Briefly describe the characteristics of three-phase balance and reactive power automatic compensation of distribution transformer

The unbalanced operation of the distribution transformer and the increase of the neutral line current will increase the copper loss and iron loss of the transformer and reduce the output of the transformer. Excessive neutral line current will burn the neutral line, affecting the safe operation of the transformer , causing three-phase voltage imbalance and reducing the quality of power. The national standard GB50052-95 "Power Supply and Distribution Design Specifications" and "Transformer Operation Regulations" both stipulate that the neutral line current of the Y/yn0 connected distribution transformer cannot exceed 25% of the transformer phase current during operation. Although the balanced operation of the transformer is very important and is one of the energy-saving methods, for a long time, there has been almost no effective means for unbalanced operation except for the reasonable distribution of loads as much as possible. In practice, Zhaodong Bureau adopted the TBRC type low-voltage three-phase unbalanced, reactive compensation and distribution transformer monitoring device to preliminarily solve the problem of three-phase unbalanced operation and reactive compensation of the transformer.

1. Technical features of the device

With the new digital signal processor (DSP) as the core, it has fast processing speed and strong computing power.

The unique anti-interference design and advanced installation technology make the system highly reliable; the hardware secondary "watchdog" ensures that the system can be reset in time when an abnormality occurs: the FRAM with multiple write lock functions saves the system and configuration to ensure that parameters are not written by mistake.

The panel has indication signals for operation, sending, receiving, status, voltage, current, power factor, active power, reactive power, electric energy, switching, etc.

Real-time 24-point AC sampling, automatic software compensation.

Telemetry function: can measure three-phase voltage, three-phase current and other parameters.

Remote control function: with 32-way open contacts.

Remote signaling function: with 2-way open input contacts (expandable to 4-way).

With automatic test function of output point.

Use RS-232 or RS-485 to communicate with the data transmission module, execute downlink commands, and upload measurement data.

2. Device model code and function

Three-phase unbalanced and reactive power compensation control function: 32 contactless outputs. Up to 5 groups of star-connected capacitors and 5 groups of delta-connected capacitors can be connected. Overvoltage quick cut-off and undervoltage protection cut-off. Overvoltage and undervoltage values ​​can be input from the outside. The switching of capacitors is controlled according to the numerical value of the target algorithm to minimize the zero-sequence current of the system and make the power factor of each phase close to 1.

Communication function. With RS232/RS485 interface and built-in DL/T645 protocol, it can read and receive data in various ways. The background software is powerful and complete, and can output reports. The handheld operator reads and receives data, using Zhenzhong thinpad-600 handheld operator, and the background software processes. Wireless mobile phone public telephone network mode. GPRS network, GSM SMS mode. These two methods have the advantages of being easy to use and reliable.

Energy metering function. Forward and reverse active energy, reactive energy metering, multi-period metering, active energy accuracy 1.0. 8-period 14-rate energy metering. Three-month forward and reverse active and reactive energy totals, full-period energy storage. Active and reactive energy pulse output.

Electrical parameter measurement function: A, B, C three-phase current, voltage, active power, reactive power, power factor indication.

Demand statistics function. Total maximum demand of forward and reverse active and reactive power for three months. Maximum demand of 14 rates in 8 time periods. Time of occurrence of various maximum demands.

In addition, the device has good data statistical analysis functions and can perform statistical analysis on load characteristic curve parameter data.