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.

Ground Potential Counterattack Solutions A. For the system using opposite grounding, that is to say, there are more than two independent grounding grids in a computer room. For example, one grounding grid uses steel bars in the building frame as grounding grids, and the other system is independent grounding grids, then when When the distance between the two ground grids is less than the safety distance against ground potential counterattack, it is necessary to use an "equipotential connector" for equipotential connection between the two ground grids. The function of the equipotential connector is to ensure that the two grounding grids are not connected and do not interfere with each other under normal working conditions. When a grounding system is struck by lightning, the GI 1000-5 equipotential connector makes the two grounding grids instantly form an equipotential to eliminate the Damage caused by this transient high potential within the device due to line-to-line voltage differences. B. According to the requirements of Chapter VI of GB 50057-94 (2000) "Code for Design of Lightning Protection of Buildings", metal water pipes, communication cables and power cable armored sheaths or cable metal pipes and other external pipelines, all water pipes and cables should be Buried into the equipment room, the water pipe and cable armored sheath and protective metal pipe should be grounded when entering the equipment room, the cable should be armored cable or buried into the equipment room through the metal pipe. For grounding wires with long wiring distances in the building, such as power PE wires, in the equipment room with higher requirements, the "equipotential connector of the equipment room" can be used to connect the AC working ground, DC working ground, anti-static and protective grounding in the equipment room. Equipotential connection is carried out inside to ensure that the precision system equipment is not disturbed under normal working conditions, and no breakdown occurs in the equipment when there is transient overvoltage.

Highway electromechanical and intelligent traffic control systems have a large number of sensitive electronic equipment requiring surge protection. Why is surge protection necessary? High exposure: Equipment is usually installed in a high point or protruding position (LPZ0A/B), the high exposure characteristics increase the risk of lightning strike damage Multiple connections: Such as DC power + data communication combined equipment, its overvoltage tolerance and anti-interference ability are reduced Long outdoor extension distance: Weak outdoor shielding ability and long transmission lines greatly increase the risk of system failure Large indirect losses: System failure may result in high system maintenance costs such as charging and high security risks Device Sensitive: The internal components of smart devices are delicate and extremely sensitive Numerous devices: A large number of equipment installations increase the probability of system failure under overvoltage How to protect more reasonably? Risk Analysis: Thunderstorm Day (Ground Lightning Density), Line Length, Equipment Density… Analyze protected device or system sensitivity Protection of all incoming equipment (AC/DC power supplies, communication systems, etc.) Consider the situation on site: Protected power/signal network characteristics Type of surge and expected magnitude of attack Mounting Features (Indoor/Outdoor, DIN Rail)

A properly designed air-termination device will significantly reduce the possibility of lightning strikes requiring lightning protection spaces. Only when the design of the lightning protection device and the structural design of the building are carried out at the same time, the optimal combination of technology and economy can be obtained. Especially when designing buildings, the metal objects of buildings should be fully utilized as parts of lightning protection devices. IEC1024-1:1990 The air-termination arrangement is suitable when the requirements in the table below are met. Arrange the air-terminations according to the protection level. Protection angle method: the positions of the lightning conductor, lightning rod, lightning protection tower and lightning protection line should be such that each part of the protected building is in the shape formed by the points on the conductor of the lightning protection device with the "angle projected to the ground in all directions". within the track surface. The protective angle method has geometric limitations. Rolling ball method: For buildings with complex geometric shapes, or when the protective angle method is excluded from Table 1 of IEC1024-1, the rolling ball method shall be used to determine the area of the building and the protective space of each part. The radius of the "rolling ball" should be in accordance with the selected level of protection of the lightning protection system. The rolling ball method is to use a ball of radius "R" on a building to roll around the building until it hits the ground level, or any permanent structure or object that is in contact with the ground level and can be used as a lightning conductor until. It is possible to be struck by lightning in places where rolling contact with buildings. At such points and locations, lightning protection by lightning conductors is required. The protected space of a lightning protection system is the volume of space that the "rolling ball" does not pass through when it contacts the conductor and acts on the building. The level of protection and the installation cost of the lightning protection system increases with the size of the ball selected. Mesh method: Air-termination conductors or roof conductors shall form a closed polygon with the perimeter laid close to the edge of the roof. This polygonal air-termination device shall be completed by the addition of interconnected transverse air-termination conductors to form a grid complying with the requirements of Table 1 of IEC 1024-1.

In recent years, the technology of the photovoltaic industry has developed faster and faster, the power of a single module has become larger and larger, and the current of the string has become larger and larger, and the current of high-power modules has reached more than 17A. In terms of system design, the use of high-power components and reasonable over-provisioning can reduce the initial investment cost and kWh cost of the system. DC cables are installed outdoors. It is generally recommended to select photovoltaic special cables that have been cross-linked by irradiation. After high-energy electron beam irradiation, the molecular structure of the insulating layer material of the cable changes from linear to three-dimensional network molecular structure, which is resistant to temperature. The grade is increased from non-cross-linked 70°C to 90°C, 105°C, 125°C, 135°C, and even 150°C, which is 15-50% higher than the current carrying capacity of cables of the same specification, and can withstand severe temperature changes and chemical erosion. Used outdoors for over 25 years. When selecting the DC cable, it is necessary to select products with relevant certifications from regular manufacturers to ensure the needs of long-term outdoor use. The AC cable can be selected according to the maximum output current of the inverter. Because no matter how much the components are over-configured, the AC input current of the inverter will never exceed the maximum output current of the inverter. The circuit of the photovoltaic system is divided into a DC part and an AC part. The two parts of the circuit need to be wired separately. The DC part is connected to the components, and the AC part is connected to the grid. There are many DC cables in medium and large power stations. In order to facilitate future maintenance, the wire number of each cable should be firmly attached. Separate strong and weak wires. If there are signal wires, such as 485 communication, they should be routed separately to avoid interference. When routing the cables, prepare conduits and bridges, and try not to expose the cables. It will look better when the cables are routed horizontally and vertically. Try not to have cable joints in the threading pipes and bridges, because maintenance is inconvenient. If aluminum wires are used instead of copper wires, reliable copper-aluminum transfer terminals must be used.

The replacement of products is the law of industry development. People usually pay attention to the performance quality of products, but often ignore the time quality of products, that is, reliability. The introduction of any new product should provide users with the performance quality, time quality and economic indicators of the product. The main methods to improve SPD reliability include a. Manufacturers have improved MOV chip designs, using new materials and improved processes, to produce products with low failure rates and improved inherent reliability. b. Provide a good environment such as suitable temperature, humidity and air pressure to maintain environmental reliability. c. Screen and age the SPD to shorten the early failure period. d. Replace deteriorating SPDs as appropriate or periodically. e. Select an intelligent SPD and monitoring system capable of life early warning. f. Derating design is the main method to improve SPD reliability. The derating design is to reduce the electrical stress (surge) of the SPD, and a reasonable derating can greatly reduce the failure rate of the SPD