Why the injection of reactive power is needed?
To inject reactive power you need to phase shift the injected current with respect to the grid voltage. Thus, by controlling the phase and amplitude of the injected current you can control the active and reactive power injected into the grid.
Why does inductive load absorb reactive power?
The current flowing through capacitors is leading the voltage by 90°. The corresponding current vector is then in opposition to the current vector of inductive loads. This why capacitors are commonly used in the electrical systems, in order to compensate the reactive power absorbed by inductive loads such as motors.
What is the reactive power consumed by the load?
Reactive Power can best be described as the quantity of “unused” power that is developed by reactive components in an AC circuit or system. In a DC circuit, the product of “volts x amps” gives the power consumed in watts by the circuit.
What is the purpose of reactive power?
Reactive power is used to provide the voltage levels necessary for active power to do useful work. Reactive power is essential to move active power through the transmission and distribution system to the customer.
What is the reason for voltage collapse?
(b) If adjacent generators are overexcited and overloaded then it leads to voltage collapse due to increase in reactive power loss. (c) Due to large load demand or large rapid magnitude of power transfer, reactive power demand increases and voltage reduces.
What are symptoms of voltage collapse?
The main symptoms of voltage collapse are – low voltage profiles, heavy reactive power flows, inadequate reactive support, and heavily loaded systems. The collapse is often precipitated by low-probability single or multiple contingencies.
What are the methods used to prevent voltage collapse?
Some of the control actions used as counter measures against voltage collapse is as follows:
- Switching of shunt capacitors.
- Blocking of tap-changing transformers.
- Re-dispatch of generation.
- Rescheduling of generator and pilot bus voltages.
- Secondary voltage regulation.
- Load shedding.
How does injecting reactive power affect voltage support?
Injecting reactive power into the system raises voltages, and absorbing reactive power lowers voltages. Voltage-support requirements are a function of the locations and magnitudes of generator outputs and customer loads and of the configuration of the DER transmission system.
When does reactive power need to be used?
Motor loads and other loads require reactive power to convert the flow of electrons into useful work. When there is not enough reactive power, the voltage sags down and it is not possible to push the power demanded by loads through the lines.
How is reactive power used in a transmission line?
Reactive power (VARS) is required to maintain the voltage to deliver active power (watts) through transmission lines. Motor loads and other loads require reactive power to convert the flow of electrons into useful work.
Why does a transformer consume more reactive power at no load?
When reactive power supply lower voltage, as voltage drops current must increase to maintain power supplied, causing system to consume more reactive power and the voltage drops further . If the current increase too much, transmission lines go off line, overloading other lines and potentially causing cascading failures.