Frequency converter power electronics controllable loading method based on grid connected inverter

Abstract

The invention discloses a frequency converter power electronics controllable loading method based on a grid connected inverter. In a present frequency converter test, a dissipating energy type load completely wastes the electricity energy in a test process, and is difficult to accurately simulate load characteristics of the subsidiary engine of the frequency converter. In the method, the output terminal of a frequency converter is directly in connection with a three-phase grid connected inverter to be used as the artificial load of the frequency converter; the main circuit structure successively comprises a front transformer, an uncontrolled rectifier, an intermediate DC capacitor, an inverter, a filter and a rear transformer from front to back; different current given signals are given to the three-phase grid connected inverter to stimulate different load current characteristics; and the three-phase grid connected inverter is controlled by employing the current inner loop strategy based on a PI regulator in a two-phase rotating coordinate system. The method can be used in a high power frequency converter test, and realize reactive power balance control; in a whole process, almost all energy can be fed back to a power grid.

Description

technical field [0001] The invention relates to the technical field of power electronics, in particular to a controllable load method of frequency converter power electronics based on a grid-connected inverter. Background technique [0002] Regardless of the need for technology or energy saving, frequency converters have been widely used in auxiliary machines of steam turbine generator sets in thermal power plants. The fluctuation of the input power supply voltage of the inverter will affect the stable operation of the inverter. In order to improve the high and low voltage ride-through capability of the low-voltage inverter, an additional voltage support device is often used to solve the impact of swaying electricity on the stable operation of the inverter. [0003] In order to check whether the anti-voltage fluctuation level of a type of auxiliary low-voltage inverter itself and the high-voltage and low-voltage ride-through capabilities after the configuration of additional...

AI Technical Summary

Problems solved by technology

Hysteresis dynamometers, excitation motors and other simulated loads can be used for inverter testing, but energy-consuming loads not only completely waste the electrical energy in the test process, but also are affected by the control response speed and quality, making it difficult to accurately simulate the auxiliary loads of the inverter. machine load characteristics

On the other hand, energy-consuming loads are limited by heat dissipation and other factors, and the power consumption level is limited, which is limited to the simple test application of low-power inverters, and cannot be applied to the test of high-power inverters, and the remaining electric energy cannot be fed back to the inverter during the test. power grid, resulting in a waste of energy

At the same time, this test method is difficult to simulate the exact characteristics of the auxiliary load of the frequency converter

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