Tuesday, October 5, 2010

Call of UPS power pollution


IGBT rectifier technology with the development of power electronics technology created a new type of rectification, using IGBT technology, UPS, can achieve the purpose of two-way protection not only to protect the load, but also protect the power grid.

Uninterruptible power supply has two basic role is usually the first to provide high-quality power to the load, to regulation, frequency stabilization, inhibition of surges, spikes, electrical noise, offset voltage subsidence, such as long-term low-voltage power supply interference; followed by the breaking uninterrupted power supply when using the battery energy storage to DC inverter to AC, providing high-quality power to the load to continue to support the load.

UPS put into operation in the traditional when the power will be injected into a large number of harmonic currents, causing harmonic loss and interference, there is also power factor device network deterioration, or "power pollution." Harmonic current not only pollute the power grid, also may contaminate the system itself.

Furthermore, UPS input power factor is low, input reactive power, power distribution required system capacity and system power capacity of other equipment have increased by 50%; This makes the grid voltage waveform interference, network wiring load capacity decreased, serious power supply system may lead to the shock of the line or other equipment, abnormal working.

Also consume large amounts of high harmonic reactive power, line loss increases, causing malfunction of electronic protection devices to opportunities to generate additional power and additional torque loss, Ying Xiang, the instrument measurement accuracy, on computer networks, communications systems produce electromagnetic interference phenomena.

UPS itself is the source of interference

UPS itself has become a major source of electromagnetic emission, the load for the protection of power while providing clean, self-will generate new electromagnetic interference. How to effectively eliminate these interference UPS technology has become an important issue in the development of the user on the pollution-free green increasing demands for UPS.

Green power system has two meanings: First, a significant saving, followed by the power supply can not (or less) on the grid pollution.

International Electrotechnical Commission (IEC) have developed a series of standards such as IEC555, IEC917, IECl000 so. Since 1996, the European Union, the International Electrotechnical Commission IEC EMC made the following definition: "of equipment or system in its electromagnetic environment to work normally, without any thing on the environment can not constitute the ability to withstand electromagnetic interference."

Can be seen from the definition of electromagnetic compatibility: The device should not only inhibit the external system to the electromagnetic interference; and its electromagnetic interference generated by the same electromagnetic environment should not affect other electronic equipment in the work.

UPS is a device by the electric power grid to providing active and reactive power, while power grid surges, spikes and other sharp harmonic wave transmission will come, in addition to radiation, inductively coupled electromagnetic interference signals coming in; UPS has is a source of interference, which in addition to providing stability to the load frequency, regulated clean power supply, because UPS is a power electronics converter, rectifier part of the grid generated by high harmonic back into the grid, can cause power grid voltage distortion, impact with an electric line of electrical equipment, it becomes the source of interference.

In addition, these high harmonics also by way of electromagnetic fields, internal and external space to produce RF interference will affect computers, electronic instrumentation, communications and radio work.

To UPS as a green power supply, we must contain and limit the high harmonics of electromagnetic interference.

Experts began to try to increase the filter approach to improve UPS, but a variety of filters, not only increases the weight of UPS, the cost to buy UPS, while the effect is not ideal, it has added a point of failure.

UPS IGBT technology began to be introduced

With the UPS technology continues to evolve, many computers, power electronics, new technology, new ideas are introduced into the UPS.

And the IT industry, similar to other products, the current phase UPS products compared with the previous, both in the main performance, appearance, size, on-site environmental adaptability and reliability, there has been significant progress, some indicators are even qualitative leap is especially true for medium and large UPS.

IGBT rectifier technology using high frequency switching PWM rectifier current, sine wave input current to achieve the purpose. Increased pulse rectifier will reduce the number of high-frequency and harmonic current values.

IGBT rectifier technology can therefore be reduced to very low input harmonic current. IGBT rectifier technology is not subject to the impact load, the efficiency of the filter with the power to overcome the size of the problem changes, filter-free true sine wave input current input.

Currently high-power three-phase rectifier circuit for power factor correction can usually only be passive power factor compensation, 6 pulse rectifier without filter is only about 0.65, and 12 pulse rectifier is only 0.8, and filter large volume, weight high, expensive applications in the field, not economic.

However, the application of IGBT rectifier technology, UPS, its single input power factor greater than 0.99, the network performance is similar to pure resistive load. As shown, IGBT rectifier technology advantages are obvious.

Generator compatibility only example: 80KVA UPS need to configure the 6 pulse 200KVA diesel generator power capacity; 80KVA UPS needs 12-pulse configuration 120KVA diesel generator power capacity; 80KVA of IGBT high-frequency rectifier UPS, only need to configure 80KVA diesel generator power capacity.

In short, UPS using IGBT rectifier technology, light weight, simple topology, with higher stability. And by other circuit topology and operating principle of the UPS compared with the current harmonics is small and can be adapted to a variety of loads, efficiency has nothing to do with the load amount, less components, small size and placement of the required space for small, non-resonance and risk of over-capacity and overall reliability.

UPS using IGBT rectifier technology is a two-way protection not only protect the load, but also protect the power grid. All kinds of electrical equipment and power equipment harmonic currents are generated pollution network, and computer load power is nonlinear way of equipment, will produce harmonic pollution and reactive power.

UPS using IGBT rectifier technology, in addition to the grid can reduce their own pollution, it can eliminate the load carried by the harmonic pollution on power and power factor correction.

IGBT rectifier technology with technology, but also allows users to find the UPS back-end is a pure sine wave UPS to provide power for UPS and power was brought in front of the load group is similar to the low harmonic resistive load such an ideal target.

Currently, UPS using IGBT rectifier technology, existing products into China, with early UPS PWM inverter technology gradually replace the scene when the square wave technology is very similar.

However, the UPS using IGBT rectifier technology there are high price, high-power devices difficult to manufacture finished products is low and so on. The technology also has the power of the UPS first to achieve small, gradual transition to high-power characteristics.






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