Current Carrying Capability Of Power Grid Considering The Relationship Between Current And Temperature Research

The exhaustible resources and the problems of environmental damage are gradually serious,renewable energy generation has got rapid development.Power system is characterized by diversification and complex relationship.The transmitting capability of power system is insufficient,that has become an important factor restricting the development and the economic operation of power system.How to exploit the transmission components' potential capacity sufficiently under the exiting grid operation conditions has become the focus of attention from all walks of life.DTR technology has played an important role in relieving the stress transmission of key sections and enhancing the capacity of new energy generation.The electro-thermal coordination theory in power grid operation which reflects the essence of transmission components' transfer capability in power grid's operation dispatch and control decisions further exploit the existing power transmission capacity.This dissertation research the thermal and mechanics nature of the overhead load capacity and further considers the mechanical properties as well as the influence of the temperature and weather environment on the stress and sag of overhead line.The main research work is current carrying capability of power grid considering the relationship between current and temperature.The main research work and innovation can be summed up as follows:(1)Two kinds of forecast method for transmission capacity of the line are proposed.One is based on meteorological elements forecast use the metrological regression method.The meteorological elements(wind speed,ambient temperature and sunshine intensity)which affect the thermal rating of the line are predicted respectively.Based on the forecast of meteorological elements,the transmission capacity forecast can be implemented.The other is based on the quantile regression analysis theory to realize the probabilistic prediction of transmission capacity of the line.The weather parameters which have significant influence on the thermal rating and historical line ratings are embedded in the quantile regression prediction model.The proposed method can effectively reduce the prediction result deviation result from meteorological prediction error.Can not only give the interval prediction result,but also can provide the forecasting results of probability distribution function.Finally,the validity of the proposed method is illustrated by case studies.The new method can provide reliable and useful information for the dispatching department to facilitate scientific decision-making.(2)Electro-thermal coupling power flow calculation considering meteorological distribution along overhead transmission lines(ETCPF-CMD)is proposed.By introducing the virtual node and the line simulation in the traditional electro-thermal coupled power flow calculation to consider the meteorological distribution in the region,and analyzes the complexity of the power flow caused by the introduction of virtual nodes and lines.The simplified calculation is made by using the physical law of electro-thermal coupling and the numerical characteristics of jacobian matrix.The large-scale correction equations are decomposed into three independent small-scale correction equations.On the basis of ensuring the accuracy of the calculation results,the computational efficiency can be improved remarkably.Based on the distribution of meteorological information,this method can realize the distribution of the temperature along the line,so that the electro-thermal coupling power flow calculation is closer to the actual.(3)On the basis of the ETCPF-CMD,this paper further considers the mechanical properties as well as the influence of the temperature and weather environment on the stress and sag of overhead line.Based on the coupling of the electrical,thermal and mechanical characteristics,alternative solution form of algebra-differential equations,the new power flow calculation model can achieve operation temperature and form of the overhead line in the variety of expected scenarios.And then get the trajectory of the operation temperature and form of the line under the expected accident.Based on this,a static safety assessment method to take into account the thermal and mechanical characteristics is proposed.That reflects the nature of the load capacity decided by the thermal and mechanical characteristics of overhead line.The new method provides the possibility of exploiting the transmission components' potential capacity sufficiently under the exiting grid operation under the premise of ensuring the safety of power grid.