A model predictive control method for three-phase converter without voltage sensor

Abstract

The invention belongs to the field of power converter control, and discloses a three-phase current transformer model prediction control method free from a voltage sensor. The method comprises the following steps: 1, sampling AC-side currents and DC-side voltages of a current transformer; 2, performing integration on network-side voltages of the current transformer under an alpha-beta coordinate system, then after a low-pass filtering link, together with power grid currents i<alpha> and i<beta>, observing AC network-side virtual magnetic linkages (phi<alpha>, phi<beta>); 3, according to the observed virtual magnetic linkages phi<alpha> and phi<beta>, reconstructing power grid voltages and calculating magnetic linkage space angles; 4, based on a voltage outer loop, by use of model prediction control, through a solving algorithm of secondary planning, calculating optical voltage instructions (v<d><*>,v<q><*>); and 5, obtaining driving signals of a power switch tube after the voltage instructions pass through dq / alpha beta and then is subjected to an SVPWM algorithm. According to the invention, under the condition that an AC-side voltage transducer is omitted, the provided current transformer model prediction control algorithm performs searching optimization by use of a secondary planning solving algorithm, such that the system reliability is improved, the computational complexity is reduced, the difficulty of parameter setting is reduced, and the realization is easy.

Description

Technical field [0001] The invention relates to the field of three-phase converter control, in particular to a voltage sensor-free converter model predictive control method. Background technique [0002] In today's society, various industries have higher and higher requirements for power quality. At the same time, coupled with the development of new energy distributed power generation, the energy Internet has become the development trend of the energy industry. Because the three-phase PWM converter has the advantages of two-way energy flow and adjustable power factor, it has been widely studied and applied. The reduction of the system cost of the PWM converter and the study of easy-to-implement control algorithms have become current research hotspots. [0003] Model predictive control is to determine the current control action according to the future output state of the system. It is predictable and superior to the classic feedback control system that generates control actions by f...

AI Technical Summary

Problems solved by technology

[0004] For power electronic devices, due to the high switching frequency, the system sampling period is very small, which requires the designed intelligent control algorithm to find the optimal solution in a very short period, which has become the biggest obstacle to the practical application of model predictive control.

At the same time, the existing PWM converter model predictive control needs to use more AC electromotive force sensors, which not only increases the hardware cost, but also is easily affected by the harmonics of the electromotive force, which reduces the system reliability.

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