海上风电多类型直流送出系统拓扑经济性分析

Economic Analysis of Multi-type DC System Topologies for Offshore Wind Power Transmission

相比于柔性直流输电(VSC-HVDC)送出方案,送端采用不控整流器(diode rectifier,DR)的DR-HVDC方案具有损耗低、体积小和成本低的优点,是未来海上风电送出技术的重要发展方向之一。为了解决黑启动和海上交流电压调控问题,现有的DR-HVDC拓扑主要采用海上平台装设储能、系统增加交流联络线路、送端换流站并联VSC三种方案。以深远海海上风电送出为背景,对上述三种DR-HVDC拓扑方案进行了经济性分析,并与VSC-HVDC方案进行比较。采用了全寿命周期成本分析(life cycle cost analysis,LCCA)方法,建立了上述四种送出方案的经济性分析模型,并对各方案的离岸距离、装机容量、上网电价以及有效工作时长等因素进行单一变量分析。结果表明,相比于VSC-HVDC,DR-HVDC送出方案的换流站成本、运行损耗和维护成本均显著降低。同时,随着海上风电容量和输送距离的增加,采用送端并联VSC和送端储能的DR-HVDC方案的经济性优势更加明显。因此,DR-HVDC送出方案在海上风电并网中具有广阔的应用前景。

Compared with the VSC-HVDC scheme,the DR-HVDC diode rectifier at the sending end has the advantages such as lower power loss,smaller converter size,and low cost,which are important for the development of offshore wind power transmission in the future.However,to solve black startup and offshore AC voltage regulation problems,the existing DR-HVDC topologies mainly adopt three schemes,such as installing the energy storage on the offshore platform,adding additional AC connecting links to the onshore system,and paralleling VSC at the sending end.For the background of deep-sea offshore wind power transmission,this paper makes an economic analysis on the three DR-HVDC topology schemes and compares them with VSC-HVDC.The economic analysis models of the above delivery schemes are established through the life cycle cost analysis(LCCA)method.Furthermore,the influences of related factors are analyzed,including offshore distance,installed capacity,on-grid price,and effective working hours.The results show that DR-HVDC can significantly reduce the converter station cost,operation loss cost,and maintenance cost compared with VSC-HVDC.Meanwhile,with the increase of offshore wind power capacity and transmission distance,paralleling VSC or energy storage schemes of DR-HVDC show more edges in the economy.Therefore,DR-HVDC topologies have a broad application prospect for offshore wind power integration.