IEEE Power & Energy Magazine - November/December 2020 - 58

SVC
1,990 kW G

G 1,990 kW

Off→On

G 1,260 kW

D Feeder

Substation

G
297 kw

G
1,500 kW
Exis. SVC

C Feeder

Substation

A Feeder

figure 17. Example countermeasures for voltage management in a distribution system.
Red and green letters show new implementations and network connection changes,
respectively. Exis.: existing. (Source: Kyushu EPCO; used with permission.)

Utility-Scale PVs

Substation
Telecommunication
Link

Small-Scale PVs
Commercial
Demand

Industrial
Demand

Residential
Demand

figure 18. Enhancing the system monitoring by using sensor-latching pole gas
switches. The symbol represents a distribution switch with sensors, while shows
a pole transformer. (Source: Kyushu EPCO; used with permission.)

Higher Costs

Grid Constraints

More Flexibility Needs

* Expand Auction
Scheme for Solar PVs,
Wind, and Bioenergy

* Reinforce Grid
Based on
Cost-Benefit
Considerations

* Enhance Conventional
Flexibility Sources
(Thermal Power, Pumped
Storage, Interconnection,
and So Forth)

* Construct Better
Business Environment
for Offshore Wind
* Reform FIT Scheme
to Be Suitable for the
Characteristics of Each
Power Source
(a)

* Maximize Use
of Existing Grid
("Connect and
Manage")

(b)

* Explore New Flexibility
Sources
(Renewable Generation,
Virtual Power Plants,
Demand Response,
and So Forth)
(c)

figure 19. Future strategic directions toward renewable energy as a major power
source. Actions related to (a) expenses, (b) constraints, and (c) flexibility.
58

ieee power & energy magazine

6.6 kV. On a fine day, the voltages
at nodes 30 and 51 between the
substation and the PV connecting points are reduced to below
the operational range, whereas the
voltage at the PV site is managed
within the range.
Figure 17 depicts two measures
that are taken to manage the voltage profile in the 6.6-kV feeder to
accommodate new PV generation
of 1,900 kW and 297 kW, shown in
red: 1) an SVC is deployed near
the 1,990 kW of PV power at the
end of feeder A, and 2) the connection point of the existing 1,260 kW
of PV energy is moved from feeder
A to feeder C via the connection
shown in green.
The voltage management and
control in a distribution system are
supported by a new voltage-monitoring system that uses sensorlatching pole gas switches (Figure 18), which were additionally
deployed under the penetration of
PV energy in distribution systems.
The enhanced voltage monitoring,
which examines synchronized
voltages at different points, not
only provides voltages but also
estimates of PV unit generation
and loads at distribution points.

National Strategy and
Further Challenges
The rapid and mass penetration
of renewable generation, in conjunction with other technical and
institutional changes in the energy
industry, have posed issues of
affordability and supply security.
Japan's national energy strategy
and policies are being adjusted to
address these issues. The guidelines
address three strategic matters:
higher costs, transmission/distribution system congestion (grid constraints), and the need for increased
operational flexibility in power system operation (Figure 19).

Higher Costs
Higher costs are caused by various factors. One reason for higher
november/december 2020

IEEE Power & Energy Magazine - November/December 2020

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