Section 1: Team Responsibilities

Section 1: Team Responsibilities

Before assigning tasks to group members, a project scope must be outlined. The developed system should allow a utility to moderate and control certain appliances on a local neighborhood scale. It should recognize user inputs and queue them after the commands of other customers, while also considering customer satisfaction. To do this effectively, our system must have the ability to control certain aspects of select appliances. The project should also take into account any possible methods for retrofitting existing appliances to allow for remote control, and different methods for connecting appliances to the network.

In order to accomplish these goals, the project responsibilities were delegated as follows:

●Tim D’Emidio: Communication between house and utility

●Greg Prodzenko: How appliances can communicate with our servers

●Alex Cihanowyz: In-house integration of appliance infrastructure

●David Cabrita: Develop logic behind appliance control and usage monitoring

●Dan Collins: Generate software and support control logic

Section 2: Summary of Information

House to Utility Communication

Since the end result of the project is to lower the peak demand of the utility, our servers must interface with certain data generated from the power grid. One must first understand the power grid itself before observing data. The grid consists of the following components: generation, step up transformers, transmission conductors, step down transformers (substations), distribution conductors, secondary transformers (customer transformers), and the customer. (1a)

Utilities use a system called SCADA (1b) to monitor the power demand at each substation. SCADA runs 24 hours a day on any equipped substation, and its data is refreshed every 5 minutes. The data, which includes kW, KVA, Amps/phase, Volts/phase, etc. is then entered into a database. Our servers would mostly be concerned with the kVA (kilovolt-amps) measurement, since this is the standard unit for power demand.

Electric utilities analyze the data produced by SCADA to improve the reliability of their grid. The transmission and distribution conductors have thermal limitations associated with them. Therefore, routing high amounts of load through a weak conductor would eventually burn it to the ground. SCADA is needed to ensure that peak energy usage does not violate safe grid conditions.

With the method of detecting system conditions understood, the purpose of this project can be explained. Our system must be designed to lower the peak demand of the utility. If successful, both customers and utilities can save money. The generation aspect of the utility becomes expensive at peak times. Consider the fact that generation plants do not really just output “more or less energy than usual” to meet peaks, but rather additional plants must turn on. Starting these plants is expensive and so if the utility can avoid this transaction, the customer saves money. The target customer is the residential customer, which accounts for 21.4% of the US’s power demand. (1c) Their satisfaction is the balancing factor in the equation. In order to reduce peak demand, customers must either use less energy or schedule their use in accordance with other users. Our system aims to accomplish the latter because no one wants to sacrifice comfort for the sake of (what they perceive is) a couple extra dollars. Optimizing power consumption on a large scale must be balanced against the needs of the individual household.

The architecture of the overall system to be designed includes: the Control Server (CS), the Home Base Station (BS), and home appliances. In order for the Control Server to effectively make decisions for the Base Stations, it must be given inputs from the utility. At this stage of the project, we do not know which information will be a priority but SCADA will be strongly considered as the primary source of information. Other more real-time sources should first be considered before moving forward.

Appliance to Server Communication

Communication between the appliances and the home base station (BS) will be covered in this section. The appliances and the BS need to communicate with each other so that they can be controlled remotely. This communication could be accomplished via several communication standards.

One common standard for applications such as this is Controller Area Network (CAN). It is a standard which was designed for vehicles so that micro controllers can communicate with each other, without the need for a host computer. The usable range for CAN is between 40 and 500 meters.(2a)

Another possible communication standard is Ethernet. Ethernet is capable of transferring data at 10 Mbits/s at a distance of 50 meters. The standard which we would follow for communicating over ethernet is the IEEE 802.3i standard. (2b,2e) Communication over Ethernet would be useful because of its decent range, high speed, error correction, and the popularity and low cost of CAT5 Ethernet cabling. (2c) Ethernet is also easily extensible to wireless, and many common microcontrollers, such as the PIC series from Microchip have built-in Ethernet controllers, which will make designing the system hardware and software easy. (2d)

The most common functionality which this system will provide will be the ability to remotely turn on or off many household appliances. Some of the appliances controlled by this system will be refrigerators, lights, Heating, Ventilation and Air Conditioning (HVAC) and hot water heating. Refrigerators can be kept from being turned through the use of an external relay, much like a light timer. Certain lights can be turned on or off remotely in the same manner, depending on time of day, and whether or not they were left on when they shouldn’t be, such as when no one is home. The HVAC system will have a special thermostat which is capable of being controlled remotely. Lastly, the hot water heating system will be controlled so that energy is not wasted by heating water when it is not going to be used.

In addition to controlling these appliances, various sensors will also be implemented so that control of the home can be done correctly. These sensors will gather data from both indoors and outdoors. Data such as ambient light, temperature, occupancy, etc will be useful in determining the best way to balance comfort and efficiency.

The functionality of the system is not restricted to merely turning devices on or off. In the case of a home’s HVAC system, the system will collect data and determine if the AC/Heating should be running. Data such as indoor/outdoor temperature, time of day, desired indoor temperature, and others, will be used to determine if the HVAC system should be running. For example, if the outdoor temperature drops during the day when it is likely no one is home, the air conditioning will be turned off. Or, the set-point of the thermostat will be changed so that the air conditioning does not run unnecessarily. Similarly, with the hot water heating system, the hot water heater will be monitored, and can be turned off if it is not being used during the day.

Other, simpler, appliances can just be turned off when they should not be on. If a light is left on during the day, the system can turn that light off. Or, if on a cloudy day when indoor lights are used, the sun suddenly comes out, those indoor lights can be turned off so that energy is not wasted when sunlight can be utilized.

In-house Integration of Appliance Infrastructure

Alex’s section

One way for the system to connect the home appliances to the home base station is by using power line networking. The technology known as HomePlug is a cheap and effective way to manage the smart energy applications by using the electrical wires in homes to distribute broadband Internet and connect the appliances to the base station. With these wall-plug adapters we can make our connections to the base station anywhere there is an outlet.

This technology is preferable to using wifi and other forms of networking. Homeplug is more reliable than wi-fi, and other forms of networking. If we use a wireless communication network we can run into problems such as limited range, data transmission speeds, and dead spots. Homeplug adaptors use the IEEE P1901 standard which promises a performance speed of 200 Mbps, throughout the entire home regardless of whether the wire is hot or neutral.(4a)

We need to find a way to get the appliances and network to “speak the same language.” The appliance will be running on a server on port 8888. The clients connect and send data over port xxxx, and will wait for response from server. Once the connection is made, the client and server will transmit data back and forth, which will achieve the monitoring we need for each appliances electricity use. The home base station will then tell the appliance what state it should be on based off of the preset limit conditions the user makes, or by their commands.

Program Logic of Appliance Control and Usage

Always on/Major Appliances

As illustrated in reference (4a), central air is a major contributor toward electricity usage. This can be mitigated during peak hours by a system focused on a desired percentage. As mentioned in reference (4b), air conditioning startup consume a large amount of electricity, but are very inefficient during this time. This means startup would need to be minimized. By monitoring in-house activity, we could observe that a particular house is typically empty from 8am to 5pm during workdays. This means, we could shut off air conditioning during that time and save roughly 40 hours a week in electricity. According to reference (4a), that is a set time period of 40 hours in which air conditioning is not running, which saves about 240 KWh. In addition, with enough data, the system could anticipate the arrival of residents by determining that the return of residents at 5 should be preceded by 20 minutes of start-up operations of the unit.

In addition to observed usage, the system would prioritize a percentage of operation time. For example, the system would read the outside and inside temperature of each house and determine that 70% of a day, the air conditioning would need to operate for a comfortable temperature of 74 degrees Fahrenheit. This time would have to be prioritized in terms of longest time running due to the high power consumption at startup. In order to account for this usage, the system would monitor outside air temperature and inside air temperature to calculate the time period for which the system will reach an uncomfortable level. It would then enable the system to run for a given time period that brings the house to slightly below the comfortable level.

The system would keep in memory the logic that has been used for each operating interval of each house. With this information, it can determine that a specific house may require more or less operation to maintain an average temperature of 74. In addition, a remote control of the thermostat would be ideal to allow for optimal function of the system.

Refrigerator

A refrigerator would require special attention. Specific “smart home capable” refrigerator could tell the system the inside temperature of the refrigerator. From there, the system could use a similar model the that of the air conditioning unit and ensure the refrigerator only operates to keep the necessary average temperature.

However, non-”smart home capable” refrigerators must be accounted for. As reference (4a) describes, the power consumed by Energy Star compliant refrigerators is about 800 Watts, while pre-1992 refrigerators consume only 600 Watts. The lower power consumption of pre-1992 refrigerators is negated by the average operation of the unit which is described as using over 100kWh more each month than modern, Energy Star compliant systems. This system would take the concept of this timed operation to ensure the refrigerators do not run too often. Without the information of inside refrigerator temperature, the system would have to monitor the operation of a refrigerator and begin slightly cutting the power as necessary and possible. There would be a careful level of how often this could be done without spoiling the contents. This means the system would need very detailed testing in order for it to apply to this system.

General Outlet

Controlling a generic universal outlet presents some challenges not present when the specific appliance is known. While many devices like TVs and lighting can be shut down while not in use, others cannot. Alarm clocks, for example, would be impossible to shut down. Computers can be turned off, but then users may lose work. Computer peripherals can always be turned off. Some devices such as cell phone chargers may intentionally be left plugged in - but are also often left accidentally. So we propose a generic outlet design with multiple modes. Ideally the device could "request" a specific mode - such as a cell phone charger asking not to be shut down until it iis finished charging - and the outlet could send feedback to the device - such as a computer being told that it must shut down as its power will be cut. The feasibility of this communication is discussed above.

Some examples of operating modes include:

●Always on - as in an outlet being used to power another smart energy device which controls its own power, or a device which should never lose power such as a clock or life-critical medical equipment.

●Timer based - as in an outlet for a light or TV, which automatically shuts down when the residents are out of the house (work hours) or asleep (night time).

●Occupant based - as in the timer based, but on when the room is occupied rather than specific times. More efficient but requires additional hardware and programming.

●Smart-device based - as in for a computer. Contacts the device to instruct it to shut down during set hours or during long periods of non-occupancy. Once the device is shut down, cut power to a set of peripherals or connected devices. When the device turns back on (user hits the power button), reactivate the peripherals.

●Charger based - as for a cell phone, monitor current use. When the current falls below a certain cutoff determined by experiment as the point where the power is only being used to run the charger’s electronics, shut the outlet down for a set period. Even “polling” every 15 minutes for a few seconds to see if a device is plugged in would be a huge improvement, and having a button for the user to say they have plugged a device in which needs charging would be even better.

Allowing the user to select within these modes as well as allowing a manual always on would allow the most user-friendly and device-friendly operation. It covers the vast majority of use cases.

Section 3: Additional Information

(customer surveys)

(existing appliance technology)

(example of existing utility/appliance interface)

(1a)

(1b)

(1c)

(2a)

(2b)

(2c)

(2d)

(2e)

(3a)

(3b)

(4a)

1