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Project Subjects

Background and Objective

Power system ICT (Information and Communication Technology) infrastructures indispensable in the next-generation grid have been well implemented for power generation and delivery, but have yet to be developed for customer communications including smart metering and power asset maintenance and diagnosis. In addi-tion, communications for power system protection are still proprietary and legacy (non-IP-based) whereas others mostly are IP-based.

This project deals with network design and development of fundamental technologies for demand area communications interconnecting customers, distributed energy resources and distribution grids, wide-area and high-speed communications promoting reliable and flexible power system protection and control, and sensor communications enhancing asset management and operations.

Main results

1. Performance evaluation and security requirement analysis for the demand area networkWe evaluated the performance of meter data collection using a protocol suite combining IEC 62056 and

multi-hop wireless LAN (IEEE 802.11g). For the estimation of the data collection time, we developed a simple simulation program incorporating experimental result of the multi-hop wireless LAN and IEC 62056 transmission characteristics. The estimation results show that the meter data collection is completed within several seconds for about six hundred meters (Table 1) [R10035].

We also performed security risk assessments for typical system configurations. The required security countermeasures were mapped to each system configuration. Fig. 1 illustrates an example of security countermea-sures deployment to a typical network configuration [R10019].

2. Proposal of Ethernet deployment method for the wide-area and high-speed control networkAs Ethernet, providing a real-time transmission feature, is promising for wide-area monitoring, high-speed

control and protection of power system, we had already proposed a wide-area Ethernet architecture that accom-modates substations in a hierarchical manner. We newly proposed a flat-type Ethernet structure that achieves a more real-time feature to show its applicability to wide-area protection system interconnecting many substations [R10029].

3. Developments of a Plug-and-Play method and other technologies for the sensor networkIn the power facilities condition monitoring sensor system, a Plug-and-Play (PnP) method to automate the

software setup of sensor data processing was proposed and the fundamental procedure was verified by an experi-mental system. This method is expected to improve the efficiency of maintenance operation because the modular software at every monitoring object associated with IEC 61850 can be automatically deployed and linked in response to the detection of sensor installation (Fig. 3) [R10023].

In the wireless sensor network system to collect many sensor data, we proposed an easy estimation method of data acquisition time with the number of sensor nodes and the link topology, and verified its validity for a typical ZigBee network [R10038]. For the optical sensor network system using optical ground wire (OPGW) for power transmission facilities monitoring, we successfully demonstrated the basic performance of optical remote power supply to multi-point optical sensor nodes [R10006].

Other reports [R10012] [R10033]

Next-Generation Communication Network System

02-3Environmental_52_79_2010.indd 70 11/10/03 16:08

2

Wide Area Protection Relays

IEEE 802.1ahSwitch

Local Area Network

Wide Area Network(IEEE 802.1ah)

Local Area Network(IEEE 802.1Q)

Tag Conversion of Wide/Local Area Networks

(IEEE 802.1ah amendment or converter)

By IEEE 802.1ah enabling designation of communication paths, the same-route, two-way communications can be achieved with the least number of repeater switches (minimum latency) en route, indispensable for protection relay systems.

Reduction of packet transfers (flooding) for learning communication routes in an ordinary Ethernet avoids the increase of communication latency.

Advantage

Local Area Network

Fig. 2 Flat-structured wide-area Ethernet network suitable for wide-area protection system

The wide-area Ethernet standard, IEEE 802.1ah, is amended to achieve a flat structure with a tag conversion mechanism, realizing simplified network configuration with every route designated and unnecessary traffic reduced for power system protection communications.

Table 1 Estimated data collection time Number of meters*

624 (25×25，an access point is located at the center of target area)

Target area 1 km×1 km Meter allocation

Uniformly distributed at 40-m intervals

Method of multi-hopping

Select a meter with a certain reception level and the minimum number of hops

Radio propagation

Line-of-sight and ground plane reflection taken into account

Communication protocol IEC 62056

Estimation results**

No. of maximum hopping： 8 No. of average hopping： 4.8 Max. response time： 5.9 [ms]Overall collection time： 2.8 [s]

* A target area is expected to have 500 to 1000 meters. ** The estimation is based on the number of hops.

PnPmodule Layer 1

Layer 2PnPmodulePnP server

PnP module for PnP server

Databasefor PnP

Power equipment

Processing for condition monitoringProcessing for PnP

Notes Communications for condition monitoring

1. Sensor detection

Communication for PnP

2. Notification of sensor attachment

4. deploy, link,

activate, deactivate

S/W module for reading switching position

S/W module for diagnosis of switching

characteristics

IEC 61850 basedcommunication

Sensor for switching position (including information about sensor itself such as calibration date)

1,2,3,4: processing order

3.deploy

PnP: Plug and Play

4. deploy, link,

activate, deactivate

Fig. 3 A method to realize the PnP of sensors for power facilities maintenance

The PnP modules deploy and link the appropriate software automatically triggered by the data detection of sensor installation.

Photovoltaicgeneration

Utility

Serviceprovider

Load

Photovoltaicgeneration

Smartmeter

PCS

Wind generation

Mobileterminal

MeteorologyInformation

Poletransformer

Customer

Smartmeter

Photovoltaicgeneration

Storage

Load

BEMScontrollerUtility dedicated

network

：Encryption

：Firewall

：Authentication to control command etc.

Customer

Internet

Mobile phonenetwork

PHEV/EV

HEMScontroller

Line switch

Securitycountermeasures

Wireless LAN

Fig. 1 Example of security countermeasures deployment to demand area network

The countermeasures and their deployment were developed based on the system configuration and the risk assessment results.

71

Environment and Energy Utilization Technology

Fig. 3　A method to realize the PnP of sensors for power facilities maintenanceThe PnP modules deploy and link the appropriate software automatically triggered by the data detection of sensor installation.

Fig. 1 Example of security countermeasures deployment to demand area network

The countermeasures and their deployment were devel-oped based on the system configuration and the risk assessment results.

Fig. 2　Flat-structured wide-area Ethernet network suitable for wide-area protection systemThe wide-area Ethernet standard, IEEE 802.1ah, is amended to achieve a flat structure with a tag conversion mecha-nism, realizing simplified network configuration with every route designated and unnecessary traffic reduced for power system protection communications.

Table 1　Estimated data collection time

* A target area is expected to have 500 to 1000 meters.** The estimation is based on the number of hops.

Number of meters*

624 (25×25，an access point is located at the center of target area)

Target area 1 km×1 km Meter allocation

Uniformly distributed at 40m intervals

Method of multi-hopping

Select a meter with a certain reception level and the minimum number of hops

Radio propagation

Line-of-sight and ground plane reflection taken into account

Communication protocol IEC 62056

Estimation results**

No. of maximum hopping： 8 No. of average hopping： 4.8 Max. response time： 5.9 [ms]Overall collection time： 2.8 [s]