Electric Co-ordination And Its Application

In the electric power system operation, the uncoordinated problems between the generation, the transmission and the user because of insufficient of the transfer capacity occur frequently; in particular this problem becomes more prominent after the introduction of the competitive mechanism. According to the power system operation, solution of transfer capacity insufficient need expand and speed up continuation of the ultrahigh voltage, extra-high voltage electric network, but span a new transmission line is limited by economic conditions and space, especially in the latest few years the enhancement of environmental protection consciousness causes to erect a new transmission line to be more difficult. Thus subjectively excavating latent transfer capacity of the existing power transmission network to guide and control the power system operation is profound.Based on the former studies, this article discussed the heating process and the adverse effect of transmission lines. Starting from the Heat Balance Equation, the calculation of electric current heat gain, solar heat gain, the convection heat loss and the radiated heat loss is analyzed particularly, the determination of transmission lines capacity are generalized in different technique conditions, and the influence of the wind speed, the wind direction, the sunshine density, the conductor maximum permissible temperature and the conductor radiance to transmission lines capacity is comparatively analyzed.The models and method of the electrothermal coordination power flow and transmission line temperature variation process is studied deeply. The electric transmission conductor's temperature changes along with the environment and the current, the temperature changes similarly causes the resistance to change. On the condition of the measuration is provided, take the transmission line resistance changes as the link, involve the transmission line's heat balance equation as the core, alternate with the power flow, thus forms the models and method of the electrothermal coordination power flow and transmission line temperature variation process. Through solving the algebraic equation and differential equation alternately, the temperature dynamics of transmission lines (critical transmission lines especially) adapting each fluctuation of power system operation mode is obtained.Combining the electrothermal coordination power flow and the optimal power flow, the electrothermal coordination optimal power flow is elementarily discussed. Through the electrothermal coordination optimal power flow, consequently whether the transmitting capacity is restricted can be differentiated directly by the real-time temperature of the lines, the potential transmitting capacity will be excavated, thus the security and economy of system operation are improved. The results are base theoretical research to electric power system operation dispatching considering electrothermal coordination.The research indicated that implements the electrothermal coordination based on the implementation of Dynamic Thermal Rating can excavate the electric power system latent transfer capacity, strengthens the system's ability to resist the accident under the turbulent conditions. At the same time, with the limit of the environment, the region, the economy and etc, the existing electric network transfer ability need to use and excavate sufficiently. Considering the electric specification and thermal characteristic of the key transmission conductor organically, then realizing ascertaining transfer capacity by variational temperature will be significant to extremely to the actual transfer capacity decision-making and the judgment.