For good energy generation, when choosing the power plant, we must take into account the choice of location of the different power plants and their advantages and disadvantages.' In this thesis we have discussed about different types of power plants, their merits and demerits, power generation in Bangladesh, energy demand and shortage of installed capacity of power plant under construction. We have included the mechanical design of the transmission system, the electrical design of the transmission system, various types of transmission loss and the solution of loss.
For the distribution system, we have included Bhurulia distribution substation. We believe that this study will be very useful for better understanding the generation and empowerment system of Bangladesh. Fig.-5.3: Exterior and inner construction diagram of line post insulators Fig.-5.3: Exterior and inner construction diagram of line post insulators Fig.-6. Non-symmetrical spacing (inductance) Fig.-6.2(b): Asymmetrical lines (inductance) Fig.-6.3: Equilateral spacing (capacitance) Fig.-6.4: Asymmetrical spacing (capacitance) Fig.-6.5: Two-port network.
BACKGROUND
OBJECTIVES OF THE THESIS
CHAPTER 2
TRANSMISSION SYSTEM
2.L CLASSIFICATION OF TRANSMISSION SYSTEM
GRID SYSTEM
- CLASSIFICATION OF OVERHEAD TRANSMISSION LINE
- DEFINATION OF IMPORTANT TERMS
- Solid earth or ffictive earth line: Connecting to the neutral point to earth without
- ADVANTAGE OF HIGH VOLTAGE TRANSMISSION LINE
- ADVANTAGES OF HIGH VOLTAGE DC TRANSMISSION
- DISADVANTAGES OT HIGH VOLTAGE DC TRANSMISSION
Medium transmission line Long transmission line .. a) short transmission line: when the length of an overhead transmission line is up to 50km and the line voltage is relatively high (<20KV), it is usually considered a Short transmission line. 150Km and the line voltage is relatively high (>100KV), it is usually considered a Long transmission line. Neutral earthing: Connects to earth, the neutral point i.e. the star point of generator' . transformer, rotating machine, nose end of earthing transformer.
-effective of grounding: it is defined as the ratio of the highest r.m.s voltage of healthy line to ground to the line r'm.s voltage. It is calculated at the selected point in the system for a given system' It . is a ratio of error factor =Vt/Vz. Where,. Bus coupling transformers: it is a special type of transformer used in electric power transmission line.
CHAPTER 3
CONDUCTORS' MATERIALS
3.I. TYPES OF CONDUCTOR
Although aluminum-copper connections can be made, it is better to use aluminum conductors for service connections as several forms of covered cable are available for this purpose. The most common conductor sizes are listed on the datasheets, but other sizes, according to recognized standards or customer specifications, are also possible. The mixed construction of ACSR makes it a very flexible medium from a design perspective.”
By varying the relative proportions of aluminum and steel, the ideal conductor for each specific application can be produced. In general, ACSR consists of a galvanized steel core of 1 wire, 7 wires or 19 wires surrounded by concentric layers of aluminum wire. high current carrying capacity and relatively low strength are required, special constructions are available with a high aluminum content. Normally, a coating of non-oxidizing grease is applied to the steel cores of all conductors, in addition to the protection provided by galvanizing the steel wires.
Because they are lighter, alloy conductors can sometimes be used to advantage in place of the more conventional ACSR; with lower breaking loads than the latter' their use becomes particularly favorable when ice and win loads are low'.
LINE SUPPORT
TYPES OF LINE SUPPORT
CHAPTER 5
INSULATORS
TYPES OF INSULATORS
CHAPTER 6
ELECTRICAL DESIGN OF TRANSMISSION LINE
6.I ELECTRICAL DESIGN ASPECTS
CONSTANTS OF TRANSMISSION LTNE
The resistance is distributed uniformly over the entire length of the line. transmission line can be conveniently analyzed if distributed resistance is considered as.
6.I.2 CALCULATION OF CONSTANTS'
CHARACTERISTICS OF DIFFERENT TRANSMISSION LIIYE
I SIIORT TRANSMISSION LINE
Vn + ZIn,I.= In
- MEDIUM TRANSMISSION LINE
In this method, total capacitance is divided into two equal parts which are added together at the shedding and receiving ends, resulting in the nominal r representation as shown in fig 5.9.
The V-I quation,
TI{E LONG TRANSMISSION LINE
Let dx be an elementary portion of the line at a distance X from the receiving end with series impedance Hz and shunt access Ydx.
STANDARDIZATION OF TRANSMISSION VOLTAGE
One of the difficulties encountered in standardization was to use the maximum continuous voltage or the nominal voltage to establish a standard for a system voltage. Again, there is a margin discrepancy between these values in European and American practice. In the former case the maximum value is ten percent higher than the nominal value, while in the latter this difference is only five percent.
It has been proposed to compensate the nominal values in such a way that they have the same maximum value in both the systems to avoid this margin. It is preferred to have the measure of maximum value rather than the nominal value for the purpose of standardization. This voltage was the standard voltage used in many countries above 230KV and the international standardization was not so successful.
EXTRA HIGH VOLTAGE TRANSMISSION
CHAPTER 7
TRANSMISSION LINE LOSSES
7.L TYPES OF LOSSES
7.L.L COPPER LOSSES
7.I.2 DIELECTRIC LOSSES
- RADIATION AND INDUCTION LOSSES
- SKIN EFFECT
- MINIMIZATION OF TRANSMISSION LOSS
- CHAPTER 8
Therefore, polyethylene is often used as a dielectric because less current is consumed when its electron orbits are distorted. Induction loss occurs when the electromagnetic field around a conductor cuts through any nearby metallic object and a current is induced in that object. As a result, current dissipates in the object and is lost. Radiation losses occur because some magnetic lines of force around a conductor do not return. to the manager when the cycle changes.
These lines of force are projected into space as. radiation and these result in power loss. That is, current is supplied by the source' but is not available to the load. The trend of alternating current power. to concentrate near the surface of a conductor is known as skin.
Please note that the skin effect is negligible if the power frequency is low.
DTSTRIBUTION SYSTEM
SUB-STATION
- DEFINITION
8.1,.2 IMPORTANCE OF SUBSTATION
EQUTPMENTS OF SUBSTATTON
For voltages up to l lkv, the transformer station's equipment is installed indoors because for voltages above 66kv, the equipment is invariably installed outside. This is because, for such a voltage, the distance between the conductor and the necessary space for contact, switch and equipment becomes so great that it is not economical to install the equipment indoors.
Polemounted substation
- I TRANSFORMER
- ISOLATOR
- LTGHTING ARRESTER
- INSULATOR
A power transformer is used in a substation to step up or step down the voltage. Except at the power station, all subsequent substations use step-down transformers to gradually reduce the voltage of the electrical supply and finally supply it at utility voltage. The function of these instrument transformers is to transfer voltages or currents in the power lines to values convenient for operating measuring instruments and relays. The primary of this transformer consists of one or more turns of thick wire connected. in series with the line.
The secondary line consists of a large number of windings of fine wire and provides the measuring instruments and relays with a current that is a constant fraction of the line current. Suppose a current transformer with a rated power of 100i5A is connected to a current measuring line. if it is 1004 in the line then the current in the secondary will be 54.. the current in the line is 50 A then the secondary is c.T. will have a current of 2.5A. Thus the considered c'T' will step down the line cuff by a factor of 20. b) Voltage/potential transformer (P'T). The primary of this transformer consists of a large number of windings of fine wire connected across the line.
Where the power system is operating normally, the lighting arrester experiences off conditions. When the surge voltage is applied to the application to the power system, the spark gap is contacted by this high voltage and current. There are various types of insulators (eg pin type, suspension type, post insulator, etc.) and their use in the substation will depend on the service requirement.
This type of insulator consists of a number of porcelain discs connected in series with metal links in the form of strength. The conductor is suspended from the lower end of this string, while the other end of the string is attached to the cross stem of the tower. When the line is at a dead end or in a corner or sharp bend, the line is under more stress.
To relieve the line of excessive voltage, sffain insulators are used. For low voltage lines, clamp insulators are used as strain insulators.
Single Bus bar
- CIRCUIT BREAKER
- Power triangle
The biggest weakness of this system is the complete stoppage of the line in the event of a rod failure. To maintain or repair the circuit breaker, it is necessary to disconnect the circuit from the bus. Even for regular maintenance, it is necessary to disconnect one of the guides.
A common breaker switch involves the simple process of separating the contacts under all the oil in the tank. The bubble of hydrogen gas created around the arc cools the arc column and helps deionize the medium between the contacts. The gas creates turbulence in the oil and helps eliminate arc products from the arc path.
As the arc is extended due to the separating contacts, the dielectric length of the medium increases. There is no special control over the arc other than the increase in length by separating the movable contacts. The production of the arc due to ionization of metal ions and depends a lot on the materials of the contacts.
The arc is quickly extinguished because the metallic vapors, electrons and ions produced during the arc dissipate in a short time and are caught by the surfaces of moving and fixed elements and shields. In the closed position of the switch, the contacts remain surrounded by SF6 gas at a pressure of approx. 2.8 Kglcm2. The movement of the movable switch is synchronized with the opening of a valve which admits SF6 gas at 14Kglcm1 pressure from the reservoir to the arc interruption chamber.
The high pressure current of SF6 quickly absorbs the free electrons in the arc path to form immobile negative ions which are ineffective as charge carriers.
KVAR) Apparent power (KVA)
CONCLUSION
FUTURE WORK
