Among them, the power frequency non-partial discharge resonance test system and the fault location test system are the most advanced and mature products in China, which have passed the national appraisal, are batched and always remain the industry's first choice of ultra-stable products. Partial discharge test of cross-linked power cables and accessories of 132, 220, 500kV voltage levels, and passed the national appraisal.
(1) The background harmonic at the connection point of the capacitor device is 3rd (when the background harmonic at the connection to the power grid is 3rd and above, it is generally 12%; 4.5% to 6% and 12% can also be used. reactance rate.)
The choice of reactance ratio also depends on the harmonic background:
1 The background harmonic at the access point of the capacitor device is the 3rd order
1) If the third harmonic content is small, a series reactor of 0.1% to 1% can be selected, but it should be checked whether the third harmonic amplification exceeds or is close to the national standard limit after the capacitor device is put into use, and there is a certain margin.
1. Incoming line reactor
Also known as input reactor or power supply coordination reactor, it can limit the current impact caused by grid voltage mutation and operating overvoltage, and effectively protect the inverter; it can not only prevent the interference from the grid, but also reduce the harmonic generated by the rectifier unit. The wave current pollutes the power grid and improves its power factor.
1) The choice of series reactor in the capacitor device of the new substation must be careful, and it cannot be arbitrarily combined with the capacitor, and the harmonic background at the connection point of the capacitor device must be considered.
2) For the capacitor device that has been put into operation, it is necessary to further check whether the selection of the series reactor is reasonable, and organize on-site measurement to understand the changes in the harmonic background of the power grid. Reasonable selection of capacitor devices for reactance rate shall not arbitrarily increase or decrease the capacity of the capacitor bank.
3) When the capacity of the capacitor bank changes greatly, you can choose a reactor for synchronously adjusting the taps of capacitors or choose a mixed installation of reactors. Through the analysis and calculation of the static overvoltage condition of the capacitor bank during normal operation and the voltage rise of the capacitor terminal during reactive power overcompensation, a 0.5%~1% w reactor is selected to prevent the overvoltage generated when the capacitor bank is switched.
During the use of the inverter and the governor, they are often hit by inrush current and surge voltage, which will seriously damage the performance and service life of the inverter and the governor. Therefore, an input reactor should be installed in front of them. , to protect the inverter and regulator, prolong its service life and prevent harmonic interference.