With the increase in the size and complexity of the grid, substation automation technologies are gaining importance in order to ensure the efficiency, security and reliability of the power system. Substation automation essentially helps in intelligently managing grid operations. It allows the continuous monitoring and control of various substation components from a remote location. It also enables users to lower operational costs by reducing manpower needs at substations.
Moreover, the use of smart devices helps the utility to enhance predictive maintenance and adopt condition-based monitoring of equipment which ensures reduced asset downtime, faster restoration of faults and effective asset management.
Substation automation can be broken down into five components: power system equipment (transformers and circuit breakers, etc.), intelligent electronic device (IED) implementation, IED integration, substation automation applications, and utility enterprise.
Substations are now smarter, with condition monitoring, automation and analysis systems. The condition monitoring of substations is an element important to both asset management and operation support, providing recommendations based on the diagnostics of measured values.
Condition monitoring modules are implemented in such a way that complete asset-related information is available to the operator and the asset manager in a common format. Condition monitoring is indispensable if companies need to optimise the efficiency of their existing power network. Managers and operators need access to reliable condition data to know about the substation components that have to be manufactured, repaired, or replaced. Condition monitoring allows utilities to make well-informed decisions, and thus, to optimally manage substation assets and support the operations.
Equipment condition monitoring
Utilities need to make decisions regarding power network equipment performance, maintenance schedules, and the replacement of existing assets and addition of new ones on a regular basis. This not only has a significant impact on their operational performance, but also affects costs. To facilitate this decision-making process, companies undertake equipment condition monitoring (ECM), which provides valuable data to operators and asset managers on the working condition of select grid components. ECM involves the use of condition-based monitoring systems for substation assets through a combination of IEDs, smart sensors, open protocols and head-end software.
Typically, the monitoring of specific and individual components of substation equipment is undertaken rather than that of the complete substation. It can be done through manual inspections (periodic visual inspections), continuous monitoring with a change-in-status/condition alarm as the only output (low-level alarm), periodic automated monitoring connection of portable analysis instruments (dial-up computer analysis) or continuous online monitoring (full-time measurement of parameters to assess the condition while in service).
This monitoring provides data that is diagnosed through innovative algorithms and knowledge modules, which allows the accurate evaluation of condition information and predictive diagnosis. It can be seamlessly integrated in the existing substation communication and visualisation infrastructure, from simple bay controllers to high-end control centre applications.
In addition, ECM analyses data to identify potential equipment failures and therefore, undertake maintenance planning for a large population of similar equipment. ECM can help determine the anticipated remaining life of the equipment by employing residual life assessment techniques.
ECM solutions can be customised as per the individual requirements of the substation to monitor all relevant components of the electricity supply network, from transformers and switchgear to overhead lines and cables.
As a result of reduced outages, reliability improves as reflected by the lower system average interruption duration index. Similarly, ECM helps bring down operations and maintenance costs via condition-based maintenance wherein an asset is serviced only when needed. It helps in extending the asset’s lifespan, thus reducing capital replacement costs. It also helps achieve greater efficiency with reduced manpower levels and higher corporate savings. Improved safety for the workforce and better power quality through ECM ensures employee retention and customer satisfaction.
Besides, ECM ensures proper verification tests by confirming correct installation conditions and adjustments. It automates the collection and preservation of baseline condition data and characteristics. ECM also provides information on the prior condition of the equipment after a failure has occurred and prevents unsafe conditions for workers.
All secondary equipment within a substation is interlinked with communication buses. In conventional substations, communication devices relied on one-way communication. Serial communication buses or proprietary communication interface with associated protocols were used for local human-machine interface, as well as for remote supervisory control and data acquisition communication.
Modern communication systems entail the two-way exchange of substation data within the three levels – station, bay and process. The three levels communicate through a high speed ethernet station bus and a process bus. Most of the substation protection and control functions rely on the performance of the process bus. While at the station level time-based data from multiple bays or substation-level database is analysed and processed, at the bay level, the protection unit and the control unit collect data from bays and perform actions on the primary equipment. At the process level, performance and condition information is read from essential station equipment.
The way forward
A proper understanding of the condition of substation equipment helps prevent failure, maximises future operations, enables appropriate scheduling and determines the extent of inspections and maintenance, provides personnel safety and protects the environment. It is also critical for ensuring that the substation automation equipment is in the best operating condition. Constant tracking and monitoring of various operational parameters of different substation devices improves the availability and reliability of the equipment.
In the near future, ECM can grow multifold to cover a wider range of substation equipment. However, the challenge is to gather the expertise of equipment manufacturers, users, manufacturers of monitoring devices and systems integrators for ensuring the seamless delivery of equipment condition information in an effective, efficient and economical manner. Individual online monitoring efforts need to be integrated with long-term solutions for a modular approach towards the implementation of online condition monitoring.
The standardisation of online condition monitoring systems and protocols is required instead of the current system wherein ECM applications are implemented on an ad hoc or experimental basis. Net, net, ECM is an effective, economical and efficient means of gaining the required understanding of equipment condition through the monitoring and tracking of data regarding equipment failure and taking the necessary preventive actions.