The ideal UpS should be purely resistive to the grid, that is, the power factor of the UpS is preferably 1, so that it has no pollution to the grid. But the reality is that most UpS generally use a 50Hz low-frequency thyristor rectifier, which generates a large amount of harmonic feedback pollution to the mains. The problem facing all users is to control harmonic pollution, just as we treat chemical plants to discharge sewage. The harm caused by harmonics is great.
Harmonic hazards are mainly:
1. The motor generates additional losses and heat, generates pulsating torque and noise. The electric power is transformed, the motor is subjected to additional loss and heat generation, and pulsating torque and noise are generated. The power transformer coil is heated, accelerating insulation aging, shortening the life, causing additional loss and noise.
2. It causes interference to the protection and automatic control devices of circuit breakers, leakage protectors, relays, etc., causing malfunctions.
3. Shorten the life of lighting facilities.
4. Cause measurement error of ammeter, voltmeter, power meter and electric energy meter.
5. Electrostatic interference and electromagnetic interference are generated on adjacent communication lines.
6. Causes serial/parallel resonance of the electrostatic compensation capacitor of the power distribution system.
7, increase distribution line loss, heat, shorten insulation life, and even cause short circuit, fire.
8. Due to harmonics, the sudden change of voltage causes the electronic equipment to be damaged and malfunction, which affects the normal operation of the computer program. Loss of data, or even damage to the hardware, causing building automation, fire alarm systems, security systems to malfunction, or even work.
At present, there are mainly ways to control UpS harmonic pollution on the market: 6-pulse rectifier + input filter; 12-pulse rectifier; 12-pulse rectifier + input filter; active filter. All of these methods have a common shortcoming, that is, pollution after treatment. Because UpS uses the structure of a thyristor rectifier, it will inevitably cause harmonic pollution, and then users are forced to spend large sums of money to control harmonic pollution. If the UpS does not produce or rarely produces harmonic pollution, then the user does not have to spend money to govern it.
If you want to achieve the same specifications, you need to add a large number of options such as input filters, 12-pulse rectifiers, etc. Each additional option will further reduce the overall efficiency of the UpS. Therefore, the 12-pulse rectifier will reduce the efficiency by 2%, and the active filter will reduce the system efficiency by 4%. Therefore, the actual efficiency of many 12-pulse UpS is less than 88% in actual measurement. Many people only pay attention to the UpS price comparison when purchasing UpS, but they don't know the operating cost of UpS. For example, an Hp9330C series 80KVA (64KW) UpS has a total efficiency of 95%, while a 12-pulse rectifier has an efficiency of only about 88%. In the 10-year UpS life cycle, the electricity cost saved by the Hp9330C Series UpS is 64 (KW) × (95% - 88%) × 24 (hours) × 365 (days) × 10 (years) × 1 (yuan / kWh) = 392,448 yuan. The power consumption will be emitted in the form of heat, so that the user has to pay a large amount of electricity for the user to cool the air conditioner, and UpS unconsciously saves the user nearly 40 million yuan in electricity bill.
In recent years, energy and environmental protection issues have attracted people's attention. Energy and the environment have also become popular topics. UpS reduces harmonic pollution and improves machine efficiency. It not only contributes to environmental protection and energy conservation, but also to users. Save a lot of electricity bills and improve economic efficiency, which further illustrates that UpS "green, low carbon" is what the times demand.