Why can the speed of the generator change the active power while adjusting the excitation voltage ch

Primarily, the speed of the generator cannot be changed because the system frequency is fixed.

In order to increase the active power, the only way to increase the torque of the prime mover is to increase the torque, in this process, the rotor of the generator is temporarily accelerated, and the generator voltage increases, but it is soon balanced with the resistance torque generated by the load current, and the generator still runs stably at the synchronous speed.

Increase the excitation current.

Yes, it is possible to increase the reactive power.

Target. As soon as the excitation current increases, the armature.

The current will increase, and the increased armature current lags by 90 degrees compared to the voltage, and the inductive reactive power output by the generator increases.

Increasing the speed is to increase the rotor torque, but because the speed is proportional to the frequency, and the frequency can be understood as a fixed parameter, so if the rotor torque is increased but can not make the speed rise, the resistance of the rotor can only increase the resistance torque of the rotor, the resistance of the rotor comes from the electromagnetic torque of the stator winding, according to the armature reflection of the generator, the greater the stator current (the greater the load) the greater the resistance to the rotor, so the frequency is certain, and the increase of the rotor torque can increase the active power.

Adjust the excitation current, adjust the magnetic flux density of the rotor according to the principle of electromagnetic induction to change the induced electromotive force of the stator, and the induced electromotive force is ahead of the current, so the inductive reactive current is output.

The generator emits inductive reactive power by increasing the excitation voltage and increasing the excitation current; The capacitive reactive power is emitted by reducing the excitation voltage and the excitation current, so as to achieve the purpose of regulating the reactive power.

As a result of increasing the excitation current of the generator, the output voltage of the generator rises synchronously, and for resistive loads, the voltage increases and the power also increases, and the reactive current does not change in any way.

Upstairs is right, for the resistive load, increasing its voltage (because you increase the excitation of the generator), can only increase the power of the generator, to maintain the generator speed unchanged, you need to increase the power, otherwise the frequency will decrease. However, it does not generate or increase reactive power.

Purely resistive loads have no reactive current;

Increasing the excitation current can increase the output voltage, and the current of the load will definitely increase with the same resistance, but this is the active current.

The load is divided into resistance, inductance and capacitance.

Summary. Dear, I'm honored to have your question The information that the teacher found for you here is: when the load torque and excitation current of the DC motor are unchanged, why does reducing the armature voltage cause the motor speed to decrease?

When the load torque and excitation current remain unchanged, the armature voltage is reduced, so that the power of the motor is reduced. According to the formula of the relationship between power and rotational speed p=, p decreases, while t does not change, then n must decrease. Otherwise, the output of normal torque will not be satisfied.

The reason why the DC parallel generator cannot establish the voltage should be mainly because the motor has no remanence, or the excitation winding is open.

When the load torque and excitation current of the DC motor are unchanged, why does reducing the armature voltage cause the motor speed to decrease?

Dear, I'm honored to have your question The information that the teacher found for you here is: when the load torque and excitation current of the DC motor are unchanged, why does reducing the armature voltage cause the motor speed to decrease? When the load torque and excitation current remain unchanged, the armature voltage is reduced, so that the power of the motor is reduced.

According to the formula of the relationship between power and rotational speed p=, p decreases, while t does not change, then n must decrease. Otherwise, the output of normal torque will not be satisfied. The reason why the DC parallel generator cannot establish the voltage should be mainly because the motor has no remanence, or the excitation winding is open.

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1. All reactive power is generated by inductive and capacitive loads, and synchronous generators do not carry loads, so naturally there will be no reactive power.

When there is reactive power generated by inductive load, it is reflected in the generator that the magnetic property of the armature will decrease, resulting in a decrease in output power, then the excitation can be adjusted and the excitation current can be increased to offset the reactive power, so that the generator can restore the original power.

When the capacitive load produces reactive power, it is reflected in the generator that the magnetic property of the armature will increase, resulting in a decrease in the output power, and then the excitation can be adjusted to reduce the excitation current to offset the reactive power and restore the original power of the generator.

In this way, the reactive power is eliminated by adjusting the excitation.

Summary. PM is not the actual active power emitted by the generator, but the maximum electromagnetic power. This is because the maximum electromagnetic power of the generator is proportional to the system voltage and the induced potential.

That is to say, increasing the excitation current can increase the maximum electromagnetic power of the generator and improve the stability of the generator operation. These are reactive with the actual active power of the generator. The actual active power of the generator depends on the mechanical torque transmitted by the prime mover to the generator, the increase of torque, the active power will increase, but it cannot exceed PM, otherwise it will lose synchronization.

Hello, I will sort out the answer for you immediately, please don't be in a hurry and wait patiently.

PM is not the actual active power emitted by the generator, but the maximum electromagnetic power. This is because the maximum electromagnetic power of the generator is proportional to the system voltage and the induced potential. That is to say, increasing the excitation current can increase the maximum electromagnetic power of the generator and improve the stability of the generator operation.

These are reactive with the actual active power of the generator. The actual active power of the generator depends on the mechanical torque transmitted by the prime mover to the generator, the increase of torque, the active power will increase, but it cannot exceed PM, otherwise it will lose synchronization.

The larger the excitation current, the stronger the rotor magnetic field, and the higher the induced electromotive force in the stator coil at the same speed; At no load, the extreme voltage depends on the magnitude of the rotor's magnetic field; When a load is applied, the magnetic field generated by the load current in the stator coil (armature reaction magnetic field) and the rotor magnetic field form a resultant magnetic field, and the terminal voltage depends on the magnitude of the resultant magnetic field.

Due to the difference in the magnitude and nature of the load current, the armature reactive magnetic field has the effect of strengthening (when entering the phase) or weakening (when the phase is delayed) on the rotor magnetic field, and the current in the stator current that produces the enhanced or weakened magnetic field is the reactive current, and the current multiplied by the voltage is the reactive power.

If the reactive power is balanced, then the terminal voltage remains unchanged, if the load changes, the armature reaction magnetic field changes cause the change of the synthetic magnetic field, the terminal voltage will fluctuate, then we need to adjust the excitation current to adjust the size of the rotor magnetic field to keep the synthetic magnetic field unchanged, so as to maintain the terminal voltage unchanged.

The excitation current is the current flowing in the rotor of the synchronous motor (with this current, the rotor is equivalent to an electromagnet, with n pole and S pole), and during normal operation, this current is generated by the DC voltage applied to the rotor externally. This DC voltage is supplied by DC motors, and most of them are supplied by thyristors after rectification.