Smart Grid / Smart Home
PJM – How Do They Do It
Our current electricity grid is not so much one of design as much as it is one that evolved through incremental extensions. Consequently, it has not kept pace with the recent changes in new types of loads and the increasing addition of renewables. The explosion of digital loads from computers are placing ever more demands on the grid for steady, high quality power. At the same time, more and more intermittent renewable power sources such as Solar and wind are being added that further strain the grids capabilities. Unfortunately, utilities have felt that there were insufficient financial incentives to pursue any significant modernization.
Even without this sorely needed modernization, the grid is one of the engineering achievements of the 20th Century. And those who operate it continue to amaze us with their ability to balance, in real time, the dynamic nature of customer demand with the necessary sources of generation. As you and I, turn things on and off, the grid operators are monitoring and responding with a corresponding increase or decrease in generation capacity. At an individual event level, things can often average out. But things get interesting when lots of people start arriving home from work around the same time and crank up their A/C on a hot summer day… this is when the grid operators perform their magic with no recognition or fanfare.
So the grid has evolved into a real-time balancing act… why not just add some storage to give the operators some breathing room? Up until recently, it’s just been too expensive. And there is something else we need to understand… that the grid was originally intended to be a one way flow system. All the generators were upstream and the power flowed “downstream” thru transmission and distribution networks to the end use customer.
A relatively new policy objective has been to increase the amount of clean renewable energy in our national energy portfolio. This has resulted in a growing number of “distributed generators” (DG) of electricity coming online at various points throughout the grid. These range from the small rooftop Solar arrays to the new large utility scale Solar (and wind) power plants. While the benefits of adding clean, sustainable power sources are worthy objectives… there are complications.
In our opinion, every Solar company should understand how the grid works and what the issues are that concern the grid operators… it is definitely an eye opener and should bring us closer together as collaborators rather than adversaries. Here is a link to a great high level overview of grid operations called “PJM 101 – The Basics”.
System of Systems… Smart Grid / Smart Home
Although the internet has impacted virtually every aspect of modern day living… it has had little impact on the electricity grid… yet!
Over the past 50 years, everything has become smarter and more accessible for us to monitor and control… our digital devices in the home, our entertainment systems, our phones, even our cars. Yet, for the most part, we have no clue how much energy we are consuming or which devices in our homes are the real energy consumers. We can’t tell which things are operating properly and which are old and ready to fail. This may have been an acceptable state of affairs before residential Solar systems and Electric Vehicles(EVs) came along, but these significant new electric load additions will require us to finally become Energy Conscious.
Our current approach to residential electric design is to size the service panel to support the possibility of everything coming on at the same time. This is an inefficient and wasteful use of electrical resources. What if we applied some intelligence to the system and, for example, alternated between the refrigerator coming on and the heater coming on. They both need to cycle but there’s no reason why they can’t take turns. This type of intelligent system could improve the efficiency of the electrical system in our home and it could have significant effects on the grid when multiplied by thousands of smart homes. Instead of needing a 200A service, we might be able to get away with only a 100A service.
You might be tempted to say “That’s nice and all, but I’ve already got the 200A service in place”. But what about when you add a Solar system and/or an EV? You could very well be faced with having to increase the size of your service panel OR apply the intelligence mentioned above to give you the extra capacity you need… free of charge. What would really help is an “Internet of Energy” within the home. All the consumers (and sources) of energy that can talk to each other and adjust their operation accordingly.
At the heart of this Smart Home, we see an Energy Management System (EMS) or master controller. This is a device that can communicate with all the major power players in the home, monitoring and controlling each device based on the homeowners preferences. As a simple, but very important example, it would allow the homeowner to come home after work and plug in his EV, safe in the knowledge that the EMS will not overload his home or the grid. It will be smart enough to hold off letting the EV charge until the late afternoon/evening peak is over and everyone is asleep and there is plenty of electrical capacity to charge. It could even coordinate with other homes in the neighborhood, to ensure that they don’t collectively overload the neighborhood lines and transformer. This would truly be a system of systems… perfect for internet technologies.
Smart Home – Good Grid Citizen
Discussion of how the smart home can be a good grid citizen. Describe how the HEMS will orchestrate all the power flows based on accumulated day ahead profiles of electric supply (based on local weather i.e. sun if includes PV) and demand (based on weather i.e. temperature for heating/cooling load). This discussion should include how the homeowner can override the daily “plan” set out by the HEMS… it’s cheaper and easier on the grid to run the dishwasher in the later evening but there are guests coming for dinner so you push the override button and the HEMS updates the remaining daily “plan”.
Discussion of orchestration (balancing) all sources and loads
Discussion of the Smart Home being an intelligent microgrid “node” on the overall utility grid