In the whole process of production, strengthening personnel safety management and technical training, optimizing and improving equipment as much as possible is an important aspect of power plants to improve reliability. For power plants, reliability of power generation equipment is a comprehensive indicator, including: unplanned outages, equivalent availability factors, equivalent unplanned outage factors, reduced output times, utilization hours, etc. The indicator can provide a comprehensive understanding of the safe and stable operation level of a power plant.
Today, as power is getting tighter, how to improve equipment reliability is increasingly being valued by power plants. Based on his long experience in thermal control overhaul in power plants, the author from the dcs control system perspective on how to improve the reliability of the entire DCS control system in terms of control system selection, equipment installation, program design, test and acceptance, and technical training. Sexuality was elaborated.
1. Reliability of DCS control system With the development of the national economy and the improvement of people's quality of life, the relationship between the importance of electricity to the national economy and the improvement of people's quality of life is getting closer. Due to the particularity of power production, under the corporate goal of “grasping safety and efficiencyâ€, improving power reliability has become a social task. Only by giving full play to the enthusiasm and creativity of managers at all levels, relying on the advancement of technology and effectively mobilizing the initiative of all employees, can we improve the reliability of power generation equipment in a more detailed and practical manner to achieve good performance.
For large power plants, the reliability of the control system is critical to the safety and reliability of the entire plant. Around the 1970s, with the development of 4C technology and the improvement of single-machine parameters of thermal power plants, the control system has been developed in the direction of functional dispersion and management concentration, and its reliability has been greatly improved. Foreign countries began to operate in large power plants (stations). The Dispersion Control System (DCS) was introduced in the middle. In the middle and late 1980s, China also applied DCS to the complete set of imported generator sets. Up to now, the newly-built units have adopted various mature DCS control systems in the selection of control systems, and the old units with larger single-unit capacity have also passed. The control system was modified and the DCS control system was basically adopted.
As a manifestation of technological progress, the wide-scale promotion of DCS control systems has made great contributions to the safety and economic operation of power production. However, after the reform of the national power system, especially under the control of the market economy, how to improve the reliability of the DCS control system as much as possible, thus ensuring the safety and economy of power production, to become the safety and profit index as much as possible The more important the work is.
2, DCS control system selection Whether in the new unit or the old unit to carry out the control system transformation, are faced with the problem of choosing the ideal control system as cheap and cost-effective as possible. Here, let's take a look at the price of the control system, only from the perspective of improving reliability, we need to pay attention to the following aspects in the selection process of the DCS control system:
2.1 When selecting the DCS control system, priority should be given to the control system with good performance on similar units. Such a complete control system has passed the factory test and actual operation, and its reliable operation has been tested by time. At the same time, it is necessary to know as much as possible about the use of different DCS in other power plants, especially the major problems that are mainly present, so as to make comparisons and trade-offs in the bidding.
2.2 The hardware of the control system must have high reliability. Mature technology is adopted in all aspects of the production process on the electronic components. The electronic modules are preferably hot-swappable. The controller's computing and storage capabilities are sufficient, and the IO card has strong anti-interference ability.
2.3 The control system should be fully redundant in its structure. The control system controller, network communication, etc. must be redundant, and each redundant device must be able to achieve bumpless switching. The redundant structure can not only avoid the local fault expansion of the control system, but also ensure the safe and stable operation of the unit. It also ensures online troubleshooting of equipment failures, thus eliminating accidents.
2.4 The control system software is better maintainable. Especially the following aspects: the stability of the program and software is good, there will be no problems such as system or single controller crash; the system self-diagnosis is good: the controller and IO signal have error alarm; the human-machine exchange is friendly: it can be modified online. Procedures and downloads; spare parts are reliably guaranteed: easy to purchase within 15 years and short cycle, low price; powerful function. The software of the control system is readable, and the type of configuration function block can easily realize the various process functions of the DCS control system.
In addition, in the selection of DCS control system, we must fully consider the following aspects: In order to ensure the safety and reliability of the control system, the investment should not be less, in order to give full play to the advantages of DCS technology. For example, the logarithm of the controller should not be too low, so as to facilitate the reasonable allocation of control function allocation; the number of I/O modules should be reasonable, so as to avoid excessive concentration of important signals when allocating IO channels, to ensure each I/O mode. The balance of the pieces is reasonable.
3. Construction technology and quality have strict regulations on the installation of DCS control system, especially for the transformation system, it is especially important to choose a construction unit with good qualifications and construction experience. Once the selection of the control system is determined, the technical personnel of the construction unit must intervene in the design of the control system, out the construction drawing, formulate the construction measures and carry out technical training. Before the project starts, it is necessary to formulate a strict schedule according to the requirements of the construction period, and request The construction units organized the power to arrange their construction plans. Pay particular attention to the following issues during DCS control system installation and commissioning:
3.1 During construction, it is necessary to pay attention to the reliable insulation of the cabinet and the ground and the reliable grounding of the busbar of the cabinet. At the same time, it is necessary to do fire prevention for the holes, etc., and the cabinets should have anti-vibration measures.
3.2 When laying cables, pay special attention to the separation of strong and weak electricity, reliable grounding and anti-interference of shielded wires. In the wiring process, it must be in accordance with the design drawings (must be handed over to the person for careful review), according to the drawing construction, in the wiring, the cable and core mark should be clear and complete, can be maintained for a long time; the crimp terminal must be pre-insulated with the end of the tube deal with.
3.3 Strictly control the environmental conditions between electronic equipment, pay attention to fire, air conditioning, ventilation and lighting. In particular, ventilation and air conditioning are required. Due to the strict temperature requirements of the DCS control system, the air conditioning system should be put into operation as soon as possible. The air outlet of the central air conditioner should not be facing the cabinet or DCS other electronic equipment to prevent the condensate from penetrating into the equipment. At the same time, the electronic card must not be allowed to carry out dust. Therefore, it is required to keep the environment clean and the filter clean, pay attention to dehumidification and adjust the temperature.
4, program equipment and adjustment test in the process of program design and acceptance, we must fully mobilize the enthusiasm of all employees, so that everyone as much as possible with the new DCS control system to understand, familiar and master. Pay special attention to the following issues in configuration and acceptance:
4.1 In the program configuration design, it is necessary to adopt a safe operation control strategy for the unit. The logic of protection or chaining must be necessary and sufficient. For steam turbine speed, turbine lubricating oil pressure, etc., it is recommended to use hard wiring protection and software protection. It is recommended to use normally closed signal to ensure reliable input of protection; for important three-two protection signals, analog and switching quantities should be used. In combination, it is recommended to use a normally open signal as much as possible to ensure the safety of important main equipment to avoid the malfunction of protection.
4.2 In the various stages of control system selection, design, testing, acceptance, commissioning and online adjustment, the program design and test personnel must participate in the whole process. It is necessary to combine the problems in the use of similar control systems and strictly review the protection control logic design and group. The rationality of the state, all tests must be fully tested in the test. Carefully record the results of each inspection and test. If you find any problems related to the software, you should immediately contact the supplier and give the situation a complete feedback to them to solve the problem as soon as possible.
4.3 Must have the necessary backup means: important protection and interlocking, in addition to communication connection, must also have hard wiring; for important adjustment equipment, in addition to soft hands on the operator station, there must be Backup hands-on exercises allow timely intervention of critical equipment in the event of a DCS control system controller or I/O module failure.
4.4 For the programmer to strengthen management, the use of authorization system, and anyone to change the procedures must perform the relevant approval procedures, and make a record before and after the transaction. The PID parameters and threshold detection blocks of the important adjustment system must be recorded. In the process of optimizing the adjustment parameters, the monitoring system must be implemented, and the parameters should be tested in time after the parameters are modified to avoid potential safety hazards.
5. Personnel management and technical training Whether the new control system is put into operation or the old system is modified, once the DCS control system selection is determined, it must have strong practical experience before system construction, hardware testing and program configuration. The thermal control engineer and the operation operator carry out relevant training work. The training work must be combined with the simulation machine and the actual system to achieve a targeted target.
5.1 Training for operators: Improper operation may affect the performance of DCS hardware or software, which will indirectly affect the safety and economic indicators of the unit. Therefore, during the DCS screen process, the opinions of the operators should be extensively consulted, so that they can participate in familiar design and Debugging to familiarize them with the operational changes of the control interface (picture) and know how to operate. For daily operations such as start-stop equipment, hand/automatic switching, and accident intervention in accident situations, complete operating procedures, technical training and drills should be prepared. Fully use the DCS control system debugging stage to conduct comprehensive training for relevant operators.
5.2 Training for thermal control personnel: The training of thermal control personnel should pay attention to each other's strengths. Because the modern DCS control system involves a wide range of knowledge, it is impossible to fully grasp it in a short time. Therefore, we must fully consider the differences in the cultural quality and business level of the thermal control personnel, and give priority to the in-depth training of different aspects of thermal control and engineers. Through training, they can gradually take up the task in the construction of DCS control system, the establishment of network communication, hardware testing and acceptance, design of program configuration, testing and adjustment of control loop. At the same time, it is necessary to make full use of the problems in the process of equipment commissioning and step-by-step operation, and ask them to analyze, judge and solve the technical manual with the assistance of the supplier. On this basis, these thermal control engineers conduct “online†training to other personnel. For the management of the control system, special reminder: in the case of unit operation, it should try to avoid modifying the configuration and important parameters online. If it is necessary to modify and download the configuration, it is necessary to make accidents and implement various safety. Measures and improve related approval procedures.
Conclusion
The wide application of DCS control systems in power plants has brought the automation level of modern power plants to a new level. In industrial practice, it is normal for the control system to have problems, but our engineers and technicians have the responsibility and obligation to make the control system have as few serious problems as possible. For the problems that occur in the control system many times, we need to analyze more, sum up, find commonalities of problems, and take measures to improve them. Due to my lack of knowledge and experience, and the rush of time, the expression in the text is not comprehensive and complete, and I welcome criticism. I hope that I can inspire and promote the communication and exchanges with the majority of DCS technicians, and learn from each other's strengths, so that the DCS control system can better serve the safe and economical power production.
Wire harnesses are commonly used in the electronics industry, the automotive industry, in the manufacture of construction machinery and industrial equipment, as well as in the manufacture of white goods such as washing machines and dryers, refrigerators, and other household appliances.A industrial wire harness is typically designed to simplify the manufacture of a larger component, and is designed based on the geometric and electrical requirements of the equipment it is to be installed in.
Industrial Cable Harness,Mechanical Cable Assembly,Industrial Cable Harness,Mechanical Cable Assembly,Accessories Service
ETOP WIREHARNESS LIMITED , https://www.wireharnessetop.com