What is a power system?

A power system is a network that distributes the electric power produced by the generating plants to the loads using the distribution network. The network is mostly an alternating current (AC) network. The power system mainly consists of generators, loads, transformers, transmission networks, and switchgear (protection equipment).

Types of power systems

Based on the design and distribution of power systems, they can be classified into three types:

• Radial
• Loop
• Network

Radial

The radial power system is the simplest system for electricity distribution. In this system, the group of customers receives electricity from only one power source. The arrangement in the radial system resembles a tree in which each customer has a single supply source.

Advantages of the radial system:

• Easy to implement.
• Less initial cost.
• Ideal for sparsely populated areas.

Disadvantages of the radial system:

• Less reliable.
• In case of short-circuit or failure, the entire line connected to the system will be interrupted.

Loop

The loop system is a ring-like structure in which the loops from the service area reach back to the initial point. Loops are connected to alternate power sources, and switches are used to supply power to the clients from either direction.

Advantages of the loop system:

• Voltage fluctuations are lesser on the consumer’s end.
• It is a reliable system since it uses two feeders. So, if a failure occurs, power can be supplied from an alternative power source.
• The cost to repair faults in the loop system is less.

Disadvantages of the loop system:

• The cost of building the loop system is high.

Network

The network system uses multiple power sources to supply power. These power sources operate parallelly. Hence, a fault in one source will never affect the entire line. In other words, it is a power system with interconnected loop systems, and every customer can receive a power supply from multiple sources.

Advantages of the network system:

• It is best suited for highly populated areas.
• Most reliable system amongst the other two.
• Minimum power interruptions.

Disadvantages of the loop system:

• It is a highly complex system.

Use of computers in a power system

Nowadays, power systems are highly complex and large. Therefore, the systems are controlled from an energy-controlled center (ECC) which allows a hierarchical control on the power system. However, it becomes hard to handle the system in case of faults.

Hence, modern power systems are managed using digital computers. These computers help in several tasks data acquisition, data processing, data analysis, controlling, and alerting the operator.

All of these computer operations are categorized into two tasks called:

1. Supervisory control and data acquisition (SCADA)
2. Automatic generation control (AGC)

SCADA

SCADA deals with collecting information, transferring data to the central site, analyzing and displaying information on the operator screens or displays. It involves two parts:

1. The supervisory control part involves the operation of the energy control center.
2. Data acquisition represents that information is collected and sent for monitoring to the ECC.

The controlling functions of SCADA perform tasks like controlling devices, transformers, automatic switching sequences, and time synchronization using the clock signal. It also manages automatic functions like load shedding and power restoration.

The monitoring functions include tasks like measuring current, voltage, power, temperature, and energy. It also collects and maintains data and evaluates time-stamped events.

AGC

Due to continuous changes in the system load, the power generation is automatically adjusted to maintain the frequency to the nominal value. This process is called AGC.

AGC involves two significant functions called load frequency control and economic dispatch. In addition to this, it performs several minor tasks like reserve monitoring, interchange scheduling, and recording functions.

Load frequency control deals with maintaining the frequency at a predefined value, maintaining power interchanges, and maintaining power allocation among all units. The economic dispatch control unit does economic dispatch. It divides the load among units such that the fuel cost or energy used is minimal.

Advantages of using computers in power systems

• Computers help in automating power systems.
• Computers work faster.
• Controlling large and complex power systems with computers is easier.
• Calculations made by computers are accurate.

Disadvantages of using computers in power systems

• If one computer in the interconnected network fails, the entire system may fail.
• Computers often face cyberattacks.

Power systems that use computers

Computers are used to handle various types of power systems. Some of the commonly used power systems and how they are controlled using computers are explained below.

Global positioning system (GPS)

GPS is a satellite-based navigation system used by guiding and mapping applications and location-related services. GPS techniques are widely used in almost every industry to position, navigate, or map any location. Almost everyone, including doctors, farmers, pilots, hikers, sailors, fishermen, soldiers, and athletes, uses GPS to boost productivity and travel safely and quickly.

The main uses of GPS are as follows:

• Location: It is used to identify the position of a thing or person.
• Navigation: It helps in moving from one place to another.
• Tracking: It helps track an object or person’s movement.
• Mapping: It helps in generating maps of different regions all over the world.
• Timing: It is used to bring precise timing to the world.

GPS performs all the above operations using various technologies and computer systems. The GPS receiver computes its position and time depending on the data obtained from several GPS satellites. Every satellite has its position and time, and this information is transferred to the receiver.

The satellites also contain atomic clocks synchronized with each other and ground clocks. Similarly, satellite locations are also marked with great precision. GPS receivers also have clocks, but they are less accurate and steady. The time delay between the satellite transmission signal and receiver signal is proportional to the distance from the satellite to the receiver because the radio wave speed is constant.

A minimum of four satellites are needed to calculate the position coordinates, clock deviation between the receiver and satellite time. After calculation, the data is sent to the moving map display, to a computer system like a vehicle guidance system, or recorded for future use.

Elevators

Computers control modern elevators. The computers handle all the necessary information related to the elevator, like turning it on, where to put the elevator, and much more. The computer identifies where people want to go, where a floor is located, and where the elevator is currently. It then operates accordingly to take the people from one place to another.

The buttons on an elevator are connected to a computer, and when people press any of the buttons, the computer records this request. This data helps the elevator to determine where people want to go.

Next, to identify where the elevator is, a magnetic or light sensor is attached to the side of the elevator car. It reads the series of holes, and by counting the holes speeding by, the computer can identify the elevator's current position. When the elevator reaches a floor, it gradually slows down.

Nowadays, some elevators come with load sensors that tell the computer how full the elevator is. Such elevators do not allow people beyond their capacity.

Traffic signals

Traffic signals are electronic machines found at intersections to control the light sequence. These devices use computers, communication devices, and detectors. Traffic signals work in three parts:

1. The controller or brain of the traffic signal is the first part. The computer controls the controller unit using sensors. It handles the selection and timing of traffic movements.
2. Signal visualization is the second part. It consists of three lights yellow, red, and green.
3. The detector/sensor is the third part. It senses the presence of vehicles.

Advantages of power systems

• Power systems reduce labor costs and capital expenses.
• They increase production.
• Power systems operate faster than humans and are more efficient.

Disadvantages of power systems

• Power systems require 24x7 monitoring.

Context and Applications

The power system is an essential topic in computer and electronics subjects. The topic is covered in courses like:

• Bachelors in Computer Science
• Masters in Computer Science
• Bachelors in Technology (Electronics)
• Masters in Technology (Electronics)

Practice Problems

Q1. What does SCADA stand for?

1. Supervisor computer and data analysis
2. Supervisory control and data acquisition
3. System control and data acquisition
4. Supervisory control and data analysis

Answer: Option b

Explanation: SCADA is the acronym for supervisory control and data acquisition.

Q2. What type of system is GPS?

1. Satellite-based
2. Television-based
3. Radio-based
4. Communication-based

Answer: Option a

Explanation: GPS is a satellite-based navigation system. It uses satellites to track, locate, monitor, and map a person or object.

Q3. Which of the following is an advantage of power systems?

1. They are electrical.
2. They work faster than humans.
3. They are cheaper.
4. None of the above

Answer: Option b

Explanation: One of the advantages of using power systems is that they work faster than humans.

Q4. Which of the following is a major task of AGC?

1. Data acquisition
2. Data controlling
3. Load frequency control
4. None of the above

Answer: Option c

Explanation: The two major functions of AGC are economic dispatch and load frequency control.

Q5. Which of the following is a disadvantage of power systems?

1. It is expensive.
2. It works slowly.
3. It is electrical.
4. It requires constant monitoring.

Answer: Option d

Explanation: The downside of using computers for power systems is that they need constant monitoring.

Common Mistakes

Different power systems need computers for different purposes. Some need computers for transmitting signals, while others need computers to monitor or track activities. Students should understand the primary use of computers in controlling power systems and carefully choose the correct type of computer for a particular power system. Otherwise, it may fail the system.

Related Concepts

• Power engineering software
• Power system simulation software
• Voltage regulation in power system
• Frequency regulation in power system