A power plant controller configured to control a renewable power plant comprising a plurality of power generating units, the power plant controller comprising a balance of plant estimator configured to provide an internal power loss estimation of the renewable power plant, the power plant controller comprising - a sensor arrangement adapted to provide - at least one first pair of associated first and second power values (P prod, P meas) in a first power range, - at least one second pair of associated first and second power values (P prod, P meas) in a second power range, wherein the first and second power values are P prod and P meas, respectively, and P prod is a total amount of produced active power from the plurality of power generating units and P meas is a measured active power at a PoM, - a processor adapted to - determine a representative of the first pairs of associated first and second power values (P prod, P meas), and determining a representative of the second pairs of associated first and second power values (P prod, P meas) in accordance with predetermined rules, wherein respective average values of the associated first and second power values (P prod, P meas) form the representatives of the associated first and second power values (P prod, P meas) in the first and second power ranges, and - calculate a first set of performance parameters for the balance of plant estimator using the representatives of the first and second pairs of associated first and second power values (P prod, P meas), - apply the performance parameters in a power loss estimation algorithm of the balance of plant estimator. - a sensor arrangement adapted to provide - at least one first pair of associated first and second power values (P prod, P meas) in a first power range, - at least one first pair of associated first and second power values (P prod, P meas) in a first power range, - at least one second pair of associated first and second power values (P prod, P meas) in a second power range, wherein the first and second power values are P prod and P meas, respectively, and P prod is a total amount of produced active power from the plurality of power generating units and P meas is a measured active power at a PoM, - a processor adapted to - determine a representative of the first pairs of associated first and second power values (P prod, P meas), and determining a representative of the second pairs of associated first and second power values (P prod, P meas) in accordance with predetermined rules, wherein respective average values of the associated first and second power values (P prod, P meas) form the representatives of the associated first and second power values (P prod, P meas) in the first and second power ranges, and - calculate a first set of performance parameters for the balance of plant - determine a representative of the first pairs of associated first and second power values (P prod, P meas), and determining a representative of the second pairs of associated first and second power values (P prod, P meas) in accordance with predetermined rules, wherein respective average values of the associated first and second power values (P prod, P meas) form the representatives of the associated first and second power values (P prod, P meas) in the first and second power ranges, and - calculate a first set of performance parameters for the balance of plant - apply the performance parameters in a power loss estimation algorithm of the balance of plant estimator.