalance include low power ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02J3/18H02J3/26
CPCH02J3/1842H02J3/26Y02E40/30Y02E40/50
Inventor 高晗璎刘旭
Owner HARBIN UNIV OF SCI & TECH
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