Models and Solution

Updated 04/01/2014: Model solutions were compared between WindMil and CYME, requiring updates to the models and assumptions. The updated model information and results can be found at:

Data File

Solution

Updated 04/01/2014: In case questions arise for comparison, the original models and solutions are also available:

Comprehensive Test Feeder Files

Comprehensive Test Feeder Solutions

Description of

The Comprehensive Distribution Test Feeder

-

July 2010


 

W. H. Kersting, Life Fellow, IEEE

W. H. Kersting is a consultant to Milsoft Utility Solutions and a partner in WH Power Consultants, Las Cruces, NM. 

 mailto:bjkersting@zianet.com

 

 

  Abstract – In 1991 a paper giving the data for four distribution system test feeders was published [1].  The purpose of the test feeders was to give software developers a common set of data that could be used to verify the correctness of their programs.   Since then the original four test feeders along with additional special purpose test feeders have been made available on the IEEE website [2].  The purpose of this paper is to present a “comprehensive” test feeder that will allow for the models of all the standard components of a distribution system to be tested.  Only the system will be described in this paper.  The total data will be found on the IEEE website [2]. 

 

  Index Terms-Test feeders, distribution lines, regulators, transformers, capacitors, loads, component models

 

I.  INTRODUCTION

 

Each of the original test feeders had special characteristics that provided a test for the accuracy of the distribution component models and the convergence characteristics of the program being tested.  The original four test feeders are:

·         13 Node Test Feeder – provided a good test of the convergence of a program for a very unbalanced system

·         34 Node Test Feeder – a very long feeder requiring the application of voltage regulators to satisfy ANSI voltage standards

·         37 Node Test Feeder – a three wire delta underground system

·         123 Node Test Feeder – a large system consisting of overhead and underground single phase, two phase and three phase laterals along with step voltage regulators and shunt capacitors

 

Additional test feeders have been added for the special purpose of testing transformer connection models and induction machine models. 

 

II.     COMPREHENSIVE FEEDER

 

Figure 1 displays the one-line diagram for the comprehensive feeder.  It should be noted that this drawing is not to scale.  All nodes, transformers, regulators switches and capacitors have been numbered.

 

 

Examples of Overhead Lines

 

Type

Node A

Node B

Three-phase 4 wire

717

727

Three-phase 3 wire

765

771

Two-phase 3 wire

736

737

Single-phase 2 wire

757

758

Single-phase triplex

720

721

Three-phase quadraplex

732

733

 

The spacings of the conductors on the poles are defined in the data on the website.

 

A special case for the overhead lines is to model two lines in parallel.  In Figure 1 the parallel overhead lines go from node 713 to nodes 717 and 704.  The mutual coupling between the two lines must be modeled.  This is a case of two lines physically in parallel but not electrically parallel. 

 

Transformer T2 at node 719 is a single-phase centered tapped transformer serving a secondary system composed of a triplex cable.  Each of the load points consists of two 120 volt loads and a 240 volt load. 

 

Transformer T4 is an ungrounded wye-delta bank serving a three-phase secondary system consisting of a quadraplex cable.  Two load points serve the 120 and 240 volt single phase loads.  The third load point serves a three-phase induction motor.

 

Examples of Underground Cables

 

Type

Node A

Node B

Three concentric 1/3 neutrals + 1

760

761

Three concentric 1/3 neutrals

706

707

Two concentric full neutrals

707

709

Two tape shielded cables + 1

737

738

One full concentric neutral

718

719

 

A special case for the underground lines is to model two lines in parallel.  In Figure 1 there are two concentric1/3 neutral cables in parallel between nodes 702 and 703 and 713.  For this case there is a three phase switch that connects node 703 to 713.   With the switch open the lines are physically in parallel and with the switch closed the two lines are electrically in parallel.  Since the cable sizes are different for the two lines, there is a difference between the results for physically parallel and electrically parallel.

 

 

 

 


Transformer Connections:

 

Xfm Num.

Node

Connection

Transformers

T1

717

Grd. Y – Grd. Y

3 – Single Phase

T10

753

D-Y Grd. thru R

1 – Three Phase

T3

727

Grd. Y – D

3 – Single Phase

T7

742

Ungrd. Y – D

3 – Single Phase

T5

737

Open Grd. Y – D

2 – Single Phase

T12

758

One Grd. Y – D

1 – Single Phase

T11

755

D – Grd. Y

3 – Single Phase

T19

771

Open D – Grd. Y

2 – Single Phase

T17

709

One D – Grd. Y

1 – Single Phase

T9

750

D – D

1 – Three Phase

T13

761

Open D – D

2 – Single Phase

T16

707

One D – D

1 – Single Phase

 

 

Center Tapped Transformers

 

Xfm Num.

Node

Connection

Transformers

T4

731

Grd. Y – D

3 – Single Phase

T8

747

UnGrd. Y – D

3 – Single Phase

T6

738

Open Grd. Y – D

2 – Single Phase

T2

719

One Grd. Y – D

1 – Single Phase

T22

769

D – D

3 – Single Phase

T14

763

Open D – D

2 – Single Phase

T18

711

One D – D

1 – Single Phase

 

Step Voltage Regulators:

 

There are five step voltage regulators in the system.  The regulators utilize different connections.  For all regulators the primary CT rating and PT ratios are defined as well as the compensator R and X settings and the desired voltage level.  The five regulators are:

 

Reg. Num

Node

Connection

Regulators

Reg – 1

701

Grd. Y – Grd. Y

3 – Single Phase

Reg – 2

735

Grd. Y – Grd. Y

3 – Single Phase

Reg – 3

766

D – D

3 – Single Phase

Reg – 4

717

Grd. Y

1 – Single Phase

Reg – 5

705

Open D – Open D

2 – Single Phase

 

Switches

 

Sw. Num

From Node

To Node

Position

SW-1

741

745

Closed

SW-2

744

757

Open

SW-3

703

713

Closed

 

Initially SW-1 is closed with the other two switches open.  Closing SW-2 will be a test on program convergence for a loop.  With SW-1 open and SW-2 closed a new configuration is established.  The purpose of SW-3 is to model the two underground three-phase lines as either physically parallel or electrically parallel. With SW-3 open the physically parallel is modeled while with SW-3 closed the electrically parallel case is modeled.

 

 

Induction Machines

 

Mtr. Num

Transformer

Operating as

Specified

Gen

T9

Generator

- kW

Mtr. 1

T24

Motor

+slip

Mtr. 2

T13

Motor

+kW

Mrt. 3

T8

Motor

kW & PF

Mtr. 4

T4

Motor

+ slip

 

 

Examples of Distributed Loads

 

 

Node A

Node B

Model

713

717

Y – PQ

717

717

Y – Z

745

746

Y – I

746

747

D – PQ

747

749

D – Z

749

752

D - I

 

Examples of Spot Loads

 

 

Node

Xfm. Num.

Model

715

T1

Y – PQ

756

T11

Y – Z

728

T3

Y – I

759

T12

D – PQ

740

T5

D – Z

743

T7

D - I

 

Switched Capacitor Banks

 

There are four three-phase switched shunt capacitor banks in the system. 

 

Center Tapped Loads

 

The loads on the centered tapped transformers will be modeled the same as spot loads.  For single phase centered tapped transformers there will be two 120 volt loads and one 240 volt load.  For three-phase banks the center tapped transformer will have the two 120 volt loads, one 240 volt load and a three-phase load.  Some of the three phase loads are static loads and others will be induction machines.

 

Substation Transformer

 

The substation transformer is three phase connected delta-grounded wye.  The impedance is specified.  The station voltage is regulated by Regulator – 1.

 

 

 

Equivalent Source System

 

The equivalent source system is specified by the nominal voltage of 115 kV.  For short circuit studies the three phase and single phase short circuit studies the equivalent system positive and zero sequence impedances are given.

 

III.               CONCLUSION

 

The comprehensive IEEE test feeder has been developed in order to test the models of all distribution components and to test the convergence qualities of a verity of switching schemes.  In this paper only the one-line diagram and a description of the various components has been presented.  The actual data for the feeder can be found in [2].  Preliminary results for the power flow analysis will appear also in [2].  It is hoped that more developers will use this test feeder to test all aspects of their software.  In time additional components such as photovoltaic arrays will be added. 

 

IV.                REFERENCES

 

1.       IEEE Distribution Planning Working Group Report, “Radial distribution test feeders”, IEEE Transactions on Power Systems,.  August 1991, Volume 6, Number 3, pp 975-985.

2.       http://ewh.ieee.org/soc/pes/dsacom/testfeeders/index.html