76

Project Subjects

Next Generation Electric Power Equipment forDistribution and Transmission Systems

Background and Objective

Next-generation electric power distribution and transmission systems must be flexible enough to deal with changes such as connection of large amount of photovoltaic power generation to build a low carbon emis-sion society. Moreover, in the near future, replacement of electric power equipment will be a significant problem. Therefore, technology menu for replacement should be prepared.

In this project, super conductive fault current limiters and equipment for transformer substrate are devel-oped to add to a list of technology menu for replacement.

Main results

1. Development of superconducting fault current limiter (SFCL) Fault current limiters (FCLs) can reduce the limitation on the system configuration caused by a short

circuit current. Especially, magnetic shielding type SFCLs are suitable for relatively high voltage system. By opti-mizing preparation conditions for superconducting thick films, the critical current density (JC) of a small sample has achieved up to 5,400 A/cm2 required for practical SFCLs (Fig. 1). Furthermore, large-scaled superconducting thick film cylinders with 450 mm in diameter used for practical SCFLs were produced on the base of technology established in CRIEPI. Moreover, examination was conducted on the introduction of SN transition type SFCLs with an excellent compact size into a looped distribution system by computer simulation. As a result，the opti-mum setting location of these SFCLs for the limitation of a blackout area is shown in (Fig. 2) [R10008].

2. Development of elemental technology for an all solid insulated transformerThe all-solid-insulated transformer is very attractive because of its high safety, compactness and low

environmental loading owing to its oil-free insulation. Based on the technique accumulated in this project for the insulation and thermal design of the all-solid-insulated transformer, 60kV-class outer-layer grounded all-solid-insulated transformer model was designed and fabricated (Fig. 3). In this model transformer, all solid compact connector “hyper-connector” being developed in CRIEPI was also adopted. Fundamental data for the design of actual all-solid-insulated transformer for 60kV-class will be obtained using this model.

3. Development of SF6-free gas/solid hybrid insulation systemCRIEPI is developing a new type of electrical insulation method “gas/solid hybrid insulation system”.

High-electric-field part of the hybrid insulation system is insulated using a solid insulator. Therefore, the same degree of compactness as the present apparatus can be achieved without using SF6, which has a high global warm-ing potential. However, there are important issues to be resolved before practical applications, such as methods of jointing and supporting a thickly coated conductor. Therefore, we proposed actual model jointing and supporting a thickly coated conductor based on electric field analysis (Fig. 4). Moreover, the insulation performance of the actual model was evaluated. The obtained results verified that these joint and support models are applicable to the gas/solid hybrid insulation system for 300kV-class.

02-3Environmental_52_79_2010.indd 76 11/10/03 16:08

2

Fig. 3 All-solid-insulated transformer model This model is an outer-layer grounded molded transformer. All-solid compact connector “hyper-connector” is adopted. #: Hyper-connector is a compact connection system

between high-voltage equipments constituting “All-solid Insulated Substation”, and is featured by a bendable bus and compact connectors united with sensors.

Fig. 4 Basic structure of gas/solid hybrid insulation system (upper), coated conductor joint and support model (middle), and result of electric field analysis (lower) A long shield electrode in the insulating spacer was installed at the joint part. Therefore, the electric field of the joint part was widely shielded. The maximum electric field strength on the gas side of this model appeared at the surface of the dielectric coating.

6000

5500

5000

4500

4000

3500

3000

Crit

ical

Cur

rent

Den

sity

(A/c

m2 )

Sele

ct io

n of

si

nter

ing t

emp.

an

d tim

es

Opt

imiz

atio

n of

sint

erin

g hou

rs

Add

ition

of

anne

alin

gO

ptim

izat

ion o

f si

nter

ing t

emp.

Critical current density :JC ~5,400A/cm2

Fig. 1 Improvement on critical current density (JC) of superconducting thick films

As a result of optimization of preparation conditions, JC of 5,400 A/cm2 was achieved.

Fig. 2 Optimum setting location of SN type SFCL in a looped distribution system

In case of a looped distribution system, the breakout area can be limited by the setting of SFCL near the loop switches (FCL4~6)

Terminal of hyper-connector

Molded winding

Iron core

Cooling fan

FCL1

～

6.6kV

FCL2

L1,L2,L3:ループ用開閉器

分散形電源

フィーダ1

フィーダ3

フィーダ4

FCLb

FCLa

上位系統

上位系統or分散形電源

Ry1

Ry2

L1

Ry3

FCL3FCLｃ

フィーダ2

L2

FCL4

FCL5

FCL6

L3

6.6kV

6.6kV

Distributed power generation

Feeder 1

Feeder 2

Feeder 3

Feeder 4

L1, L2 and L3: Loop switches

High voltage transmission line

L1

L2

L3

6.6kV

6.6kV

6.6kV

High voltagetransmission line or Distributed power generation

2

Fig. 3 All-solid-insulated transformer model This model is an outer-layer grounded molded transformer. All-solid compact connector “hyper-connector” is adopted. #: Hyper-connector is a compact connection system

between high-voltage equipments constituting “All-solid Insulated Substation”, and is featured by a bendable bus and compact connectors united with sensors.

Fig. 4 Basic structure of gas/solid hybrid insulation system (upper), coated conductor joint and support model (middle), and result of electric field analysis (lower) A long shield electrode in the insulating spacer was installed at the joint part. Therefore, the electric field of the joint part was widely shielded. The maximum electric field strength on the gas side of this model appeared at the surface of the dielectric coating.

6000

5500

5000

4500

4000

3500

3000

Crit

ical

Cur

rent

Den

sity

(A/c

m2 )

Sele

ct io

n of

si

nter

ing t

emp.

an

d tim

es

Opt

imiz

atio

n of

sint

erin

g hou

rs

Add

ition

of

anne

alin

gO

ptim

izat

ion o

f si

nter

ing t

emp.

Critical current density :JC ~5,400A/cm2

Fig. 1 Improvement on critical current density (JC) of superconducting thick films

As a result of optimization of preparation conditions, JC of 5,400 A/cm2 was achieved.

Fig. 2 Optimum setting location of SN type SFCL in a looped distribution system

In case of a looped distribution system, the breakout area can be limited by the setting of SFCL near the loop switches (FCL4~6)

Terminal of hyper-connector

Molded winding

Iron core

Cooling fan

FCL1

～

6.6kV

FCL2

L1,L2,L3:ループ用開閉器

分散形電源

フィーダ1

フィーダ3

フィーダ4

FCLb

FCLa

上位系統

上位系統or分散形電源

Ry1

Ry2

L1

Ry3

FCL3FCLｃ

フィーダ2

L2

FCL4

FCL5

FCL6

L3

6.6kV

6.6kV

Distributed power generation

Feeder 1

Feeder 2

Feeder 3

Feeder 4

L1, L2 and L3: Loop switches

High voltage transmission line

L1

L2

L3

6.6kV

6.6kV

6.6kV

High voltagetransmission line or Distributed power generation

2

Fig. 3 All-solid-insulated transformer model This model is an outer-layer grounded molded transformer. All-solid compact connector “hyper-connector” is adopted. #: Hyper-connector is a compact connection system

between high-voltage equipments constituting “All-solid Insulated Substation”, and is featured by a bendable bus and compact connectors united with sensors.

Fig. 4 Basic structure of gas/solid hybrid insulation system (upper), coated conductor joint and support model (middle), and result of electric field analysis (lower) A long shield electrode in the insulating spacer was installed at the joint part. Therefore, the electric field of the joint part was widely shielded. The maximum electric field strength on the gas side of this model appeared at the surface of the dielectric coating.

6000

5500

5000

4500

4000

3500

3000

Crit

ical

Cur

rent

Den

sity

(A/c

m2 )

Sele

ct io

n of

si

nter

ing t

emp.

an

d tim

es

Opt

imiz

atio

n of

sint

erin

g hou

rs

Add

ition

of

anne

alin

gO

ptim

izat

ion o

f si

nter

ing t

emp.

Critical current density :JC ~5,400A/cm2

Fig. 1 Improvement on critical current density (JC) of superconducting thick films

As a result of optimization of preparation conditions, JC of 5,400 A/cm2 was achieved.

Fig. 2 Optimum setting location of SN type SFCL in a looped distribution system

In case of a looped distribution system, the breakout area can be limited by the setting of SFCL near the loop switches (FCL4~6)

Terminal of hyper-connector

Molded winding

Iron core

Cooling fan

FCL1

～

6.6kV

FCL2

L1,L2,L3:ループ用開閉器

分散形電源

フィーダ1

フィーダ3

フィーダ4

FCLb

FCLa

上位系統

上位系統or分散形電源

Ry1

Ry2

L1

Ry3

FCL3FCLｃ

フィーダ2

L2

FCL4

FCL5

FCL6

L3

6.6kV

6.6kV

Distributed power generation

Feeder 1

Feeder 2

Feeder 3

Feeder 4

L1, L2 and L3: Loop switches

High voltage transmission line

L1

L2

L3

6.6kV

6.6kV

6.6kV

High voltagetransmission line or Distributed power generation

Sheath (Tank)

77

Environment and Energy Utilization Technology

Fig. 4　Basic structure of gas/solid hybrid insu-lation system (upper), coated conductor joint and support model (middle), and result of electric field analysis (lower)

A long shield electrode in the insulating spacer was installed at the joint part. Therefore, the electric field of the joint part was widely shielded. The maximum electric field strength on the gas side of this model appeared at the surface of the dielectric coating.

Fig. 3　All-solid-insulated transformer modelThis model is an outer-layer grounded molded trans-former. All-solid compact connector “hyper-connector” is adopted.※） Hyper-connector is a compact connection system

between high-voltage equipments constituting “All-solid Insulated Substation”, and is featured by a bendable bus and compact connectors united with sensors.

Fig. 2 Optimum setting location of SN type SFCL in a looped distribution system

In case of a looped distribution system, the breakout area can be limited by the setting of SFCL near the loop switches (FCL4~6)

Fig. 1 Improvement on critical current density (Jc ) of superconducting thick films

As a result of optimization of preparation conditions, Jc of 5,400 A/cm2 was achieved.