news information
DC screen maintenance knowledge
 1. Selection of DC screen battery    As a device that provides uninterruptible power supply, DC storage battery is the core of DC system. Early DC systems mostly used ordinary lead-acid batteries, but due to their low overload capacity and prone to acid corrosion, they were gradually replaced by alkaline cadmium tweezer batteries after the 1980s. Alkaline cadmium tweezer batteries have the following advantages over original lead-acid batteries:    1) Small size, good mechanical strength, will not be damaged by large impact and strong vibration.    2) Small voltage drop, small energy loss caused by self-discharge.    3) Strong over-discharge capacity, can withstand large overload in a short time.    4) Strong overcharge resistance, no internal short circuit caused by overcharge.    5) Stable discharge voltage, long life, if used properly, can reach more than 3000 cycles.      At present, alkaline cadmium tweezers battery is still a good DC battery, but it also has some shortcomings, mainly such as low battery cell voltage, large number of uses; large battery maintenance workload; cumbersome maintenance work, high maintenance requirements. In response to the above problems, a maintenance-free valve-controlled sealed lead-acid battery has now entered the market. Its biggest advantage is that it has low maintenance, high battery cell voltage, small number of uses, and easy battery cell monitoring. However, there are still some shortcomings, such as low discharge overcurrent multiples and slightly poor low-temperature performance. The lifespan is also slightly shorter than that of cadmium tweezer batteries. The battery cannot be restored after aging, and it is prone to online aging when it is close to its lifespan. The capacity drops sharply. If the inspection is not timely, it is easy to become a hidden danger of accidents.      Based on the above comparison, if the DC system load is heavy, the overload may be large (such as the operating power supply of the electromagnetic operating mechanism), the installation site environment is good, the ambient temperature is not high, and there is strong maintenance force, it is recommended to consider using alkaline cadmium tweezer batteries. On the contrary, if the load is light, the possibility of overload is low (such as the operating power supply of the spring energy storage switch operating mechanism), the installation environment is general, and the maintenance force is weak, it is recommended to use maintenance-free lead-acid batteries.    2. Choice of charging system      In terms of charging equipment, the thyristor phase-controlled DC charging system is currently used more. The battery charging is divided into two stages: main charging and floating charging. The charging current is divided into two methods: high current strong charging and trickle charging. The common control methods include thermal sensor method, timing method, negative sequence voltage slope method, volt-ampere method, etc. In recent years, many manufacturers have continuously improved this type of DC system, mainly in its control technology, such as integrated circuit technology, PLC technology, microcomputer monitoring, "three remote" communication and other technologies, so that the reliability of the phase-controlled charging equipment system is continuously improved. Therefore, the reliability and practicality of this type of DC screen system are basically satisfactory.      However, the phase-controlled charger still has the shortcomings of large output voltage harmonics, large current ripple, and difficult to improve the current stabilization accuracy. At the same time, since it generally adopts the master-slave backup mode, in some occasions, the system reliability is still a little bit lacking. Therefore, in some places where DC power supply is required to be high, a relatively new type of high-frequency switching power supply is gradually adopted abroad. The overall structure adopts a module combination mode. The module schematic diagram is as follows, that is, the three-phase AC is first rectified into phase-controlled DC, and then converted into high-frequency AC. The high-frequency AC is then isolated by a transformer, rectified by a full bridge, and filtered to be converted into a stable DC output. The biggest feature of this DC power supply is high current stabilization accuracy, small ripple, and small harmonic distortion. It is a high-quality DC power supply. When forming a DC system, a combination of N unit modules can be used to provide DC output, so the backup degree is high and the overall reliability of the DC system is high. This type of DC power supply is currently produced by domestic manufacturers, but it is slightly inferior to the traditional phase-controlled DC panel in terms of overall appearance. Enterprises can make comparisons when choosing a DC power supply.       3. DC panel system maintenance     Cadmium nickel batteries should pay attention to the following issues when using:     1) Regularly charge and discharge the battery pack at high power to activate the chemical substances inside the battery, reduce the battery inertia, and restore the battery capacity.     2) Check the battery liquid level frequently, and adjust the battery liquid level that is too high or too low in time when the battery is full.     3) Check the battery solution concentration regularly, add alkali solution or water when the specific gravity changes, and re-prepare the electrolyte if necessary.     4) Check the battery terminal voltage regularly one by one, and perform "activation" treatment on individual batteries with large voltage drops.     5) Pay attention to the battery ambient temperature. It is best to operate the battery at a temperature below 40℃ to avoid aggravating the self-discharge of the battery and causing the battery capacity to decrease.     6) Keep the battery clean and the environment dry to avoid battery alkali creep, which will cause the battery capacity to decrease and the insulation of the DC system to decrease. During normal times and maintenance, the alkali solution overflowing from the battery should be wiped clean with a dry cloth in time, and the outside of the battery must not be rinsed with water.    2. Maintenance of maintenance-free lead-acid batteries    Maintenance of maintenance-free lead-acid batteries requires less maintenance work during operation. Usually, you only need to check whether the battery connections are intact and keep the connections free of rust and corrosion; observe whether the battery is swollen or deformed; whether the sealing valve is intact; whether the electrode column has signs of melting; and keep the battery clean and dry, etc. At the same time, regularly check the battery cell terminal voltage to promptly detect and deal with failed batteries.     3. Other maintenance of DC system    The main maintenance work in DC system is battery maintenance. In addition, the following should be noted during the operation of DC system:    1) Keep the DC system dry and clean, especially to avoid battery leakage from contaminating wires and devices, which may cause the insulation of DC system to decrease and DC grounding to occur.    2) Regularly check the functions of DC panel system, such as equalization charging, floating charging, insulation monitoring, fault monitoring, alarm and other functions, to ensure that the equipment is in good condition.    3) Regularly check the status of components of the system, especially pay attention to common problems such as overheating of thyristor components and DC melting of contacts of feeder switch components.
2025-01-14
THK Series Embedded DC Power Devices
   The THK series embedded DC power devices are high-reliability DC power supply equipment designed for various application scenarios. This series of products adopts advanced technology and has the characteristics of high efficiency, energy saving, and easy maintenance. It is suitable for use in power plants, substations, communication base stations, data centers, and other fields.   The main features of the THK series embedded DC power devices are as follows:   1) High efficiency and energy saving: The product adopts advanced power electronic technology, with high power conversion efficiency and low energy loss, which can effectively reduce operating costs.   2) Modular design: The device adopts a modular design, which is convenient for installation, maintenance, and expansion. Users can flexibly configure the system according to actual needs.   3) Intelligent monitoring: The product is equipped with an intelligent monitoring system that can monitor the operating status of the device in real-time, providing users with timely fault alarms and maintenance suggestions.   4) Strong adaptability: The device has strong environmental adaptability and can operate stably in high temperature, high humidity, and other harsh environments.   5) High reliability: The product uses high-quality components and advanced manufacturing processes to ensure the long-term stable operation of the device.   The THK series embedded DC power devices have been widely used in various industries and have received unanimous praise from users. In the future, with the continuous development of technology, the performance and application range of this series of products will be further improved, providing users with more high-quality DC power solutions.
2025-01-13
Overview of Power Reform and Development
   The power industry is the foundation of national economic development and social progress. The development of the power industry is closely related to economic growth, technological progress, and social stability. In recent years, with the rapid development of the global economy, the demand for electricity has continued to grow, and the power industry has entered a new stage of reform and development.   Power reform is an inevitable requirement for the modernization of the power industry. Through reform, the power market can be established, competition can be introduced, and the efficiency of resource allocation can be improved. At the same time, power reform also aims to solve the problems of monopoly and inefficiency in traditional power systems, promote the diversification of energy sources, and ensure the sustainable development of the power industry.   The development of the power industry is inseparable from technological innovation. With the continuous advancement of science and technology, new energy technologies, smart grid technologies, and energy storage technologies are constantly emerging, providing strong support for the development of the power industry. For example, the application of renewable energy such as solar and wind energy has greatly reduced dependence on traditional fossil fuels and improved the environmental friendliness of the power industry.   In addition, the development of the power industry also faces many challenges. For example, how to balance the relationship between economic growth and environmental protection, how to ensure the safety and stability of the power supply, and how to deal with the impact of climate change on the power industry are all issues that need to be addressed in the future development of the power industry.   In general, the power industry is an important part of the national economy. Through reform and development, we can build a more efficient, cleaner, and more sustainable modern power system, providing strong support for economic and social development.
2025-01-08
Insights from European and American Power Development Models for China's Power Reform
The recent large-scale power outage in Europe surprised many and was regarded as a signal of power shortages and weak power grids in Europe and the United States. China's power reform model, which takes Western power reforms as a benchmark, has bypassed the government intervention market model that has been used in the West for nearly a century and has chosen the popular market competition model. The "market mechanism" is an unavoidable hurdle. How to make the market the main force in resource allocation will become an increasingly clear focus of reform.   European and American power reforms were once called the "textbook" for Chinese power reforms. Now, this textbook has an upgraded version. In October 2006, the Cambridge Energy Research Associates (CERA) completed the research report "Lessons from Foreign Power Reforms for China." Recently, the author interviewed Dr. Zhang Chi, a senior researcher at CERA who chaired the project.From Efficiency Excavation to Attracting Investment   Dr. Zhang Chi believes that in the four years since the start of China's power reform, the global power reform process, which serves as a reference, has progressed much slower than expected. To date, no country has completed the complete separation of "generation, transmission, distribution, and sales" as outlined in the "textbook." The design of "efficiency excavation" on the basis of "mature markets" in Europe and the United States is being troubled by power shortages and environmental issues. Attracting power investment has become an increasingly serious problem.   The U.S. power system is currently in a "hybrid mode" of "half regulation and half freedom." The "New Energy Act" introduced in 2005 is considered a "system patch that recognizes the status quo." To encourage corporate investment in power grids, the U.S. Federal Energy Regulatory Commission announced tax refunds or tax reductions for grid investors and increased reasonable profit margins. After the surge in natural gas prices, new power producers have chosen coal-fired power generation, and more discussions are being held about nuclear energy projects. "It has become easier to renew licenses for old nuclear power plants."   "The recent federal government policies encouraging grid and clean energy investments all need to bear huge environmental pressures, fully demonstrating the importance the U.S. attaches to power investment," Zhang Chi said. "At the beginning of China's power reform, there were two misunderstandings. One was that developed countries did not need power investment, and only developing countries like China did. However, it now seems that attracting investment is a common challenge. The other misunderstanding was that attention should be focused on competition in power generation. However, in recent years, more and more countries have found that if the grid lacks investment, the foundation of the power market is difficult to guarantee."   But attracting power generation investment is not easy. Due to the large amounts and long cycles involved, investors often need sufficient commitments. The lessons from the failure of California's power reform prove that long-term transitional contracts are the foundation for market stability. Another "universal principle" is that the transmission and distribution links must be completely independent of market transactions to dispel concerns about fair competition among market participants.   However, these issues have become somewhat unique in China. After the cancellation of long-term power purchase contracts in 2002, on one hand, state-owned power generation groups expanded aggressively, while on the other hand, foreign investors shifted their interest from building factories to the stock market. Private capital, limited by funds and channels, tested the waters in small thermal or hydroelectric power. Existing power producers are concerned about fairness, while the potential danger lies in new investors being hesitant to enter.   Can't China's rapid economic growth dispel foreign investors' concerns?   "Investors across the Pacific value regulatory risks and clear returns. China's power reform has no definite timetable, and only state-owned enterprises dare to invest. After 2002, foreign power plant investors withdrew, and those who entered were buying stocks and bonds," Zhang Chi said. "Korean Electric Power Corporation, Hong Kong's CLP Holdings, and some Southeast Asian companies familiar with China's system and culture are relatively bolder."   The core issue is not whether China's five major power generation groups can meet the needs of power development, but whether the quality of development has lost its standard. "China introduced foreign investment largely to use foreign companies as benchmarks to pressure Chinese companies. But in power generation enterprises, this pressure does not exist because foreigners have all withdrawn."   More challenging is grid investment. On congested sections, even a Ferrari may not outrun a tricycle. The "rally race" of the power market will be constrained by weak grids. Compared with the world average ratio of 1:0.5:0.7 for generation, transmission, and distribution investment, China's ratio is 1:0.23:0.2. The long-term imbalance in investment is becoming increasingly apparent. However, there is still controversy over increasing grid investment. A strong grid is seen as a tool and symbol of monopoly. The State Grid Corporation's investment plan for ultra-high voltage grids has sparked numerous questions. Compared with Brazil's successful use of nodal pricing to attract transmission facility investment, China's grid projects rely mainly on bank loans, and the listing plans of grid companies have been repeatedly shelved.Markets Do Not Pursue Administrative Divisions   "Now the EU grid is somewhat like China's grid. China's grid needs to break provincial barriers, while the EU needs policies to promote grid investment and strengthen power interconnection to break the division between countries," Zhang Chi said.   To ensure that power interconnection becomes the "public transportation system" of member states, the EU initiated 50 related lawsuits in April 2006 against 17 member states for not following the reform direction of the electricity and natural gas directives. In July 2007, Europe will operate a unified power market. While Europe has chosen market integration with a "synchronized grid, the bigger the better," Chinese experts are still debating the scope and model of the power market.   Zhang Chi believes that the power market is an auxiliary to commercial power transactions, not to mandate or force these transactions. It is not a political or geographical concept. For example, the PJM power market in the United States spans multiple states but only includes parts of certain states, not all of them. Even within the PJM market, there are local areas that do not participate in competition and operate under traditional regulatory methods. On the one hand, the market needs to start at a certain point, but the most important thing is that it is dynamic and expands with the development of power transactions and grids. Establishing a unified and effective power market requires strong political authorization. For example, in countries like the UK and Sweden, strong national will has ensured the true integration of domestic markets with neighboring countries, thereby truly opening up the power market.   On the other hand, it is necessary to avoid artificially defining market boundaries based on traditional government jurisdiction concepts. Currently, China's power reform deliberately emphasizes the establishment of six regional markets while excluding any other considerations (this could be modified to be more neutral, such as "Currently, the construction of power markets is constrained by administrative boundaries at the provincial or regional level, which may hinder the development of power transactions"). In fact, this approach has not captured the essence of building a market: it is about providing a platform for transactions and voluntary and independent transactions between buyers and sellers, not government-mandated transactions.   Energy resources being far from load centers is not unique to China. Like China, large countries such as India, Brazil, Russia, and the United States have long-distance transmission issues and market trends of selling cheap electricity from remote areas to load centers. Their experience proves that competition in the wholesale market is of great significance for resource optimization. For example, the PJM regional market in the United States is currently expanding to the south and Midwest. Its boundaries are not artificially defined. New power generation resources benefit a large number of consumers in the market. Especially when natural gas prices are high and unstable, the allocation of resources over a larger area is one of the main manifestations of its market success.   Are national, regional, and provincial power markets mutually exclusive or open to each other? Domestic debates cannot overshadow the voice of the market: the loss of trading opportunities is the real loss of efficiency and social welfare.Increasingly Clear Reform Focus   The basic debate on power reform is called the debate between engineers and economists, but everyone also believes that a path suitable for national conditions must be taken. What is unclear is how to combine the thinking of engineers and economists. What exactly are the "national conditions" of China's power reform?   "The way engineers think is not the real factor affecting China's power reform. The real factor is that people have not theoretically established full trust in the market," Zhang Chi said.   Tracing back to the source, Zhang Chi pointed out that the starting point of China's power reform is different from that of the West. The traditional models of "state-owned and state-operated" and "privately owned and state-supervised" at the beginning of Western power reforms are still market models, but competition was introduced after the reforms. In China, the government is the controller and decision-maker of resource allocation. In contrast, in the West, electricity is allocated according to the market, and all parties are subject to legal systems that maintain market fairness.   Due to the physical characteristics of the power network, market failure is inevitable. Western governments try to correct market failures by simulating market environments as much as possible, such as implementing emission trading or formulating energy policies, using measures like taxes, regulating financing costs, electricity prices, and profit margins to overcome monopolies, reduce pollution, and attract investment. In comparison, these policies in the West often achieve good expected results without distorting the energy market.   It is as if the government's role is to repair roads and traffic lights, rather than stepping on the brakes or pressing the accelerator for businesses. Now, domestic attention is increasingly shifting to unbundling, as if the means have become the end. But who can clearly explain what comes after unbundling?
2024-12-30
1234 共48条 4页,到第 确定
186-3733-3097
189-0380-1549

关注微信