SVG (static var generator) reactive power compensation device is currently the most mainstream reactive power control equipment type. The amplitude and phase of the output voltage, or directly control its AC side current, make the circuit absorb or emit reactive current that meets the requirements, so as to achieve the purpose of dynamic reactive power compensation.
The configuration of SVG reactive power compensation device in photovoltaic power station can improve the transmission capacity of photovoltaic power generation and the stability of the system, and prevent voltage collapse. SVG reactive power compensation devices mainly include dynamic reactive power compensation, harmonic control complete sets, connecting transformers, complete sets of equipment including transformer fences, quick oil drain valves, frames, equipment supports, grounding cables between equipment or supports, installation accessories and All primary, secondary cables, etc. inside the package.
SVG reactive power compensation has three operating modes: constant voltage mode, constant reactive power mode, and power factor mode. Different regions have different modes of operation according to the requirements, but they are all included in the assessment scope of the “two detailed rules” of the public power grid, which is an important factor affecting the power quality indicators of photovoltaic power plants. Sufficient attention should be paid to the routine inspection and maintenance of the power station.
The specific functions of the reactive power compensation device are:
(1) According to the voltage, reactive power demand or power factor of the power supply bus, the capacitor bank is automatically switched, and the reactive power compensation is performed by tracking the change of the load, thereby improving the power factor, improving the power supply quality and reducing the power loss.
(2) The special design takes into account the filtering function. With the wide application of power electronics technology, high-order harmonics generated by nonlinear loads enter the power system, causing waveform distortion of the power supply voltage, increasing the loss of power equipment, aging of temperature and insulation, shortening equipment life, and causing interference to the communication system. Misoperation occurs in the timing, which increases the measurement error and affects the normal operation of the equipment. At the same time, higher harmonics may also cause harmonic amplification of the system due to unreasonable configuration of the capacitor bank, and even generate parallel resonance, damage the power supply equipment, or amplify the harmonic current entering the capacitor bank, overload the capacitor bank and cause failure.
In order to ensure the stable operation of the reactive power compensation device, the power station shall conduct daily inspection inspections, and conduct real-time monitoring and analysis of its operating parameters. The routine inspection items are as follows:
(1) Whether the position of the reactor is incorrect, and whether there are abnormal phenomena such as skew and looseness.
(2) Whether the SVG device box is damaged or not fixed firmly.
(3) Whether the grounding of the SVG device box has virtual connection, falling off, fracture, corrosion, etc.
(4) Whether the filter screen of the power cabinet of the SVG device is blocked by debris or has serious dust accumulation, the filter screen is generally cleaned once a week, and the power station can timely clean the dust according to the on-site environment judgment.
(5) Check whether the ventilation ducts on the box of the SVG device are free from damage.
(6) Whether there is discharge at the connection of the SVG incoming cable.
(7) Whether there is abnormal sound or abnormal sound in the SVG power cabinet.
(8) Check whether the cooling fan is stuck, stopped or cannot be started according to the fixed value.
(9) Whether the displayed value of the SVG industrial computer is inconsistent with the value of the monitoring system, whether there is abnormal operation, whether there is abnormal sound or smell; whether there is an alarm signal on the display screen and indicator light.
(10) Check whether the AC power dry-type transformer has abnormal sound and smell, and whether there is overheating and discharge.
(11) Whether the name identification of the secondary power switch has fallen off, the handwriting is blurred, and whether the running position does not match the actual running mode.
(12) Check whether the secondary wiring is missing or not, whether there is a virtual connection, loosening and heating of the wiring terminals, and whether there is a discharge sound at the current terminals.
(13) Whether there is serious dust accumulation in the SVG control cabinet, and whether the fire blocking is missing or falling off.