The development trend of Delta's highly intelligent and fault-tolerant UPS

Looking at the development history of UPS, from dynamic to static, from power frequency to high frequency, from low index to high performance..., huge changes have taken place in just a few decades. What is the reason for its development and change?

First of all, people's needs are the driving force behind the development and change of UPS, and the change of needs determines the development direction of UPS. When the city power is frequently interrupted, making it impossible to carry out normal production, people need a device that can keep the power on, so the primary dynamic UPS appears; when the use place and application scope of UPS change, people need a lighter and quieter UPS, so the static power frequency UPS appears; when people are more and more pursuing benefits and paying more and more attention to energy saving and environmental protection, people need a UPS with higher efficiency and better energy saving index, so the high frequency UPS appears...

Secondly, technological progress and the replacement of components are the objective guarantee for the development and change of UPS. The emergence of power and control components such as IGBT, high-performance magnetic devices, CPU, DSP, and the maturity and wide application of control technologies such as PFC and PWM waves have enabled the high power density, high efficiency, low cost, and low pollution characteristics of UPS to be realized.

Third, the rapid development of computer and network technology has led to a rapid expansion in the demand for UPS, which has provided a rare historical opportunity for the development and change of UPS.

The interaction between these three factors promotes the rapid development of UPS, but the most important and decisive factor is people's demand. Without demand, no matter how advanced the technology is or how good the components are, people may not think of applying them to UPS, and even if they are applied, they may not be widely adopted by the market. In short, there is no market without demand, and changes in people's needs guide the development trend of UPS.

So what kind of UPS do people need at this stage?

According to the survey, people's demand for UPS is mainly concentrated in the following five aspects:

1. Reliability is required. Is there any that never breaks down?

2. Emphasize availability. Is it possible to repair it immediately if it breaks?

3. If capacity expansion is required, is there any flexible configuration without restrictions?

4. Is there any method that has lower cost than others when it comes to operation?

5. To strengthen management, are there any functions that are practical and easy to implement?

In fact, these five aspects can basically be summarized into two points: intelligence and fault tolerance.

People pay the most attention to the reliability of UPS. So is there a UPS that never breaks down? No! Not only that, compared with other links in the entire power supply system, UPS is the easiest to break down and the least reliable.

A set of data from IEEE (Institute of Electrical and Electronics Engineers) shows that the MTBF (mean time between failures) of the battery is 1402524 hours, the MTBF of the circuit breaker is 2502878 hours, the MTBF of the terminal is 22993791 hours, and the MTBF of the UPS with static bypass is only 156362 hours, which is more than 150,000 hours, which is lower than the battery, circuit breaker, terminal and other links in the system. Some people may say that 150,000 hours is equivalent to 20 years, and the reliability is already very high! In fact, although MTBF is scientific, it is not credible because it cannot be measured and only represents the average time between failures of the equipment. The specific time of each failure is uncertain. Even a device with an MTBF of 20 years may fail in the first week of startup.

Since there is no UPS that never breaks down, people can only settle for the next best thing: Can the impact of UPS failure on the load be minimized or even eliminated? Can the faulty UPS be repaired quickly? In order to meet the first need, people have adopted complex system solutions such as series hot backup, 1+1 or N+1 parallel redundancy, dual bus or even triple bus. In fact, the more complex the solution, the more failure points there are, and the higher the system failure rate. People spend huge amounts of money to build complex UPS systems in order to improve the fault tolerance of the system.

Fault tolerance is a capability, that is, the ability of UPS to tolerate failures. The indicator that best reflects the fault tolerance of UPS is availability. Availability measures the ability of the system to provide continuous services. For a UPS system with high availability, when a UPS fails, it will not affect the continued operation of the system and can be repaired quickly. With the development of informatization, people have higher and higher requirements for power supply. Power cannot be cut off 24 hours a day, 365 days a year, so the demand for UPS is also changing from reliability to availability. The formula for availability is as follows:

From the formula, we can see that in order to improve the availability, we must increase the mean time between failures (MTBF) of the UPS or reduce the mean time to maintenance (MTTR) of the UPS. In fact, it is very difficult to improve the reliability of a single UPS system, which is restricted by many factors. However, it is very effective to improve the availability of the UPS by reducing the mean time to maintenance (MTTR) of the UPS.

The core of fault tolerance is the redundancy of internal system resources, and the technical support for resource redundancy is modularization. Solutions such as series hot backup, parallel redundancy, dual bus and even triple bus achieve system fault tolerance through mutual redundancy between UPS. However, the purchase, operation and maintenance costs paid to achieve this goal are also expensive, and even so, it may not necessarily meet people's needs for "fast repair of faulty UPS" because the modularity of these systems is not high enough. Taking Delta's HIFT series UPS as an example, a truly modular UPS has the following advantages in terms of fault tolerance:

1. Highest system reliability. When the UPS capacity is constant, the lighter the load, the more redundant modules there are, while a single unit or 1+1 parallel system with the same capacity cannot improve system redundancy as the load changes. For example, for a 4+1 redundant module UPS consisting of 5 20kVA modules, when the load is only 75%, the system configuration becomes 3+2, and its reliability is 20 times higher than that of a 1+1 parallel system with the same capacity configuration.

2. Fastest repair time. In the N+X redundancy mode, the faulty module can be replaced online, and the system repair time is completely controllable, which will not affect the normal operation of the system, and the MTTR is close to 0. In addition, the standardized factory repair of the module can also reduce the "recurrence rate of failure" by 500-2000 times.

From the above two points combined with the availability formula, it can be seen that modular UPS has the highest availability, that is, its fault tolerance is the strongest. Fault-tolerant UPS with low cost, high efficiency, high reliability and rapid repair will definitely become the development trend of UPS.

In current practical applications, over-configuration of UPS capacity has become the norm. It is not surprising that a 160kVA UPS is configured for a 30kVA load. This is mainly due to the following reasons:

1. The load capacity expands quickly. If the designer designs a UPS with insufficient capacity at the beginning, the mistake he makes is unforgivable.

2. The cost of increasing UPS capacity during equipment operation is very high.

3. Adding capacity while the equipment is in operation creates a serious and incalculable risk of downtime.

Over-configuration brings huge costs to users, which is not only reflected in the initial purchase cost, but also in other related aspects. For example, the purchase cost of air conditioners, operating costs, equipment installation costs, capital and time costs, etc. Modular UPS can gradually expand capacity as the business grows, saving resources to the maximum extent. The intelligent feature of flexible expansion without restrictions is becoming one of the needs of people for UPS.

In addition to the initial installation cost, people are also concerned about the operating cost of UPS, which is mainly reflected in the efficiency of UPS.

Because the efficiency of UPS not only determines its own power consumption, but also directly affects the cooling cost. Energy saving and consumption reduction is a hot topic in today's world. Many industries or units have formulated hard targets for energy saving and emission reduction. The intelligent feature of being able to operate with low emissions and high efficiency has also become one of the important demands of people on UPS.

In terms of energy conservation and emission reduction, Delta's HIFT series UPS is also excellent. Let's take this as an example. When the load is 15%, the overall efficiency of the HIFT UPS exceeds 90%, and when the load is 27%, its overall efficiency reaches 94%. Light load and high efficiency is a very practical intelligent feature, because the UPS works under a lower load in most cases. The benefits it can bring to users can be seen from the following examples.

Assuming the UPS power is 120kVA and the load is 30%, the annual power consumption of a single UPS is as follows:

It can be seen that the 94% efficient Haifu series UPS can save nearly 20,000 kWh of electricity per year compared with the ordinary UPS with an efficiency of only 88%. If calculated at 1.8 yuan per kWh, it can save nearly 40,000 yuan per year, and this does not include the cooling costs saved due to the improved UPS efficiency. So it is a small step in efficiency, but a big step in energy saving.

At present, the management function of UPS is getting more and more attention. Because the cost of personnel is getting higher and higher, whether the management function of UPS is intelligent directly affects the operating cost of the equipment, and even directly threatens the safety of the system. There are more than 20 stations on a subway line, and it is impossible to put a maintenance person at each station. The Qinghai-Tibet Railway is more than 4,000 to 5,000 meters above sea level, and it is impossible to send people to guard there for a long time. Therefore, the intelligent management function of UPS has become very important.

The management function of UPS is not only the management function of UPS itself, but also the management function of UPS for the power environment monitoring of the computer room, including the temperature and humidity, access control, smoke, fire alarm, etc. in the computer room. At present, UPS that can realize its own management function is very common, and the power environment monitoring of the computer room can also be realized through a special power environment monitoring system. However, the complex and expensive special monitoring system is difficult for people to accept. The intelligent power environment monitoring function of the computer room is another demand of people for UPS.

In short, as people's needs change, fault-tolerant capabilities that can be repaired quickly and intelligent features including convenient expansion, efficient operation, and comprehensive management will surely become the development trend of UPS. In this regard, Delta's HIFT series UPS is ahead of all brands of UPS. It is closely aligned with customer needs, has a clear positioning, and its modular system with pluggable replacement and repair and redundant configuration has reached the highest level of UPS availability. It emphasizes the fastest system repair time, the highest reliability, the most economical investment strategy, the lowest operating cost, and the most comprehensive dynamic environment supervision. It embodies the core value of customers and is a truly highly intelligent and fault-tolerant UPS.