1. Introduction Electricity, as a high-quality secondary energy source, has become an indispensable energy supply in modern industry. With the development of modern large-scale industry and the improvement of people's living standards, electricity consumption will continue to increase, especially in large steel enterprises, which consume a significant amount of electricity during production, accounting for a considerable proportion of their production costs. Electricity production requires a large amount of secondary energy. Currently, primary energy is becoming increasingly scarce, and energy conservation has become a major issue concerning the national economy and people's livelihood, directly affecting the country's sustainable development. The most important aspect of energy conservation is to start with energy saving. Against this backdrop, many energy-saving technologies have been developed both domestically and internationally, some of which are being commercialized or have already been commercialized and applied. It is foreseeable that strong demand will greatly promote the development and progress of the energy-saving industry. As a leading steel enterprise, Baosteel is a major electricity consumer, consuming nearly 10 billion kWh of electricity annually. Electric motors, electric furnaces, and other electrical loads require a large amount of electricity. In this context, energy conservation is not only a necessary measure for enterprises to reduce costs, but also a corporate social responsibility . 2. Overview of Energy Conservation at Home and Abroad Broadly speaking, energy conservation can be divided into management-based energy conservation and technical energy conservation. Management-based energy conservation involves strengthening management, improving measures, and raising the energy-saving awareness of personnel at all stages of energy use, thereby avoiding human-caused waste of energy and optimizing energy use. Examples include the lack of standardized temperature settings for office air conditioners in summer and winter, the phenomenon of running air conditioners while windows are open, and lights left on continuously in offices. Since 2005, Baosteel has formulated a series of energy-saving management measures. Through about a year of strengthened on-site enforcement, inspections, and rectification, the awareness rate of non-production electricity usage regulations among employees has reached 10-1%, and the phenomena of lights left on continuously and air conditioners running while windows are open have been greatly reduced. It is estimated that this can save 15 million kWh of electricity annually. It should be said that management-based energy conservation still has considerable potential in some enterprises. Energy saving through technology mainly involves analyzing the different characteristics of energy consumption in the use and transmission of electricity, and then taking corresponding technical measures and equipment upgrades to achieve energy savings. Currently, energy saving technologies can be divided into energy transmission energy saving and equipment energy saving according to their application scope, which will be introduced below: 2.1 Energy Saving in Power Grid Transmission Electric energy generally needs to pass through transmission and distribution lines and transformers from the access point to reach the final electrical equipment. This is especially true for large industrial enterprises, which have their own internal power grids. The external power grid is connected to the enterprise's internal power grid through transmission lines, and the internal power grid distributes the energy to various usage points. Lines and transformers both generate a certain amount of energy loss. Therefore, optimizing the configuration of lines and transformers can achieve energy saving, i.e., upgrading outdated, high-loss lines and transformers to reduce network losses. Furthermore, optimizing the power flow distribution through the economical operation of lines and transformers can further reduce network losses. The power quality of the power grid directly affects the energy use of electrical equipment. Therefore, improving the power quality of the power grid, including harmonics and reactive power compensation, can also achieve energy saving to a certain extent. Currently, this field is developing rapidly both domestically and internationally, with various energy-saving technologies and products that reduce losses by improving power quality emerging in the market. 2.2 Equipment Energy Saving The final link in the use of electrical energy is the electrical equipment, and this is also the link with the greatest potential for energy saving. This mainly includes the transformation of aging and inefficient electrical equipment and the application of new energy-saving technologies. In equipment transformation, power electronics technology plays an important role, such as equipment speed regulation and reactive power compensation. This area is also developing rapidly. 3. Basic Situation of Baosteel's Power Supply and Consumption and Baosteel's Energy Saving Potential 3.1 Main Characteristics of Baosteel's Power Supply and Consumption Structure As a super-large integrated steel enterprise, Baosteel has an average power load of 1.1 million kW and a maximum load of 1.45 million kW, with a daily power consumption of about 26 million kWh, close to 1/10 of Shanghai's power load. As a regional power grid, Baosteel has its own self-owned power plant, namely three 350MW units and one 150MW gas turbine unit. In addition, there are 8 waste heat and waste pressure units (with an installed capacity of 146MW), and the self-owned power plant has enabled Baosteel to save on electricity costs to a certain extent. 3.2 Basic Composition of Baosteel's Load Due to the continuous production characteristics of the steel plant, Baosteel's electricity load is greater at night than during the day, and greater on holidays than on weekdays. The impact of annual unit maintenance on the electricity load is greater than that of seasonal changes. Secondly, the production involving electric furnaces and rolling mills generates impact loads on the power grid. Baosteel's main power-consuming equipment can be summarized as follows: 1) Electric Blowers: Electric blowers provide ironmaking air to the blast furnace, currently consisting of 5 blowers (1 of which is a backup). The blower motor power is 48,000kW/unit, with a total annual power consumption of approximately 1.1 billion kWh. 2) Oxygen Generators: Currently, there are 6 oxygen generator units. Oxygen generators #1 and #2 each have an oxygen production capacity of 26,000 Nm³/h, with a total installed capacity of 45,340 kW. They were put into operation in 1984. Oxygen generator #3 has an oxygen production capacity of 30,000 Nm³/h and an installed capacity of 20,500 kW, and was put into operation in 1987. Oxygen generator #4 has an oxygen production capacity of 30,000 Nm³/h and an installed capacity of 20,400 kW, and was put into operation in 1991. Oxygen generator #5 of Baosteel Phase III has an oxygen production capacity of 60,000 Nm³/h and an installed capacity of 57,220 kW, and was put into operation in 1997. The No. 6 oxygen unit has an oxygen production capacity of 60,000 Nm³/h and an installed capacity of 48,950 kW. It was put into operation in 2000. The power consumption of the oxygen production equipment in phases one, two, and three is 0.461 kW•h/Nm³, 0.428 kW•h/Nm³, and 0.423 kW•h/Nm³, respectively, with a total annual power consumption of approximately 1.2 billion kW•h. 3) Electric arc furnace: The electric arc furnace steelmaking system includes one 150-ton DC electric arc furnace and one AC refining furnace, with installed capacities of 99 MVA and 22 MVA, respectively, totaling 121 MVA, and an annual power consumption of approximately 460 million kW•h. 4) Rolling mill: Baosteel's hot rolling and cold rolling are among Baosteel's main production processes. The rolling mill system consumes approximately one-third of Baosteel's total electricity consumption, about 2.8 billion kWh. 3.3 Potential and Challenges of Energy Conservation in Steel Enterprises Steel enterprises consume enormous amounts of electricity, presenting both significant potential for energy conservation and considerable challenges, primarily in the following aspects: 1) Insufficient investment in energy conservation over the years has resulted in relatively weak awareness and urgency among employees regarding energy conservation. 2) Production and operation often focus on preventing equipment power outages rather than energy conservation. While there is significant potential for energy conservation, the challenges are also considerable. Balancing energy conservation with system safety, process and product quality is sometimes difficult, making decisions that struggle to effectively manage the relationship between risk and reward. 3) Systematically plan and promote energy conservation efforts to achieve breakthroughs. Gradually phase out energy-intensive power supply and distribution equipment, reduce electricity consumption per ton of steel, and decrease the planned power shortage. 4) Further optimize the company's main production process maintenance model, shorten power plant maintenance time, and minimize the company's reverse power supply. 5) Conduct labor competitions to generate more surplus energy, improving the operating rate and power output of power generation equipment. 6) Strengthen power consumption management, optimize operation modes, and improve power utilization efficiency by combining process production characteristics. Strengthen the evaluation , assessment, and benchmarking of process power consumption. 4. Application of Energy-Saving Products and Technologies at Baosteel Currently, Baosteel is actively promoting the application of energy-saving technologies and products within the company. Specifically, this can be divided into the following six aspects: energy-saving measures for main road lighting and indoor/outdoor lighting circuits in production areas; power quality management and energy-saving measures for low-voltage power distribution systems in production areas; promotion and application of frequency conversion energy-saving technology; application of coating and lubrication material technology; benchmarking analysis of process power consumption; and adjusting power plant maintenance time based on gas balance. 4.1 Energy-Saving Measures for Main Road Lighting and Indoor/Outdoor Lighting Circuits in Production Areas Baosteel's production area covers a large area with numerous production plants, resulting in a large amount of lighting equipment used 24 hours a day. Statistics show that the annual power consumption of lighting in the main plant of Baosteel's production area alone exceeds 90 million kWh. Therefore, Baosteel has significant potential for energy saving in lighting. Recently, energy-saving measures were mainly implemented for indoor and outdoor lighting circuits on main roads and in production areas, resulting in annual energy savings of 30 million kWh. The technical measures implemented were mainly twofold: First, energy-saving controllers were connected in series in power supply circuits with lighting loads above 30A to reduce voltage and limit current. The measured energy-saving rate in the implemented areas was approximately 23%, with a payback period of 3 years. Second, in areas where lamp replacement was feasible, high-energy-consuming mercury lamps were replaced with metal halide lamps. According to illuminance and energy-saving rate test reports in the areas already implemented at Baosteel, after lamp replacement, not only did the illuminance of the area increase, but the energy-saving rate also reached approximately 40%, with a payback period of 2 years. 4.2 Power Quality Management and Energy-Saving Measures for Low-Voltage Distribution Systems in Production Areas The low-voltage distribution systems of oxygen production, water treatment, and water production units in Baosteel's production areas contain many rotating equipment, such as fans with frequency converters, water pumps, and dewatering machines. These rotating devices generate instantaneous surges and harmonic currents during operation, polluting the power quality. We recently conducted power quality tests on the low-voltage power distribution systems of the water treatment units. The results showed that these systems suffer from severe current surges and high harmonic content. This leads to a high failure rate of electrical equipment connected to the system, reduced equipment lifespan, unexplained downtime, and wasted energy. Based on the current status of the low-voltage power distribution systems in each unit, the following improvement measures are proposed: 1) Continue to conduct power quality tests on fan and water pump systems with frequency converters to obtain transient surge and harmonic measurement data. 2) Based on the test results, conduct an overall evaluation of the power quality of the low-voltage power distribution systems connected to rotating equipment in the production area, and propose solutions for professional discussion. 3) Estimate the quality improvement and economic benefits after the measures are implemented. 4) The transformation goals are to reduce equipment downtime, annual equipment maintenance and spare parts costs, and achieve a 5% energy saving rate. This work is currently being implemented through research channels. If the research conclusions are largely consistent with the test results, we will vigorously promote this work. 4.3 Promotion and Application of Variable Frequency Drive (VFD) Energy-Saving Technology After the VFD devices for medium and low voltage systems such as water pumps and fans in Baosteel's production area were put into operation, the energy-saving effect was significant, with an average energy saving rate of over 25%. However, the VFD devices generate instantaneous surges and harmonic currents during operation, polluting the power quality. Therefore, this work needs to be carried out in conjunction with power quality management. It is considered that each department, based on its power distribution system configuration, will collectively propose modification plans for discussion by the company's professional departments. After plan certification and optimization, each department will implement the plans through technical upgrades or equipment improvements. The expected energy saving rate after implementation is over 30%. 4.4 Application of Coating and Lubricating Material Technology A survey and evaluation of the energy consumption of the company's currently in-service water pumps and fans will be conducted. A survey and energy consumption analysis will be performed on the configuration, operating efficiency, and other parameters of high-power water pumps and fans above 200 kW. Applying suitable polymer lubricating materials can reduce the internal flow resistance of water pumps and fans, thereby improving efficiency and saving energy. Based on the test results of the implemented 200kW water pump system, the energy saving rate is 3%, and the investment payback period is 1-2 years. 4.5 Process Power Consumption Benchmarking and Analysis Firstly, a survey was conducted on the current application status of some electrical equipment (including electrical rooms, transformers, relay protection devices, motors, etc.) designed within the Baosteel branch. The collected data was used for in-depth analysis of energy-saving potential. Simultaneously, through the collection of various data on process power consumption in Baosteel and other domestic steel mills (including coking, sintering, blast furnace, steelmaking, electric furnace, primary rolling, high-speed wire rod, hot rolling, cold rolling, steel pipe, etc.), the composition of process power consumption was decomposed and analyzed from various parameters such as raw materials, structure, process, and production scale. By comparing data from Baosteel with major domestic steel mills, the main influencing factors of high power consumption in certain unit processes were analyzed, along with the existing energy-saving potential. The investigation and analysis revealed that Baosteel, compared with domestic companies such as Maanshan Iron & Steel and Ansteel, and foreign companies such as Sinosteel and POSCO, has no advantage in electricity consumption per ton of steel except for the electric furnace process. This is not only due to differences in production processes and product processing depth, but also related to calculation methods and the need to strengthen the management of process electricity consumption. If efforts can be made to reduce electricity consumption in the rolling mill process, such as increasing equipment operating rates, reducing equipment standby rates, and improving the power factor of the rolling mill power system through reactive power compensation devices, Baosteel's electricity consumption per ton of steel can be further reduced. Currently, an investigation is underway into areas of Baosteel's power supply and distribution system with a power factor below 0.7, and preliminary conclusions have been reached. Optimization is planned through technical transformation projects. 4.6 Adjusting Power Plant Maintenance Time Based on Gas Balance Baosteel's power plant units are blast furnace generator units, capable of burning blast furnace gas, converter gas, coke oven gas, and coal. The power plant's four generator units require annual planned maintenance. If the generator unit maintenance time can be rationally arranged in conjunction with the company's main process annual maintenance plan, it can not only utilize various types of coal gas and reduce gas emissions, but also significantly reduce the back-supply from the power system. That is, generator unit maintenance can be arranged simultaneously with the annual maintenance of the most power-consuming processes. Conservatively estimated, this will reduce the company's back-supply by approximately 90 million kWh, reducing back-supply price difference losses by 12 million yuan. This work was carried out smoothly as planned last year, achieving the goal of annual electricity savings of 100 million kWh and generating economic benefits of over 50 million yuan. Considering the reduced equipment failure rate, extended equipment lifespan, reduced spare parts costs, and social benefits after system improvement, the results are substantial. 5. Prospects for Baosteel's Energy Saving Energy saving is a long-term endeavor, involving both management and technology. Baosteel has made significant progress in energy saving, but still has considerable potential, and the prospects for energy-saving applications are broad. Furthermore… Energy conservation sometimes conflicts with system safety. In some cases, reducing the safety margin can save energy to a certain extent. This requires case-by-case analysis. When the two conflict, a comprehensive consideration is needed. This is also an issue that needs to be considered comprehensively in Baosteel's energy conservation efforts. 6. Conclusion Energy conservation, especially for large industrial enterprises, has become essential. This is both a necessity for enterprises to reduce costs and a social responsibility. Large industrial enterprises have significant energy conservation potential, but specific problems need to be addressed to explore this potential. Energy conservation is not just a technical issue; it often involves both technical and management aspects, both of which have significant potential for energy conservation. Sometimes, management has even greater potential for energy conservation. Baosteel's energy conservation efforts have progressed rapidly and achieved good results, but in the long term, further progress in energy conservation still requires considerable work. (Article sourced from "Energy Saving Innovation 2006—Proceedings of the First National Electrical Energy Conservation Competition")