AC Transmission System vs DC Transmission System in 2024 - Electronicsinfos

Electrical Transmission System

In the Early days, the energy demand was low but over time, the demand increased. As per demand, we need to generate more energy and transmit it over long distances. There are two ways of transmission of electrical power either in AC or DC.

Every Energy Supplier wants to reduce losses, if he uses an AC system for transmission and distribution, he can easily step up and Step down the voltage using an Electrical transformer. 

If the Energy supplier uses a DC system For transmission and Distribution it needs to use a large size of conductor to reduce the losses ultimately The System cost is high.

Every System Either AC or Dc have three components of electrical energy that consist of Generating stations, transmission systems, and distribution systems. The most commonly used system is a three-phase three-wire system to transmit the electrical energy but the distribution of electrical energy is done by a phases 4 wire system.

Now there are two possibilities either we transmit energy using the overhead system or the underground system. So we discuss the comparison between the AC Transmission and the DC transmission system. Each system has its own advantages and disadvantages.

DC Transmission System

DC transmission systems are the system of transmission of electric power using direct current (DC). DC transmission is used in certain areas where it is more efficient or practical than AC transmission, such as for long-distance power transmission or for interconnecting different AC systems with different frequencies.

In a DC transmission system, the AC power is first converted to DC using a converter station. The DC power is then transmitted through a transmission line with a positive and negative conductor.

The DC power is also voltage-regulated and controlled using various equipment, such as transformers and inverters, to ensure optimal transmission efficiency.

Advantages of DC Transmission System

• We need two conductors in the DC Transmission System.
• The Inductance and surges are not present in the DC transmission.
• due to low inductance, the voltage drop is low in the DC system.
• The skin effect is not present in the DC system so we need less size of the conductor in terms of area.
• We need less insulation in the DC transmission because the charge tension at the insulator is low.
• The corona loss is low in the DC transmission.
• The interference with the telecommunication lines is low.
• In the high voltage DC transmission, the Dielectric losses are not present.
• there is no stability and synchronizing problem in the DC transmission system.
• The DC transmission system is Economical as compared to the AC system.
• The speed control of the generator is more in the DC system.
• due to less insulation, the cable cost is low in the DC system
• There are no sheath losses that occur in the underground cables.
• With the lower value of charging current, we draw more long-distance wire in the DC system.

Disadvantages of DC Transmission System

• Due to the Commutation process, we do not generate high DC power.
• we do not power up the DC to travel long distances.
• there are some limitations of DC switches and breakers.
• to reduce the dc voltage we used a motor-generator set whose efficiency is less than the transformer.
• we do not regulate the voltage as per our requirements.

AC Transmission System

AC Transmission system is the most used system nowadays due to the ability of long-distance transmission.AC transmission systems are the most commonly used type of power transmission system in the world, and they consist of several key components.

The first component of an AC transmission system is the power plant or generation source, which produces the electric power. The power is then stepped up to a high voltage level using a transformer, which makes it more efficient to transmit over long distances.

Next, the power is transmitted over high-voltage transmission lines, which are typically made of aluminium or copper and supported by tall transmission towers. 

The transmission lines may span hundreds or even thousands of miles, and they are used to transmit the power from the generation source to the distribution network.

Once the power reaches its destination, it is stepped down to a lower voltage level using a transformer and then distributed to homes and businesses using the local distribution network.

Advantages of AC Transmission

• The AC circuit breaker is less expensive compared to the DC circuit breaker.
• The maintenance of the AC substation is easy and stable.
• We step up and step down the voltages as per requirements.
• AC voltage can be efficiently transformed using transformers for long-distance transmission and distribution.
• AC power is easily generated and can be converted between voltage levels with transformers.
• AC transmission lines and equipment are generally more cost-effective to install and maintain.
• AC power systems can be easily synchronized and interconnected, contributing to grid stability.
• AC systems allow for the easier design and operation of switching devices.
• AC systems enable frequency control to match load and generation requirements.
• AC power systems provide a safety advantage due to the zero-crossing point during each cycle.

Disadvantages of AC Transmission

• We need more conductor material in the AC lines as compared to the DC lines.
• The Cost of an AC transmission system is High compared to DC.
• More losses occur in an AC system like skin effect and Corona loss.
• there is more power consumption in the AC System due to charging the Current
• The line losses occur due to the inductance.
• we need more insulators in the AC system.
• AC transmission system interferes with the telecommunication lines.
• In AC transmission, there are stability and synchronism issues occur.
• The efficiency of the AC system is less than the DC system
• We face a problem controlling the reactive power.

Conclusions

According to our analysis, we see that the efficiency of the DC system is more than ac system. Some Countries still use a DC system at a voltage level of 100 kV to 800kv, for example, Australia and Oceania but most countries are shifted to the AC transmission system due to easily transmitting at long distances.

Frequently Asked Questions – FAQs

What is the difference between an AC Transmission System and a DC Transmission System?

AC Transmission System uses alternating current for transmitting electricity, while DC Transmission System uses direct current.

What are the advantages of an AC Transmission System?

AC Transmission System offers easy voltage transformation, lower transmission losses over long distances, and compatibility with AC generators and loads.

What are the advantages of a DC Transmission System?

DC Transmission System offers lower line losses, higher efficiency for long-distance transmission, and easier integration with renewable energy sources like solar and wind farms.

Which system is more suitable for high-voltage transmission?

AC Transmission System is generally more suitable for high-voltage transmission due to its ease of voltage transformation.

What are the main components of an AC Transmission System?

The main components of an AC Transmission System include generators, transformers, transmission lines, substations, and loads.

What are the main components of a DC Transmission System?

The main components of a DC Transmission System include rectifiers, inverters, transmission lines (often using HVDC cables), converter stations, and loads.

How does the AC Transmission System handle reactive power?

AC Transmission System requires reactive power compensation devices like capacitors and reactors to manage reactive power flow.

How does the DC Transmission System handle reactive power?

DC Transmission System does not require reactive power compensation.

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