Electric Springs: A Smart Grid Technology for Taming the Intermittent Nature of Wind and Solar Power

Abstract

With the CO2 concentration passing the 400 ppm mark, there is an urgent need to substantially increase wind and solar power penetration as soon as possible. The success of the 2015 Paris Climate Change Summit has resulted in many countries setting targets in reducing greenhouse gas emission. One obvious solution is to substantially increase renewable energy generation. However, the intermittent nature of wind and solar power has been identified as a de-stabilizing force to the power grid. It is envisaged that more stability issues will evolve as the amount of renewable power generation increases. With more distributed power generation, the control paradigm has to be changed so that ‘the load demand will follow the power generation', in contrast to existing control paradigm that ‘the power generation follows the load demand'. In this tutorial, we shall introduce the concept of electric springs as a smart grid technology for demand response. Based on power electronics technology, Electric Spring is a new distributed technology that can (1) tame the intermittent nature of wind and solar power and (2) ensure ‘the load demand to follow the power generation'. Electric springs are power electronic circuits that act as ‘active suspension' systems. When distributed over the distribution networks, they provide a robust stability support system for future power grid. The Electric Spring concept can be incorporated easily either (1) into non-critical electric appliances, (2) as part of the power supply infrastructure or (3) into grid-connected wind/solar power inverters. The tutorial will cover (i) the basic Electric Spring concept, (ii) various forms of electric springs and their functions, (iii) the application potentials in mitigating voltage/frequency fluctuationsin power grids, peak load shaving, reducing power imbalance, and reducing energy storage requirements, (iv) hardware and control designs, (v) dynamic modeling for power system simulation studies. Practical results obtained from a 100kVA hardware setup will be included for illustration. At the end of the tutorial, new industrial projects and future trend of demand response and power system infrastructure will be addressed.