Translated Abstract
The electric transimission ability can be promoted by increasing transmission line capacity with transmission line environment and condition monitoring on the condition of maintaining line structure and ensuring the safety of power grid. There are three main problems about line capacity increasing, including high-quality monitoring data about line environment and condition, proper transmission line capacity calculation method, line capacity increase risk assessment. It is of great significance for promoting line capacity ability and ensuring the safety of power grid to promote the line transmission capacity and ensure the safety of power grid.
On-line monitoring data of high quality including environment temperature, wind speed, sunlight intensity, and current line capacity is needed when increasing the line capacity and assessing its running risk. The performance of the wireless sensor network (WSN) which is used for collecting and sending data in the transmission line effects the data quality heavily. In this paper, the structure and performance of the transmission line WSN was analyzed. Some problems related to the performance were found, including data jamming (the network bottleneck effect) of sensors near the network sink sensor due to the special topology of the network, competition and disturb in wireless sensor nodes caused by the high power transferring of sensor nodes. Solutions were proposed to strengthen the performance of the network, including sharing the sink nodes in different transmission lines to reduce the bottleneck effect and applying improved LEACH protocol to achieve cluster communication. Simulation of the methods was carried out in OPNET. The results showed that the network delay time and queue size was reduced, and quality of service was optimized heavily. The reliability of collecting and transferring monitoring data was ensured.
Besides the requisite line monitoring data, proper transmission line capacity calculation model is necessary to calculate the line capacity increase. This paper analyzes several different line rating standards, models and corresponding boundary conditions, proposing the capacity calculation model suitable for line capacity increase considering emergency conditions. Influence of wind speed, wind direction and the environment temperature on steady line capacity are deeply analyzed. Emergency line capacity calculation method is proposed The uncertainty of line capacity was calculated with self-adaptive Monte Carlo method, so that the dependability of line capacity calculation was guaranted.
To ensure the safety and reliability of line capacity-increase running , this paper analyzes the risk of line capacity increase and proposes the risk assessment method based on Markov Chain Monte Carlo (MCMC) method. This method firstly gets posteriori distributions of different environmental parameters, and then sets up the climate probability of those parameters including wind speed, wind direction and environment temperature. Finally, with Monte Carlo method, the capacity increase risk is calculated out by forecasting the line temperature distribution. Monitoring data in different time was used to analyze the reliability of capacity-increase running in different areas of Qinghai Province. The result indicates that the operation risk is controllable and meets the safety requirements of transmission line and power grid.
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