Abstract:

This paper proposes a simple mechanical analogy to visualize the dynamic response of electrical energy systems that is easy to understand for a non-technical audience and/or early-stage undergraduate engineering students.

The author has recently been involved in a H2020 project, RE-SERVE, that is aimed at the definition of novel frequency and voltage controls for networks with high penetration of renewable energy resources and non-synchronous generation. One of the activities of the project is the dissemination of results and the presentation to a non-technical audience of the problems to be solved and the solution found. This has made necessary to show in an as visual and direct way as possible the dynamic behavior of an electrical energy system. This has to be done assuming that the audience not only does not have a strong base on electrical machines or nonlinear system dynamics, but might not be an engineer at all. This leads to the need to avoid, whenever possible, equations, technical language and conventional plots.

At the same time, the author has become the coordinator of the module Electrical Energy Systems, which is a second year module for mechanical, electrical and electronic engineering students at University College Dublin, Ireland. This is a challenging module for a variety of reasons. First, the module is offered at a stage at which students have seen only very basic concepts of electric and electronic circuit theory. These students have little knowledge of dynamical systems and no knowledge of control theory, electrical machines and power system operation. Thus, they are, to some extent, comparable to a non-technical audience.

This paper presents a novel graphical simplified visualization of power system dynamics that resembles the most important dynamic response and controls of a power systems. This includes the generation/load balance, synchronous machine response, and primary and secondary frequency control. The impact of renewable sources on the dynamic response of the system is also illustrated.

The proposed approach, while necessarily approximated, is based on a mechanical analogy. The power system is represented as a mechanical scale with generation on one arm and load on the other one. Synchronous machine inertia and frequency controllers are represented as springs and dampers connected to the arms of the scale. Since the underlying core behavior of a power system resembles a second order differential equations, i.e., shows damped oscillations after the occurrence of a disturbance, the analogy is good enough to introduce basic dynamic and control concepts.

The final paper will provide the following contributions.
• A simplified mechanical analogy to visualize most important electric power system dynamics.
• A thorough discussion on the physical appropriateness as well as of the limitations of the proposed analogy.
• A discussion on the main difficulties encountered by non-technical audience to grasp the main concepts of electrical energy system dynamics.
• A discussion on the didactic value of the proposed analogy based on the feedback of the students of the module Electrical Energy Systems offered by the author at University College Dublin, Ireland.

Keywords:

Power system dynamics, power system visualization, non-technical audience, early-stage engineering students.