DSP (Digital Signal Processor) based improved instantaneous detection and control system of cascaded active power filter

Abstract

The invention relates to a DSP (Digital Signal Processor) based improved instantaneous detection and control system of a cascaded active power filter. The system comprises a signal shaping and transformation processing circuit, a central data processing circuit, an insulating and driving circuit and a gate turn off thyristor circuit. The system proposes an improved instantaneous detection method based on a dq transformational theory, and fundamental wave positive-sequence components of voltage and current are synchronously extracted through dq transformation; and through coordinate transformation and projection, a current fundamental wave positive-sequence active component is obtained, and three-phase voltage distortion and fundamental wave positive-sequence active current while asymmetry can be detected in real time. In the invention, a high-performance digital signal processing chip is utilized to control a cascaded multi-level active power compensator, thereby the control speed and precision are greatly improved, the device capacity and the voltage class are improved, the stability of the grid is enhanced, and the influence on the running of whole system due to harmonic pollution is avoided.

Description

【Technical field】 [0001] The invention belongs to the technical field of detection and control of a cascaded active power filter (APF) in a power system, and relates to a cascaded active power filter based on a digital signal processor (DSP) Detection and control system. 【Background technique】 [0002] Active power filter is a kind of power electronic compensation system, which is connected between the power supply and important loads, and has good dynamic performance and harmonic characteristics. The active power filter can be regarded as a controlled current source. Its basic working principle is to detect the harmonics and reactive currents contained in the system, and generate a compensation current equal in magnitude and with a phase difference of 180°, and inject it into the transmission line , to offset the harmonics and reactive currents. Currently widely used i p -i q Although the detection method can accurately detect the harmonic current under the non-ideal gr...

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Problems solved by technology

Currently widely used i p -i q Although the detection method can accurately detect harmonic currents under non-ideal grid voltages, it cannot accurately detect reactive currents. The reason is that when the grid voltage is asymmetrical, there is a phase difference between the actual zero-crossing point of the voltage and the zero-crossing point of the voltage fundamental wave. Difference

In many cases, the actual grid voltage waveform has different degrees of distortion and asymmetry.

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