Distributed optimal load frequency control considering nonsmooth cost functions Abstract   This work addresses the distributed frequency control problem in power systems considering controllable load with a nonsmooth cost. The nonsmoothness exists widely in power systems, such as tiered price, greatly challenging the design of distributed optimal controllers. In this paper, we first formulate an optimization problem that minimizes the nonsmooth regulation cost, where both capacity limits of controllable load and tieline flow are considered. Then, a distributed controller is derived based on the primalxe2x80x93dual gradient method, where the Clark generalized gradient is utilized to address the nonsmoothness. We also prove the optimality of the equilibrium of the closedloop system as well as its stability. Simulations carried out on the IEEE 68bus system verifies the effectiveness of the proposed method.

A Datadriven Convexoptimization Method for Estimating Load Changes This paper presents an optimizationbased method to detect the occurrence, estimate the magnitude, and identify the location of load changes in the power system. The proposed method relies on measurements of only frequency at the output of synchronous generators along with a reducedorder power system dynamical model that captures locational effects of load disturbances on generator frequency dynamics. These locational aspects are retained in the estimation model by incorporating linearized powerflow balance into differential equations that describe synchronousgenerator dynamics. The sparsity structure of loadchange disturbances is leveraged so that only a limited number of measurements are needed to estimate load changes. Furthermore, a convex relaxation of the problem ensures that it can be solved online in a computationally efficient manner. Timedomain simulations involving the Western Electricity Coordinating Council 9bus test system demonstrate the accuracy of the proposed method.