From August 2002 to December 2002, Beijing Gangzhen Electromechanical Technology Co., Ltd. carried out the site survey and selection of seismic monitoring network in the Wujiang River Basin. In January 2003, the technical design of the digital telemetry seismic network for hydropower projects in the Wujiang River Basin was completed. On March 25, 2003, Wujiang Company commissioned the China Earthquake Administration to organize an expert evaluation committee composed of Academician Xu Shaoqiang and Academician Chen Houqun to review and approve the "Technical Design Document for Digital Telemetry Seismic Network of Hydropower Projects in the Wujiang River Basin". The Expert Evaluation Committee believes that the "Design Book" embodies the principle of "comprehensive planning and careful design", all technical indicators are advanced and feasible, and the instrument selection is reasonable, representing the advanced level of contemporary seismic observation.
On July 1, 2003, Wujiang Hydropower Development Co., Ltd. and Beijing Gangzhen Electromechanical Technology Co., Ltd. signed a contract for the construction of a digital telemetry seismic network (phase one) for the Wujiang River Basin Hydropower Project.
The construction content of the first phase of the digital telemetry seismic network of the Wujiang River Basin Hydropower Project includes:
16 telemetry seismic stations; Hongjiadu, Dongfeng and Wujiangdu 3 relay stations; Hongjiadu Network Center; Dongfeng, Suofengying, Wujiangdu 3 information stations and Wujiang Company Seismic Information Main Station.
The center of the Wujiang Seismic Network is located at Hongjiadu Power Station. The network center receives the seismic signals from various telemetry stations through spread-spectrum microwaves and satellites; real-time processing of seismic waveform data; when an earthquake event occurs, an earthquake warning is automatically issued. The staff use professional seismic analysis software system to complete the tasks of seismic analysis, earthquake quick report and earthquake cataloging.
The key equipment such as microwave communication, real-time processing computer and UPS power supply of the station network center adopts the working mode of dual hot backup to ensure the stable and reliable operation of the central system. The center implements a 24-hour on-duty system; the maintenance of the center and external stations is in charge of special personnel to ensure the uninterrupted operation of the station network system.
Digital telemetry seismic relay station has two kinds of transmission methods, one is transmission through satellite channel, the other is transmission through (spread spectrum) microwave channel. The signal from each telemetry station and the signal from the local station are sent to the center of the station network via a small satellite station or a spread-spectrum microwave through a combined synchronization signal through a multiplexer.
Digital telemetry seismic stations are equipped with short-period seismometers, broadband seismometers or accelerometers, and seismic data collectors; the transmission method adopts ultrashort wave channel transmission or satellite channel transmission.
Both stations and relay stations use AC power supply and are equipped with UPS uninterrupted power supplies, which can ensure continuous operation for 4 to 6 days after the local power grid fails. Lightning protection is provided for AC input, ultra-short wave and satellite antennas.
The seismic information station mainly provides mirroring services by the network center. Realize data exchange with the network center through VPN virtual network technology, and query earthquake information. In an earthquake emergency, the information station can also complete the data analysis and processing tasks of the mobile seismic observation system.
The relevant leaders of Wujiang Hydropower Development Co., Ltd. and the China Earthquake Administration have attached great importance to the construction of the Wujiang Seismic Network, and have visited the site several times to guide the work. The experts of the supervision team worked tirelessly to visit all the field stations, carefully checked the quality and progress of the project, and put forward many constructive opinions on the Wujiang network project.
The Wujiang Digital Telemetry Seismic Network is the first seismic network in my country that considers the entire river basin and focuses on monitoring earthquakes induced by cascade power stations and reservoirs. The Wujiang Network has a large dynamic range and wide frequency bandwidth, and is the largest among the professional network of reservoir-induced earthquakes in China. Based on the characteristics of the terrain, the Wujiang Network uses multiple channels such as ultrashort wave, microwave, and satellite for real-time transmission; adopts IP-based Data transmission technology, real-time waveform data exchange and sharing with national seismic network and local seismic network in professional network for the first time; VPN virtual network technology of the Internet is used for the first time to realize the interconnection and access of two internal address networks to complete seismic information Feedback: For the first time in China's seismic network, the integration of seismic data processing software with seismic analysis and prediction software provides a basic platform for exploring the organic combination of seismic monitoring and seismic situation analysis.