Osami Tsukamoto Professor Emeritus, Yokohama National University

Yokohama, Japan

Satoshi Morozumi Smart Community Dept., New Energy and Industrial Technology

Development Organization Kawasaki, Japan

Contents -Background -Introduction -Anti-Islanding -FRT -Certification, Collaborative work -Concluding remarks

IRED2014 Kyoto

Annual growth Growth rate

32%

Growth rate 9 %. Growth rate

5 %.

FiT

PV

Wind p. Hydro p. Geothermal Biomass

Growth of installation capacity of renewable energy in Japan

Back ground

Due to recent rapid growth of introduction of distributed energy systems, amount of works to permit their introduction to grid increases rapidly.

Well regulated grid code is necessary to establish for safe operation of

power grid keeping power quality.

Aug. 1986 Establishing “Grid connection Technical Requirement Guideline

Oct. 2004 Update to “Grid connection Technical Requirement related to Power quality Guideline”

Government The Agency for Natural Resource and Energy

2006 Establishing “Grid-interconnection Code” JEAC 9701-2006

2001 Establishing “Technical guidance of interconnection for distributed power supply ” JEAC9701

Domestic Standard The Japan Electric Association (JEA: Non governmental )

Each utility prepares its own “ Grid Code” (according to the codes)

Utilities

Updating Year by Year

Introduction

The Newest is “JEAC 9701-2012” “JESC E0019(2012) ” ( Revised every year based on requirements from utilities including general ones and amendments are published timely.)

Authorized by those two committees in the Japan Electric Associates “Specialized sectional committee regarding Grid

Interconnection “ (Chairman : Prof. Osami Tsukamoto) “Japan electric standard and code committee” (Chair : Prof.

Kunihiko Hidaka)

Low voltage distribution line (100/200V):

・Single or three phase power sources can be connected.

・Principally, only inverter based power sources can be

connected.

・Anti-islanding is required.

High voltage distribution line (6.6kV-33kV):

・Principally, three phase rotating machine or inverter

based generators can be connected.

・Anti-islanding is required.

Spot Network:*

・Principally, reverse power flow is not allowed.

Extra High Voltage (Sub transmission) :

・Anti-islanding is not required, if frequency relay is

installed, or if transfer-interrupting is available.

* 22kV or 33kV, Three phase parallel underground cable system, where customer connected to

secondary side of transformer.

When a fault happens on the grid, anti-islanding is required,

To protect operators who recover system from shock

hazard,

To protect inverter from over current accident., To protect home appliance from damages due to over voltage.

Grid code JEAC9701-2006 requires that islanding must be detected within 0.5 sec in the case of using a passive method and within 0.5sec.-1.0 sec in the case of using an active method.

6

Anti-Islanding

7

Newly developed anti-islanding system can detect islanding within 0.1 sec. and cope with a fault by a short between

primary and secondary of a pole transformer.

Substation Circuit Breaker Open in 0.9 sec by detection of fault current by OCR

Pole transformer

Anti-islanding system must function within 0.1 sec.

Fault caused by a short between primary and secondary winding of a pole transformer 600V over voltage apearsens across grounding resistance

CB in substation will be opened in 0.9 sec after a fault happens. Then, PV must stop generation within 0.1 sec to protect home appliances. JIS requires home appliances to with stand 600V for1 sec..

Demonstration of clustered PV (Ota-Project) (2002-2007) Development of new anti-islanding method.

30 inverter test-bed for testing anti-islanding method.

Technology development for testing anti-islanding(2008-2009)

Standardization of testing method of anti-islanding for cluster PV.

Discussion about FRT requirement for PV

Reflected to Grid Interconnection Code

Follow Up project of clustered PV(2008-2009) Replacement of PCS including new anti-islanding system

Research about International Standard of PCS for distributed generators (2010-2011)

Disclosure of the patent of new anti-Is. method to the domestic manufactures

Research about international standardization of PSC

US-Japan Smart Grid Demonstration in New Mexico(2009-2015)

Comparison of testing of anti-islanding methods

Mention of anti-islanding technique to a standard of IEEE

8

9

Large residential area where more than 800 houses are constructed. PVs were installed on roof tops of 553 houses Demonstration test of power quality and safety

PV systems:

Number of PV

systems installed: 553

Total PV capacity:

2,129 kW

Average PV capacity:

3.85 kW

Battery storage:

Number of

installations: 550

Storage capacity:

4704 Ah≒9 kWh

11

Detection by “the Frequency feed back” method

Injection of 2Hz reactive power

Injection of maximum reactive power

Detection of frequency drop

2Hz reactive power is fluctuated synchronously with GPS signal or wave clock signal. (There was an objection from the utility side because the system was dependent on other party’s facility.)

Reactive P

ow

er

frequency

12

By detection of change of commercial frequency voltage or harmonic voltage system starts injection of reactive power

Detection by “the Frequency feed back” method

Injected Reactive Power

commercial frequency voltage

Frequency Change

Injected Reactive Power

Harmonic frequency voltage Frequency Change

Islanding starts

Step injection of reactive power

In the case of commercial frequency voltage is changed

In the case of harmonic voltage is changed

2012 - 2016

2016 -

Voltage

Voltage

Keeping operation

Gate Block or keep operation

Keeping operation

Gate Block or keep operation

PCS Output

PCS Output

80% recovery within 0.5 sec when voltage drop is above 30%. And 1.0 sec for below 30%.

80% recovery within 0.1 sec when voltage is dropped above 20%. And 1.0 sec for below 20%.

FRT for PV and wind power for all voltage

levels

Change as Step

50Hz Area: +0.8Hz 3cycles

60Hz Area: +1.0Hz 3cycles

Lumping Change

50Hz Area: +2Hz/sec up to 51.5Hz

50Hz Area: -2Hz/sec down to 47.5Hz

60Hz Area: +2Hz/sec up to 61.8Hz

60Hz Area: -2Hz/sec down to 57.0Hz

FRT

The system has to continue operation for

Step change Lamp change

sec Sec Sec

Continue operation

Continue operation

15

Testbed in Sandia National Lab. In New Mexico (up to 8 PCS）

Testbed in Akagi site in Japan. (Up to 30 PCS)

Testing PCS each other

Technical exchange of anti-islanding and FRT system for PV

Japanese anti-islanding system is being involved as “Recommended Practice” in IEEE 1547.8.

This testbed was established for testing and certificating new PCS standard in 2012 based on JEAC9701-2012.

The grid code is continued to be revised year by year based on requests from utilities ( general ones and others) and updated according to progresses of interconnection technology.

Questionnaires are distributed to utilities to collect requirements by JEA (Japan Electric Association).

Continuous efforts are exerted to improve the grid code for smooth introduction of distributed power supplies to utility grids.

Thank you for your attention.