Detailed answers to the relevant questions related to the active and reactive power generation of the generator set

When searching for such as Baidu Know, Soso Questions and Google Q&A generator sets , Haixing Generator's employees found that many questions were related to the generator's active and non-reactive, so they specially answered them in detail for netizens. Below, Jiangsu Haixing Power Technology adopts a question-and-answer model to explain common questions.

You need to understand the basic concepts
: What is merit? What is resonance?
Answer: During the generation, transmission and use of alternating current energy, the part of energy used to convert into non-electric and magnetic forms is called active; the part of energy used for electrical and magnetic exchange in the circuit is called reactive.

Q: What is power rate? What are the progression phase and the delay phase of force?
Answer: The power factor of an AC motor is also called the force rate, which is equal to the ratio of active power to apparent power.
The so-called incoming phase of force rate is to send out the operating state of active absorption of reactive power; the late phase of force rate is to generate both active and reactive power.

Secondly, the practical problems related to active and reactive problems encountered during the regulation and use of generator sets
: What is the physical process of adjusting the active generator set? What should you pay attention to when adjusting active load?
Answer: Let’s talk about the process of adjusting the active power based on the motor’s work angle. At this time, it is assumed that the excitation current of the generator set remains unchanged and the voltage of the system remains unchanged.
(1) Load increase process: When the large steam valve is opened, the main torque on the generator rotor shaft increases. At this time, since the electric power has not started to change, that is, the magnitude of the resistance torque has not changed, the rotor needs to be accelerated, so that the angle between the rotor and the stator is opened a little. According to the power angle characteristics of the motor itself, once the power angle increases, the output power of the motor increases, that is, with more loads, will the rotor continue to accelerate? It will not happen when normal, because the motor has too much load, and the resistance torque increases. When the resistance torque is so large that it is balanced with the main torque, the rotor speed stabilizes. At this time, the output of the generator rises to a new value.
(2) Load reduction process: When the small steam valve is closed, the main torque on the rotor shaft of the generator set decreases, so the rotor slows down and the work angle becomes smaller. When the power angle becomes smaller, the electromagnetic power decreases, and the corresponding resistance moment becomes smaller. When the resistance moment decreases to the same large as the new main moment, a new balance is reached, and the motor is less loaded.
When adjusting the active load, pay attention to two points:
(1) The force should be kept as much as possible within the range specified in the regulations, and should not be greater than the 0.95 of the late phase, because a high force rate means that the excitation current corresponding to the active at that time is small, that is, there are few magnetic lines of force used to pull between the generator and the rotor poles, which is easy to lose stability. From the perspective of the power angle characteristics, the power angle sent will increase, and the power angle will be close to 90 degrees, which will easily lose stability.
(2) It should be noted that the load adjustment should be slow. When the unit increases its output, its overload capacity will generally be reduced.

Q: Why does voltage change and reactively adjust?
Answer: Voltage fluctuations are mainly caused by reactive loads. Active loads also have an impact on voltage fluctuations, but their impact is smaller. When the reactive power is short, that is, when the inductive load is over, the inductive load produces a demagnetization armature reaction to the generator set, causing the magnetic field of the air gap to be weakened and the terminal voltage is reduced. At this time, to maintain the terminal voltage unchanged, it is necessary to increase the rotor current, that is, increase the reactive power to compensate for the demagnetization armature reaction part. On the contrary, when the reactive power is over, the terminal voltage will rise. At this time, to maintain the terminal voltage unchanged, it is necessary to reduce the rotor current, that is, reduce the reactive power. This is the reason why voltage changes and reactive power adjustment.