A frequency stability and load flow analysis of
the Japanese system in response to highrenewables penetration levels
Tatsuya Wakeyama
Senior Research fellow, Renewable Energy Institute
Associate Professor, Kyushu University Platform of Inter/Transdisciplinary Energy Research

Methodology

Dispatch modelling

Grid modelling• Database• Projection of generation
capacity• Estimation of RE output• Evaluation of hourly
demand-supply structure• Selecting snapshot
assessed in grid model• Evaluation of stability offrequency• Load flow analysis• Impact evaluation ofhigher VRE penetration

GWScenario development

200150100Geothermal
BiomassWindSolarHydro

Maximum demand

Minimum demand

5002015

2020

2025

2030

Integrated discussion: Issues and countermeasure to expansion of RE capacity

Scenario development
Two scenario in 2030
Government target scenario：long-term energy projection by government ( PV:64GW, Wind:10GW）
Higher renewable energy scenario: based on target by RE industrial association（PV:100GW,Wind36GW）+ zero nuclear

5

Government target

Figure: Energy mix in FY2030 based onlong-term energy projection publishedin 2015

Higher renewable energyFigure：Distribution of PV and Wind capacity

KyushuShikoku

ChugokuKansai

Chubu

Hokuriku

TokyoTohoku

Hokkaido

Kyushu0Shikoku

LNG, 27%

10Chugoku

Nuclear, 22~20%

15KansaiOil, 3%20

Chubu

Biomass, 3.7~4.6%

PV

25

Hokuriku

Geothermal,
1.1~1.0%

Coal, 26%

WIND

30TokyoHydro, 8.8~9.2%

35Tohoku

Wind, 1.7%

Hokkaido

GWPV, 7.0%

Dispatch modelling

Chugoku

8064-2

20-2

15915

Hokuriku

2GWGW

GW

Simulate hourly demand-supply in minimum/maximum demand day in each month in 2030
by using SWITCH model＊
49205915-2

9九州559159Tohoku

10500-5

1a.m. a.m. a.m. p.m. p.m. p.m.

GW

GWa.m. a.m. a.m. p.m. p.m. p.m.
10

4a.m. a.m. a.m. p.m. p.m. p.m.

1

Hokkaido

6-5
15

9

15-10915
102

500-2-5591

59a.m. a.m. a.m. p.m. p.m. p.m.

1

5915

9a.m. a.m. a.m. p.m. p.m. p.m.

Chubu

1510GW

4Kansai

20GWShikoku

6

1

15

9

1

5

9a.m. a.m. a.m. p.m. p.m. p.m.
GWGWa.m. a.m. a.m. p.m. p.m. p.m.

30

520010-51591

59a.m. a.m. a.m. p.m. p.m. p.m.

Tokyo

40

0

1591

5

9a.m. a.m. a.m. p.m. p.m. p.m.

*SWITCH model was distributed capacity expansion model developed by Dr. Fripp Mathiass (Assistant professor @ Hawaii University）
and maintained by Renewable & Appropriate Energy Laboratory of UC Berkeley. Hourly supply-demand of each area are simulated tominimize cost considering interregional electricity trade.

Government target scenario/ hourly demand-supply in representative days
Instantaneous VRE penetration reached up to 42%

GW

200

Figure Hourly demand-supply at maximum/minimum demand day in each month in 2030
（government target scenario）

150
100
50

揚水発電

水力

太陽光

風力※Negative direction indicates hydro pumping

地熱バイオマス

石炭ガス

3月最小

3月最大

2月最小

2月最大

1月最小

1月最大

12月最小

12月最大

11月最小

11月最大

10月最小

10月最大

9月最小

9月最大

8月最小

8月最大

7月最小

7月最大

6月最小

6月最大

5月最小

5月最大

4月最小

※-50

4月最大

0原子力

Higher RE scenario/ hourly demand-supply in representative days

GW

Instantaneous VRE penetration reached up to 72%
200

Figure Hourly demand-supply at maximum/minimum demand day in each month in 2030
（Higher renewable energy scenario）

150
100
50

揚水発電

水力

太陽光

※Negative direction indicates hydro pumping

風力地熱バイオマス

石炭ガス

3月最小

3月最大

2月最小

2月最大

1月最小

1月最大

12月最小

12月最大

11月最小

11月最大

10月最小

10月最大

9月最小

9月最大

8月最小

8月最大

7月最小

7月最大

6月最小

6月最大

5月最小

5月最大

4月最小-50

4月最大

0原子力

Grid model analysis
Evaluation on impact of increasing instantaneous VRE penetration to frequency
stability and load flow
Frequency stability：It is necessary to keep frequency variation caused by an incident on gridwithin tolerable range
Figure: IEEJ power system model（EAST30）

Methodology：• IEEJ power system model (2001）is reconstructed andvalidated on Powerfactroy (DIgSILENT) for this analysis.
• The constraint of frequency stability is set to maintainfrequency nadir within the range of 0.98 p.u. whichequal to the threshold of 58.8Hz for Western grid.

Figure: Example of validation results by PowerfactoryGrid model result ①
Frequency nadir may be increased with increasing instantaneous penetration of VRE. Thosefrequency nadir can be maintained within tolerable range by using FFR service of VRE.
Figure: frequency response after loss of 1 500 MW for western Japan +RES scenario; with and without wind and solar FFR

Low vRES (S1)：August（Max. demand day）7 p.m. / VRE 9.4%
mid vRES (S2)： August（Max. demand day） 1 p.m. / VRE 44.8%
High vRES, medium (S2b)：July （Max. demand day） 1 p.m. / VRE 49.1%
High vRES, low load (S3)：May（Mini. Demand day）1 p.m. / VRE64.9%

出典：EGI, Gridlab

Grid model result ②Frequency stability can be maintained within tolerable range by using FFR service of VRE when
the instantaneous penetration of VRE increased up to 60% for EAST and 70% for WEST.
Left: Evaluation of the frequency nadir for thewestern synchronous area

Right: Nadir frequency and VRES penetration ineastern Japan with and without the 600MW
ancillary service

出典：EGI, Gridlab

議論：変動型自然エネルギーの瞬時供給率と出力抑制
The curtailment can be necessary to maintain frequency stability within tolerable range when
the instantaneous penetration of VRE increased over 60% for EAST and 70% for WEST. The
curtailment amount is evaluated less than 2% in Higher RE scenario and less than 4%
considering more RE expansion up to 40% RE (29% of VRE).
Table Estimation of curtailment amount by setting upper limitation of instantaneous VRE penetration

Higher RE scenario
33% RES （23% VRES）
EAST

JAPAN*2

More RE expansion
40% RES (29% VRES)

WEST

JAPAN*2

EAST

WEST

Annual demand (TWh)

916

412

503

916

412

503

PV(GW)

100

44.755.3

12544.8

80,2Wind(GW)

3624.9

11.1

54

37.5

16.5

SNSP limit

-60%

70%

-60%

70%

22,1%

28,4%

16,9%

28.9%

34.7%

24.1%

33,0%

38,9%

28,3%

39.8%

45.2%

35.5%

1,8%

3%

0%

3.9%

5.1%

2.5%

Annual VRES share %Annual RE incl. hydroshare %
Annual VRES
curtailment %*1 FY2013 data
*2 Excluding Okinawa area