ABSTRACT:
The
concept of ‘Electric Spring (ES)’ has been proposed recently as an effective
means of distributed voltage control. The idea is to regulate the voltage
across the ‘critical loads’ while allowing the ‘non-critical’ impedance-type
loads (e.g. water heaters) to vary their power consumption and thus contribute
to demand-side response. In this paper a comparison is made between distributed
voltage control using ES against the traditional single point control with
STATCOM. For a given range of supply voltage variation, the total reactive
capacity required for each option to produce the desired voltage regulation at
the point of connection is compared. A simple case study with a single ES and
STATCOM is presented first to show that the ES and STATCOM require comparable
reactive power to achieve similar voltage regulation. Comparison between a
STATCOM and ES is further substantiated through similar case studies on the
IEEE 13-bus test feeder system and also on a part of the distribution network
in Sha Lo Wan Bay, Hong Kong. In both cases, it turns out that a group of ESs
achieves better total voltage regulation than STATCOM with less overall
reactive power capacity. Dependence of the ES capability on proportion of
critical and non-critical load is also shown.
KEYWORDS:
1. Demand response
2. Electric
springs
3. STATCOM
4. Voltage
control
5. Voltage
regulation
SOFTWARE: MATLAB/SIMULINK
BLOCK DIAGRAM:
Fig.
1. Electric Spring set-up for Smart loads.
Fig.
2. Simulation set up with an intermittent source and an equivalent power grid.
EXPECTED SIMULATION RESULTS:
Fig. 3. System response following decrease
in reactive power consumption of the intermittent source from 467 to 110 VAr
Fig. 4. System response following
increase in reactive power consumption of the intermittent source from 1100 to
467 VAr.
Fig.
5. System response for different distribution of non-critical and critical
loads (NC:C). Disturbance is increase in reactive power consumption of the
intermittent source from 467 to 1100 VAr.
CONCLUSION:
In
this paper a comparison is made between distributed voltage control using ES
against the traditional single point control with STATCOM. For a given range of
supply voltage variation, the total voltage regulation and the total reactive
capacity required for each option to produce the desired voltage regulation at
the point of connection are compared. A simple case study with a single ES and
STATCOM is presented first to show that the ES and STATCOM require comparable
reactive power to achieve similar voltage regulation. Comparison between a
STATCOM and ES is further substantiated through similar case studies on the
IEEE 13-bus test feeder system and also on a part of the distribution network
in Sha Lo Wan Bay, Hong Kong. In both cases, it turns out that the ESs requires
less overall reactive power capacity than STATCOM and yields better total
voltage regulation. This makes electric springs (ESs) a promising technology
for future smart grids where selective voltage regulation for sensitive loads
would be necessary alongside demand side response.
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C. K. Lee and S. Y. Hui, "Reduction of Energy Storage Requirements in
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