The problem of profit allocation of Unified Power Flow Controller-Supplementary Damping Controller (UPFC-SDC) and accelerating power PSS model (PSS2B) is an important and update issue which has not been properly directed yet. The model of UPFC-SDC that has been used in this paper is a dual-dimensional controller that first dimension of control is resulted from local signals and the second dimension is covered by global signals as additional measuring data from appropriate remote network locations, where swings are well observable. Thus, in this paper the profit allocation of Wide Area Damping Controller (WADC) is also presented as an undefined problem in security subject of deregulated power system. Assuming control action by UPFC-SDC and WADC as an Ancillary Service (AS), the contribution of UPFC-SDC in stability enhancement is evaluated. It is important to appropriately choose a criterion to assess the performance of UPFC-SDC, so that a suitable allocation of profit can be achieved. The sum of deviations of damping ratios and real part of eigenvalues is selected as Oscillation Damping Criterion (ODC). Two scenarios for valuation of small signal stability as an AS provided by UPFC-SDC is considered. The first scenario without retuning of controllers and in the second scenario controllers is retuned due to response of the market situation. A multi-objective optimization approach based on ODC, generation costs and UPFC cost is considered and then Non-Dominated Sorting Genetic Algorithm-II (NSGA-II) is utilized for solving this problem. A two area four machine test power system is considered for investigation of results. (C) 2013 Elsevier Ltd. All rights reserved.