1. The Role of Smart Transformers within Microgrids
February 2016

2. Key Questions What are Smart Transformers?
How do Smart Transformers fit into the Smart Grid?
What are the potential benefits of having Smart Transformers?
What are foreseen challenges?

3. Microgrids Generation, storage and loads that form an entity
The building blocks of the Smart Grid
Single, controllable entities
Single point of connection with the larger grid
Components within the microgrid (generators, loads and storage) posses “microgrid agents” that provide them with monitoring and communication capabilities.
Stability within a microgrid can be maintained by ensuring the microgrid voltage remains stable

4. Smart Transformers
There are 40 times more transformers than generators on the grid
How are we utilizing them?
Definition not “set in stone”
Transformers with intelligence and remote control capabilities
Intelligence consists of monitoring and communication capabilities
In the research, it is suggested that the smart transformer be placed at the point of connection between a microgrid and the larger grid.

5. Smart Transformers in Microgrids
Smart transformers act as microgrid and market managers
They are in constant communication with other microgrid agents, and are capable of gathering data from, and issuing instructions to other microgrid agents
Smart Transformers:
Monitor the operations of microgrid agents
Issue generation set-points to generators to maintain voltage stability
Monitor and orchestrate interaction between various microgrid agents
Monitor and control interaction between the microgrid and the larger power grid.

6. SRAPET Transformer Developed in 2006
Has a OLTC for voltage regulation on the LV side
For application in deep-rural areas, where LV feeder can be extended by LV voltage regulation
Possesses data monitoring capabilities

7. Eskom Remote Data Retrieval
Released in 2013, applicable on all remote data-retrieval devices
Required DNP3 for data retrieval of non-substation based devices
Required various other protocols to achieve uniformity in functionality (SNMP, FTP, HTTP-based web interface, NTP, SSH etc.)
A device (the STCD) was created to interface with the SRAPET transformer and allow it to meet this specification
This equips the SRAPET with “Smart Grid” technologies, thus, moving towards a Smart Transformer

8. The STCD
An open-source solution built on the hardware foundation of the Beaglebone black
Interfaces with the SRAPET controller board to gather monitoring data and issue commands
Interfaces with a modem (GRPS / 3G) to communicate with central data servers
Allows for the remote monitoring and control of transformers

9. The STCD Measurements include:
Voltages, currents, temperatures, tap position of OLTC etc.
Employs a monitoring strategy based on both periodic, and event- based monitoring
Periodic readings are taken every 5 minutes (or user-defined time)
Event readings are triggered when user-defined events occur

10. The STCD
Graphs showing monitoring

11. Smart Transformers as Market Manager
Smart Transformers communicate with generators, loads and storage within the microgrid
It monitors the measurements taken at these key points and can control them in various ways
Generators: Gives generation set points that limit the possible generation
Storage: Controls the charging and decharging of storage via a Battery Management System (BMS)
Loads: Controllable loads can be offset in their electricity usage

12. Microgrid Simulation
A simulation was conducted to investigate the management of interactions between microgrid agents by the Smart Transformer
A generation and load agent was simulated using raspberry PI development boards. These boards were connected in a network, and web services were used as a common language between devices over the network
Electricity bids are manually entered into the load agent over a web interface hosted on it. The bid is communicated to the Smart Transformer, that checks with generators within the microgrid to determine the possibility of meeting the bid
The Smart Transformer decides how the bid should be met (by the utility and local generators), and records the interaction as well as the financial implications thereof. The Smart Transformer keeps track of relevant tariff information to perform such actions.

13. Future Considerations
Utility and DG agreements
Sustainable design
Communication security and reliability
Full benefits of remote monitoring and control
Self-healing grids, demand-response, condition monitoring / predictive maintenance, electric vehicle integration etc.

14. Thank you
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