What is Coupling?
The transmission process (or transmission method) of energy from one medium to another is called coupling. For example, the transmission process of electrical energy from metal wires to optical cables is a kind of coupling, the kinetic energy of the motor becomes the pressure energy of the hydraulic pump, and the intermediate transmission process is also a kind of coupling. It can be understood that coupling is a transmission tool, or a way of transformation.
What is DC?
What is a DC system?
Direct Current is referred to as DC for short, which refers to a current that does not change periodically in direction and time, but the size of the current may not be fixed, resulting in a waveform, also known as a constant current.The circuit through which it passes is called a DC circuit, which is a closed conductive circuit composed of a DC power supply and a resistor.Such as: dry batteries, lead-acid batteries.
The DC system provides reliable DC power supply for control, signal, protection, automatic devices, and accident lighting in substations.It also provides a reliable operating power supply for operation.The reliability of the DC system plays a vital role in the safe operation of the substation and is the guarantee of the safe operation of the substation.
Advantages of DC direct current:
There is no stability problem in the DC grid. Direct current is used for DC loads, and it can be used without rectifier and filtering equipment, which saves energy and reduces consumption compared to alternating current.
Disadvantages of DC direct current:
DC voltage boost is difficult, and the use of transformers to boost voltage is not feasible. Only special electronic circuits can be used to achieve voltage boost.If the power generation capacity is the same, the DC power generation equipment is more complicated than the AC power generation equipment. So far, there is no large-scale special case of power grid, and the technical standards and technical systems are not complete.
What is AC?
The current whose intensity and direction change periodically over time is called alternating current, or alternating current for short.The direction and size of the current will change over time.The generator of a power plant uses power to make the coil in the generator run. The direction of the output current of the generator will change once every 180° revolution, so the size of the current will also change regularly over time. This kind of power supply is called “AC power supply”.
Advantages of AC alternating current
1.As long as the AC power supply uses a transformer, the voltage (boost, buck) can be easily converted.
2.When transmitting power, it can maintain high voltage/low current and reduce the phenomenon of voltage drop (I2R loss).
3.It can easily convert AC power supply into DC power supply, and it is easy to supply power to DC drive equipment.
However, there are stability problems in the AC power system. If it is an AC power supply, the load is DC, and it must be rectified and filtered several times before it can be used.