Multi-machine graded type complete active control device for low-voltage heavy-current harmonic waves

Abstract

The invention discloses a multi-machine graded type complete active control device for low-voltage heavy-current harmonic waves. Low-voltage heavy-current harmonic waves are optimally allocated to all small-capacity grid-connected power units for multi-machine graded compensation according to the frequency band and the effective value; compensation group power unit modules in the same frequency band are identical and used for optimally allocating the compensating current in the frequency band according to the effective value, realizes multiple operations by adopting the mixed PWM (Pulse Width Modulation) strategy, cancels out ripple current and improves the compensation accuracy; for compensation group power units in different frequency bands, the ones with higher compensation frequency band have higher switching frequency and lower compensation capacity, the ones with lower compensation frequency band have lower switching frequency and higher compensation capacity, and the integral compensation capacity is maximized; and the whole control task is realized in a distributed manner through a main numerical control system and subsidiary numerical control systems, the main control system is in charge of compensation command current calculation and allocation, and all the subsidiary control systems are in charge of compensating current close-loop control of corresponding power units. The multi-machine graded type complete active control device provided by the invention can realize high-precision and fast-dynamic-response complete active control of low-voltage heavy-current harmonic waves.

Description

technical field [0001] The invention relates to a multi-machine fractional fully active treatment device, in particular to a multi-machine fractional full active treatment device for low-voltage and high-current harmonic pollution sources. Background technique [0002] Low-voltage and high-current harmonic pollution sources widely exist in the power grid, such as low-voltage and large-capacity rectifiers for electrolysis in the chemical caustic soda industry. These large-capacity harmonic currents will have a serious impact on the power grid, other electrical equipment, and especially the reliability of electricity consumption. The best solution is to invest in a compensation device at the nearest source of low-voltage and high-current harmonic current pollution. Currently, there are three common solutions: passive filter bank treatment, multi-machine full compensation parallel active filter treatment, and multi-machine full compensation parallel connection Hybrid treatment ...

AI Technical Summary

Problems solved by technology

The advantage of passive filter bank management is that its structure is simple, but its compensation accuracy is not high, and it cannot output overcurrent and limit the output. It may resonate with the power grid and amplify harmonics. The large-capacity passive filter bank is bulky and inconvenient to install. Therefore, this scheme is not suitable for the compensation and treatment of low-voltage and high-current harmonics; for the active filter treatment of multi-machine full compensation parallel connection, because the switching frequency of the power unit is required to be high when the single machine is fully compensated, the compensation capacity of the single machine cannot be large. When compensating low-voltage and high-current harmonics, too many power units are required and the implementation cost is huge, so it is not suitable for the compensation and treatment of low-voltage and high-current harmonics; the combination of multi-machine parallel fully compensated active filter and passive filter combination Type governance is a combination of the above two methods. When the absolute content of low-voltage and high-current harmonics is large in both low-frequency and high-frequency bands, this method also faces compensation capacity and cost, compensation capacity and reliability, compensation capacity and Contradictory limitations of compensation accuracy, less feasible

Images