Electric Springs: Basic Principles, Circuit Topologies and Applications to Smart Grids

Abstract

Traditional control paradigm of 'power supply following demand' does not suit emerging power grids that are fed with increasing renewable energy generation of intermittent nature. In order to achieve power system stability, it is necessary to maintain instantaneous balance between power supply and demand. A new control paradigm of having 'power demand following supply' must be adopted. This opens a new research area of demand-side response. Electric springs is an emerging demand-side response technology. Based on power electronics technology, Electric Springs are designed to provide distributed support for maintaining the stability of mains frequency and voltage. Similar to having many small mechanical springs supporting a mattress without the need for mutual communication, they are expected to be distributed over the power gird. By using input control, they provide instantaneous active and reactive power compensation so as to reduce fluctuations in mains voltage and frequency caused by the injection of intermittent renewable power. This tutorial will be divided in three parts. The first part covers the basic principles of the Electric Springs and their functions. The second part deals with various circuit topologies and control methodologies that can achieve electric spring functions. The last part is related to the application potentials of electric springs on power systems.