Learning-based data-enabled economic predictive control with convex optimization for nonlinear systems

TL;DR

This paper introduces a data-enabled economic predictive control approach for nonlinear systems that uses neural network-based lifting functions to transform the problem into a convex optimization framework, enabling efficient and constrained control.

Contribution

The method extends economic predictive control to nonlinear systems by employing neural network mappings, allowing convex optimization despite system nonlinearity.

Findings

Effective in biological water treatment process

Applicable to solvent-based carbon capture

Maintains convexity for nonlinear dynamics

Abstract

In this article, we propose a data-enabled economic predictive control method for a class of nonlinear systems, which aims to optimize the economic operational performance while handling hard constraints on the system outputs. Two lifting functions are constructed via training neural networks, which generate mapped input and mapped output in a higher-dimensional space, where the nonlinear economic cost function can be approximated using a quadratic function of the mapped variables. The data-enabled predictive control framework is extended to address nonlinear dynamics by using the mapped input and the mapped output that belong to a virtual linear representation, which serves as an approximation of the original nonlinear system. Additionally, we reconstruct the system output variables from the mapped output, on which hard output constraints are imposed. The online control problem is formulated as a convex optimization problem, despite the nonlinearity of the system dynamics and the original economic cost function. Theoretical analysis is presented to justify the suitability of the proposed method for nonlinear systems. We evaluate the proposed method through two large-scale industrial case studies: (i) a biological water treatment process, and (ii) a solvent-based shipboard post-combustion carbon capture process. These studies demonstrate its effectiveness and advantages.