Smart Grid: Technology and Applications

10

Power Electronics in the Smart Grid

10.1 Introduction

In the future Smart Grid there will be increasing connection to the distribution network of renewable energy sources, electric vehicles and heat pumps. More flexible loads will be expected to support the grid by accepting varying supplies of energy from renewable sources and by controlling peaks in demand. For sensitive loads such as computers and high value manufacturing plants, the quality of supply will be important. Therefore visibility, controllability, and flexibility will be essential features throughout the future power system with power electronics playing a key role

The power output of some of renewable energy sources is always DC (for example, photovoltaic systems) and an inverter is needed to interface them to the AC grid. Even though renewable energy sources using an AC generator (for example, wind turbines) can be connected directly to the grid, often some form of AC to DC and then DC to AC conversion is used. Some power system operating conditions demand rapid independent control of the active and reactive power output of the renewable energy generators. These control actions can only be achieved conveniently using a power electronic interface.

With the connection of a large number of distributed generators, including micro-generators, traditional methods of active power/frequency control and reactive power/voltage control will no longer be effective. The traditional voltage control method in a distribution ...