DC power screen selection

How to choose the right (variable) DC power supply screen for power station

The power operation power supply is DC power supply equipment for power plants and various substations such as 550KV, 220KV, 110KV, including instrumentation for circuit breaker switching and secondary circuit, relay protection, control, emergency lighting and various types. Low voltage equipment uses electricity.

At present, most of the DC switching power supplies used in China's electric power use phase-controlled power supplies, but the phase-controlled power supplies are not satisfactory in terms of ripple, efficiency, volume, etc. The monitoring system is imperfect, the master-slave is divided, and the users are inconvenient to use. New requirements for power systems are not up to standard. In addition, since the charging device operates in parallel with the battery, when the ripple system is large and the floating charging voltage fluctuates or is low, the battery pulse charging and discharging may occur, which is disadvantageous to the battery.

Since the 1990s, new power plants and substations in the United States, Germany and other Western countries have all adopted switching power supplies. The batteries have also been converted from lead-acid-free batteries to the original cadmium-nickel batteries, due to the new circuit breaker vacuum switch or spring energy storage type. Adoption, the closing current is greatly reduced, and the double busbar is gradually replaced by a single busbar.

The high-frequency switching power supply caters to the trend of modern power supplies because of its small size, light weight, high efficiency, small output ripple, module stacking, N1 hot backup design, and easy computer management. Switching power supplies have been widely used in computer, aerospace, communications, instrumentation. In recent years, domestic power supplies have gradually replaced phase-controlled power supplies with switching power supplies. It is expected that switching power supplies will gradually replace phase-controlled power supplies in power-operated power supplies.

With the increasing popularity of high-frequency switching power supplies in China's power systems, more and more conventional DC power panels of substation power plants have been replaced by high-frequency switching power supplies. The former Ministry of Electric Power and the Ministry of Water Resources also clearly promoted the miniaturization and unattended mode of power stations. This trend has led to the emergence of numerous manufacturers in the DC power supply market. So how do you choose the DC power screen you need?

1. Is the selected device suitable?

When many people choose high-frequency DC power supply devices, they often have the understanding that the higher the technical level, the better, the higher the price, the better. This is not the case. There is a process for any product from trial production to perfection. This requires the user to feedback the problems in actual operation to the manufacturer for continuous improvement, and the principle of high-frequency switching power supply is very mature. Most manufacturers use classic circuits. Therefore, the device you choose is preferably a product with more than one year of stable operation experience. On the other hand, we should consider the adaptability of the technical requirements of our substation. For example, most rural (variable) power stations in China do not have the conditions of unattended operation, so there is no need to select four remotely functioning devices, such as considering possible networking in the future. For communication requirements, the communication interface can be reserved when ordering, so that it can be modified in the future. Secondly, battery selection is also very important. The battery is divided into acid-proof, sealed and fully sealed.

2. Anti-interference and reliability of equipment

With the rapid development of science and technology, in recent years, new achievements in microcomputer technology have been widely adopted in power plant integrated automation devices, which greatly improved their automation. But the most important and fundamental requirement of the power system is the safety and reliability of the equipment. For this reason, when selecting a DC power supply unit, special attention should be paid to the main measures of its anti-interference. For example, the high-frequency interference performance of the charger and the central controller, the lightning resistance of the system and the reliability of the system grounding must be strictly evaluated.

High-frequency switching power supplies are controlled by microcomputers. Some manufacturers use industrial computers, some use programmable controllers, some use single-chip microcomputers, and computer technology develops rapidly. Therefore, the situation often arises: representing the most advanced technology production of the year. The product lacks the necessary running time, and its reliability is a question. In general, programmable controllers are highly reliable but expensive.

3. Whether operation and maintenance is simple and convenient

When users adopt high-frequency switching power supply to affirm their advanced performance, they should also consider whether their operation is simple and easy to learn, and whether maintenance is convenient. Therefore, the control software of the central controller should be intuitive and easy to operate, no matter how advanced. Convenience. In the event of a fault, the display can automatically display the main parameters such as the nature of the fault, the time of occurrence, the location of the fault, etc., and has a strong self-test function to facilitate user maintenance. Therefore, when selecting the DC power supply screen, pay attention to observe the software display of the manufacturer, and combine with the actual situation of its future operation and maintenance, and examine whether the operation and display of the central controller are simple and intuitive.

4. Is the price reasonable?

A reasonable price is one of the factors that most users must consider. When many users consider DC power supply screens, they often feel that the price difference between different manufacturers of the same type of equipment is too large. In fact, this is caused by several reasons: First, the cost of high-frequency switch modules is different, and some manufacturers are high. The frequency switch module adopts imported components, and the cost of the module is high, and some manufacturers' high-frequency switch modules use domestic components, and the cost thereof is low. Second, the cost of the central controller is different. Some manufacturers' central controllers use programmable controller PLC, which is used by most manufacturers nowadays, and the manufacturers of programmable controllers are different, among which domestic brands The price is lower, the price of the original import is higher. Third, the output current of the modules used by different factories is not the same. For example, the output current of the module is small, the number of modules is large, and the reliability is high, but the cost is increased. For all of the above factors, users should consider it when ordering equipment.

5. After sales service

The quality of after-sales service directly affects the determination of users to choose high-tech products, and ultimately determines the manufacturer's sales market. In this regard, some manufacturers have neglected after-sales service under the prevailing market conditions, which ultimately led to a decline in corporate image and a shrinking market. There are profound lessons. Because the high-frequency DC power supply screen is a high-tech product, users, especially those with relatively low technical level, have a certain risk when making this choice for the first time. If the manufacturer does not do after-sales service, the user has worries. , it will inevitably affect its enthusiasm, and ultimately affect the promotion and application of products. There are many internal information exchanges in the power system. When selecting users, users can first understand the usage and opinions of the manufacturers, as a reference for selecting manufacturers.