Research On Key Technologies For Power System Perception

With the development trend of power industry foundation and industrial chain modernization,State Grid Corporation of China has established the goal of "building a full-service ubiquitous power Internet of Things" in the new era of information and communication strategies.Supporting efficient perception and accurate collection of business and status information in all scenarios is an important feature of the full-service ubiquitous power Internet of Things,the reliable and efficient perception of power overhead transmission lines is the core point to ensure the safe of the power system.The insulation performance of transmission line insulators and the tensile force of transmission lines mostly adopt the methods of electronic device measurement and wireless public network transmission at present,there are problems such as the measurement device needs power supply support,the failure rate is high,it is difficult to maintain,and the information transmission is unsafe and unstable,there is an urgent need to study an efficient and reliable monitoring system for the insulation performance of transmission line insulators and the tensile force of transmission lines.The fiber Bragg grating based sensing technology has the advantages of equipment-side passive,anti-electromagnetic interference,and optical fiber transmission,due to the short application time,the core sensing component structure of the sensing system currently lacks a mature systematic design method.The lack of a general model for the force of the sensor structure and the wavelength shift of the fiber grating,the sensing components are often continuously improved due to poor structural sensitivity,which greatly consumes the cost of raw materials and the time cost of structural processing.On the other hand,for the sensor structure design with specific requirements,the sensor structure that meets the requirements obtained through a large amount of time simulation or actual measurement may have poor sensitivity,and an efficient sensor structure design technology is urgently needed.Therefore,this paper has carried out several key technologies for power system sensing,which are summarized as follows:1.Aiming at the lack of mature systematic design methods for the core sensing components,this paper proposed and verified the general model of the force and wavelength shift of the fiber grating sensor structure based on ANSYS simulation.Taking the structural design of the tensile force sensor based on fiber grating as the example,a structural design scheme of the tensile force sensor driven by force simulation based on ANSYS is proposed.Results show that there is a certain first-order linear relationship between the wavelength shift difference and the simulated value of the comprehensive linearized equivalent stress on the fiber grating obtained by simulation,and the above relationship is independent with the simulated structure and the placement position of the fiber grating.2.Aiming at the low efficiency of sensor structure design with specific requirements,this paper proposed and verified the cantilever beam structure design technology based on machine learning.Taking the design of the cantilever beam structure with specific resonant frequency requirements as the example,a sensor structure design scheme driven by a back-propagation-based multilayer perceptron neural network is proposed.The simulation results show that the maximum error between the simulated value of the resonance frequency of the three cantilever beams autonomous designed based on the cantilever beam neural network model and the predicted value of the model output is 1.52%.On the other hand,we carried out the static stress simulation of the structure under the same stress conditions in SolidWorks,and the results show that the structure with the highest strain sensitivity is 2.8 times more sensitive than the structure with the lowest strain sensitivity.3.Aiming at the problem that the traditional insulator string insulation performance perception method is unreliable,this paper proposes a monitoring scheme of insulator string leakage current based on coil,magnet,dual-frequency sensing cantilever beam and fiber grating.Results show that the leakage current dual-frequency sensing system proposed in this paper can distinguish 50Hz and 150Hz signal input,and the leakage current resolutions at the two frequencies are 1.2858nm/A and 1.2863nm/A respectively.The resonant frequency is around 100Hz.In the artificial fog chamber exacerbated insulator flashover experiment,the sensing system proposed in this paper matches the data in the first 10 minutes of the discharge phase,the monitoring system error is about ±200mA.4.Aiming at the problem that the unreliable electronic monitoring of power transmission line tension and the complex structure of fiber grating monitoring sensors,this paper designed a simple and easy-to-install fiber grating-based pull-ring shaped pull-compression type tension sensor for overhead transmission lines.Results show that the structure designed in this chapter has good linearity and fatigue stability,and the sensing accuracy reaches 0.0543pm/N,which is only slightly lower than 0.0489 pm/N and 0.0415pm/N for the more complex S-type shear tension sensor and column-type tension sensor developed by other research institutes.On the other hand,this paper proposes an overhead transmission line tension and leakage current co-measurement sensing system,completed the installation and pilot application of the dual-frequency sensing part of insulator string leakage current in the actual power grid system,and the system is still running normally.