Double-transformation-ratio manual and automatic switching current transformer and control method thereof

Abstract

The invention discloses a double-transformation-ratio manual and automatic switching current transformer and a control method thereof, and relates to the field of small current collection. A current transformer is provided with two secondary windings, the secondary winding with the fixed transformation ratio is used for sampling and judgment of a control unit, and the secondary winding with the adjustable transformation ratio comprises two sets of output with different transformation ratios; at the same time, only one transformation ratio of the adjustable transformation ratio secondary winding is on the output contact, and the other transformation ratio contact is disconnected. According to the invention, the control unit carried out sampling and calculates the incoming line current of the system in real time, and judges the operation state of the system according to the real-time current of the system so as to control the output of the secondary winding of the current transformer. Under the condition of two different primary currents of the system, the current transformer can also be automatically switched to two corresponding secondary outputs with different transformation ratios, and the possibility of wide-range and high-precision sampling is provided for other sampling devices.

Description

technical field [0001] The invention belongs to the field of small current collection, in particular to a double-variable-ratio hand-automatic switching current transformer and a control method thereof. Background technique [0002] In order to save energy and reduce energy consumption, more and more distributed new energy sources such as photovoltaics, synchronous machines, and waste heat power generation are connected to the power supply systems of large industrial and mining enterprises. In current practical applications, the access of distributed new energy sources does reduce the active power that customers draw from the grid, and the primary current rating decreases, which brings a series of derivative problems that cannot be solved, such as digital integrated automatic protection devices It cannot be accurately protected, reactive power compensation cannot be accurately compensated, and the instrument cannot be accurately displayed. The main reason is that after the d...

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Problems solved by technology

In current practical applications, the access of distributed new energy sources does reduce the active power that customers draw from the grid, and the primary current rating decreases, which brings a series of derivative problems that cannot be solved, such as digital integrated automatic protection devices It cannot be accurately protected, reactive power compensation cannot be accurately compensated, and the instrument cannot be accurately displayed. The main reason is that after the distributed new energy is connected, the incoming current of the public connection point (PCC) connected to the grid rapidly changes from the original larger rated value. Reduced to a smaller rated value, while the current transformer is still the original high-current rated transformation ratio output, and all electrical equipment sampling current transformers are still set and calculated according to the original transformation ratio

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