electrical systems in metro system and engineering

this is notes of metro system and engineering as per PTU

1. Metro system and engineeri ng Electrical systems SHUBHAM SHARMA Department of civil engineering BGIET, SANGRUR

2. OHE system OHE, or Overhead Electrification, is commonly used as the electrical system in metro systems. It consists of a network of overhead wires that supply power to the trains. The wires, known as catenary wires, are suspended above the tracks and carry the electrical current needed to power the trains. The OHE system typically uses a pantograph, which is a device mounted on top of the train, to make contact with the catenary wires and draw power. The pantograph collects the electricity from the wires and transfers it to the train's electrical systems, which power the traction motors that propel the train. OHE systems are preferred in metro systems because they provide a reliable and efficient method of supplying power to the trains. They eliminate the need for on-board energy storage and allow for continuous operation of the trains without the need for frequent recharging or refuelling.

3. How the pantograph works The pantograph is a device mounted on the roof of a train that allows it to collect power from the overhead wires in the OHE system. It's like a fancy arm that reaches up and connects with the catenary wires. The pantograph has a set of carbon or metal strips called collectors that make contact with the catenary wires. When the train moves, the collectors slide along the wires, creating a connection that allows electricity to flow from the wires to the train. The electricity collected by the pantograph is then transferred to the train's electrical systems, which power the traction motors that move the train. It's like the pantograph acts as a bridge between the overhead wires and the train, allowing the power to flow smoothly. The pantograph is designed to maintain a good contact with the catenary wires, even when the train is moving at high speeds or going through curves in the tracks. It's an important part of the OHE system that ensures the train receives a steady supply of power.

4. Types of OHE In metro systems, there are primarily two types of OHE (Overhead Electrification) systems commonly used: 1. Single Wire with Return Current (SWRC): This type of OHE system uses a single catenary wire to supply power to the trains, while the return current flows through the running rails. The catenary wire carries the positive current, while the negative or return current is conducted through the tracks. SWRC systems are simpler in design and installation but may have limitations in terms of power capacity. Two Wire with Insulated Return (TWIR): In TWIR systems, two catenary wires are used to supply power to the trains. One wire carries the positive current, while the other wire carries the negative or return current. The return current is insulated from the running rails, reducing the risk of electrical interference with other systems. TWIR systems offer higher power capacity and better electrical performance but are more complex to install and maintain.

5. OHE, or Overhead Electrification, offers several advantages over other electrical systems in metro systems: Cost-effective: OHE systems are generally more cost-effective to install and maintain compared to other electrical systems. The overhead wires are relatively simple to install, and the infrastructure required is less complex than other alternatives. Flexibility: OHE systems can accommodate a wide range of train types and sizes, making them flexible for different metro system requirements. They can easily adapt to changes in train technology and can be expanded or modified as needed. Energy Efficiency: OHE systems are known for their energy efficiency. The power is supplied directly to the trains from the overhead wires, reducing energy losses during transmission. This results in more efficient energy usage and lower operational costs. Reliability: OHE systems have a proven track record of reliability. The overhead wires are less prone to disruptions caused by weather conditions, such as heavy rain or snow, compared to other systems that may have underground components. Safety: OHE systems are designed with safety in mind. The overhead wires are placed out of reach of pedestrians and vehicles, reducing the risk of accidents or unauthorized access to the electrical infrastructure.

6. Traction power in metro Traction power is essential aspect of metro systems. Traction power refers to the electrical energy that is supplied to the trains to power their motors and enable them to move. In metro systems, the traction power is typically provided through the overhead electrification (OHE) system we talked about earlier. The catenary wires carry the electrical current, and the pantograph on top of the train collects this power from the wires. The collected power is then transferred to the train's electrical systems, which include the traction motors. These motors convert the electrical energy into mechanical energy, propelling the train forward. The amount of traction power required depends on various factors, such as the weight and speed of the train, the grade of the track, and the number of passengers on board. Metro systems are designed to ensure that there is enough traction power available to meet the demands of the trains and maintain smooth and reliable operations. Traction power is a crucial component in keeping the trains running efficiently and providing reliable transportation in metro systems.

7. TSS AND ASS In metro systems, TSS and ASS refer to important components known as traction substations and auxiliary substations, respectively. Traction substations (TSS) are responsible for converting the incoming high voltage electrical power from the power stations to the appropriate voltage and current required for the operation of the trains. These substations step down the voltage and distribute the power to the catenary system, which supplies the trains with traction power. On the other hand, auxiliary substations (ASS) provide power for various auxiliary systems and equipment within the metro network. These systems include lighting, ventilation, escalators, elevators, signalling systems, and other electrical components necessary for the smooth functioning of the metro system. Both TSS and ASS play crucial roles in ensuring the efficient and reliable operation of metro systems by providing the necessary power for train propulsion and auxiliary systems.

8. traction substations auxiliary substations

9. Traction substations Traction substations are essential components in metro systems. They play a crucial role in supplying the required electrical power to the trains for their propulsion. Traction substations receive high voltage electricity from the power grid and then convert it to the appropriate voltage and current levels needed by the trains. These substations distribute the power through the overhead catenary system, which allows the trains to collect the power through their pantographs. This power is then used to drive the traction motors, enabling the trains to move along the tracks. Traction substations are strategically located along the metro network to ensure a reliable and efficient power supply to the trains.

10. Auxiliary substations Auxiliary substations, also known as ASS, are an important part of metro systems. These substations provide power for various auxiliary systems and equipment within the metro network. They supply electricity to systems such as lighting, ventilation, escalators, elevators, signalling systems, and other electrical components necessary for the smooth operation of the metro system. Auxiliary substations ensure that all the essential functions and services in the metro, apart from the train propulsion, are powered effectively. They play a vital role in maintaining the comfort, safety, and functionality of the metro system.

11. SCADA for power supply system The SCADA (Supervisory Control and Data Acquisition) system is an important component of the power supply infrastructure in metro systems. It is used to monitor and control the electrical distribution and power management within the metro network. The SCADA system collects real-time data from various substations, including traction and auxiliary substations, to provide operators with a comprehensive view of the power supply status. It allows operators to remotely monitor and control the power distribution, detect faults, and take necessary actions to ensure uninterrupted power supply to the trains and other auxiliary systems. The SCADA system plays a crucial role in maintaining the reliability and efficiency of the power supply in metro systems

12. Working of SCADA The SCADA system works by collecting data from various sensors and devices in the power supply system of a metro. This data includes information on voltage levels, current flow, temperature, and other relevant parameters. The SCADA system then processes and analyses this data, providing real-time monitoring and control capabilities to operators. Operators can use the SCADA system to remotely monitor the status of substations, transformers, circuit breakers, and other components of the power supply system. They can also control the operation of these devices, such as switching on or off certain circuits or adjusting voltage levels. The SCADA system uses a network of communication channels to transmit data between the central control station and the remote devices. This enables operators to have a comprehensive view of the power supply system and make informed decisions to ensure its efficient and reliable operation.

13. SCADA system

14. Standby and backup system In metro systems, standby and backup systems are critical for ensuring the continuous operation of essential services. A standby system is an essential component that provides backup power in case of a primary power failure. It ensures the continuous operation of critical systems, such as train propulsion, signalling, ventilation, and lighting, during power outages or emergencies. The standby system typically consists of backup generators or batteries that can supply power to the necessary systems when the primary power source is unavailable. These backup systems are designed to automatically activate in the event of a power failure, ensuring minimal disruption to metro operations. The backup system , on the other hand, encompasses a broader range of components and measures to ensure system resilience. It includes redundant equipment, duplicate control systems, and backup communication networks. These redundancies help mitigate the impact of failures or emergencies, ensuring the safety and reliability of the metro system. Both the standby and backup systems work together to provide uninterrupted power supply and maintain critical operations during power outages or other unforeseen events. They play a vital role in keeping the metro system running smoothly and ensuring passenger safety.

15. Green buildings in metro systems Green buildings in metro systems are an exciting aspect of sustainable urban design. They focus on incorporating environmentally friendly features and practices to reduce energy consumption, minimize waste, and promote a healthier indoor environment. These green buildings in metro systems often integrate energy-efficient systems, such as solar panels for renewable energy generation, efficient lighting and HVAC systems, and water-saving fixtures. They may also use sustainable construction materials, implement proper waste management strategies, and prioritize green spaces and landscaping. By incorporating green buildings within metro systems, cities can reduce their environmental impact, improve energy efficiency, and create healthier and more sustainable spaces for commuters and surrounding communities. There are several countries who focus on green buildings in metro systems. One notable example is the Taipei Metro in Taiwan. They have implemented green building practices in their stations, including energy-efficient lighting, rainwater harvesting systems, and green roofs. These features help reduce energy consumption and promote sustainability.

16. Green buildings in metro systems contribute to sustainability in several ways. First, they promote energy efficiency by incorporating features like solar panels, efficient lighting, and HVAC systems. This reduces the overall energy consumption and carbon footprint of the metro system. Second, green buildings prioritize water conservation through the use of water-saving fixtures and systems. This helps reduce water consumption and promotes responsible water management. Third, sustainable construction materials are used in green buildings, which are environmentally friendly and have a lower impact on natural resources. This reduces the depletion of resources and minimizes waste generation. Moreover, green buildings in metro systems often prioritize indoor air quality and occupant comfort. They utilize proper ventilation systems, non-toxic materials, and natural lighting, creating healthier and more pleasant spaces for commuters and employees.

17. Carbon credits Carbon credits can play a significant role in reducing the carbon footprint of metro systems. Metro systems generate greenhouse gas emissions through their operations, such as energy consumption and train operations. To offset these emissions, metro systems can participate in carbon credit programs. Carbon credits are a market-based mechanism that allows organizations to invest in projects that reduce or remove greenhouse gas emissions. By purchasing carbon credits, metro systems can support projects that promote renewable energy, energy efficiency, or carbon sequestration. These projects help to offset the emissions produced by the metro system, effectively neutralizing their carbon footprint. Implementing carbon credits in metro systems can have multiple benefits. It not only helps to reduce greenhouse gas emissions but also contributes to sustainable development and supports the growth of renewable energy projects. Additionally, participating in carbon credit programs can enhance the environmental reputation of the metro system and demonstrate a commitment to sustainability. Overall, carbon credits provide a valuable tool for metro systems to mitigate their environmental impact and contribute to global efforts in combating climate change.

18. For example, the Delhi Metro in India has been involved in carbon credit projects since 2008. They have implemented various initiatives such as regenerative braking systems, solar power generation, and energy-efficient operations, which have helped them earn carbon credits. Another example is the São Paulo Metro in Brazil, which has implemented projects focused on energy efficiency, waste management, and renewable energy generation, earning them carbon credits as well. These are just a few examples, and many other metro systems around the world are actively working on reducing their carbon footprint through carbon credit projects.

19. Clear air mechanics Clear air mechanics in the context of the metro refers to the systems and measures put in place to ensure good air quality within the metro system. Metro systems often face the challenge of maintaining clean and breathable air for passengers and staff. To address this, several mechanisms are implemented. One important aspect is proper ventilation and air circulation within the metro tunnels and stations. This involves the use of ventilation systems that supply fresh air and remove pollutants or stale air. Additionally, metro systems may employ air filtration systems to remove particulate matter and improve air quality. These filters help capture dust, allergens, and other pollutants, providing a cleaner environment for passengers. Furthermore, some metro systems have implemented measures to reduce emissions from trains. This includes using electric or hybrid trains, which produce fewer pollutants compared to traditional diesel-powered trains. By reducing emissions, metro systems can contribute to better air quality both inside the tunnels and in the surrounding areas. So, "clear air mechanics" in the metro encompass ventilation systems, air filtration, and emission reduction measures, all aimed at ensuring a healthier and more comfortable environment for everyone using the metro

20. Thankyou