I am following a course on udemy and it deals with PV model. This course tutorial was done on matlab but I replicated the modelling on plecs by following each video step. In the Is sub system of the video, Taref and Tact was modeled using the reciprocal functions of math functions in the matlab. When I searched for maths function on plecs library, there was no reciprocal function on the math functions block, then I used the function f(u) block to model Taref and Tact. After modeling, I try to run the model and I keep getting Taref and Tact as undefined variable and it keeps giving error.

Please, what can I do? Attached to this write up is the model and a screenshot of the particular subsystem

model pv.plecs (58.8 KB)