Picture Name

Products

PRODUCT CENTER

XDGZ transformer neutral point isolation DC complete set
+
  • XDGZ transformer neutral point isolation DC complete set

XDGZ transformer neutral point isolation DC complete set

1. Product Overview In recent years, HVDC transmission has been applied in China's long-distance transmission because of its high efficiency and economy. More and more DC transmission lines are put into operation. When the DC power transmission unit is operated greatly, part of the earth's pole current flows into the neutral grounding circuit of the system transformer, which has different degrees of influence on the AC power transmission system. In particular, the earth's polar current flows into the neutral point of the transformer, causing the magnetic neutrality of the transformer's neutral point to be superimposed on the DC component, causing magnetic saturation, causing harmonics, vibration, and noise of the transformer, affecting the safe and stable operation of the transformer and the AC system.

Category: Product Center

Key words: equipment


Product Description

1. Product Overview
In recent years, HVDC transmission has been applied in China's long-distance transmission because of its high efficiency and economy. More and more DC transmission lines are put into operation. When the DC power transmission unit is operated greatly, part of the earth's pole current flows into the neutral grounding circuit of the system transformer, which has different degrees of influence on the AC power transmission system. In particular, the earth's polar current flows into the neutral point of the transformer, causing the magnetic neutrality of the transformer's neutral point to be superimposed on the DC component, causing magnetic saturation, causing harmonics, vibration, and noise of the transformer, affecting the safe and stable operation of the transformer and the AC system.
The XDGZ transformer neutral point isolation DC complete set (hereinafter referred to as XDGZ device) can be connected to the neutral point of the transformer to effectively block the DC current flowing through the neutral point of the transformer, and has no effect on the operation of the AC system. The problem of the influence of the DC single-maximum operation on the AC system in the AC-DC hybrid power supply system is solved.
2. Main technical features
The solution of the series capacitor in the neutral point of the transformer is adopted, and the bypass protection loop is formed by the thyristor and the fast switch, and the neutral point direct current is effectively isolated;
The components from the measurement, control, and action are all configured in a dual configuration, including voltage, current sensor, thyristor protection module, and control device. The dual device redundancy configuration does not cause damage to the complete device, which improves the device. reliability;
Utilizing a large-capacity fast switch to realize the state transition of the direct ground of the neutral point and the grounding of the capacitor;
In the capacitor grounding state, when the neutral point is overvoltage, the bidirectional anti-parallel high-power thyristor is used for fast bypass, the conversion time is only subtle, and the conversion voltage threshold can be set by adjusting the thyristor over-voltage triggering component;
In the capacitor grounding state, the neutral point AC ground resistance is less than 0.1Ω, and the relay protection and other automatic devices do not need to be re-tuned;
The embedded control unit detects the neutral point current or voltage according to different operating states to realize automatic or manual running state transition.
3. Device structure
The device adopts the outdoor installation mode, the incoming line is the cable going in and out, and the complete device is a box structure, which is convenient to install.
XDGZ transformer neutral point isolation DC complete set
4. Technical parameters
4.1 Mechanical and environmental parameters
Chassis structure size 2000mm×1700mm×2100mm(length × width × height)
Weight 2000kg
Colour gray
Normal operating temperature -10℃~50℃
Extreme working temperature -15℃~55℃
Storage and transportation 25~55℃
Maximum relative humidity without condensation 95%
4.2 rated electrical parameters
Working power AC220V   DC220V
Long-term operation of the supply current <0.5A
Capacitive resistance ≦0.1Ω   50HZ
Isolated DC capacitor rated voltage 1500VDC
Overvoltage bypass voltage value 600~1000V(±10%) adjustable
Thyristor bypass conduction time ≦10µs
Bypass switch closure time ≦40ms
Thermally stable current 8KA/1s(effective value)
Dynamic steady current 20KA/0.2s(peak)
5. Technical advantages
(1) Dual configuration
The components from the measurement, control, and action are all configured in a dual configuration, including voltage, current sensor, thyristor protection module, control device, etc., all of which adopt dual redundant configuration. The damage of a single device will not cause failure of the complete device, and the device is improved. reliability.
(2) Strong impact resistance
The device is resistant to high current surges and can withstand 8KA/1S (rms) thermal stability current and 20KA/0.2S (peak) dynamic steady current surge.
(3) Perfect function
The device adopts embedded control unit, which can monitor the AC and DC voltage, current and other signals in real time. The function interface is perfect. Manual/automatic, local/remote control mode can be selected according to site requirements.
(4) Fast response
Using power electronics as a fast bypass branch, the conversion time is only a few subtle. When the capacitor is subjected to an overvoltage, the thyristor is directly turned on by the hardware, and the overvoltage bypass signal is sent to the controller by the optical fiber to close the mechanical bypass switch.
(5) Using imported devices
The mechanical bypass switch adopts the German imported vacuum circuit breaker, which has fast closing speed and guarantees quality.
6. Testing and testing
The complete set of equipment commissioned the quality supervision and quality inspection center of the medium and low voltage transmission and distribution equipment under the Guangdong Quality Inspection Institute to carry out the dynamic thermal stability test. The test currents are 8KA/1S (effective value) and 20KA/0.2S (peak) respectively.