Application of new electromechanical technology in

2022-08-10
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After more than 40 years of development, small and medium-sized hydropower and rural electricity in China have formed a large industry and made great contributions to local economic and social development. At the same time, we have accumulated rich experience in practice and made great progress. We have made new achievements not only in engineering design, construction, equipment manufacturing, operation and maintenance, but also in the application of new technology and the development of new equipment. Some characteristics of mechanical action of ceramic materials in order to improve the technology and operation level of small and medium-sized hydropower and electricity in order to obtain the maximum economic benefits, technological innovation in rural hydropower and equipment is very important. At present, the main new technologies in the electromechanical field of small hydropower include:

-- pressure regulating valve. When the Σ lv/h of the long pressure Headrace Tunnel of the hydropower station is greater than, the surge shaft is generally required to be set, but the surge shaft has a large amount of civil engineering work, a long construction period, and also needs an ideal terrain. Small and medium-sized hydropower stations use the surge valve to replace the surge shaft, which can save investment and shorten the construction period. The function of the pressure regulating valve is to quickly open when the load rejection guide vane of the unit is quickly closed. Discharge the original flow through the unit from the pressure regulating valve, and then slowly close the pressure regulating valve after the standby group is closed, so that the flow of the water diversion system changes slowly, so as to prevent the water pressure of the water diversion system from rising and the unit from flying

-- guide vane control mechanism. For the small and medium-sized hydropower units that bear the base load in the electricity, because they do not need frequency modulation, the mechanical hydraulic governor with complex structure, high price and high maintenance and operation cost can be cancelled, and the TC type spring energy storage electric manual operator or hydraulic operator with simple and reliable structure, low price and low maintenance and operation cost can be used instead. When the operating power supply of the unit disappears, the hydraulic turbine can be automatically shut down by using the spring energy storage, and can be shut down in sections. When it is used together with the microcomputer hydraulic turbine speed control, it can also be frequency modulated

-- automatic control system of the unit. The automatic control, regulation and protection system of the unit is based on a single-chip microcomputer. The system can realize automatic shutdown and manual shutdown, and has the advantages of high operation reliability, small design, maintenance and installation workload, and small floor area. It is an ideal equipment for small and medium-sized hydropower units with no one on duty and few people on duty. Its main functions include single machine and parallel operation. Single machine operation mode enables the unit to operate at a given frequency and voltage; The unit can perform automatic quasi synchronization or quasi synchronization; It can operate according to the water level of the forebay; The unit has the protection functions of over-voltage, over-load, over-voltage, under voltage, over-speed, low frequency, interruption of technical water supply, high bearing temperature, air pressure drop and so on

-- heavy hammer butterfly valve. In the past, the inlet valve of small and medium-sized hydropower units mainly used electric manual butterfly valve, ball valve or gate valve. When the unit had an accident, it often could not be closed automatically due to the unreliable auxiliary power. In order to overcome this shortcoming, the heavy hammer butterfly valve and ball valve have been developed in recent years, which can be closed automatically and reliably by relying on the heavy hammer, and the closing time is adjustable, which can realize sectional closing, prevent the pressure of the water diversion system from being too high, and at the same time, the unit can be closed quickly to prevent speeding

-- energy saving transformer. At present, the use of high loss transformers in rural power is still large. In recent years, through the efforts of scientific researchers and relevant manufacturers, S7 (sl7) and S9 series energy-saving transformers have been developed successively. In order to meet the needs of rural power voltage regulation, SZ7 (szl7) and SZ9 series on load voltage regulation transformers are also developed for grading voltage regulation, so as to stabilize the secondary voltage, improve the quality of power supply and ensure the safety of electrical equipment

-- reactive power compensation screen. For lines with heavy inductive load, the reactive current is often too large, resulting in increased line loss. The solution is to carry out reactive power compensation, reduce the reactive current of the line and reduce the line loss. Now, the more advanced reactive power compensation screen is controlled by microcomputer, which can maintain the constant power factor, and also has over-current and over-voltage protection

-- SF6 circuit breaker. Among 35kV and 10KV voltage levels in rural areas, SF6 switchgear is currently an electrical appliance with better performance. SF6 short circuit breaker adopts SF6 gas insulation and arc extinguishing medium, which has excellent performance, high rated parameters, long service life and non maintenance cycle (5-10 years), and there is no fire risk, which can greatly improve the reliability of the power system. In particular, the 10kV SF6 circuit breaker is small in size and covers less land, which can reduce the project cost

-- 10kV YCW column oil recloser and 10kV YCW column oil recloser are successfully developed based on the characteristics of rural electricity in China. They do not need external operation power supply and can conduct fault current breaking and reclosing according to the pre selected operation procedures. If the fault is temporary, the reclosing is successful; If the fault is permanent, it will be opened again. The recloser adapts to and meets the needs of rural power development and transformation in China, and makes rural substations develop in the direction of outdoor type, miniaturization, low cost, safety, reliability and advanced technology. It is generally installed on the framework of the substation, making the beginning of 10kV outgoing line. It is a special high-voltage circuit breaker with control and protection functions

-- microcomputer centralized control console. Rural 35kV and 110kV enterprises should establish information sharing platforms, upgrade relevant computer software or replace integrated systems, and unite with excellent interconnected enterprises and vocational and technical colleges to enhance their technology and ability in this field. The microcomputer centralized control console of substation integrates control, protection, central signal and measurement, changing the traditional electromagnetic panel and cabinet assembly structure. The console collects the status of circuit breakers and disconnectors and the operating parameters of the power station through the i/o port, processes them, outputs relevant instructions, and realizes telemetry/remote communication/remote control through the communication interface. The microcomputer system adopts a series of measures to increase reliability, which has the ability of diagnosis, self recovery and very strong system generation function. It can generate databases, various simulation flow charts and various reports offline

the centralized control console can collect 512 switch input signals and 128 analog input signals, control the opening and closing of 32 circuit breakers, complete the primary reclosing of 32 circuit breakers, continuously monitor 32 circuit breakers and protection templates, and give audible and visual alarms. It has overcurrent, current quick break, overload and low-voltage locking protection for the line, and differential protection, overcurrent protection, current quick break protection, zero sequence protection, heavy gas, light gas, overtemperature and other protection for the main transformer. It can measure analog quantities such as current, voltage, active power, frequency, power factor, and the measurement of active and reactive kwh. It has the function of statement and accident printing. It is the preferred control, measurement, and protection equipment for outdoor and miniaturized rural substations

-- SCADA system of local electricity. In recent years, with the development of small and medium-sized hydropower, small and medium-sized hydropower has merged one after another, forming a rural power composed of small and medium-sized hydropower, electricity and users. Rural power needs a reliable real-time dispatching management center, and the establishment of dispatching automation system (SCADA) based on computer monitoring is the technical way to achieve this goal. From the perspective of hardware, the dispatching automation system can be divided into master station MS, communication transmission equipment, remote terminal RTU, etc. The master station is the most direct equipment for SCADA man-machine contact, which can complete dispatching instructions, operation monitoring, dispatching diary, operation report, data processing, analog electrical network, parameter display and accident fault report. Operation parameter modification, electric energy measurement, application software development and system testing and diagnosis. Remote terminal unit (RTU) is the equipment that is most directly connected with the power station or substation. It directly collects the switching value of the power station/substation or the analog value through the transmitter, and preprocesses the collected data. Communication transmission equipment is the channel for information exchange between MS and RTU, and the communication between MS and RTU is carried out by carrier wave or radio through modem

-- modular substation. The modular substation is mainly of outdoor type, and the primary equipment adopts small high-performance switching electrical equipment, energy-saving transformers, etc. The secondary equipment is mainly microcomputer centralized control console, which changes the traditional cabinet and screen mode when the load can no longer rise, reduces the floor area of indoor and outdoor equipment, and saves civil engineering investment. As the centralized control console is a complete set of equipment, its primary design is very simple. Only the interface design is provided, and the rest are designed and manufactured by the factory. Accordingly, the installation and commissioning time on site is very short and the maintenance workload is small. Therefore, Mr. Frazer Barnes, the managing director of ELG, said that the miniaturized outdoor modular substation was: "Chery new energy EQ1 electric vehicle uses a lot of aluminum, which represents a big step forward in the future development direction of China's automotive industry in terms of lightweight.

-- speed increaser mechanism. After the adoption of speed increaser in the transformation of old power stations, although the energy loss may be increased by less than 0.5% - 1%, the cost of power stations can be greatly reduced by using high-speed generators. The service life of speed increasers is generally 100000 hours to a few About 100000 hours, it can operate reliably for a long time and bring more economic benefits to the power station. The transmission ratio of low head power station can be changed through the speed increaser, so that the hydraulic turbine can maintain the optimal working condition and maintain high efficiency operation; It can also improve the layout structure of the plant

-- unmanned trash cleaning machine. The use of unmanned trash cleaning machine can reduce the operation and maintenance costs and improve the reliability of power station operation, and the cost is not high, which is worth promoting. For head loss, the trash rack water level difference cm is very common, but for low head hydropower stations, it is not easy to obtain or improve the efficiency of 2-3%

-- Micro units use water pumps to replace hydraulic turbines, and asynchronous generators to replace synchronous generators. When the unit capacity is below 100kW, using water pumps to replace hydraulic turbines and asynchronous generators to replace synchronous generators will have greater investment benefits. Compared with units of the same capacity, the price is only about half, and the efficiency is not much different. For small units operating in isolation, the generator connected to the capacitor can meet the stable operation of electricity, and because the unit adopts asynchronous motor, the synchronization is simpler, and the automatic control is more convenient

intelligent digital display meter series. With the decline of the price of microcomputer chips, foreign intelligent digital display meters continue to emerge, with powerful products and sometimes lower prices than conventional meters and transmitters. In the power station automation system, it can not only improve the reliability, but also reduce the transmitter cabinet, input interface and a/d conversion template. For example, the 3000 series electric power monitoring terminal produced by Hong Kong Delai power automation equipment Co., Ltd. has some functions of replacing pulse electric energy meter, electric power transmitter and AP conversion board, and locally displays a variety of measured electric parameters, real-time current, voltage, power, electric degree, frequency parameters, etc., which can not only save the screen cabinet of meter and transmitter, but also simplify the processing information of local units in hydropower stations and substations. The device cabinet is equipped with rs232/rs485 communication card, It is easy to connect directly with the monitoring system. And the price of the two is equal

the promotion of the above new technologies will form a kind of advanced parameters, reasonable price and reliable operation. The new technology of small hydropower industry with convenient maintenance will greatly promote the further development of small hydropower in China. (end)

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