DZZB-D type microcomputer grid-connected device
1. Overview:
Quasi-synchronous paralleling of generators is a very frequent daily operation of power plants. Large inrush current and mechanical vibration when connected to the grid are harmful to the generators. Serious non-synchronous paralleling will cause accidents to the unit and the grid. Traditionally, small generator sets are connected to the grid using the lighting method or the full-step meter monitoring method. It is difficult for operators to grasp the accurate closing timing, and there is often a large inrush current to the generator set, which may cause strong vibration to the generator set. , The switch contact burns, and even causes the switch to trip the unit.
For this reason, many domestic manufacturers have produced many simple automatic grid-connecting devices to solve this problem, but they only set a checkpoint for the grid-connected conditions, and cannot accurately determine the grid-connected point, so there is still a certain impact on the unit.
The DZZB-D microcomputer grid-connected device produced by Chongqing Yongyuan calculates the phase difference with a high-precision time scale. The phase difference pulse train is scientifically smoothed through the microcomputer to determine the accurate closing point and realize the closing with millisecond precision. . When the pressure difference on both sides of the parallel connection is qualified, the frequency difference is qualified, and the advance time of the setting is consistent with the mechanical action time of the switch, fast and shock-free closing can be achieved. The device has stable characteristics and no need for debugging.
2. Principle:
The basic working principle of this device is to first convert the sine waves on both sides to be combined into digital signals, and then calculate and process them through a microcomputer to accurately determine the closing output time.
The whole device is based on 51 single-chip microcomputer, equipped with signal input and conversion circuit, setting value reading circuit, indication and closing output circuit to form a real-time monitoring system.
3. Technical indicators:
a. The working power of the machine:
The system PT voltage with PT: 85VAC~130VAC,
180V~260VAC without PT;
b. The output contact capacity of the machine: 30A, 28VDC/240VAC;
c. Power consumption of the whole machine: <4W;
d. Closing phase erro r: <2°;
e. Frequency judgment error: <0.02HZ;
f. Setting value of frequency difference: 0.35HZ, 0.5HZ;
g. Pressure difference setting value: 10%;
h. Setting range of closing advance time: 0.10s~0.24s;
i. Working environment temperature: -10ºC~50ºC;
j. Environmental relative humidity: <85%;
k. No corrosive gas around;
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