8. Synchronous generators and power grid side by side What are the methods?
A: synchronous generator and grid parallel methods are self-synchronous method and quasi-synchronous method.Usually in order to reduce the impact of parallel current are generally used quasi-synchronous method, parallel to adjust the generator excitation current and speed, in the generator and the grid phase sequence of the same frequency equal to the voltage equal to the same phase and the same phase.
9. What are the main data on the nameplate of asynchronous motor?
A: Rated power. Rated voltage. Rated current. Rated speed. Phase number. Model. Insulation class. Work. Allowable temperature rise. Power factor. Quality. Date of manufacture.
10. Asynchronous motor by structure how to classify?
A: divided into squirrel cage and winding type.
Power Systems
1. What is the power quality indicator?
A: Frequency. Voltage. Waveform. Symmetry
2. What are the indicators to characterize the economics of power system operation?
A: coal consumption (g/kw×h). Net loss rate
3. What are the voltage levels of our standard?
A: 0.22KV, 0.38KV, 0.66KV, 3kV, 6kV, 10kV, 35kV, 60kV, 110kV, 220kV, 330kV, 500kV, 750KV, 1000KV.
4. Which two types of power lines are divided according to the structure? The basic components of what?
A: The overhead line: wire. Lightning wire. Tower. Insulator
Cable line: conductor. Insulating layer
5. 220kv above the line often used split wire What is the purpose?
A: Improve the parameters of the line (to reduce line reactance) and to prevent the occurrence of corona phenomenon
6. What are the contents of the power flow calculation?
A: power loss calculation; current and power distribution calculation; voltage loss and node voltage calculation
7. What is the trend to calculate?
A: system design and design to select the knot line. Select the electrical equipment and wire cross-section; determine the system operation mode and develop maintenance plan; for relay protection. Automatic device design and setting calculation; Short circuit and stable calculation.
8. What are the losses of the transformer?
A: The changing losses (ie winding loss, with the load size and change); fixed loss (ie no-load loss or excitation loss)
9. What is the active power of the system? What is the use of spare capacity?
A: The active power supply is the generator; the standby capacity is used as: standby load. Accident backup. Overhaul spare. National economic reserve; Standby forms: cold standby (standby).
use)
10. What are the reactive power sources of the system?
Power supply - Static electricity compensator - Charging power for high - voltage lines
11. What are the system's voltage regulation measures?
A: The use of the generator voltage regulator; adjust the transformer variable voltage regulator; series capacitor voltage regulator; parallel compensation reactive power equipment regulator
12. What are the main uses of a capacitor in a system?
Improve the economy (increase power factor, reduce power loss); improve the stability of the system (series compensation, reduce the system reactance); improve the economy (increase power factor,
13. What are the short-circuit faults occurring in the power system? What is the highest probability of occurrence? Which equipment has the highest probability of a short-circuit fault?
Symmetrical short circuit: three-phase short circuit; the highest probability of occurrence of the short circuit: one phase short circuit; the highest probability of occurrence of short-circuit fault device : Power lines
