Research On Power Transmission Scheme Of UHV Half-Wavelength And DC Submarine Cable Connection

With the acceleration of industrialization,increasing fossil energy has been mined and excavated.As energy is increasingly depleted,environmental pollution and climate change problems have also arisen,seriously hampering human survival and development.Vigorously developing clean energy is an effective way to solve the energy dilemma.However,there is a geographical imbalance between heavy load demand and sufficient energy resources around the world.Therefore,the global energy interconnection program will greatly promote the development and consumption of clean energy.Based on the example of China-Korea power grid interconnection,this paper carries out the power transmission scheme of UHV half-wavelength and DC submarine cable connection,the characteristic analysis of UHV half-wavelength transmission(HWLT)technology and the grid planning considering global energy interconnection.According to the official Korean research report,the geographical wiring diagram of the Korean power grid and the geographical distribution of its renewable energy are obtained.In combination with the Korean economic situation,Korea's total power generation,installed capacity and peak load in 2030 are predicted,and the power balance in Korea in 2030 is calculated.The submarine cable technology development and worldwide UHV submarine cable engineering are summarized.The selection of submarine cable AC/DC transportation modes and the choice of submarine cable material types under different conditions are analyzed.The HWLT technology is adopted to provide clean energy for Shandong Power Grid,the half-wavelength access scheme is initially planned,and the China-Korea submarine cable converter station and substation site are selected.The distributed parameters are adopted to obtain ideal HWLT line model,and the relationship between voltage distribution,active power and power factor along line is analyzed.The influence of the active power and power factor at the end of the line on the maximum voltage and reactive power distribution along line is deduced.The HWLT power upper limit and the HWLT line electrical distance are theoretically calculated.Aiming at that in actual situation the non-ideal factors have noticeable influences on HWLT line,the HWLT line model is deduced under non-ideal conditions,such as conductor type,line length,coupling effects of double circuit lines on the same tower and complex landscapes.Two network examples are used to verify the accuracy of the deduced HWLT line model and compare the difference between complex non-ideal factors and single non-ideal factor impacts.A single-objective planning scheme for traditional power grids and a multi-objective planning scheme for Eastern Shandong Power Grid considering UHV HWLT line and submarine cable access are established.Taking the minimum life cycle cost as the planning goal,ensuring "N-1" safe and stable operation,the function model of traditional power grid planning is established.For the complex power system with interconnection project accessing,considering the economic,safety,stability and social impact of the large power grid planning,the electric power network is modelled by three objective functions including life cycle cost."N-2" operation risk probability and "N-2" fault average load shedding.The different impacts of different load importance degrees on society are also taken into account.Niche genetic algorithm is used to solve single-objective grid planning.To avoid the large-scale grid dimension disaster problem.Monte Carlo method and NSGA-? algorithm are used to solve multi-objective grid planning.Examples verify the accuracy of the chosen algorithm and provide planning reference for the Eastern Shandong power grid construction considering China-Korea interconnection.