China is accelerating the construction of large-scale solar and wind bases in deserts and Gobi regions to achieve the goals of Carbon Peaking and Carbon Neutrality. However

the lack of conventional power sources and the weak grid strength in such areas severely restrict the application of line commutated converter (LCC) which is dependent on power gird to provide commutation voltage. The grid-forming converters can improve the strength of the power gird but the additional configuration of grid-forming converters at renewable energy bases will significantly increase construction costs. Considering the demand for energy storage in renewable energy bases

if the grid-forming capability of the power conversion systems (PCS) can be fully utilized

it can provide stable voltage support for renewable energy bases and LCC with a moderate increase in cost. This paper proposes a large-scale photovoltaic (PV) transmission scheme via LCC dominated by grid-forming PCS. First

the topology is introduced and the capacity of grid-forming energy storage is designed. Then

based on the direction of frequency changes under PV power fluctuations

a control scheme of LCC and PCS coordinating and participating in power grid frequency regulation is designed. To prevent LCC blocking caused by nighttime solar unavailability

a control sequence for DC power flow reversal is proposed to achieve low-power operation of LCC night hours. The simulation results demonstrate the feasibility of the proposed scheme

offering a new solution for large-scale photovoltaic integration and power transmission.