Online optimal switching of single phase DC/AC inverters using partial information

Abstract

This paper proposes an online optimal tracking algorithm to provide the desired voltage magnitude and frequency at the load. This eventually will work as a DC/AC inverter that with appropriate switching of semiconductor devices will convert low DC voltage to high AC voltage. An L´C filter is used to reduce the effects caused by switching semiconductor devices. The proposed control scheme ensures a good tracking of an exosystem that provides the desired voltage magnitude and frequency. It builds upon the ideas of approximate dynamic programming (ADP) and uses only partial information of the system and exosystem. A Lyapunov stability proof ensures that the closed-loop system is asympotically stable. Finally, simulations show the effectiveness of the proposed approach.Index Terms-Power systems, voltage source inverter, approximate dynamic programming.

Sub-Optimal Tracking in Switched Systems With Controlled Subsystems and Fixed-Mode Sequence Using Approximate Dynamic Programming

“…For this example, Method 2 in Remark 2, i.e., integration of the costate analytically, was used to find the value function and then minimized the value function with nonlinear programming methods. Through integration, one can find the analytical value function as Substituting the initial conditions for x 1 = 1 and x 2 = −0.5, one can find the value function as a function of the switching time as V (t 1 ) = 67088t 3 1 − 1.823 × 10 5 t 2 1 + 7.073 × 10 5 t 1 − 1.846 × 10 6 . Using nonlinear programming, the best switching time is sought as t 1 = 2.654 (sec).…”

“…Due to the discontinuous nature of the switched systems, control of these systems are challenging. Control of switched systems addresses many critical problems in automotive engineering [1], power engineering [2], [3], and many other engineering fields.…”

“…ADP solutions for optimal control of switched systems with free mode sequence were investigated in [3], [5]- [10]. As for the fixed mode sequence, a transformation was introduced in [11] to treat the switching times as parameters.…”

“…When t < t 1 mode 1 is active and when t ≥ t 1 mode 2 is active 2. Since the mode sequence is known, one can consider the integral from t 0 to t 1 with the first mode, and from t 1 to t f with the second mode 3. By definition, costate is the gradient of value function, i.e., λ (x) = ∂V (x) ∂ x .…”

Robust event‐triggered output feedback learning algorithm for voltage source inverters with unknown load and parameter variations

“…[8][9][10] As stated in the work of Venayagamoorthy, 11 there is an emergent need for computational intelligent controllers that allow the smart grid to self-heal, resist attacks, allow dynamic optimization of the operation, and improve power quality and efficiency. Following this line of research, Vamvoudakis and Hespanha 6 propose an integral reinforcement learning algorithm to achieve the desired voltage magnitude and frequency at the load, without having full information about the dynamics of the systems. Inspired by these ideas, we design a controller for a VSI to produce a desired voltage in the presence of an input disturbance (eg, transients, interruption, overvoltage [surge], undervoltage [sag], voltage fluctuations, electrical noise, and adversary).…”