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A bus is a node at which one or many lines, one or many loads and generators are connected. In a power system each node or bus is associated with 4 quantities, such as magnitude of voltage, phage angle of voltage, active or true power and reactive power in load flow problem two out of […]

1) Power flow analysis is very important in planning stages of new networks or addition to existing ones like adding new generator sites, meeting increase load demand and locating new transmission sites. 2) The load flow solution gives the nodal voltages and phase angles and hence the power injection at all the buses and power

Transient stability is very much affected by the type of the fault. A three phase dead short circuit is the most severe fault; the fault severity decreasing with two phase fault and single line-to ground fault in that order. If the fault is farther from the generator the severity will be less than in the

The controlled rectifier circuit is divided into three main circuits, (1) POWER CIRCUIT This is the circuit contains voltage source, load and switches as diodes, thyristors or IGBTs. (2) CONTROL CIRCUIT This circuit is the circuit, which contains the logic of the firing of switches that may, contains amplifiers, logic gates and sensors. (3) TRIGGERING

DIAC (Diode for Alternating Current) is like a TRIAC without a gate terminal. DIAC conducts current in both directions depending on the voltage connected to its terminals. When the voltage between the two terminals greater than the breakdown voltage, the DIAC conducts and the current goes in the direction from the higher voltage point to the

In the center tap full wave rectifier, current flows through the load in the same direction for both half cycles of input AC voltage. The circuit shown in Figure has two diodes D1 and D2 and a center tapped transformer. The diode D1 is forward bias “ON” and diode D2 is reverse bias “OFF” in

TRIAC are used for the control of power in AC circuits. A TRIAC is equivalent of two reverse parallel-connected SCRs with one common gate. Conduction can be achieved in either direction with an appropriate gate current. A TRIAC is thus a bi-directional gate controlled thyristor with three terminals. Figure 1 shows the schematic symbol of

A GTO thyristor can be turned on by a single pulse of positive gate current like conventional thyristor, but in addition it can be turned off by a pulse of negative gate current. The gate current therefore controls both ON state and OFF state operation of the device. GTO V-I characteristics is shown in Figure

The thyristor is the most important type of the power semiconductor devices. They are used in very large scale in power electronic circuits. The thyristor are known also as Silicon Controlled Rectifier (SCR). The thyristor has been invented in 1957 by general electric company in USA. The thyristor consists of four layers of semiconductor materials

The V-I characteristics of the silicon diode and germanium diode. The icon used to represent the diode is drawn in the upper left corner of the figure, together with the polarity markings used in describing the characteristics. The icon ‘arrow’ itself suggests an intrinsic polarity reflecting the inherent non-linearity of the diode characteristic. As shown