Green UPS Solution for Communication Room

1 Introduction

With the country's vigorous promotion of energy conservation and environmental protection, and the increasing cost of energy supply, more and more users are beginning to pay attention to the issue of green power supply for UPS used in information computer rooms.

According to statistics: the communications industry consumes more than 20 billion kWh of electricity each year; various energy consumption costs exceed 10 billion yuan; the total power consumption ranks 14th among all industries, and with the continuous growth of business, the above data is still increasing year by year. Faced with fierce competition, energy consumption costs are putting increasing pressure on communications companies. Therefore, China Telecom proposed a macro-control target of energy conservation and emission reduction in 2008, with a year-on-year decrease of more than 3% in energy consumption per 10,000 yuan of business revenue, and China Mobile also proposed a 40% reduction in energy consumption in three years.

To achieve the above energy-saving goals, it is very necessary to control energy consumption in all links. As we all know, there are a large number of small and medium-sized information rooms in the communications industry. UPS, as a special and important uninterruptible power conversion device, is an indispensable device in these rooms. Energy-saving and environmental protection measures for these UPS devices are of great significance.

The following is a discussion on what features UPS used in small and medium-sized information rooms of communications companies should have in order to be truly green and energy-saving.

2 What characteristics should a green energy-saving UPS for information room have?

2.1 The overall efficiency of the UPS should be high (especially at low load)

UPS is a power conversion device. The conversion efficiency directly determines how much electricity customers have to pay for UPS equipment. However, because UPS conversion efficiency is related to load, generally speaking, UPS efficiency is highest when fully loaded. In actual applications, most users' loads are less than 50%, and there are also many users with loads less than 30%. Therefore, the efficiency at low loads can better reflect the significance of energy saving. UPS equipment works 24 hours a day. If the conversion efficiency is increased by one percentage point, the electricity bill saved will be considerable for communication customers with many UPS equipment.

2.2 UPS input power factor is high and input current harmonics are small

The higher the input power factor, the higher the utilization rate of the UPS for the mains, that is, the lower the reactive power consumption; the smaller the input current harmonics, the less pollution the UPS causes to the mains, and the less energy the harmonic loss. This is because for the mains, the UPS is a rectifying load, which will produce harmonic pollution and reactive power consumption. These are what the power supply company does not want to see.

(1) Excessive reactive power consumption will increase the UPS upper transmission and distribution investment, that is, the wire diameter and circuit breaker capacity will increase; it will also increase line losses, etc. Therefore, the power department generally requires that the power factor of electrical equipment cannot be lower than 0.92 (in Guangdong), otherwise, the customer will be fined.

(2) The main hazards of power harmonics are:

①Cause series resonance and parallel resonance, amplify harmonics, and cause dangerous overvoltage or overcurrent;

② Generate harmonic losses, reducing the efficiency of power generation, transformation and power consumption equipment;

③ Accelerate the aging of insulation of electrical equipment, making it easy to break down, thus shortening its service life;

④ Cause equipment (such as motors, relay protection, automatic devices, measuring instruments, power electronic devices, computer systems, precision instruments, etc.) to operate abnormally or fail to operate correctly;

⑤Interfere with the communication system, reduce the transmission quality of the signal, destroy the correct transmission of the signal, and even damage the communication equipment.

Therefore, the lower the harmonics generated by the UPS, the more in line with environmental protection requirements. Generally, when the PF of the UPS is ≥ 0.99 and the THDI is ≤ 5%, the pollution to the mains can be basically ignored.

2.3 Scalability, that is, the ability to easily expand the capacity of the UPS

For the communication room, information equipment is gradually invested as the service volume increases. Therefore, for UPS, its load will gradually increase, which requires that UPS can increase capacity according to the increase in load within a certain range. For users:

(1) Customers can configure UPS capacity as needed, so that UPS is in a more efficient power range, saving energy consumption and avoiding unnecessary waste of UPS capacity. When users choose UPS, they often consider the need for increased capacity. When investing in the initial stage, the UPS capacity selected is larger, but the telecommunications business is growing slowly, which results in a relatively low UPS load for a considerable period of time, resulting in low UPS efficiency and increased losses at low loads. At the same time, part of the precious UPS capacity resources are also wasted.

(2) If the UPS capacity is insufficient, the traditional solution requires the purchase of a new UPS, which not only results in duplicate investment but also wastes valuable computer room space.

Therefore, the scalability of UPS is also an important factor in green UPS solutions.

2.4 High Availability

High availability reflects the reliability and maintainability of UPS. We say that green and energy-saving cannot be achieved at the expense of power supply reliability. Therefore, the availability of equipment is also listed as one of the characteristics of green and energy-saving UPS for communications.

The higher the availability, the more guaranteed the uninterrupted operation of the load. There are three aspects to improve availability. The first is to improve the reliability of the system itself, that is, the longer the mean time between failures, the better. However, no matter how long the mean time between failures is, it cannot guarantee that the UPS device will not fail. Therefore, the second aspect is to adopt a redundant method, that is, if one UPS device fails, it can be replaced by another UPS device. Third, the faulty UPS device must be repaired in the shortest time, that is, the mean repair time should be short.

Specifically, it should have:

①The UPS system itself must be highly reliable;

②Adopt modular design to minimize maintenance time;

③The UPS system itself must have redundancy function, that is, if a part fails, it can be replaced by a part with the same function without affecting the normal operation of the system.

2.5 Green production and manufacturing process, compliant with RoHS Directive

The green and energy-saving of the communications industry not only reduces the consumption of the enterprise itself, but also takes the protection of the environment and human health as its own responsibility. Lead is a heavy metal. In the production and manufacturing process of electronic equipment, it will cause heavy metal pollution, pollute the environment, and affect people's health. Therefore, in order to avoid heavy metal pollution in the production and manufacturing process of electronic equipment, the production process should introduce lead-free process, namely RoHS. For example, the EU has required that imported products must comply with RoSH process.

To sum up, a green UPS solution should be an energy-saving, highly available, and environmentally friendly uninterruptible power solution.

3 To meet the needs of users in communication information rooms for green uninterrupted power solutions, Zhongda launched the DELTA C (surpass) UPS solution

3.1 How does Delta's green UPS solution meet the above requirements?

3.1.1 High conversion efficiency, especially at low load

DELTA C UPS adopts patented IGBT rectification technology and three-level inverter design, which greatly improves the conversion efficiency of the whole machine. As shown in the figure below, the efficiency curve of DELTA C UPS 20KVA module is shown in Figure 1.

Figure 1 Efficiency curve

As can be seen from the figure, when the load is less than 2kW, that is, about 10% (2/18), the conversion efficiency reaches 90%. As the load increases to 30% (6/18), the efficiency reaches more than 94%. When the load increases further, the efficiency even reaches 95%. Therefore, the conversion efficiency of DELTA C UPS is very high, whether it is fully loaded or lightly loaded. Long-term use can save users a lot of electricity bills.

3.1.2 UPS input power factor is high and input current harmonics are small

DELTA C UPS adopts IGBT rectifier design, and adopts patented technologies such as digital signal processor (Duble-DSP) and space vector pulse width modulation (SVPWM: Space Vector Pulse Width Modulation) technology, so that the input THDI can be ≤5%, PF≥0.99. It solves the problem of UPS harmonic pollution to the mains and high mains utilization rate. The following figure shows the measured waveform of output current harmonics:

(Yellow is the UPS input current waveform)

Figure 2 Output current harmonics

3.1.3 Scalability

DELTA C UPS adopts modular design concept. One UPS can be composed of one or more power modules. Each power module is 20kVA. Users only need to select UPS with appropriate capacity according to the current load situation and the future load increase. When the load increases, users only need to add power modules to conveniently increase the capacity of UPS without adding a new UPS. It can greatly save user investment and reduce the floor space of the computer room. More importantly, it can also keep the UPS in an appropriate load state, always keep the UPS in a high conversion efficiency, and achieve maximum energy saving. As shown in the figure below.

Figure 3 Convenient expansion

3.1.4 High Availability

(1) Since DELTA C UPS adopts a modular design, when the UPS is damaged, it can be repaired by simply replacing the damaged UPS module, which greatly shortens the time for UPS fault finding and repair. Each power module is only 25kG and can even be replaced by the customer themselves.

(2) The rectifier, inverter and monitoring module of DELTA C UPS are all controlled by independent DSP, which greatly simplifies the circuit design, reduces the number of components and improves the system reliability.

(3) The auxiliary power supply circuit and static switch control circuit of DELTA C UPS are both designed with redundancy, that is, the auxiliary power supply and static switch are designed as two circuits, which back up each other. This can ensure the long-term stable and reliable operation of the system.

(4) DELTA C UPS can record 500 event data, which will not be lost even if the power is off, making it easier to find the cause of the fault.

(5) Maintenance bypass switch. It has electronic protection function, and the UPS will not be damaged when it is operated incorrectly.

(6) Manageability. Extra large screen, powerful monitoring function, 2 independent SNMP slots, RS232, dry contact, etc.

The above measures have effectively solved the three aspects of high availability: the system itself has high reliability, the system itself has redundancy, and the maintenance time is short when the system fails.

3.1.5 Greening of manufacturing engineering

DELTA UPS is not only sold domestically, but also exported to Europe, the United States and other places. Therefore, DELTA UPS products began to undergo RoHS process transformation as early as 2006, and currently all products comply with RoHS process.

3.2 Delta's green UPS solution meets the development needs of the industry and has been widely used in the communications industry

The following are two simple examples to illustrate this.

3.2.1 A computer room of Guangzhou Telecom uses Delta C series 60kVA UPS to form a power supply solution that integrates single machine, redundancy and green. (As shown below)

Figure 4 Power supply solution for a computer room of Guangzhou Telecom

3.2.2 A certain computer room of Dongguan Mobile uses two Delta C series 40kVA UPS to form a parallel redundant power supply system. (As shown below)

Figure 5 Parallel redundant power supply system in a computer room of Dongguan Mobile

4 Conclusion

Environmental protection and energy saving have long been Delta Electronics' business mission, and "energy saving, environmental protection, and love for the earth" is Delta Electronics' corporate slogan. Therefore, Delta's C series green UPS solution was born in such a corporate environment. At the beginning of its design, it has always placed green, environmental protection, and energy saving as the top priority. Therefore, DELTA C UPS fully meets green and environmental protection needs and provides a true green UPS solution for customers in the communications industry. I believe that as green power solutions continue to become more popular, it will bring more value to customers. At the same time, it will also contribute to the realization of the environmental protection and energy saving goals of communications companies.