كهربجي يقدم لكم شرح لـ25 مصطلح مهم في الهندسة الكهربائية :
Power factor correction:
Is a process for increasing the power factor without altering the voltage or current to the original load , by adding a capacitor that would exactly match the reactive load component .
model of medium transmission line:
The transmission line having its effective length more than 80 km but less than 250 km is generally referred to as a medium transmission line. Due to the line length being considerably high, admittance Y of the network does play a role in calculating the effective circuit parameters, unlike in the case of short transmission lines. For this reason the modeling of a medium length transmission line is done using lumped shunt admittance along with the lumped impedance in series to the circuit.
model of transformer:
The transformer is the most common application of the concept of mutual inductance. In the transformer, the effect of the mutual inductance is to cause the primary circuit to take more power from the electrical supply in response to an increased load on the secondary. For example, if the load resistance in the secondary is reduced, then the power required will increase, forcing the primary side of the transformer to draw more current to supply the additional need.
Model ( Equivalent circuit ) of synchronous generator:
Voltage EA is the internal generated voltage induced in one phase of a synchronous generator. However, this is not the usual voltage that appears at the terminals of the generator. In reality, the internal voltage EA is the same as the output voltage Vcp of a phase only when there is no armature current flowing in the stator.
These factors cause the difference between EA and Vcp:
The armature reaction, which is the distortion of the air gap magnetic field by the current flowing in the stator
The self-inductance of the armature (stator) windings
The resistance of the armature windings
Economic Dispatch :
Economic dispatch is the short-term determination of the optimal output of a number of electricity generation facilities, to meet the system load, at the lowest possible cost, subject to transmission and operational constraints.
Power ( load ) flow :
In power engineering, the power-flow study, or load-flow study, is a numerical analysis of the flow of electric power in an interconnected system. A power-flow study usually uses simplified notations such as a one-line diagram and per-unit system, and focuses on various aspects of AC power parameters, such as voltages, voltage angles, real power and reactive power. It analyzes the power systems in normal steady-state operation.
Optimal power flow :
The Optimal Power Flow (OPF) model represents the problem of determining the best operating levels for electric power plants in order to meet demands given throughout a transmission network, usually with the objective of minimizing operating cost.
Power system security :
Power System Security is defined as the ability of the power system to remain secure without serious consequences to any pre-selected list of credible contingencies. The most common operational problems are transmission equipment overloads and inadequate voltage levels at system buses .
load Frequency Control (LFC):
The key thing is to maintain the steady state at null position. effective measures like Active Disturbance Rejection Control (ADRC) have been developed that allow practical control. The main bifurcation between frequency and voltage in power system is on the account of active and reactive power. The dependency of frequency is on active power whereas that of voltage is on the reactive power. The combination of active power and frequency control is generally known as Load Frequency Control.
Automatic voltage regulator (AVR):
A voltage regulator is device designed to automatically maintain a constant voltage level. It may be a simple “feed-forward” design or may include negative feedback control loops.
flexible ac transmission system (facts) devices :
is a system composed of static equipment used for the AC transmission of electrical energy. It is meant to enhance controllability and increase power transfer capability of the network. It is generally a power electronics-based system.
Power system stability :
is the ability of the system, for a given initial operating condition, to regain a normal state of equilibrium after being subjected to a disturbance.
Reactive power :
is the resultant power in watts of an AC circuit when the current waveform is out of phase with the waveform of the voltage, usually by 90 degrees if the load is purely reactive, and is the result of either capacitive or inductive loads. Only when current is in phase with voltage is there actual work done, such as in resistive loads.
Compensation devices :
are devices connected to middle of the transmission line , they can be provided by current source , voltage source or a capacitor To the middle.
Determining the mix of generators and their estimated output level to meet the expected demand of electricity over a given time horizon.
Load forecasting :
is a technique used by power or energy-providing companies to predict the power/energy needed to meet the demand and supply equilibrium.
supervisory control and data acquisition ( SCADA ):
is a control system architecture that uses computers, networked data communications and graphical user interfaces for high-level process supervisory management, but uses other peripheral devices such as programmable logic controllers and discrete PID controllers to interface to the process plant or machinery. The operator interfaces which enable monitoring and the issuing of process commands.
Is a system that measures the value of the output and applying control signal to correct or limit the errors.
corona effect :
hissing noise comes from surrounding of a transmission line where an extra high voltage from the magnetic effect of the core of the conductor , So the air outside the conductor surface becomes conducting and due to dielectric break down of air this noisy sound is heard .
Charging Current :
In a transmission line, air acts as a dielectric medium between the conductors. When the voltage is applied across the sending end of the transmission line, current starts flowing between the conductors (due to imperfections of the dielectric medium).
Generating units are the sum and total of all equipment necessary for production of electricity
Load Duration Curve:
The Electrical Load Duration Curve is an excellent graphical representation of the amount of time the facility is above a given electrical demand level. The electric demand, or electric load, is plotted on the vertical axis, and the percent of occurrences, throughout the year, is plotted on the horizontal axis.
power system state estimation:
Power system state estimation is defined as the act of estimating the state of the network from the redundant telemetry measurements.
Transmission and distribution losses:
Transmission and distribution losses are losses in transmission between sources of supply and points of distribution and in the distribution to consumers .
Voltage level in Jordan ( Generation– Transmission Line-Distribution):
15 kV :Used in generation
132 kV, 230 kV, and 400 kV ( High Voltage) used in transmission system
33 kV, 11 kV, and 0.4 kV : Used in distribution