(1) Overview of the fault recorder
The fault recorder is a device that can automatically record when the power system fails and oscillates. The waveform and effective value of three-phase current and zero-sequence current on the line during the whole process of the fault can be recorded, and the waveform and effective value of three-phase voltage and zero-sequence voltage on the bus can be recorded, and a fault analysis report can be formed to give the fault. According to the fault type, you can check the amplitude and phase of current and voltage, the action time of the protection on this side, the time of sending and stopping the high-frequency protection transceivers on both sides of the line, and the opening and closing time of the circuit breaker. When automatic reclosing is installed on both sides of the line, the whole process of automatic reclosing action on both sides of the line can also be seen.
During normal operation, the waveform is sinusoidal. When a fault occurs, the corresponding microcomputer protection trips, and the waveform generated in the device becomes a non-sinusoidal curve. The use of the fault recorder makes it possible to visually reflect the fault condition on the fault recorder when a fault occurs. In the current power grid dispatching management practice, the fault information substation of photovoltaic power plants must be configured. After the relevant fault information is collected, it should be sent to the power grid dispatcher as required, so that the latter can grasp and analyze the fault conditions of each power station in real time.
(2) Startup of the fault recorder
The fault recorder start mode includes three basic forms: analog start, switch start and manual start. The fault recorder only collects data under normal circumstances, and records waves only when its starting element moves. Except for high-frequency signals, all signals can be used as starting quantities. Any input signal that meets the starting conditions given by the fixed value can start the recording. In order to ensure the reliable operation of the fault recording device, the fault recording device is required to have good sensitivity.
The following startup methods are usually adopted for the fault recorder:
(1) The voltage of each phase and the zero-sequence voltage sudden change is started.
(2) The frequency exceeds the limit and the rate of change starts.
(3) Positive-sequence, negative-sequence and zero-sequence voltages start when the voltage exceeds the limit.
(4) The current of the same phase of the line changes, and the difference between the maximum value and the minimum value within 1.5s is greater than 10% of the average value.
(5) The current phases and the zero-sequence current sudden change are started.
(6) The line phase current, negative sequence current and zero sequence current are out of limit to start.
(7) Switch value displacement start, one is the tripping action signal start of the relay protection, and the other is the dispatching start command.
(8) Manual start, start the recording by manual control.
(3) Operation and maintenance specifications for fault recording
- Daily inspection and inspection
(1) Operation monitoring.
1) Daily inspection and inspection of fault recording.
2) Check that each indicator light of the device indicates normal.
3) Check that each analog plug-in and switch plug-in of the micro-chassis are firmly inserted and not loose or falling out.
4) Check that the plug-ins of the transmitter box are firmly inserted without loosening or falling out, and there is no abnormal sound.
5) Press any key on the keyboard to view the contents displayed on the panel.
6) Check that the operation buttons are intact and not damaged, clean and free of dust.
7) Check that the AC power switch and DC power switch at the bottom of the screen are in the closed position.
8) Check that the screen box door is in good condition, and the transparent glass is clean and undamaged.
(2) Regular inspection and inspection.
1) Check that the power ON/OFF switch of the printer is in the ON position, that the printer is equipped with paper, and that there is no dust or spider webs on the printer needle and ribbon.
2) Check that the terminals on the terminal block are in good contact, and there is no open circuit or wet short circuit, and no burning and blackening.
3) Check that there is no abnormal sound or smoke in each box.
4) Check that the connection cables between the boxes are intact and not damaged, and the plugs at both ends are firmly inserted and in good contact.
5) Check that the ground wire in the screen is intact and not damaged or corroded.
6) Check that the inside of the screen is well ventilated, the box door is tightly closed, and the box door is free of paint peeling or rust.
- Abnormal recording and troubleshooting
(1) Frequent startup.
Frequent startup failures are generally caused by improper settings. According to the fault report, it can be judged which channel is caused by, and then the setting value can be adjusted appropriately and reset.
(2) Can not record waves.
This failure is generally caused by two reasons:
1) Improper setting of parameters and fixed values. The parameters should be re-calibrated, and each fixed value of the corresponding channel should be set.
2) The electrical connection of the channel is improper. After the setting is adjusted, the recording still does not start, you can perform manual recording and then analyze the waveform. If the corresponding channel has no normal waveform, the channel is abnormal, and the reason may be poor wiring or wrong wiring.
(3) Power failure.
If the whole machine is powered off, check whether the power supply and each air switch are in good condition.
Read more: What is an AVC Voltage Control System?