Category: Performance of Power Transmission

Voltage Control Method in Transmission Lines

Voltage Control Method in Transmission Lines: Practically each equipment used in power system are rated for a certain voltage with a permissible band of voltage variations. Voltage at various buses must, therefore, be controlled within a specified regulation figure. This article will discuss the Voltage Control Method in Transmission Lines by two methods by means […]

Power Flow through Transmission Line

Power Flow through Transmission Line: So far the transmission line performance equation was presented in the form of voltage and current relationships between sending-and receiving-ends. Since loads are more often expressed in terms of real (watts/kW) and reactive (VARs/ kVAR) power, it is convenient to deal with transmission line equations in the form of sending- […]

Equivalent Circuit of a Long Line

Equivalent Circuit of a Long Line: So far as the end conditions are concerned, the Equivalent Circuit of a Long Line can be established in the form of a T- or π-network. The parameters of the equivalent network are easily obtained by comparing the performance equations of a π-network and a transmission line in terms […]

Tuned Power Lines in Transmission

Tuned Power Lines in Transmission: Equation (5.23) characterizes the performance of a Tuned Power Lines in long Transmission line. For an overhead line shunt conductance G is always negligible and it is sufficiently accurate to neglect line resistance R as well. With this approximation Hence Eq. (5.23) simplifies i.e. the receiving-end voltage and current are […]

Ferranti Effect

Ferranti Effect: The effect of the line capacitance is to cause the no-load receiving-end voltage to be more than the sending-end voltage. The effect becomes more pronounced as the line length increases. This phenomenon is known as the Ferranti effect. A general explanation of this effect is advanced below: Substituting x = l and IR […]

Transmission Lines and Waveguides

Transmission Lines and Waveguides: As already said in Eq. (5.26), γ is a complex number of Transmission Lines and Waveguides which can be expressed as The real part α is called the attenuation constant and the imaginary part β is called the phase constant. Now Vx of Eq. (5.21) can be written as The instantaneous […]

Long Transmission Line

Long Transmission Line: For lines over 250 km, the fact that the parameters of a line are not lumped but distributed uniformally throughout its length, must be considered. Figure 5.10 shows one phase and the neutral return (of zero impedance) of a Long Transmission Line. Let dx be an elemental section of the line at […]

Medium Transmission Line

Medium Transmission Line: For lines more than 100 km long, charging currents due to shunt admittance cannot be neglected. For lines in range 100 km to 250 km length, it is sufficiently accurate to lump all the line admittance at the receiving-end resulting in the equivalent diagram of Medium Transmission Line shown in Fig. 5.7. […]

Voltage Regulation of Transmission Line

Voltage Regulation of Transmission Line: Voltage Regulation of Transmission Line is defined as the rise in voltage at the receiving-end, expressed as percentage of full load voltage, when full load at a specified power factor is thrown off, i.e. In the above derivation, ΦR has been considered positive for a lagging load. It will be […]

Short Transmission Line

Short Transmission Line: For Short Transmission Line of length 100 km or less, the total 50 Hz shunt admittance (jωCl) is small enough to be negligible resulting in the simple equivalent circuit of a short line is shown in Fig. 5.1. This being a simple series circuit, the relationship between sending-end receiving-end voltages and currents can […]