Performance assessment of photothermal power station is an essential part of power station construction

but mature and general test method and procedure for concentrating solar power(CSP) stations has not formed yet. Due to the fluctuation of the solar resource

steady-state performance test for parabolic trough CSP stations can only be carried out during the noon when the solar radiation is relatively stable. However

during this period

the energy storage system is in charge mode

which makes it difficult to assess overall plant efficiency with measured data. To solve this problem

this article compares the energy transfer model of direct generation mode and charge mode

and proposes a calculation method for overall plant efficiency by converting charge mode into direct generation mode. The design data of a 50 MW parabolic trough CSP station under charge mode are used to verify the calculation method. The calculation results maintain a high consistency with the actual design data

which demonstrates the accuracy and feasibility of the proposed method.