# Power-Imbalance Allocation Control of Power Systems-Secondary Frequency Control

## TL;DR

This paper introduces Power-Imbalance Allocation Control (PIAC), a novel secondary frequency control method for power systems that achieves faster convergence, minimizes control costs, and maintains stability even with large frequency deviations and multi-area independence.

## Contribution

The paper proposes PIAC, a new secondary frequency control approach that estimates power imbalance exponentially, avoids overshoot, and enables asynchronous control in multi-area power systems.

## Key findings

- PIAC achieves exponential convergence of power imbalance estimation.
- PIAC avoids overshoot and large frequency deviations.
- PIAC maintains stability and control efficiency in multi-area networks.

## Abstract

The traditional secondary frequency control of power systems restores nominal frequency by steering Area Control Errors (ACEs) to zero. Existing methods are a form of integral control with the characteristic that large control gain coefficients introduce an overshoot and small ones result in a slow convergence to a steady state. In order to deal with the large frequency deviation problem, which is the main concern of the power system integrated with a large number of renewable energy, a faster convergence is critical. In this paper, we propose a secondary frequency control method named Power-Imbalance Allocation Control (PIAC) to restore the nominal frequency with a minimized control cost,in which a coordinator estimates the power imbalance and dispatches the control inputs to the controllers after solving an economic power dispatch problem. The power imbalance estimation converges exponentially in PIAC, both overshoots and large frequency deviations are avoided. In addition, when PIAC is implemented in a multi-area controlled network, the controllers of an area are independent of the disturbance of the neighbor areas, which allows an asynchronous control in the multi-area network. A Lyapunov stability analysis shows that PIAC is locally asymptotically stable and simulation results illustrates that it effectively eliminates the drawback of the traditional integral control based methods.