Charging pile power grid balancing automatic phase selection device

Abstract

The invention discloses a charging pile power grid balancing automatic phase selection device. The device comprises a court transformer, the output end of the court transformer is connected with a number of electromobile alternate current charging piles respectively, the outlet side of the transformer is provided with a signal acquisition module, the inlet wire of the power supply of each alternate current charging pile of the electromobile is provided each with an automatic phase selection switch. According to the automatic phase selection device, the problem of unbalanced three-phase power system arising out of the charging pile is solved; so that when the charging pile is being charged, the impact of high current load on the unbalanced three-phase power grid is reduced, and harm to the power distribution network in the use process by the charging pile is decreased.

Description

technical field [0001] The invention relates to an automatic phase selection device for charging pile grid balance. Background technique [0002] At present, the function of the charging pile is similar to that of the fuel dispenser in the gas station. It can be fixed on the ground or wall, and installed in public buildings (public buildings, shopping malls, public parking lots, etc.) and residential parking lots or charging stations. The voltage levels charge various models of electric vehicles. [0003] At present, more than 90% of the AC charging piles installed in the domestic market are single-phase AC charging piles with a rated current of 32A and below. [0004] When the single-phase charging pile starts charging, the phase current that needs power supply provides a large current instantaneously, causing the three-phase current amplitude in the power system to be inconsistent. The unbalanced current in the power grid will increase the copper loss of the line and the...

AI Technical Summary

Problems solved by technology

In this way, not only the phase line has loss, but also the neutral line has loss, which increases the loss of the power grid line.

[0008] 2. Increase the power loss of distribution transformers

The winding insulation of the distribution transformer may also age rapidly due to overheating, resulting in reduced equipment life

At the same time, the existence of zero-sequence current will also increase the loss of distribution transformer

[0011] 5. Affect the safe operation of electrical equipment

Power supply under the condition of unbalanced voltage, that is, it is easy to burn out the user's electrical equipment connected to the high-voltage phase, and the user's electrical equipment connected to the low-voltage phase may not be able to use

Therefore, when the three-phase load is unbalanced, it will seriously endanger the safe operation of electrical equipment.

[0013] 6. Reduced motor efficiency

However, due to the braking effect of the negative sequence magnetic field, the output power of the motor will be reduced, resulting in a reduction in the efficiency of the motor.

At the same time, the temperature rise and reactive power loss of the motor will also increase with the unbalance of the three-phase voltage

Therefore, it is very uneconomical and unsafe for the motor to run under the condition of unbalanced three-phase voltage.

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