FACTS (Flexible AC Transmission) by TSR

Physical diagram

The term FACTS stands for Flexible AC Transmission System have been developing to an established technology with the high-power rating. This has ample spread application, became a peak rate, most consistent one, based on power electronics. The main reason of these systems is to provide the network as fast as possible with inductive (or) capacitive reactive power that is modified to its specific requirements, while also improving the quality of transmission and the power transmission system efficiency. With the succession and growth in power electronics application not only enhanced the performance of AC systems but also make it possible for long distance. Facts (Flexible AC Transmission) can also assist solve technical problems in the consistent power systems. These are available in two connections like series connection and parallel connection.

Flexible AC Transmission by TSR

The proposed system is intended to implement flexible AC transmission by thyristor switch reactance. This is used either when there is very low load at the receiving end, due to this the flow of current through the transmission line is very low. This causes voltage amplification.

Block Diagram of FACTS using TSR

Hardware Components

• Microcontroller (AT89S52/AT89C51)
• SCR
• Opto-Isolator
• LCD
• LM339
• Current Transformer
• Inductive load
• Shunt capacitor
• Push buttons
• LED
• 1N4007 / 1N4148
• Resistor
• Capacitor

Software Requirements

• Keil Compiler
• Languages: Embedded C or Assembly

FACTS

The term FACTS stands for flexible AC transmission system is a new integrated concept. Based on the concept of power electronic switching converters and dynamic controllers to enhance the system utilization, power transfer capacity, stability, reliability, security and power quality of AC system interconnections.

Applications of FACTS

The applications of FACTS include the following

• Steady state voltage stability
• Power flow control
• Damping of power system oscillations
• Reducing generation costs
• HVDC link application
• Deregulated power systems
• Flicker mitigation
• Interconnection of renewable, distributed generation, and storages.

TSR/SCR

• The thyristor is a 3-terminal device having Gate terminal, Anode and Cathode. Here, anode terminal is positive and the cathode is negative and the gate terminal is used to control the input signal.That means the flow of current through the thyristor is controlled by an electrical signal applied to the gate terminal.
• The anode and cathode terminals of the thyristors are the power terminals; these can handle the large voltage and conduct the major current through the thyristor.

TSR

SCR

• A Silicon Controlled Rectifier (or Semiconductor Controlled Rectifier) is a four-layer solid state device that controls current flow
• An SCR can be seen as a conventional rectifier controlled by a gate signal
• It is a 4-layered 3-terminal device
• When the gate to cathode voltage exceeds a certain threshold, the device turns ‘on’ and conducts current
• The operation of an SCR can be understood in terms of a pair of tightly coupled Bipolar Junction Transistors
• SCR has three states

SCR

AT89S51/52 Microcontroller

• It is a smaller computer
• Has on-chip RAM, ROM, I/O ports…

AT89S51 Microcontroller

Features of AT89S51/52

• Compatible with MCS®-51 Products
• 8K Bytes of In-System Programmable (ISP) Flash Memory
• Endurance: 10,000 Write/Erase Cycles
• 4.0V to 5.5V Operating Range
• Fully Static Operation: 0 Hz to 33 MHz
• 256 x 8-bit Internal RAM
• 32 Programmable I/O Lines
• Three 16-bit Timer/Counters
• Eight Interrupt Sources
• Full Duplex UART Serial Channel
• Interrupt Recovery from Power-down Mode
• Watchdog Timer
• Dual Data Pointer
• Reverse blocking mode, forward blocking mode, and forward conducting mode

Opto –Isolator

Optp-Isolator

Quad Voltage Comparator LM339

The quad voltage comparator is designed for use in level detection like low-level detection and memory applications in consumer automotive and industrial electronic applications.

Quad Voltage Comparator LM339

Liquid Crystal Display (LCD)

• Most common LCDs connected to the microcontrollers are 16×2 and 20×2 displays.
• This means 16 characters per line by 2 lines and 20 characters per line by 2 lines, respectively.
• The standard is referred to as HD44780U, which refers to the controller chip which receives data from an external source (and communicates directly with the LCD).

Liquid Crystal Display (LCD)

Project Description

The main objective of this proposed system is to implement FACTS by Thyristor Switch Reactance. This system is mainly used either when there is very low load at the receiving end or when charging the transmission line.

Due to very less flow of current through the transmission line and also shunt capacitance in the transmission line turns into main. This causes voltage amplification due to which getting end voltage may turn into double than the sending ends voltage. To balance this, shunt inductors are routinely connected across the transmission line.

Cyclo Converter using Thyristors

In this project, the lead time between the zero voltage pulse and zero current pulse duly produced by apt Op-Amp (operational amplifier) are fed to 2- interrupt pins of the microcontroller, where the microcontroller program takes over to carry the shunt reactors to the circuit to get the voltage duly compensated. Back to back SCRs duly connected through optical isolation from the 8051 family microcontroller are used in series for switching the reactor.

From the above information, finally, we can conclude that the Flexible AC Transmission by TSR (FACTS) is a new technology used to give an opportunity to increase stability, controllability and power transfer ability of AC transmission systems. Further the project can be developed by using firing angle control method for smooth control of the voltage. Therefore, this is superior to switching reactors in steps where voltage control is not very precise.

We hope that you have got a better understanding of this concept. Furthermore, any queries regarding this concept or to implement electrical projects please give your feedback by commenting on the comment section below. What are FACTS (Flexible AC Transmission)?