SUBSTATION FAULT MONITORING AND CONTROLLING USING PLC AND HMI

SUBSTATION FAULT MONITORING AND CONTROLLING USING PLC AND HMI

Introduction

The idea of distribution Automation began in the 1970s. the motivation at that time was to use the evolving computer and communications technology to improve the operating performance of the distribution system.
Distribution automation also provides many intangible benefits which should be given consideration while deciding for implementation of distribution automation. After the deregulation and restructuring issues are settled, distribution automation activities should increase. The economic growth and development of a country depend heavily on the reliability and quality of power supply. Generally, rigorous planning is done for the addition of the generation and expansion of the transmission network. However, the distribution system has generally grown in an unplanned manner resulting in highly technical and commercial losses in addition to poor quality of power.

Block Diagram

Substation automation can be defined as a system for managing, controlling, and protecting a power system. This is accomplished by obtaining real-time information from the system having powerful local and remote control application and advance electrical protection. The core ingredients of a substation automation system are local intelligence, data communications, and supervisory control and monitoring.

Working Mechanism of Project

Single line dig

In the electrical system, there are many kinds of devices are connected these devices are for controlling purpose of the electrical system. If any fault is generated in system let us say the line-line fault due to which the current exceeds at unspecified limit which is overcurrent. This current flows in the opposite direction which is harmful to the substation equipment. To overcome it in less time we use a current transformer as a sensing device. The current transformer gives the signal to PLC and HMI displays the fault on screen PLC gives the command to relay to operate a circuit breaker on the path of fault current.

Needs for Distribution Automation

The economic growth and development of a country depend heavily on the reliability and quality of the electric power supply. Generally, rigorous planning is done for the addition of the generation and expansion of the transmission generally grown in an unplanned manner resulting in highly technical and commercial losses in addition to poor quality of power.
Efficient operation and maintenance of distribution system are hampered by non-availability of system topological information, current health information of the distribution Components such as distribution transformers and feeders, historical data etc. Other reasons include the lack of efficient tools for operational planning and advanced methodology for- quick fault detection, isolation, and service restoration, etc. All these lead to the increased system losses, poor quality and reliability of power supply in addition to the increased peak demand and the poor return of revenue.

typical Substation

Keeping the above problems in mind, it becomes necessary to improve the operation of distribution systems and hence the quality of power supply. This can be achieved by the use of better methods, proper monitoring and control of the distribution system. In view of the extensive size of the network, this task can be effectively achieved through the intervention of information technology (IT) utilizing the available high-speed computers and communication networks. This system of monitoring and control of electric power distribution networks is also called as the Distribution Automation System.
IEEE has defined Distribution Automation (DA) system as a system that enables an electric utility to remotely monitor, coordinate and operate distribution components, in a real-time mode from remote locations.

Distribution Automation System encompasses data acquisition, telemetry, and decision-making system. It involves collecting information, transferring it to a DCC, displaying the information and carrying out analysis for control decisions and improvement in system operation.

Distribution System Configurations

Distribution networks are typical of two types, radial or networked. A radial feeder leaves the station and passes through the service area with no normal connection to any other supply. This is typical of long rural lines with isolated load areas.
A networked system, having multiple connections to other points of supply, is generally found in more urban areas. These points of connection are normally open but allow various configurations by the operating utility by closing and opening switches. Operation of these switches may be by remote control from a control center or by a lineman. The benefit of the networked model is that in the event of a fault or required maintenance a small area of the network can be isolated and the remainder kept on supply. Radial Network Interconnected Network
Within these networks there may be a mix of overhead lines utilizing traditional utility poles and wires and, increasingly, underground construction with cables and indoor or cabinet substations. Underground distribution, however, is significantly more expensive than overhead construction and therefore often co-located with other utility lines in what are called common utility ducts.
Distribution feeders emanating from a substation are generally controlled by a circuit breaker which will open when a fault is detected. Automatic Circuit Recloses may be installed to further segregate the feeder thus minimizing the impact of faults.

Distribution System Faults

All electricity industries worldwide experience power-delivery problems. Faults can be very destructive to the power system. A great deal of study and development of devices and design of protection schemes have resulted in continual improvement in the prevention of damage to transmission lines, equipment and interruptions in the generation following the occurrence of a fault (Stevenson, 1982). The following types of fault exist in the primary substation of the distribution system:

(i) Over-current: This fault occurs very often when there exists a short circuit on the system or anytime there is bridging of the phases of the overhead lines.

(ii) Earth Fault: This fault exists anytime the line conductor cuts or snaps and drops on the steel cross armor on the ground. Earth fault could also occur when a fresh tall tree touches the overhead lines.

(iii) Differential Fault: This fault exists when there is a problem within the transformer windings and\or the interconnecting cable between the transformer and the breakers. The differential fault normally results in the flow of unbalanced current in the transformer windings. When an unbalanced current (fault current) flows through the differential relay windings, the relay senses the fault and sends a tripping signal to the circuit breaker which automatically isolates the transformer for safety before it gets burnt as a result of circulating unbalanced current.

(iv) Buchholz Fault: This fault normally occurs inside an operating transformer in the form of insulation puncture, shorted windings, poor contact or sparks due to poor grounding with the evolution of gases resulting from the decomposition of oil or the insulation.

(v) Overvoltage: A Overvoltage is defined as an increase in the r.m.s. value of the voltage up to a level between 1.1 pu to 1.8 pu at power frequency for periods ranging from a half cycle to a minute.
 Causes of Overvoltage: overvoltages are less common than under voltage but they also arise due to system faults. Overvoltage can occur due to a single line to ground fault, which in turn will raise the voltage of the other phases. It can also cause due to disconnection of heavy industrial loads or switching on the capacitor banks. This is generally due to ungrounded or floating ground delta systems, where a change in ground reference would give voltage rise to the ungrounded system.
(vi) Under voltage: Under voltage is defined as a sudden drop in the root mean square (r.m.s.) voltage and is usually characterized by the remaining (retained) voltage. Under voltage is thus, short duration reduction in r.m.s. voltage, caused mainly by short circuits, starting of large motors and equipment failures. Furthermore, under voltage may be classified by their duration as shown in
Causes of Under voltage:
1.Closing and Opening of Circuit Breakers
2. Due to Fault
3. Due to Motor Starting
4. Due to Transformer Energizing
5. Equipment Failure
6. Bad Weather and Pollution (Lightning strikes, Flashover, etc..)
7. Construction Activity(damage to underground

8. cables

component of Project

1. LOGO 8 The new generation of logic modules

logo plc

 8 basic units for all voltages, four of them with a new display
 Several version for different supply power DC 12V/24V RCE, AC/DC 24V RCE, DC 24V

 All units come with an Ethernet interface, footprint like LOGO! 6 (4TE); and connections are compatible with previous versions

2. Human Machine Interface (HMI)

LOGO HMI

Features
• Calibrated directly in ° Celsius (Centigrade)
• Linear + 10.0 mV/°C scale factor
• 0.5°C accuracy guaranteeable (at +25°C)
• Rated for full −55° to +150°C range
• Suitable for remote applications
• Low cost due to wafer-level trimming
• Operates from 4 to 30 volts
• Less than 60 μA current drain
• Low self-heating, 0.08°C in still air
• Nonlinearity only ±1⁄4°C typical
• Low impedance output, 0.1 W for 1 mA load

3 Potential Transformer

PT 

Potential transformers (PT) (also called voltage transformers (VT)) are a parallel connected type of instrument transformer. They are designed to present a negligible load to the supply being measured and have an accurate voltage ratio and phase relationship to enable accurate secondary connected metering.

RatioThe PT is typically described by its voltage ratio from primary to secondary. A 600:120 PT would provide an output voltage of 120 volts when 600 volts are impressed across its primary winding. Standard secondary voltage ratings are 120 volts and 70 volts, compatible with standard measuring instruments.

4 Current transformer

CT

A current transformer (CT) is used for measurement of alternating electric currents. Current transformers, together with voltage (or potential) transformers (VT or PT), are known as instrument transformers. When the current in a circuit is too high to apply directly to measuring instruments, a current transformer produces a reduced current accurately proportional to the current in the circuit, which can be conveniently connected to measuring and recording instruments. A current transformer isolates the measuring instruments from what may be very high voltage in the monitored circuit. Current transformers are commonly used in metering and protective relays in the electrical power industry.Like any other transformer, a current transformer has a primary winding, a magnetic core, and a secondary winding. The alternating current in the primary produces an alternating magnetic field in the core, which then induces an alternating current in the secondary winding circuit. The essential objective of current transformer design is to ensure the primary and secondary circuits are efficiently coupled, so the secondary current is linearly proportional to the primary current.

5 Regulated Power Supply

The 78XX series consists of three-terminal positive voltage regulators with a seven-voltage option. These IC’s are designed as a fixed voltage regulator and with adequate heat, sinking can deliver output currents in excesses of 1A although these devices do not require external components can be used to obtained adjustable voltage and currents. These IC’s also have thermal overload protection and internal short circuit current limiting.

Features:

 Output current in excess of 1 Ampere.
 Internal thermal overload protection.
No external components required.
 Output transistor safe area protection.
 Internal short circuit current limit.
 Available in the aluminum TO-3 package.
The LM 78XX series is available in an aluminum TO-3 packed which will allow over 1.0A load current if adequate heat sinking is provided. Current limiting is including limiting the peak output current to a safe value.
Safe area protection for output transistor internal power dissipation becomes too high for the heat sinking provided; the thermal shutdown circuit takes over preventing the IC from overheating. Considerable effort was an expectation to make LM 78XX series of regulators easy to use and minimum the number of external components. It is not necessarily easy to bypass the output, although this does improve transient response.
Input bypassing is not needed only if the regulator is located far from the filter capacitor of the power supply. For output voltage other than 5V, 12V & 15V. The LM 117 series provides an output voltage range from 1.2V to 57 V.

6 Indicator lamps

INDICATION LAMP

A malfunction indicator lamp (MIL), or check engine light, is a tell-tale that a computerized engine-management system uses to indicate a malfunction. Found on the instrument panel of most automobiles, it usually bears the legend CHECK ENGINE, SERVICE ENGINE SOON, or a pictogram of an engine - and when illuminated it is typically either an amber or red color.

7 Push Button

Push button

A push-button (also spelled pushbutton) or simply button is a simple switch mechanism for controlling some aspect of a machine or a process. Buttons are typically made out of hard material, usually plastic or metal. The surface is usually flat or shaped to accommodate the human finger or hand, so as to be easily depressed or pushed. Buttons are most often biased switches, although many un-biased buttons (due to their physical nature) still require a spring to return to their un-pushed state. Terms for the "pushing" of a button include pressing, depressing, mashing, hitting, and punching.

8 Relay

relay

A relay is an electrically operated switch. Many relays use an electromagnet to mechanically operate a switch, but other operating principles are also used, such as solid-state relays. Relays are used where it is necessary to control a circuit by a separate low-power signal, or where several circuits must be controlled by one signal. The first relays were used in long distance telegraph circuits as amplifiers: they repeated the signal coming in from one circuit and re-transmitted it on another circuit. Relays were used extensively in telephone exchanges and early computers to perform logical operations.

Conclusion:

The use of PLCs in Substation And Distribution Automation application has grown in recent years. Many Technical issues affect the cost-benefit analysis of implementing a different type of distribution automation system however this technology for a meeting that equipment has a key challenge to implementing automation. The time required to operate is 50% less than existing Electromechanical system, the life span of this system is more than the electromechanical system, as this system has static devices so Maintenance cost is very less than the existing electromechanical system.