Automation is the use of various control systems for operating equipment such as machinery, processes in factories, heat treating ovens, aircrafts and other applications that reduce human intervention.
Power system automation controls the power plant operations through optimization against the variation of parameters to provide high efficiency and reliability depending upon the demand of operation. The power system automation has become increasingly sophisticated on the back of major advancement in computer hardware and software. However, the advancement in sensors, amplifiers, recorders, control elements, valves and measurement technologies has enabled many power operating parameters to be measured and monitored that provides a detailed picture of the state of a plant in real time.
Large power plants are typically supervised and controlled by production and maintenance staff – that uses the process control system as a tool to automate process functions and gather & present information to be used by short and long term staff decision-maker. It is preferable that an organization behaving as a community be engaged to solve short-term problems and to develop evolving procedures for optimizing performance. Thus, the role of the control system is to automate, inform, network and store data.
Advancements in power system automation are available for all types of power plants. For renewable sources, such as wind and solar, optimization strategies are being developed although the potential of renewables sources are very limited. In case of steam tubine-based combustion plant, automation provides a great advantage. A good automation system will allow control of the combustion process in boiler by controlling the combustion process, which is important for plant emission performance as well as efficiency. It will control the temperature of steam and pressure – and allow the best efficiency to be achieved.
It can also be used to control the process of gas-turbine. However, the modern gas-turbines often operate at the limits of their materials’ capabilities – and already closely controlled to ensure that they do not exceed their limits. Thus, there is often less scope. Within the realm of the nuclear power plant, automation helps in easing some of the burdens on the operator during normal operations and it also assists in the event of
an emergency.
Power system automation is the act of automatically controlling the power system via Instrumentation and Controlling (I&C) devices. Substation automation refers to use of IED data, control and automation capabilities with the substation, and control commands from remote users to control power system devices. PSA also includes processes associated with generation and distribution levels, which is power delivery automation. Together monitoring and controlling of power delivery reduces the occurrence of outages. The IEDs, communication protocols and communication methods work together as a system to perform power system automation.
Data Acquisition:- Data acquisition refers to acquiring data. This data is in the form of measured analog voltage or current. This acquisition can be used locally or sent to another device in a substation or from the substation to other several databases for use by operators and administrators.
Power system supervision:- Operators monitor the information remotely on computer displays and graphical wall displays.
Power system control:- Control refers to send command messages to a device to operator the I&Cs and power system devices. Field personnel can also control devices using front- panel push buttons or a laptop computer.
Power system automation:- System automation is the act of automatically controlling the power system via automated processes within computers and I&C devices. The processes rely on data acquisition, power system supervision and power system control – all work together. The commands are generated and then transmitted in the same way as operator initiated commands.
I&C system:- I&C devices are built using microprocessors as microprocessors are single chip computers that allow the devices to process data, accept commands and communicate information.
Instrument transformer:- They are used to sense power system current and voltage values. They are connected to power system apparatus and convert the actual power signals.
Transducer:- transducer converts the analog output of an instrumental transformer from one magnitude to another.
Remote Terminal Unit (RTU):- Remote terminal unit is and IED that can be installed in the remote location and acts as a termination point for field contacts. A pair of copper conductors are used to sense every contact and transducer values. These terminals originated at the power system device and then terminated on panel within the RTU. The RTU can transfer collected data to other devices and control commands from other devices through a serial port.
Communication port switch:- A communication switch, switches between several serial ports. The remote user can communicate with a port switch via a connection to the substation. Once the user connects, that can route their communication through the port switch to one of the connected substation IEDs.
Meter:- A meter is an IED that is used to create accurate measurements of power system current, voltage and power values. Metering values such as demand and peak are saved within the meter to create information about the activity of the power system.
Digital Fault Recorder:- DFR is an IED that records information about power system disturbances. Harmonics, frequency and voltage are examples of data captured by DFRs.
Time Synchronization Source:- A time synchronization source is an IED that creates a time-of-day value, which is then broadcast to the IEDs in order to set all their clock to the same time.
Human Machine Interface (HMI):- The front panel display or a personal computer act as an interface to system data and controls for personnel in the substation.
Future Scope:- In future the control system will supervise the systems, rather to control it. The system will incorporate the latest technologies and use multiple communication channels. The operator interface will become the human computer interface – allowing collaboration between interested parties enabling them to participate in optimization and operation of plant. In the future, computers will be at the power plant – but the operator will be somewhere else. Data will be available through portals to the outside world with the aim to optimize the process, and operation costs will be reduced.
Munazama Ali
The author is an M.Tech and working as an Assistant Professor in the Department of Electrical Engineering in the Islamic University of Science & Technology, Kashmir. She is interested in Power System, Control System, Drives and Power Electronics.
