Control method and device for power electronic transformer

Abstract

The invention provides a method and a device for controlling a power electronic transformer. The device comprises an acquisition module, a first calculation module, a second calculation module and a PWM (pulse width modulation) module. The device provided by the invention for controlling the power electronic transformer directly aims at each phase d in three-phase voltage, and acquires distribution network voltage u<s alpha> at a first moment and distribution network voltage u<s beta> at a second moment which is a preset time period 1 / (4f) after the first moment. Control for the power electronic transformer can be completed under the condition of not carrying out phase locking, and a control failure caused by a failure in phase locking can be avoided fundamentally.

Description

technical field [0001] The invention relates to the field of electric power technology, in particular to a control method and device for a power electronic transformer. Background technique [0002] Since the transformer was invented in the 19th century, it has become one of the most basic and important components of the power system. It is widely used in power distribution systems to achieve voltage level conversion and isolation. However, the traditional transformer has many disadvantages: (1) It is huge, and with the increase of the voltage level, the volume and weight of the transformer increase sharply; (2) It is sensitive to power quality, and the distortion generated when it is connected to non-linear loads such as uncontrolled rectification The current will enter the power grid through the coupling effect of the transformer, which will pollute the bus grid and cause the quality of power supply to decline; (3) When a grounding short circuit fault occurs on the load si...

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Problems solved by technology

However, the traditional transformer has many disadvantages: (1) It is huge, and with the increase of the voltage level, the volume and weight of the transformer increase sharply; (2) It is sensitive to power quality, and the distortion generated when it is connected to non-linear loads such as uncontrolled rectification The current will enter the power grid through the coupling effect of the transformer, which will pollute the bus grid and cause the quality of power supply to decline; (3) When a grounding short circuit fault occurs on the load side, the traditional transformer cannot effectively isolate the fault, resulting in the expansion of the fault range; (4 ) requires a special relay protection device for protection. When the transformer iron core is saturated, it is easy to generate a large excitation inrush current, which brings harm to the power system; (6) The function is single, without functions such as voltage regulation, power factor correction and power flow control, which cannot meet the needs of smart grid construction

[0004] The control method in the prior art is generally phase-locked control. In the process of phase-locking the distribution network voltage and the frequency and phase of the micro-source voltage, the phase-locking failure is likely to occur due to voltage quality problems and errors caused by the phase-locked loop itself, resulting in Grid control failure

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