Power Line Carrier System Essay Example

ABSTRACT
Power line carrier communication (PLCC) is primarily utilized for telecommunication, tele-protection, and tele-monitoring purposes between electrical substations via power lines operating at high voltages, such as 110 kV, 220 kV, 400 kV.

PLCC, or Power Line Carrier Communication, is a system that utilizes the same electric power cable for transmitting both communication and 50/60 Hz power signals. This system offers the advantage of combining two crucial applications into one. The voice signal undergoes compression within the range of 300 Hz to 4000 Hz and is then mixed with the carrier frequency. Subsequently, the carrier frequency goes through filtering, amplification, and transmission processes. The transmission of these high-frequency carrier frequencies ranges from 0 to +32db depending on the distance between substations.

The technology known as Power Line Carrier Communication (PLCC) uses power lines to transmit data, eliminating the need for extra wiring. This makes it a convenient solution since the infrastructure is already in place. PLCC allows for rapid data transmission through power lines in different settings like homes, offices, buildings, and factories. In this system, the existing AC power wires function as the transmission medium by relaying information from a transmitter or control station to one or multiple receivers or loads connected downstream from an AC source.

Typical applications of Power Line Carrier Communication (PLCC) include Street light control, Automatic Meter Reading, HVAC control, Low Speed Data Networks, Signs and Information Display, Fire and Security Alarm, among others. The main components of a PLCC plant are the Line trap, also known as "Wave trap", and the Coupling capacitor.

The Line trap, connected in series with the power (transmission) line, blocks the high frequency carrier waves (24

kHz to 500 kHz) while allowing power waves (50 Hz - 60 Hz) to pass through. It functions as an inductor with a rating in milli henry.

The Coupling capacitor, on the other hand, provides a low impedance path for carrier energy to the HV line while acting as a high impedance path to block the power frequency circuit.

The Line matching unit (LMU) is a composite unit comprising of several components. These include the Drain Coil, Isolation transformer with Lightning Arrester on both sides, a Tuning Device, and an earth switch. The Tuning Device consists of a combination of R-L-C circuits that function as a filter circuit. Additionally, LMU is also referred to as the Coupling Device. Working together with the coupling capacitor, the LMU effectively connects Audio/Radio frequency signals to either transmission lines or PLC terminals. Furthermore, it serves the purpose of protecting the PLCC unit from overvoltages caused by transients on the power system. Notably, this unit is utilized in digital power line carrier systems.

A digital power line carrier (DPLC) was created to deal with the rapid spread of IP devices and digital telecommunication devices. The change involved converting the transmission system from analog to digital, using power lines as the medium for transmission. To evaluate its performance, a field test was conducted, which demonstrated that DPLC had the necessary qualities in terms of bit error rate characteristics and transmission capability. This allowed for the transmission of information from monitored electric-supply stations and images. The text also includes a list of figures and a table, which provide page numbers for reference purposes. Additionally, the text is divided into chapters, each focusing on a specific

aspect of power line carrier communication.

Chapter 1 introduces R.S.E.B., or Rajasthan State Electricity Board. Established on July 1st, 1957, this organization operates under the provisions of the electricity act similarly to public limited companies. Unlike such companies, however, R.S.E.B does not have articles and a memorandum of association. Instead, it has established rules, regulations, and administrative arrangements to carry out its functions. With the aim of providing electricity to the entire Rajasthan state in an economical manner, the state government transferred six dimensions, 64 offices, and around 300 employees to RSEB. The board's objective is to operate profitably without any electricity shortages.Despite its initial success, the Rajasthan State Electricity Board (RSEB) has been operating at a loss for several years. As a result, RSEB has recently undergone privatization and has been divided into five separate entities: 1) RRVVNL, which is responsible for electricity production; 2) RRVPNL, which handles electricity transmission; 3) JVVNL, the distribution authority of Jaipur; 4) JODVVNL, the distribution authority of Jodhpur; and 5) AVVNL, the distribution authority of Ajmer.

Furthermore, Chapter No.– 2 of the AIET/DOECE/2010-11/PTS/01 document introduces Power Line Carrier Communication (PLCC), an efficient method for transmitting high power from one location to another.

Since the 18th century industrial revolution, the world has experienced numerous changes. One significant aspect of this transformation is the advancement in engineering, particularly in the electronics industry. Electronics has played a crucial role in industrial progress, providing advancements such as wireless transmission, semiconductor device production, and various communication systems based on power systems. Effective communication between different generating and receiving stations is vital for the proper functioning of the system.

This is particularly true for large interconnected systems, where

a control dispatch station must coordinate the operations of multiple units to ensure that the station maintains proper functionality. Power line carrier communication has proven to be the most cost-effective and dependable communication method for medium and long distances in a power network. For shorter distances, the conventional telephone system utilizes open wires or underground cables. In certain situations, VHF wireless communication is preferred due to its economic advantages and lack of expensive high voltage coupling equipment.

AIET/DOECE/2010-11/PTS/02 discusses the history of Power Line Carrier Communication (PLCC) in the early days of electric power generation. The text explains that initially, generating stations were located near cities with industrial consumers of power. However, the introduction of hydroelectric stations and the extension of electricity to suburban and rural areas led to the interconnection of these stations, creating a power grid. This required an economical and reliable means of communication between the stations, substations, and control rooms. PLCC technology progressed over time, with older equipment using vacuum tubes and discrete transistor logic being replaced by modern components like digital signal processors and VLSI components.

AIET/DOECE/2010-11/PTS/03 focuses on the current uses and goals of PLCC. The text mentions four important facilities that PLCC communication is expected to provide: speech transmission, remote control and telemetering, power line transmission, and direct breaker tripping.

In an interconnected power grid, there are various methods available to send speech or other signals from one point to another.PLCC, or Power Line Carrier Communication, utilizes the strength and insulation level of high voltage power lines to improve communication reliability and reduce signal loss over long distances. This concept was first explored at the beginning of the century, and practical

applications were implemented in various countries starting in 1920. Over time, PLCC systems have become incredibly advanced and are now widely utilized in modern power systems alongside public telephone networks, direct lines, and radio circuits.

When long distances are involved, it is not cost-effective to have separate communication wires. Instead, power lines can be used as a medium for transmitting information. This is why POWER LINE CARRIER COMMUNICATION (PLCC) is commonly used. The main goal of a power line carrier channel (PLCC) is to achieve a signal level at the remote terminal that exceeds the receiver's sensitivity, and with a signal-to-noise ratio (SNR) significantly higher than the minimum. This ensures that the receiver can accurately decipher the transmitted information.

If the PLC channel meets both requirements, it will be reliable. The reliability of the channel is influenced by several factors including:
1. The power output of the transmitter
2. The type and quantity of hybrids needed to connect transmitters and receivers in parallel
3. The application of a line tuner
4. The capacitance of the coupling capacitor
5. The type and inductance size of the line trap used
6. The power line voltage and physical configuration
7. The phase to which the PLC signal is coupled
8. Circuit length and transpositions within the circuit
9. Modulation type for transmitting information and demodulation circuits in the receiver
10.The received signal-to-noise ratio

Figure depicts the main component of the PLC channel, which faces challenges in safely placing carrier signals on high voltage lines without damaging equipment involved in carrying out this task.

Once the signal is on the power line, it needs to be directed correctly for reception at the remote line

terminal. FIG. NO. 2. 1 AIET/DOECE/2010-11/PTS/05 Chapter No. – 3 BASIC PRINCIPLES OF PLCC In PLCC, the higher mechanical level and strength of insulation in high voltage power lines increase communication reliability and decrease attenuation over long distances. Since telephone communication systems cannot be directly connected to high voltage lines, appropriate coupling devices must be used.

These typically include high voltage capacitors or capacitors with potential devices that are used together with suitable line matching units (LMUs) to match the impedance of the line to that of the coaxial cable connecting the unit to the PLCC transmit-receive equipment. Additionally, it is necessary to prevent carrier currents used for communication from entering the power equipment used in G.S.S., as this could cause significant attenuation or complete loss of communication signals when grounded at the isolator. To avoid this loss, wave traps or line traps are utilized.

These consist of specially designed choke coils connected in series with the line, which have a negligible impedance to RF carrier currents. Wave traps typically include one or more capacitors connected in parallel with the choke coils, allowing them to resonate at carrier frequencies and provide a higher impedance to the flow of RF currents. FIG. NO. 3. 1 [pic]AIET/DOECE/2010-11/PTS/06 The previous sketch shows that this arrangement sorts out the power frequency and radio frequency components. The RF is prevented from entering the station bus, and the power frequency is blocked by a coupling capacitor. 1 SPECIFICATIONS OF PLCC 1. GENERAL Carrier frequency range 40 to 512 KHz Gross channel bandwidth 4 KHz Useful AF band 300 to 3700 KHz 2. PERMISSIBLE ROOM TEMPERATURE IN CLIMATE Data guaranteed within reliable 0 to

45 degrees centigrade Operating guarantee 20 to 45 degrees centigrade

The R. F. oscillator has a frequency stability of 5Hz. The TRANSMITTER has a peak envelope power of 25W, a side band power of 15W, and an auxiliary carrier frequency of 15W. At the frequency of 250 KHz, their power is lower by 2 db. The I. F. carrier frequency is 16 KHz, with a pilot tone of 3600 Hz and a test tone of 1000 Hz. The synthesizer reference frequency is 8 KHz, and the dummy load is 20ohm. The TRUNK DIALING involves shifting the pilot oscillator frequency of 3600 +/-30 to transmit dialing criterions at a speed of normally 10 pulses per second. The POWER SUPPLY is a DC supply with a range of 48 to 60(+/-250%) and has a maximum power output of 180 W.

Supply 2% Capacity800AH C. Supply220+/-15%, 50 Hz Power consumption70% 10. 2 BOOST CHARGER DC output 43. 2-67. 2Vo Output current 2. 5-7ampere Over load 10% Efficiency 80% AIET/DOECE/2010-11/PTS/35 A. FLOAT CHARGER The float charger is a static three-phase charger with a stabilized output. The DC voltage is constantly compared with a standard DC reference voltage, and the error voltage is then amplified to control the triggering signals of all three thyristors of the three-phase bridge control rectifier, as the output voltage tends.

The decrease in the selected value of the output voltage results in the adjustment of the triggering signals for each thyristor in all three phases. This ensures that the output voltage remains within the specified accuracy. If the output voltage increases beyond the selected value, the firing operation of these thyristors is delayed, bringing the DC output

voltage back to its stabilized value.

The control circuit of the float charger utilizes an electronic controller to regulate the output. The phase control of the scars' feedback controls the output. The control circuits are equipped with plug-in type cards and hard type connectors for external connections. These circuits include a power supply, UJT firing for SCR phase control, an amplifier, DC under voltage/over voltage sensing, and auxiliary circuits.

The boost charger section is responsible for charging the batteries after power resumption. It is activated by switching on the mains of the rotator switch rs-1. HRC fuses F-21 to F-23 are provided for overcurrent protection and are shielded by capacitors and resistors to prevent storage effects and transit overvoltage. Charging of the batteries can be done using two rotator switches on the front panel for coarse and fine control, with the charging current displayed on an ammeter.The charger's operation involves the use of selector switches RS-1 to turn ON either the float or boost charger. Only one charger, either float or boost, can be used at a time. When the charger operates in float mode, the battery is on a float charge and the VDD is bypassed through the contact of the DC contractor. On the other hand, when the charger operates in boost mode, the contact of the DC contractor opens. The load voltage can be adjusted using VDD switch RS-8 according to the requirement. To isolate the charger from the load and battery, a mains switch RS-9 has been provided. When the selector RS-9 is in charger mode, it will supply both the load and Trickle charger.

AIET/DOECE/2010-11/PTS/37 D. MAINTENANCE & FAULT TRACING PROCEDURE:
1. Before energizing

the battery charger, ensure that the control circuit boards are firmly inserted in their respective sockets.
2. Prior to energizing, check all mounting bolts and screws to avoid vibrations caused by loose mounting.
3. Switch OFF the charger once every month.
4. Connect the battery terminals first, followed by the AC input.

AIET/DOECE/2010-11/PTS/38 [pic]

AIET/DOECE/2010-11/PTS/39 Chapter No. – 11 GENERAL MODULATION PRINCIPLE

The carrier frequency technique with single side band transmission avoids interference from unwanted signals thanks to the use of high quality band filters and converter. Only the required side band is filtered out in the intermediate frequency stages, achieving optimal selectivity. Therefore, the carrier frequency section's task is to move the low frequency AF intelligence (ranging from 300 to 3700 Hz or 300 to 2200 Hz) first to the IF stage and then into the carrier frequency (HF) band.

The carrier frequencies are spaced on a 4 KHz (respectively 2.5 KHz) raster. This setup necessitates two conversions in both the transmitting and receiving directions, resulting in an intermediate frequency of 16 KHz. The carrier channel can have a variable frequency that can be programmed to generate numerous HF carriers. In single channel equipment and channel 1 of twin channel equipment, the lower side band is employed for all frequency conversions. The useful band is inverted in the IF stage and positioned upright in the HF stage.

The text below provides an explanation of the circuit function of the PLC equipment ETI 21 and 22 using the attached block diagram. Channel 2 of the twin channel equipment is inverted in the HF stage and erect in the IF stage. The block diagram contains information on the wiring, level setting, and control

voltages, as well as the type and position number of the plug-in units (such as TELEPHONE ADAPTER O2EE, tier P7EG-N10). It also includes details on isolating links, measuring points, strapping information, and attenuator network.

AIET/DOECE/2010-11/PTS/40 [pic] Block Diagram POWER LINE CARRIER COMMUNICATION FIG. NO. 11. 1 AIET/DOECE/2010-11/PTS/41 ADVANTAGES ; DISADVANTAGE OF PLCC ADVANTAGE – 1. No separate wires are needed for communication purposes as the power lines themselves carry power as well as the communication signals.
2. When compared with ordinary lines, power lines have significantly higher mechanical strength, remaining unaffected under conditions that could damage telephone lines.
3.

Power lines provide the shortest route between the power station, thanks to their wide cross-sectional area that results in minimal resistance per unit length. Moreover, power lines are effectively insulated to prevent any leakage between conductors and the ground, even in adverse weather conditions. Nevertheless, there are certain drawbacks to consider: it is imperative to take necessary measures for safeguarding carrier equipment and individuals against the high voltage and current found on these lines. Furthermore, reflections may arise on spur lines connected to high voltage lines.

This text discusses various issues with the carrier current system in power lines. It mentions that attenuation is increased and other problems are created. The transformer connections in high voltage lines attenuate carrier current, and substation equipment negatively affects it as well. Additionally, the noise introduced by power lines is greater compared to telephone lines due to factors like discharge across insulators, corona, and switching processes. It is clear that an effective power lines carrier system must overcome these challenges and more.
AIET/DOECE/2010-11/PTS/43 CONCLUSION

PLCC is highly efficient for communication between generating and receiving stations, especially in

large interconnected systems. Power generating systems are extremely vulnerable to shocks and grid breakdowns. When these incidents occur, the electricity supply is disrupted. However, PLCC offers a superior solution by allowing point-to-point contact between stations and ensuring proper functionality even during major failures. Additionally, PLCC enables prompt action to be taken in cases of over supply caused by voltage differences.

Therefore, PLCC is a highly significant communication method for long distances interconnection and uninterrupted point-to-point link. AIET/DOECE/2010-11/PTS/44 BIBLIOGRAPHY • Principle of carrier communication-N. N. BISWAS • Manual of ETI equipments-ABB (ASEA BROWN) • Manual of battery charger -R. S. E. B. • Telecommunication engineering-ANOOP SING POONIA AIET/DOECE/2010-11/PTS/45 [pic] ----------------------- DEPARTMENT OF ELECTRONICS ENGINEERING [pic]ARYA INSTITUTE OF ENGINEERING & TECHNOLOGY SP-40, RIICO INDUSTRIAL AREA, JAIPUR (RAJASTH