Since domestic customers get single-phase supplies, they usually receive V at their inlet points. So in power systems where generation is distant from the load, it is desirable to step-up increase the voltage of power at the generation point and then step-down decrease the voltage near the load.
With concerns for the environment and conservation of fossil fuels, many alternate sources are considered for employing the untapped energy sources of the sun and the earth for generation of power.
Reactive power does no measurable work but is transmitted back and forth between the reactive power source and load every cycle.
Typically, the subtransmission voltage level ranges from 69 to kV. For safety reasons, RCDs are now installed on appliance circuits and, increasingly, even on lighting circuits.
They are at the heart of all modern electric and hybrid vehicles—where they are used for both motor control and as part of the brushless DC motor. HVDC is also desirable for interconnects because it allows frequency independence thus improving system stability.
Insulation requirements and other practical design problems limit the generated voltage to low values, usually 30 kV. Transmission voltages above kV are usually referred to as extra-high voltage EHV.
Firstly, power can be transmitted over long dist ances with less loss at higher voltages. Other techniques are discussed in the reference. For an AC supply, the ideal is the current and voltage in-sync fluctuating as a perfect sine wave at a prescribed frequency with the voltage at a prescribed amplitude.
So in power systems where generation is distant from the load, it is desirable to step-up increase the voltage of power at the generation point and then step-down decrease the voltage near the load. If more power is produced than consumed the frequency wil rise and vice versa.
Secondly, it is often more economical to install turbines that produce higher voltages than would be used by most appliances, so the ability to easily transform voltages means this mismatch between voltages can be easily managed.
Because they lack the commutator, ac generators can generate high power at high voltagetypically 30 kV. The classic function of power electronics is rectificationor the conversion of AC-to-DC power, power electronics are therefore found in almost every digital device that is supplied from an AC source either as an adapter that plugs into the wall see photo in Basics of Electric Power section or as component internal to the device.
An exception exists for centralized air conditioning systems as these are now typically three-phase because this allows them to operate more efficiently.
The next stepdown in voltage is at the distribution substation. Let us consider some typical voltage levels to understand the funtioning of the power system.
Overhead line conductors may be reinforced with steel or aluminum alloys. Power systems deliver energy to loads that perform a function.
Is the availability of the power source acceptable some renewables are only available when the sun is shining or the wind is blowing? Very large industrial customers may be served from the transmission system. HVDC is used because it proves to be more economical than similar high voltage AC systems for very long distances hundreds to thousands of kilometres.
Usually the commercial customers are supplied power at a voltage level of 11 kV whereas the domestic consumers get power supply at V. For example, the development of computers meant load flow studies could be run more efficiently allowing for much better planning of power systems.
As current flow increases through a conductor it heats up. However it is not the only challenge, in addition to the power used by a load to do useful work termed real power many alternating current devices also use an additional amount of power because they cause the alternating voltage and alternating current to become slightly out-of-sync termed reactive power.Cet the voltage generated #line to line% at the alternator be 1/ k$.Basic structure of a power system Transmission system he huge amount of power generated in a power station #hundreds of *3% is to be transported over a long distance #hundreds of kilometers% to load centers to cater power to consumers with the help of transmission.
Basic Structure of a Power System. The basic structure of a power system is shown in Fig. Fig. A typical power system. It contains a generating plant, a transmission system, a subtransmission system and a distribution system.
These subsystems are interconnected through transformers T 1, T 2 and T 3. Let us consider some typical. A. Basic Structure of Electric Power System A power plant generates electricity at approximately 25, volts. Transmission lines can carry higher voltages than the plant generates – up toV - so a transformer steps up.
Electrical power system deals with the technology of generation, transmission and distribution of electrical energy. An electric power system consists of different subsystem are explained as follows. I. Generation subsystem. The conversion from one source to electrical energy through the process of electromagnetic conversion.
This system. In order for a power plant to operate economically, it must have a high system load factor. Today’s typical system load factors are in the range of 55 to 70 percent.
Load-forecasting at all levels is an important function in the operation, operational planning, and planning of an electric power system.
Structure Of Power Systems – Generating stations, transmission lines and the distribution systems are the main components of an electric power system.
Generating stations and a distribution system are connected through transmission lines, which also connect one power system (grid, area) to another.Download