There are several types of overvoltage in China's 3-35kV system, including operating overvoltage generated during circuit breaker operation engineering, resonant overvoltage generated by capacitive components and non electrical inductors under certain conditions, atmospheric overvoltage generated during lightning strikes, and arc overvoltage generated during single-phase grounding. At present, there is no complete protection plan for these overvoltage, which may lead to accidents such as cable blasting, motor edge breakdown, lightning arrester explosion, and voltage transformer burnout. The causes of such accidents are not only related to the performance of the overvoltage protection devices installed in the system, but also to the complexity of the system itself, which has an important impact on the selection of overvoltage devices. For different systems, when selecting overvoltage protection, it is necessary to consider the type of transmission and distribution lines, the network structure of the transmission and distribution lines, the nature of the load, and the grounding method of the system.
For such a complex system, it is difficult to use one or several overvoltage protection products in isolation to comprehensively suppress various types of system overvoltage, such as lightning arresters, combined overvoltage protectors, arc suppression coils, various principle arc suppression devices, and PT suppressors. Although various overvoltage protection products are installed in these systems, their protection characteristics cannot be well matched, making it impossible to completely and effectively suppress system overvoltage. This is especially true for overvoltage protectors from different manufacturers installed in the same system. In response to the current situation of overvoltage prevention and control in medium and low voltage systems, our company has developed and produced distribution ZW-GBD. This device can compensate for the shortcomings of overvoltage protection components and devices in the system, and improve the level of overvoltage protection in the system.
Applicable scope
The system overvoltage comprehensive protection device is suitable for 3-35kV power systems, used to limit various overvoltages that occur in the power grid, and can improve the safety of power grid operation and the reliability of power supply. This device can replace voltage transformers and specialized resistance capacitance overvoltage protection cabinets.
Working principle and basic functions
The ZW-GBD resistance and capacitance overvoltage protection device adopts our company's latest developed specialized component: intelligent comprehensive resistance and capacitance overvoltage protector, which can effectively smooth out the rising edge of overvoltage and smooth out voltage dust peaks, and can withstand the super energy generated by overvoltage. This specialized component is matched with the protection characteristics of our company's resistance and capacitance overvoltage protectors and arc suppression cabinets, and can comprehensively eliminate the dead zone of system overvoltage protection. During normal operation, the intelligent microcomputer device inside the cabinet continuously detects the voltage signal provided by the PT in real time. In the event of PT disconnection, overvoltage, undervoltage, low voltage, resonance, arc grounding, and other phenomena, the intelligent microcomputer device utilizes the high-speed and repetitive data processing ability of DSO to achieve Fourier analysis. By collecting and judging the secondary voltage of the PT voltage transformer, it is timely; Accurately analyze various states of the system, determine the fault situation of the system, display the fault category, and output corresponding switch value contact signals for alarm. Simultaneously utilizing the powerful logical computing power of MCU, it can quickly achieve functions such as LCD display, remote communication, and data protection. When the system experiences resonance, The intelligent microcomputer device for PT and overvoltage comprehensive protection device can achieve rapid action according to the different frequencies of system resonance. The input signal should have switch contacts for alarm and quick LCD display. Equipped with RS485 interface and standard Modbus communication protocol, it can achieve long-distance communication and data transmission with the user's microcomputer monitoring system.
