Emerging Technologies in field of EE

2. ■
Advantages
• Highly robust / Reliable
• Highly efficient (98.5% - 99.5%)
• Relatively inexpensive
■
Weaknesses
• No capability of voltage/ frequency regulation
• Coupled harmonics and other disturbances
• Difficult to control power flow
• No DC port
• Not friendly for integration of renewable, EV and energy
storage.
• Large Weight / Volume

3. Solid state transformer(SST) is an
element/component consisted of multi
stage power electronics converters isolated
with high frequency transformer, proposed
in national science foundation (NSF)
generation- III engineering research centre
(ERC) “future electric energy delivery &
management (FREEDM) systems” which
was established in 2008 and the proposal of
SST was regarded as one of the 10 most
emerging technologies by Massachusetts
institute of technology (MIT)technology
review in 2010
SST is an emerging technology that has the
advantages of low volume, low weight,
fault isolation, and other management
features.

4. Voltage sag compensation
Outage compensation.
Instantaneous voltage regulation.
Fault isolation.
Power factor correction.
Harmonic isolation.
DC output.
Metering or advanced distribution
automation.
Environmental benefit.

5. The basic operation of the SST is firstly to change the 50/60 Hz AC
voltage to a high frequency one (normally in the range of several to tens
of kilohertz), then this high frequency voltage is stepped up/down by a
high frequency transformer with significantly decreased volume and
weight, and finally shaped back into the desired 50/60 Hz voltage to feed
the load.

7.  Stage one
In this stage is a three-phase ac/DC rectifier that regulates a high-
voltage DC bus (and ac voltage when for reactive power compensation)
is used. It produces low distortion grid current, DC voltage regulation.
 Stage two
It consists of a Dual active bridge (DAB), a high frequency transformer.
 DAB converter gives:
•Electrical isolation.
•High reliability.
•Ease of realizing soft-switching control.
 Stage three
DC-AC converter is used to convert the DC voltage in desirable voltage.

8. SST-based system configuration proposed and
implemented in Future Renewable Electrical Energy
Delivery and Management (FREEDM) Systems Center at
North Carolina State University.

9. Parameter Value
Capacity: Total SST VA Rating: 10 kVA
Port Specification:
High V AC port: 3.6 kV, -2.78 A ~ 2.78 A
Low V AC port: 120 V, -83.3 A ~ 83.3 A
Low V DC port: 200 V, -50 A ~ 50 A
Temperature
Range:
Operating temperature: -10 to 50oC
Storage temperature: -20 to 70oC
Self-Discharge
Rate:
N/A
Minimum System
Level Round Trip
Efficiency:
95%

10. In the case of an SST-control center
communication network, it is also
possible to incorporate different
intelligent electronic devices
(IEDs), remote terminal units
(RTU), substation automation
solutions(SAS), universal
gateways, smart meters, etc.
There will be an increased
complexity in the network
operation due to the large
amounts of data. Hence, these
types of applications will require
higher reliabilities and lower
latencies. For such complex
networks , a geographical
dependent structure is required.

11. Future power systems, the usage of renewable generation is
expected to increase, and will require an energy management
scheme that is fundamentally different from the classic methods.
For fast and efficient management of the changes in different loads
and sources, the SST can be used to dynamically adjust the energy
distribution in the grid.
The function of the SST as described in this scenario is
similar to that of a router, but instead of managing data, the
SST will manage the flow of energy.

16. The presence of SST in a power system can improve the power
quality of the grid. The SST allows to uncouple the side of the
network from the side of the load; then if a disturbance occurs from
one side, it does not affect the components connected in the other
side of the SST. In addition, the SST allows to enhance the power
factor, support overloads, and keep nominal voltage on the load
side, even though the input voltage is affected by either a sag or a
swell. Another advantage of the SST is their DC link, which allows
the integration of distributed generation and energy storage. The
power coming from the DC link can deliver power to the network,
if required.