DC modulation based zero transformer type single-phase dynamic voltage compensator

Abstract

The invention provides a DC modulation based zero transformer type single-phase dynamic voltage compensator including a charge module, an energy storage module, an inversion module and an AC / AC converting module. The charge module is used for realizing charging operation on a single-phase dynamic voltage compensator by a power grid. The energy storage module is used for storing electric energy charged into the single-phase dynamic voltage compensator by the power grid. The inversion module is used for converting DC current stored by the energy storage module into working frequency AC current. The AC / AC converting module is used for converting the working frequency AC current converted by the inversion module to AC current matching with the power grid and then compensating a power grid circuit with the AC current. According to the invention, the Boost type DC modulation AC / AC converter is introduced as an AC boosting conversion link and zero-transformer injection is realized by utilizing capacitance. Compared with a regular zero-transformer type DVR, the number of IGBTs is reduced; flexible and adjustable secondary boosting conversion can be realized and voltage compensation capability is enhanced.

Description

technical field [0001] The invention relates to the fields of power electronic converters and power quality, in particular to a transformerless single-phase dynamic voltage compensator based on direct current modulation. Background technique [0002] Although the current transmission and distribution system has high reliability, it is still difficult to completely avoid abnormal fluctuations in voltage levels. Any abnormal change of the voltage waveform may affect the normal operation of the user-side electrical and electronic equipment in the power grid. Power loads require the power grid to provide a voltage supply with good sine waveform, stable frequency, high synchronization, and stable effective value to continuously meet the needs of production and life. Overvoltage, undervoltage and power interruption are considered to be the main problems affecting power quality. Some important loads in the power system are very sensitive to transient fluctuations in voltage level...

AI Technical Summary

Problems solved by technology

However, since the voltage source inverter (Voltage Source Inverter, VSI) is a step-down topology, without injecting the secondary boost of the transformer, the compensation voltage amplitude output by the system is severely restricted by the DC bus voltage, and the compensation capability is relatively low. insufficient

At the same time, due to the limited output voltage range of the VSI circuit under the premise of ensuring the power quality, the adjustment control of this type of DVR is still not flexible.

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