At present, the best harmonic control ability in the market is the APF series low-voltage active filter developed and manufactured by Hongyan Electric. This is a power electronic component based on current monitoring and current introduction technology. The harmonic current component to be compensated is obtained according to the monitoring load current waveform. By controlling the IGBT trigger, the pulse width modulation conversion technology is used to introduce harmonics, reactive components and currents in the opposite direction to the power distribution system to achieve the effect of eliminating harmonics. The effective filter can exceed about 95%, thereby improving the safety factor and reliability of the power supply system, and achieving the goal of environmental protection, energy saving and efficiency enhancement.
Consideration of utility company regulations is a key driver for companies to implement harmonic governance. The power supply company is obliged to produce qualified electric energy for power engineering customers. Therefore, the power supply company proposes pulse current control requirements for users who may pollute the grid. As more and more companies require higher power quality, power companies will put forward stricter requirements for power engineering customers.
Generally speaking, partial harmonic control and centralized harmonic control can be combined to produce a cost-effective solution. For harmonic source loads with higher power (such as intermediate frequency induction furnaces, soft starters, etc.). ), using ultra-high voltage harmonic filters for local harmonic control to reduce the harmonic current introduced into the power grid. For discrete system loads with small power and relatively distributed power, unified management should be carried out on the system bus. You can use Hongyan’s active filter or passive filter.
The refining and chemical industry of non-ferrous metals must use the process of electrolysis, so a high-power rectifier is essential. People take hydrogen production by electrolysis of water as an example. People must configure a set of rectifier transformer and thyristor rectifier cabinet. The ballast method is a six-phase double inverted star type. The generated alternating current is used for the electrolytic cell: 10KV/50HZ-rectifier transformer-phase voltage 172V*1.732 phase voltage 2160A-rectifier cabinet-AC 7200A/179V-electrolytic cell. Rectifier transformer: six-phase double reverse star balanced series reactor or three-phase five-column six-phase double reverse star. Input line volume: 1576 kVA valve side volume 2230 kVA type volume 1902 kVA thyristor rectifier cabinet K671-7200 A/1179 volts (four sets in total). The rectifier equipment will cause a lot of pulsed current, which will greatly endanger the power quality of the power grid.
In the high-power three-phase full-bridge 6-pulse rectifier device, the high-order harmonics generated by the rectifier account for 25-33% of the total high-order harmonics, which will cause great damage to the power grid, and the characteristic high-order harmonics generated are 6N±1 times, that is, the characteristic times on the valve side are 5th, 7th, 11th, 13th, 17th, 19th, 23rd, 25th, etc., and the 5th and 7th higher harmonic components are generated by the PCC point on the large network side The characteristic high-order harmonics are on the same valve side, among which the 5th order is large, and the 7th order decreases in turn. The parallel operation of the rectifier transformer group with phase-shifting windings can form 12 pulses, and the characteristic times of the network side are 11 times, 13 times, 23 times, 25 times, etc., and the 11 times and 13 times are the largest.
If there is no filtering device installed on the grid side or the valve side, the total pulse current injected into the grid will exceed the industry standard of our company, and the characteristic harmonic current injected into the main transformer will also exceed the control value of our company’s industry standard. Higher harmonics will cause distribution cables, transformer heating, invalid compensation devices cannot leave the factory, communication quality degradation, air switch malfunctions, generator surges and other adverse conditions.
Generally speaking, in the larger power network of the system, the characteristic higher harmonics can be removed by using passive filter ( fc ) devices, and the management goals can be met. In the case of a small power grid system, the goal of dealing with high-order harmonics is high. In addition to installing a large-capacity passive filter device, a small-capacity active filter (apf) can also be used to achieve power quality countermeasures demanding. For rectifier installation systems with different connection methods, our professional filter compensation installations have different target designs. After on-site testing, they can “customize” for customers and choose a treatment plan that suits the actual situation on the site.
Post time: Apr-13-2023