Method for treating three-phase imbalance of transformer for mining and metallurgy furnace

Abstract

A method for treating three-phase imbalance of a transformer for a mining and metallurgy furnace comprises the following steps: acquiring three-phase active power of a low-voltage side of the transformer to obtain an active power set value; ascending and descending of three-phase electrodes are controlled through an ascending electromagnetic valve and a descending electromagnetic valve respectively, and setting an upper limit and a lower limit of each electrode; comparing the collected active power with the corresponding active power set value, if the current active power is smaller than the lower limit of the active power set value, switching on the descending electromagnetic valve of the corresponding phase, and switching off the ascending electromagnetic valve of the phase; if the current active power is between the upper limit and the lower limit of the active power set value, closing the descending electromagnetic valve and the ascending electromagnetic valve; and if the current active power exceeds the upper limit of the active set value, opening the ascending electromagnetic valve, and closing the descending electromagnetic valve. The effective capacity of the transformer is utilized to the maximum extent, the furnace yield is improved to the maximum extent, interference of reactive current in current is avoided, and reactive balance is achieved while active balance is achieved.

Description

technical field [0001] The invention relates to a method for controlling the three-phase imbalance of a transformer, in particular to a method for controlling the three-phase imbalance of a transformer used in a mining furnace. Background technique [0002] At present, the capacity of mining and metallurgy furnaces in domestic mining enterprises is very large, and the capacity of the transformers used in the furnace is also large, and many of them have a capacity of more than 30MVA. The secondary low-voltage side of each transformer has three poles for work. Due to the great difference in the working characteristics of the electrodes, the active and reactive loads of the three groups of electrodes are often very different, resulting in a serious unbalance on the load side, and the serious imbalance of the three-phase negative sequence of the transformer, which leads to the inability of the three-phase electrodes to have the same output. , the overall furnace output cannot r...

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Problems solved by technology

To control the three-phase imbalance of the transformer, there is also current method electrode adjustment. This method adjusts the current of the three electrodes by adjusting the position of the electrodes. The current is the apparent current of active and reactive power synthesis. This method is the same as reactive power compensation The three-phase balance is the same, and it has the same disadvantages. The total current of the three phases is consistent through the adjustment of the electrodes, but the output of the electrodes of each phase, that is, the active power output, cannot be accurately controlled. Coupled with the reactive power reduction of the low-voltage compensation, the final balance is achieved. The active power output of each phase in the current situation may even vary greatly, and the output of the three electrodes will not be the same. Although the three phases are balanced, the production capacity has not been significantly improved

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