There are three points for the performance requirements of the SPD backup protector. First, break the expected short-circuit current of the SPD installation line; second, withstand the surge current passing through the SPD without breaking; third, break the power frequency current that cannot be broken by the built-in thermal protection of the SPD, quoted from GB 51348 "Civil Buildings" Electrical Design Standards. In terms of 8.4.3.2 and 8.4.4.4 of the test standard GB18802.11-2020 for surge protectors, there are 8/20 waveform impulse current tests. In these tests, the surge protector and its backup protector are required to withstand the impulse current of 8/20 waveform of the magnitude of Imax. During the test, the backup protector is required not to trip. In order to find the cooperative relationship between the SPD and the backup protector, it is necessary to find the maximum inrush current withstand level of the backup protector. Using I²t to calculate the waveform and compare it with the I²t (1ms) provided by the backup protector manufacturer is a possible method to estimate the single surge withstand capability of the fuse. I²t can be estimated from the peak value of the shock, which can be seen from the following formula: ---For 10/350 wave: I²t=256.3×I²crest ---For 8/20 wave: I²t=14.01×I²crest Here, the unit of Icrest is kA, and the unit of I²t is A²·s. In the test method described in GB18802.11-2020, the backup protector must not only withstand a single shock, but also withstand a complete sequence (preconditioning test and action load test). These shocks can reduce the performance of backup protectors, thereby reducing their ability to withstand a single shock. In order to pass the above test, the test display should be multiplied by a reduction factor of 0.5-0.9 on the basis of the single impact resistance value. Although the GB18802.11-2020 standard provides a clear basis for the selection of backup protectors, in actual working conditions, SPD failures will still occur, backup protectors will not operate, and even SPDs will catch fire. The specific reason is due to the blind spot in the cooperation between the SPD and the backup protector. Since the fusing coefficient of a fuse is usually 1.5-2.0, it means that the larger the current, the faster the fusing speed, but at a small current, the fuse cannot operate. After our test, in the case of failure of the internal device of the SPD, the current of 5A can cause the SPD to catch fire.

The working principle of the lightning early warning system: as we all know, when the electric charge in the thunderstorm cloud reaches a certain amount, a strong electric field is formed between different parts of the cloud or between the cloud and the ground. Discharge occurs between clouds and clouds or between clouds and ground. That is, the occurrence of lightning comes from the accumulation of electric charges inside the thundercloud; this means that as long as the change of the electrostatic field in the space can be accurately detected, the accumulation of electric charges in the thundercloud can be indirectly understood. According to the relevant meteorological data recorded around the world over the years, the occurrence of lightning requires certain conditions and has regularity: when thunderstorm clouds approach or form, the ground electrostatic field changes in a certain way, and under standard measurement conditions (plain , flat bottom, no tip effect), the average field strength of the electrostatic field is about 150V/M when the weather is fine, and when thunderstorm clouds appear, the electric field strength of the electrostatic field can increase to +/-15KV/M, or even higher . When a single thunderstorm cloud layer or combined with the preceding thunderstorm cloud, the electric field strength increases for about 15-20 minutes. We believe that when the electric field strength exceeds 2KV/M, the thunderstorm cloud is forming or approaching, and the change of electric field strength is collected by the atmospheric field instrument. And through the back-end software platform algorithm, it can quickly and accurately predict the local lightning strike situation in advance. The role of lightning warning system 1. It can issue a lightning warning warning signal about 5 to 30 minutes before the lightning strike. 2. Remind field operators to stop or suspend outdoor operations in time, enter a safe area to avoid lightning and prevent lightning strikes. 3. For some operations that may cause major harm, take appropriate measures in time before lightning strikes to prevent major lightning strike accidents. For example: outdoor operations in flammable and explosive places must be stopped or suspended at this time. 4. The automatic opening and closing system is adopted to isolate the power supply line from lightning, automatically switch the UPS or start the generator set to supply power, and provide protection for some important equipment or uninterrupted and valuable services.

Surge Protective Device (SPD) is a device used to limit transient overvoltage and discharge lightning current. Within the withstand voltage range, or discharge a strong lightning current into the ground to protect the protected equipment or system from impact. In order to make the surge protector operate safely and reliably in the power distribution system and prevent the occurrence of dangerous accidents. It is stipulated that the SPD must be connected in series with current protectors (such as fuses, circuit breakers). The fuse as a backup protection device has a low surge withstand capability. In order to obtain a higher surge withstand capability, the selected rated current value is relatively large, and it cannot break the low short-circuit current. Therefore, the fuse still has a great potential safety hazard as a backup protection device. Anhui Jinli independently developed a back-up integrated surge protector with a dedicated overcurrent protection function, which solves the problem of secondary serious accidents caused by the deterioration of the existing surge protection device and the occurrence of power frequency fault freewheeling and exceeding the safe range value. It can quickly realize the fuse protection, prevent the explosion of the arrester, and realize the secondary safety protection of the arrester. It solves the problem that fuses and circuit breakers have poor resistance to surge and impact, are easily damaged, and cannot break power frequency fault currents. At the same time, two separate devices, SPD and SCB, are combined to form an integrated product, which not only solves the above problems, but also greatly reduces the installation space, reduces the installation process, and reduces the effective voltage protection level. It is more convenient to replace after the failure, and the system can be restored to normal work faster. Anhui Jinli adheres to the original technology as the basis, constantly develops new products and improves the market awareness of the company's focus on the industry, and makes unremitting efforts to become a well-known lightning protection brand that is respected by the society.

Due to the exposure characteristics of the installation location of photovoltaic array, the risk of direct lightning strike is high, such as: ① Direct lightning strike (direct strike on photovoltaic panels); ② indirect impact (surge impact of photovoltaic modules, combiner boxes, inverters, etc.); ③ impact on other lines (direct impact on signal lines or surge) We must consider accidental operational losses such as downtime caused by lightning strikes, especially in high-power power generation applications. In addition, the risk of operating overvoltages must also be considered when PV systems are located in industrial field applications. At the same time, the risk level is directly related to the ground flash density and the exposure of local lines. 1. For low-voltage photovoltaic application systems, taking small residential buildings and office building rooftop power stations as examples, surge protection device must be performed on the DC side of the inverter connected to the photovoltaic array and the AC side of the inverter connected to the grid system. If the distance between the protective equipment (inverter or PV array) and the upstream spd is more than 10m, it is recommended to install an additional surge protector nearby to improve the protection capability. 2. Medium to large scale photovoltaic power generation systems can be installed on industrial test and service facilities. In order to avoid downtime and production losses due to direct or indirect lightning strikes, it is critical to install surge protectors at critical locations on equipment critical power and communication networks. 3. If the building does not have an air-termination system installed, it must be mandatory to install type 2 surge protectors on the AC and DC incoming lines of the inverter. On the photovoltaic side, for cables longer than 10m, a surge protector must be added at each end of the working cable. 4. If an air-termination system is installed, type 1 surge protection device must be installed on the AC input. On the DC side as well, Type 1 surge protectors are necessary in case the air-terminations are not installed to maintain an effective safe distance.

Lightning early warning system technical indicators and early warning classification A. Technical indicators 1. The advance time of lightning warning is not less than 10 minutes. 2. The average effective alarm rate of lightning is not less than 80%. 3. The detection radius is not less than 10 kilometers. 4. The detection accuracy of atmospheric electric field is better than ±5%. 5. With three-level lightning warning function. 6. The storage time of historical lightning warning data is not less than 3 years. 7. The lightning detection module installed on site should meet the electrical explosion-proof requirements of large oil and gas storage bases. The protection level is not lower than IP65. 8. The life of the lightning detection module is not less than 3 years. B. Early warning classification Lightning warning information is divided into three levels: 1. First-class early warning: there may be lightning activities, the atmospheric electric field in the coverage area is increasing, the electric field is fluctuating, and the location of the ground flashback strike is located in a nearby area 10 kilometers away from the large oil and gas storage base, which may cause lightning accidents. 2. Secondary early warning: the possibility of lightning occurrence is high, the atmospheric electric field in the coverage area increases rapidly, the fluctuation of the electric field intensifies, and the location of the ground flashback strike point is 5-10 kilometers away from the large oil and gas storage base, which may increase the possibility of lightning strike accidents . 3. Three-level early warning: lightning is about to occur, the atmospheric electric field in the coverage area fluctuates violently, and the location of the ground flashback strike point is 0-5 kilometers away from the large oil and gas storage base, which is likely to cause a lightning strike accident. C. Operation and maintenance 1. Before the rainy season every year, the hardware equipment, network interface, software platform and surrounding environment should be checked in time to ensure that the lightning early warning system is in normal operation, including sensors (probes), host, temperature and humidity conditions in the chassis, solar module panels , battery, etc. 2. When the data of the lightning detection module cannot be received normally, the operating status and communication of the equipment should be checked immediately.

1. Introduction of distributed lightning protection ——"Centralized monitoring and decentralized installation" Principle: The integrated intelligent lightning protection module (SPD+SCB+intelligent acquisition unit) is scattered in each panel cabinet to be protected, and the communication signal is sent to the monitoring background through the 485 port of the intelligent acquisition terminal to realize the centralized monitoring of the traction substation , SPD distributed installation of intelligent lightning protection. 2. Introduction of centralized combined screen lightning protection Principle: The lightning protection devices required in each panel cabinet are centrally installed to form an independent lightning protection panel cabinet, and a monitoring background is set in the lightning protection panel cabinet to realize the intelligent lightning protection of centralized installation and centralized monitoring of the traction substation. 3. Performance comparison of distributed lightning protection and centralized combined screen lightning protection 1) Common point: all of them can realize intelligent monitoring of SPD, and can centrally display and store SPD in each panel cabinet status information of the operation. 2) Differences: The installation method of the distributed type is scattered in each panel cabinet, while the centralized combination panel type is an independent group panel. 3) Comparison of advantages and disadvantages: a. The centralized and distributed installation method SPD can be close to the protected equipment to achieve the best protection effect on the circuit; the SPD of the centralized independent group screen will be far away from the protected equipment, which does not meet the "proximity principle" of equipment lightning protection. When the SPD is too far away from the protected equipment, due to the existence of line inductance, the lightning overvoltage wave (electromagnetic wave) will appear wave reflection under the action of electromagnetic oscillation, and the amplitude will further increase, making it difficult to protect the equipment. b. The lightning protection branch connection line of the distributed installation method will be slightly longer than that of the centralized combined screen, but the centralized independent grouped screen needs to occupy the space of the inner disk, and the loop cable is in and out of the "lightning protection screen". In the process of lightning, a large loop will be formed, and in the electromagnetic field of lightning, a high loop voltage will be further induced; c. For the renovation of existing projects, after the SPD circuit is installed in the distributed installation method, the panel cabinet is For crowding; and the centralized independent panel grouping method, because the loop cable laying method of the existing project has been fixed, it is necessary to Re-laying the cables is a huge amount of work. Railway is the focus industry of Anhui Jinli. From the...

Classification of Wind Power Systems - By Power Regulation Fixed pitch fan: The blade is fixedly connected to the hub, and the windward angle of the blade does not change with the wind speed. It automatically stalls by relying on the aerodynamic characteristics of the blades, that is, when the wind speed is greater than the rated wind speed, the input power is kept basically constant by relying on the stall characteristics of the blades. Pitch pitch adjustment: When the wind speed is lower than the rated wind speed, ensure that the blades are in the best angle of attack state to obtain the maximum wind energy; when the wind speed exceeds the rated wind speed, the pitch system reduces the blade attack angle to ensure that the output power is within the rated range. Active stall adjustment: when the wind speed is lower than the rated wind speed, the control system controls the wind speed in several stages, and the control accuracy is lower than the pitch control; when the wind speed exceeds the rated wind speed, the pitch system increases the blade angle of attack to make the blades "stall" , limiting the increase in the absorbed power of the wind rotor. Classification of wind power generation systems - by transmission form Gearbox type with high transmission ratio: the rotational speed of the wind rotor is low, which usually cannot meet the requirements of the generator for power generation. Direct drive type: The application of multi-pole synchronous wind turbine can remove the common gearbox in the wind power generation system, so that the wind turbine can directly drive the generator rotor to run at a low speed, which eliminates the noise and fault caused by the gearbox. The problems of high rate and high maintenance cost have improved the operational reliability. Medium transmission ratio gearbox (semi-direct drive) type: The working principle of this fan is a combination of the above two forms. The medium transmission ratio wind turbine reduces the transmission ratio of the traditional gearbox, and also reduces the number of poles of the multi-pole synchronous wind turbine accordingly, thereby reducing the volume of the generator.

The lightning warning system employs atmospheric electric field detecting devices, sensors, etc., using the principle of measurement environmental electrostatic fields to detect thunder clouds. At any time, the system can detect thunderstorm clouds within 15 kilometers depending on the change of the environmental electrostatic field. This means that lightning is likely to occur in the measurement area of the electric field strength. After the atmospheric electric field detection device, after the lightning electric field change data value, the atmospheric warning level is analyzed, transmitting data wirelessly to the warning control host intelligent processing unit through the communication module, and the host intelligent processing unit can transmit data to the control center, and pass the upper position Machine software displays early warning information. China Meteorological Bureau "Lightning Motorion Disaster Mitigation Management Measures" clearly requires: "Meteorological authorities at all levels should strengthen the construction of lightning prevention system, improve lightning, warning and lightning protection," "" "" Meteorological authorities at all levels should organize The relevant departments strengthen the research theory of basic theories and defense technologies such as lightning and lightning disasters, and strengthen the research and development of lightning protection and mitigation techniques and lightning monitoring, early warning systems. " After more than ten years of exploration and practice, my country's lightning early warning monitoring technology has been perfectted and has a relevant group standard. According to industry analysts, only about 1/4 of oil and gas storage companies in the country are actively equipped with a lightning monitoring warning system, and this situation is changing under the requirements of government departments. Lightning warning systems are expected to become a basic configuration of large oil and gas storage bases, but the support of relevant technical specifications is very important.