Low-carbon development (or low-carbon economy) is gradually becoming a global trend, which is widely regarded as the only way for human development in the future. After the "Copenhagen Conference", the Chinese government has issued a series of "low-carbon" environmental protection policy measures, which was jokingly called "China’s low-carbon first year" in 2010. With the change of policy and consumption environment, "Green UPS" and "Green UPS technology" have become the strategic heights of the leading UPS market, lead-free production, DSP technology, IGBT rectifier technology, APFC technology and so on have been greatly developed and applied, which is very obvious in the HP9330 series UPS model of Solder Company.

The real green "low-carbon" UPS power supply is characterized by small harmonic current, small harmonic pollution to power grid, high efficiency of UPS operation and reduction of loss.

 The ideal UPS should show pure resistance to the power grid, that is to say, the best power factor of UPS is 1, so it has no pollution to the power grid. But the reality is that most UPS generally use 50Hz low-frequency thyristor rectifier, which produces a lot of harmonic feedback pollution to the power grid. The problem facing all users is to control harmonic pollution, just like we control chemical plants. Like sewage discharge, harmonics cause great harm.

The main harmonic hazards are as follows:

1. Make the motor produce additional loss, heat, pulsating torque and noise. The utility model can heat the coil of the power transformer, accelerate the aging of the insulation, shorten the service life, and cause additional loss and noise.

2. It interferes with circuit breaker, leakage protector, relay and other protection and automatic control devices, resulting in misoperation.

3. Shorten the service life of lighting facilities.

4. The measurement error of ammeter, voltmeter, power meter and electric energy meter is caused.

5. Generate electrostatic interference and electromagnetic interference to adjacent communication lines.

6. Cause series / parallel resonance of electrostatic compensation capacitor of distribution system.

7. Increase the power distribution line loss, heat generation, shorten the insulation life, and even cause short circuit and fire.

8. Due to harmonics, the sudden change of voltage will cause damage to electronic equipment and malfunction, which will affect the normal operation of computer programs. It will cause data loss, even damage hardware, cause building automation, fire alarm system, security system malfunction, or even unable to work.

At present, the main ways to control the harmonic pollution of ups in the market are: 6 pulse rectifier + input filter; 12 pulse rectifier; 12 pulse rectifier + input filter; active filter. All these ways have a common disadvantage, that is, pollution first and then control. Because the structure of SCR rectifier is adopted by UPS, it will inevitably cause harmonic pollution, and then users are forced to spend more. If UPS doesn't produce or rarely produces harmonic pollution, users don't need to spend money on it.