Transmission Lines in Smart Grid

The power flows from power utilities to consumers whereas if wireless sensor networks are added, then the real time price information will also flow from base station to consumers. If the consumer is aware of price of power in peak times, then consumer will act accordingly and regulate his consumption as per price information sent to him. - Geeta Yadav

Picture Courtesy: www.euneighbours.eu

The power flows from power utilities to consumers whereas if wireless sensor networks are added, then the real time price information will also flow from base station to consumers. If the consumer is aware of price of power in peak times, then consumer will act accordingly and regulate his consumption as per price information sent to him. The smart grid is adding smartness to the electric grid by adding smart devices like wireless sensor networks that provide real time information quickly. The smart grid includes adding renewable resources, selfhealing, real-time two-way communication between power utilities and consumers etc. The smart grid is divided into four parts as generation, distribution, transmission and consumer side. The existing power generating stations are thermal power generating station, hydro power generating station, nuclear power generating station etc. The power is transmitted to the consumer in a high voltage level. The power is generated near to sources like rivers, nuclear power plant and far away from consumers. Transmission lines and distribution system connect power generation plant to consumers. The power generated at source is at low voltage and it is stepped up to high voltage and transmitted to consumer where it is stepped down to consumer requirement.

The power flows from power utilities to consumers whereas if wireless sensor networks are added, then the real time price information will also flow from base station to consumers. If the consumer is aware of price of power in peak times, then consumer will act accordingly and regulate his consumption as per price information sent to him. Along with that, if the wireless sensor network added to existing electric grid, then the information of black out is sent to the base station quickly and the issue is resolved quickly. The power will also be directed to the affected houses through another network so that electricity will be available 24*7. The transmission lines are the network of lines that transmit power from base station to consumers. These networks are collection of wires attached to towers. The wireless sensor networks are attached to transmitting line to process the information and inform to control center if there is any situation of black-out. The batteries used in wireless sensor network will get depleted after some time so instead of using standard batteries, fiber optics can be used. The fiber cables or optical ground wires can be used to increase the energy efficiency of the overall smart grid. The transmission lines are divided into three parts based on its design as voltage drop, line loss and transmission efficiency. There are three more types based on transmission line length: short transmission line (up to 50 km, 20 kV), medium transmission line (up to 150 km, 100 kV) and long transmission line (more than 150 km and above 100 kV).

The performance indices of the smart grid are reliability, stability, energy efficiency, robustness, scalability, quality of service (QoS), availability, security of the electric grid. The smart grid based on communication layer, can be divided into three parts as home area network, neighbourhood area network and wide area network. In home area network, only home appliances are covered, and home automation is applied, whereas in neighborhood area network, all the meters located in the region communicate information to the central controller. Wide Area Network has data collection points.

Smart transmission includes early fault detection and isolation, location recovery and outage detection. These criteria can be fulfilled only by use of wireless sensor network along with transmission lines. These sensors are placed on top of the towers to detect the condition of transmission lines and send real time information even unapproachable location like isolated mountain, hazardous areas etc. These wireless sensors increase the reliability of the overall smart grid. These transmission lines are monitored using WSN and collected parameters like current, voltage, frequency and communication to central monitoring unit at periodic intervals.

There are many existing problems like growing population and demand for energy, global climate change due to use of nonrenewable sources for generation of electricity, equipment failure as current electric grid is implemented long ago, sources of electricity are limited, one-way of communication, resilience problems in the existing electric grid.

The smart grid has various components:

· Smart meter,
· Distribution automation,
· Demand response management
· Smart appliances,
· Transmission automation,
· Electric vehicles,
· Electric storage,
· Renewable energy

There are many protocols exist that will send information about transmission lines through wireless optical ground wire (i.e sensor network) to base station quickly using direct transmission, multi-hop transmission, Leach, Pegasis and many more). These towers form a chain network that transmits powers. These sensors are placed over that towers and collect data. Then the data is merged and send to base station in an efficient way. Leach is clustering protocol that form clusters of towers in an area and then send merged data to main cluster head whereas in Pegasis, chaining is used, and data is transferred to base station from the farthest node through a single chain. There is another approach that collaborates both the protocols and uses both clustering and chaining for transmitting of data quickly. This protocol is the most energy efficient protocol as it uses less energy than both the existing protocols i.e Leach and Pegasis. The clustering is done on area wise dividing the neighborhood area network and then chaining is done on top of it. The clusters send information about an area to cluster heads. Then chaining is done in the cluster heads and farthest cluster head send data to near by cluster head. Then, the whole merged data is sent to base station, which will see the whole network in one go in that instant of time. So, in this case, if there is any situation of blackout, then the power is transmitted through another existing nearby network and immediate action has been taken to recover from that situation.

Adding automation to the smart grid includes home automation, automation of transmission line and distribution system. Home automation includes the devices that will control automatically using mobile or any remote devices. The IP address of every electric device connected to the power supply can be recorded and controlled through remote system. The internet of things comes under automating the home devices like opening and closing of doors, lights, home appliances like washing machine, TV, AC etc. The automation of transmission line and distribution systems will reduce theft of electricity, automatic billing process, fault in transmission lines or distribution lines. Self-healing can also be done at transmission and distribution lines if the fault is minimal and the information of fault is sent to power station for recovering the losses.

The overall efficiency of the system is increased as the data flows quickly through internet and connecting to wireless/ mobile devices.