(367c) MPC and the Smart Grid: Optimal Operation and Transmission Expansion

In the US, an overwhelming portion of electric energy is generated in environmentally unfriendly fossil fuel based power plants. While this has been accepted for decades, society is beginning to demand a more sustainable approach. Unfortunately, it is not just a matter of replacing sources MW by MW. While fossil based plants can be located near load centers, the efficiency of renewable sources is location dependent. Unfortunately, transmission infrastructure from locations with high renewable potential is either of low capacity or nonexistent. Furthermore, the uncertain power output of renewable sources suggests that dispacthable fossil based plants will need to be utilized to a much greater extent. Again, the existing infrastructure is ill-equipped to deal with such an increase in power flow variability.

To address these issues a number of approaches may be employed: increased usage of power flow control devices, construction of energy storage systems, and the addition of new transmission lines. The first provides additional flexibility in designating how power will flow though the grid. (For example power from an overloaded line may be routed to a less loaded line.) However, not all lines will need control infrastructure, and judicious allocation of these capital investments will be prudent. The second approach allows for available power to be time-shifted to periods of high demand. Again, the capital cost of these systems is significant, and location of a storage facility is typically limited by geographic considerations. The question of adding new transmission lines is dominated by identifying the appropriate location of the line (to maximally exploit the previous two actions), as well as design capacity and system type (AC or DC). Additional questions include the sizing and placement of new generation sources as well as determining if these sources should be fossil or renewable.  

This paper will provide a review of the current methods used for optimal energy dispatch and how MPC can be used to enhance operation under the conditions of more renewable sources as well as the availability of new power flow control devices and energy storage systems. In addition, the procedure of transmission infrastructure expansion will be discussed in the context of smart grid operation.