1
Smart Grid:
Energy Monitoring
Demarcus Hamm
ECE-499
Advisor: Professor Traver
6/9/2010
Report Summary:
The purpose of the capstone design project is to give students a chance to incorporate a lot of what they have learned in the last four years into one project. This project combines research of the Smart Grid system and energy monitoring systems. The project will use an energy monitoring system to simulate smart meters in the home that will be used in the Smart Grid system. We will do this by using an energy monitoring system to measure the energy consumption in the engineering labs. The analysis of this data will provide us information that could lead to energy savings by making us more aware of wasteful energy use or helping to create an energy management system.
The goal of this project is to set up a real time energy monitoring system for one or more of the rooms in the electrical and computer engineering (ECE) labs that stores data by day and time. We want to be able to understand the energy use by the time of day and by the type of load we are monitoring. We also want to set up a visible display in the hallway near the labs to raise Smart Grid and energy conservation awareness.
The project was approached by first finding the maximum energy consumption of all the loads in the ECE labs to determine which load could lead to the most savings. Using information gathered by a student about the load and circuit connections to the circuit panels, a diagram was made to allow for easier understanding of the connections. Next, a list of design alternatives were created and evaluated on their effectiveness of meeting the goals. The system selected was the TED5000G.
2
Table of Contents:
Report Summary…………………………………………………………………………………1
Table of Figures and Tables……………………………………………………………………..3
Introduction……………………………………………………………………………………....4
Background………………………………………………………………………………...... 4-11
Smart Home Network………………………………………………………………………...... 5-7
Energy Sensors………………………………………………………………………………….7-9
Room and Layout Power Consumption………………………………………………………10-12
Effects on society………………………………………………………………………………...12
Design Requirements………………………………………………………………………..12-13
Design Alternatives………………………………………………………………………….13-15
Final Design and Implementation…………………………………………….……………15-17
Results…..……..…………………….……………………………………………...…………...17
Production Schedule……………….……………………………..………………………....18-19
Cost Analysis…………………………………………………………………………………....20
User’s Manual…………………….…………………………………………………………….20
Conclusion…………………………...………………………………………………………20-21
References………………………………………………………………………………..…..22-23
Appendix…………………...………………………………………………………………..24-33
23
Table of Figures and Tables:
Figure1: Diagram of Smart Home Network Components………………………………………...5
Figure 2: Current Shunt………………………………………………………………………...…6
Figure 3: Closed Loop Hall Effect Sensor………………………………………………………...7
Figure 4: Magnetoresisive Sensor…………………………………………………………………8
Figure 5: Optical Current Sensor………………………………………………………………….8
Figure 6: Basic Circuit Diagram…………………………………………………………………..9
Table 1: The Maximum Energy Consumption by Devices……………………………………...10
Figure 7: Components of an Energy Monitoring System ……………………………………….12
Figure 8: Connection Diagram of the Energy Monitoring System………………………………15
Figure 9: Photo of Current Transformer set up…………………………………………………..15
Figure 10: Final Connection Diagram…………………………………………………………...16
Table 2: Cost……………………………………………………………………………………..19
Introduction:
In 2007, less than 10% of the total electric energy in the US was produced using renewable resources; 49% of it was produced using coal and 22% of it was produced using natural gas. Petroleum, coal, and natural gas used in electric energy production, represented 81% of total U.S. human-caused greenhouse gas emissions in 2008 [7]. Because of the limited availability of nonrenewable resources and the effects of greenhouse gas emissions on the environment, this is a problem. How can we start to solve this problem? The problem could be addressed on the distribution side or the consumer side; we could increase our use in renewable energy sources, such as solar or wind power or we could use the most energy efficient technology available. The use of Smart Grid addresses this problem and may lead to a solution in the future. Smart Grid would help us use electric energy in a more efficient manner using technology and resources already available.
In this project, we will explore smart grid, energy monitoring and management and set up an energy monitoring system to advance smart grid concepts in Union College. Research was first conducted on Smart Grid, components of smart home networks, and energy monitoring. We then developed design requirements and produced a set of design alternatives for the project. A final design was then selected, implemented, and evaluated.
Background:
Generally, Smart Grid is a way of using sensors, actuators, and information technology to increase the efficiency of energy distribution, while allowing business and homeowners to use this energy more efficiently. Smart Grid can be defined in different ways depending on what perspective you are looking at it on. Some people like to look at it more from the distributor’s side; they emphasize Smart Grid as the use of sensors and control techniques to increase grid security and efficiency and make grids “self healers” [1]. Self healers mean that grid issues will be reported and resolved in real time. Smart Grid has also been looked at as having smart appliances that are automated to turn off when the users do not want them on. In this perspective, smart meters are also important to give consumers more control over their cost by allowing them to see how much they are spending and what the level of demand is. Demand is the total amount of electricity being used by a customer at a time and is measured in kW. For example, using 250 kW for one hour is the same amount of kWh as using 500kW for 30 minutes; however, in the first case the demand is 250kW while it is 500kW in the second case. In the second case the distributors need more generation and transmission capacity to supply the customer.
We will mainly focus on Smart Grid as a two way communication between energy distributors and customers using smart meters and sensors. These meters utilize sensors that sense energy use in homes. The meters will display this data and data from the distributors regarding demand allowing customers to use their appliances in ways that would be cheaper for them and the distributors. Energy distributors use rate structures that are either fixed, based on season, based on time of day, or other factors. With a fixed rate structure, people pay the same price to use energy during periods of peak demand, when it actually takes more to supply that energy due to loading, as they do when there is very little energy use going on. If smart meters were used with a program that varied the rate structure with demand, it would encourage energy use during times that would be more efficient. The smart meters would allow consumers to observe how much they are being charged for their energy use at specific times allowing them to use it when it would be cheaper; since this would be when the demand is lower it would be cheaper for distributors. This will also reduce greenhouse gas emissions, and it could still be used in conjunction with alternative energy sources to increase their efficiency.
Energy saving sensors is also a big part of smart grid. Sensors are being used in systems to reduce resource use in homes. Systems that include occupancy sensors are being used to turn off and on lights. Their applications also extend to water control; the sensors are used to keep water from being used wastefully. Temperature sensors are being used in heating and air conditioning control. In the future, it may be useful to use sensors to help in managing other things for instance controlling other appliances such as TV’s. Light sensors could also be used in systems to make lights dimmed in the day. In addition, they can be used in kitchens to aid in controlling stoves and ovens. Moreover, the systems could all be controlled by a centralized unit that allows users to adjust which appliances turn off, times when they will turn off, and how long they delay before turning off when they are not in use.
Smart Home Network:
Smart home networks allow computers, devices, and other appliances to communicate with each other. Smart home networks are made up of several components: the sensors, sensor interface, actuators, computing, and communication. Figure 1 shows a possible configuration of the components.
Figure 1: The components of a smart home network.
The sensors in the smart home network transform a physical property into an electrical signal. Sensor interface is circuitry that changes the sensor output into one that can be recognized by the actuator or computer. In the network, the communications can be wired or wireless. The network can also have many different topologies; the network could be arranged to allow for sensor nodes to communicate with other sensor nodes or actuators. The computing in sensor networks is done by the microcontroller, which controls the sensors, processes its data, and handles the communication protocols; there can be several computers or one central one. In a smart home network, actuators are an optional component that is controlled by a sensor or computer to change the environment or the networks relation to it. Actuators can improve sensing by repositioning sensors or pointing a camera; they also can affect the environment by opening a valve or emitting a sound.
In a smart home network, a possible sensor node could be composed of the sensor, an analog to digital converter, a bus interface, and an analog interface circuit. These smart sensors differ in the degree that they are integrated on the sensor chip. For example, one could have a sensor chip with a built in analog interface and an analog to digital converter, but the bus interface must be connected separately. Fully integrated smart sensors contain all necessary elements to function on one sensor chip. They contain one or more sensors, amplifiers, multiplexers, A/D converters, an interface, and control and power management per node. The sensor nodes can be interfaced using various methods. They could be connected using a bus interface where the nodes would all be connected to a single cable. They could also be connected using mesh topology where the sensors would communicate through each other wired or wirelessly. The nodes could all communicate to a central hub that would control each node as well.
Energy Sensors:
Electrical energy is energy resulting from work done on charged particles due to an electromagnetic force. There are various types of sensors that can be used for electrical energy monitoring. In this section a few current sensors of electrical energy are examined.
Current transformers are one that measures only AC current. The input current range of current transformers depends on the ratio of windings between the first and second coils of wire. Wound current transformers use two coils of wire; one connected to the power supply called the primary winding and the other is the secondary winding. As current travels through the primary winding a magnetic field is produced; this induces a current on the secondary winding that is smaller but proportional to the primary current. Window current transformers have one winding assembled on the core; the monitored conductor passes through the middle. Current transformers are used in meters and protection of appliances connected to AC power supplies.
Current shunt (also called ammeter shunt) is a type of energy sensor that can measure AC/DC current. Its input current ranges are up to 20A with frequencies up to 100 kHz [15]. In current shunt a resistor with very little resistance is placed in a circuit. Based on the voltage drop through the resistor and the resistance of the resistor the current can be found using Ohms Law (I=V/R). Figure 2 shows an example of a current shunt. Current shunts are primarily used for power supply monitoring.
Figure 2: An example of a current shunt. [13]
Hall Effect current sensors also measures AC/DC current. Hall Effect current sensor typical ranges are for open loop up to 1000A and from DC-20 kHz; for closed the ranges are less than 500A and from DC up to 150 kHz [15]. A open loop Hall Effect sensor is one where the amplified output of the Hall element is directly used as its measurement value. In a closed loop one, the amplified output is sent through a compensation coil on the magnetic core to make the flux in the core zero; this makes the sensor more linear and temperature independent. Hall Effect sensors are made using magnetic material, a current conductor and a hall element. The sensors work by creating a magnetic field perpendicular to a current in a conductor; this creates a voltage difference across the conductor. These sensors output voltage is proportional to the product of the magnetic flux density and the current through the conductor. Figure 3 shows a setup for a closed loop Hall Effect current sensor. Hall Effect current sensors are used for motor and inverter control, reed switches, and power supply management and protection.
Figure 3: Setup for a closed loop Hall Effect current sensor. [16]
Another type of energy sensor is called Magnetoresistive current sensor. These sensors can also measure AC/DC current up to 50A [16]. Magnetoresistive current sensors are made up of magnetoresistors arranged in a bridge and current conductors. The electric resistance of the magnetoresistors depends on the external magnetic field applied to them. The primary current produces a magnetic field that changes the resistances of the magnetoresistors. The compensation conductor is to compensate for the magnetic field produced by the current through the primary conductor; this feedback reduces nonlinearity and removes temperature dependence. The voltage drop across a resistor after the compensation forms the output. Figure 4 shows a basic setup for magnetoresistors. Magnetoresistive current sensors are used in power electronic systems, solar technology, battery management, electric vehicles, robotics, and safety devices.
Figure 4: Setup for a Magnetoresistive current sensor. [16]
Optical current sensors sense AC/DC current using the Faraday’s effect; it can also be used to determine magnetic field intensity. The input current range is up to 23 kA [21]. Current flowing in a conductor induces a magnetic field that rotates linearly polarized light traveling in a sensing path encircling the conductor. From the rotation of the plane of polarization of the light, a measurement of the magnetic field can be made and from that the current can be found. Optical current sensors uses bulk optical crystals or long lengths of optical fiber, coiled around a current-carrying conductor. Figure 5 shows a setup for an Optical current sensor. Optical sensor applications include monitoring currents on overhead electrical distribution lines, underground electrical vaults, and rectangular bus-bars within switchgear.