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Modeling and Simulation in XENDEE IEEE 34 Node Test Feeder

Shammya Saha Graduate Research Assistant

Electrical Engineering Ira A. Fulton School of Engineering

Arizona State University [email protected]

Nathan Johnson Assistant Professor

The Polytechnic School Ira A. Fulton School of Engineering

Arizona State University [email protected]

March 2, 2016

This document is one of several guides designed to support skills development in distribution

network modeling. It can be used during standard university curricula, a short industry course,

self-guided lessons, peer learning, or other training opportunities. Files resulting from the guide

can also be modified at the discretion of the user to pursue advanced topics of analysis. The IEEE

Test Feeders are used as examples given their wide recognition and use. Resulting power flow

analysis and short circuit analysis are presented in separate documents for each test feeder.

Each guide is developed through a partnership between Arizona State University researchers and

XENDEE. These training guides have been successfully used to train people individually, in small

and large classrooms, during interactive micro-grid boot camps, and during short sessions for

industry integrators and operators.

IEEE 34 NODE TEST FEEDER IN BRIEF:

IEEE 34 Node Test Feeder is an existing feeder located in Arizona, with a nominal voltage of 24.9

kV. It is characterized by long and lightly loaded overhead transmission lines, two in-line

regulators, one in-line transformer for a short 4.16 kV section, a total number of 24 unbalanced

loads, and two shunt capacitors.

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MODELING & SIMULATION IN XENDEE: IEEE 34 NODE TEST FEEDER SAHA & JOHNSON 2016

IEEE 34 NODE TEST FEEDER ONE-LINE DIAGRAM

The below figure shows the one-line diagram of the IEEE 34 Node Test Feeder available in the

IEEE 34 Node Test Feeder.doc file.

The below figure shows the one-line diagram of the IEEE 34 Node Test Feeder built in XENDEE.

800

806 808 812 814

810

802 850

818

824 826

816

820

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828 830 854 856

852

832888 890

838

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840836860834

842

844

846

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864

858

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1. OVERVIEW AND TECHNOLOGIES This document describes how to model the IEEE 34 Node Test Feeder in the XENDEE cloud

computing platform. XENDEE simulation models and system infrastructure documentation are

also included with this guide.

OpenDSS, an open-source technology developed by the Electric Power Research Institute (EPRI),

is a powerful analytics engine capable of simulating complex multi-phase electrical power

distribution systems. XENDEE enhances EPRI OpenDSS with enterprise level features such as

visualization, design, simulation, and reporting automation. XENDEE is a web-based analytical

tool that runs in Mozilla Firefox using the Microsoft Silverlight add-on.

2. ATTACHMENT AND RELEVANT DOCUMENTS

This package (IEEE34.zip) includes XENDEE model files (.xpf) that can be imported to create a

personal XENDEE project library. Additional supporting files required for independent testing and

verification are listed in Table 1.

Table 1. List of XENDEE Files Along with Supporting Files for XENDEE Modeling.

File Name File Details

IEEE_34_LVRauto.xpf XENDEE XML model with auto-adjusting regulators

IEEE_34_LVRtapsFixed.xpf XENDEE XML model with fixed tap transformers

Cap data.xls Shunt capacitor data

Transformer data.xls Transformer Parameters

Distributed load data.xls Distributed load data in kW, kVAR, and power factor

Spot load data.xls Spot load data in kW, kVAR, and power factor

Line Configurations.xls Overhead wire model and pole configuration data

Line data.xls Connectivity and configuration data for each segment

IEEE 34 Node Test Feeder.doc IEEE Power Flow Results

IEEE Test Feeder.pdf Details of wire parameters and pole construction

IEEE_34_LVRauto.xpf – A XENDEE model that implements line voltage regulators (LVRs) as

suggested by EPRI. Specifically, OpenDSS simulates tap changes and then recalculates power

flow. Many other software tools complete power flow studies using only estimates of tap changes.

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IEEE_34_LVRtapsFixed.xpf – A XENDEE model of the same network but with single-phase

transformers with fixed tap settings defined to match IEEE data.

3. THE XENDEE NETWORK MODEL

XENDEE automatically generates a one-line diagram and adjusts the layout to accommodate new

nodes added to the system. Additional nodes are needed beyond the standard 34 nodes because of

the “mid-nodes” that are created in-between nodes to simulate distributed loads.

3.1 POWER UTILITY (SLACK BUS)

The utility has been modeled as a 69 kV three phase source (Figure 1). All other parameters for

the utility were kept at their default value as shown in XENDEE.

3.2 TRANSMISSION LINE MODELING

Modeling power flow along a transmission line requires data including (1) line length between two

nodes, (2) line parameters and pole construction data at a specific bus.

Line Data.xls – Line length between two nodes with the configuration for that specific line.

Line Configuration.xls – Line parameters including the Geometric Mean Ratio (GMR) of the

line and resistance per mile. Values pulled from the XENDEE overhead line catalogue.

Figure 1. Slack Bus with model (left) and power flow solution (right).

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XENDEE code words for a specific ACSR wire are present in this file (see Table 2). Pole

construction data is also included for the each type of configuration.

IEEE Test Feeder.pdf – All details summarized for the IEEE Test Feeder.

Table 2. IEEE Conductor Models in XENDEE .

IEEE Conductor Model

Corresponding code word from XENDEE Catalogue

ACSR 1/0 IEEE8

ACSR #2 6/1 IEEE11

ACSR #4 6/1 IEEE12

3.3 TRANSFORMER MODELING

Transformers are modeled in XENDEE according to the winding connection provided in the Excel

file.

Figure 2. Transmission Line with model (left) and power flow solution (right).

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Transformer Data.xls – Transformer model data. XENDEE requires 𝑍𝑍% and 𝑋𝑋𝑅𝑅

% ratio for

modeling a transformer as given in Table 3.

Table 3. Transformer Parameters for IEEE 34 Node Test Feeder

𝑹𝑹% 𝑿𝑿% 𝒁𝒁% = �𝑹𝑹𝟐𝟐 + 𝑿𝑿𝟐𝟐 (𝑿𝑿/𝑹𝑹)% Substation Transformer

Ignored in the IEEE results 1.00 8.00 8.062 8.000

XFM-1 1.9 4.08 4.500 2.147

Substation transformer impedances are provided but they are not used by IEEE for power flow

analysis. IEEE reports results that assume voltage begins at the substation bus at the designated

voltage. To address this issue, a substation transformer in XENDEE has 𝑅𝑅% of 0.001% and �𝑋𝑋𝑅𝑅�%

of 1.001%.

3.4 LINE VOLTAGE REGULATOR MODELING

A line voltage regulator is connected between two nodes or two buses. This regulator modifies the

line voltage in case of sudden addition or loss of load connected to the distribution network.

Regulator Data.xls – Contains line voltage regulator information.

IEEE_34_LVRauto.xpf – uses LVR with automatic tap control. This is used for modern

distribution system analysis rather than estimated tap control. Additional information required to

model the LVR in XENDEE is provided in the following table.

Figure 3. Transformer with model (left) and power flow solution (right).

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Table 4. LVR Parameters for IEEE 34 Node Test Feeder.

Parameter Value Rating 2MVA

Impedance 0.001% 𝑿𝑿/𝑹𝑹% ratio 1.001

Delay 30s Tapping Secondary

The LVR is modeled by a single phase transformer with a fixed tap setting. Similarly, a three phase

LVR is modeled by three single phase transformers each associated with an individual phase and

a fixed tap position.

IEEE_34_LVRtapsFixed.xls – uses single phase transformers with fixed tapping instead of LVR.

The fixed tap values are present in IEEE 34 Node Test Feeder.doc in the power flow results

section. Each LVR fixed tap setting is calculated using the following equation:

𝑡𝑡𝑡𝑡𝑡𝑡% 𝑖𝑖𝑖𝑖 𝑋𝑋𝑋𝑋𝑋𝑋𝑋𝑋𝑋𝑋𝑋𝑋 = 100 + 0.625 × 𝐴𝐴𝐴𝐴𝑡𝑡𝐴𝐴𝑡𝑡𝐴𝐴 𝑇𝑇𝑡𝑡𝑡𝑡 𝑖𝑖𝑖𝑖 𝐿𝐿𝐿𝐿𝑅𝑅

For example, if the transformer tap in the power flow solution is kept at position 12, the

corresponding percentage tap in XENDEE is: 100 + 0.625 × 12 = 107.5%

3.5 MODELING LOADS

There are two types of loads in the IEEE test system:

• Spot loads – Loads connected to a specific node

• Distributed loads- Loads distributed between two connected nodes

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3.5.1 SPOT LOADS

All spot loads have their respective load model (constant power, constant impedance, constant

current) type defined and are considered balanced across all three phases. These loads are modeled

as three phase with appropriate load model.

Spot_Load_Data.xls – includes spot load data.

Figure 5. Spot loads with model (left) and power flow solution (right).

Figure 4. LVR with model (top) and power flow solution (bottom).

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The power factor for the load is calculated in the Excel file. XENDEE requires the power factor

be given as a percentage of the load. See column heading “Power Factor (%)”.

3.5.2 DISTRIBUTED LOADS Unbalanced load data for distributed loads are included in a separate file.

Distributed_Load_data.xls – includes distributed load data.

Modeling a distributed load requires creating an additional node between the two nodes across

which the distributed load is applied. For example, the IEEE test case provides information for

distributed loads that can be connected between two nodes as shown in Figure 6a.

XENDEE / EPRI OpenDSS approach this scenario by inserting a middle node and modeling two

overhead wires of the same configuration but each having one-half the length of the original line.

Figure 6b shows this approach for the original line shown in Figure 6a.

Figure 6a. Distributed load schematic for IEEE test case.

Figure 6b. Distributed load schematic using one-half line length.

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In looking at an example from the actual IEEE 34 Node Test Feeder system, Figure 7 shows an

extra node created at the midpoint between nodes 802 and 806. That distributed load is connected

to that middle node.

3.6 MODELING SHUNT CAPACITOR

The shunt capacitor parameters are available in the “Shunt Capacitor” Excel file. They are modeled

using the “capacitor bus” in XENDEE according to their phase information.

Figure 7. Distributed loads with model (left) and power flow solution (right).

Figure 8. Shunt capacitors with model (left) and power flow solution (right).

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4. MODEL AND SIMULATION VALIDATION: IEEE_34_LVRTAPSFIXED.XPF

4.1 RADIAL FLOW SUMMARY

Real power, reactive power, and system with losses are given in Table 5 with comparisons between

XENDEE simulation results and those reported in IEEE 34 Node Test Feeder.doc.

Table 5. Comparison of Power and Losses between IEEE Results & XENDEE Simulation.

Output Result IEEE XENDEE Difference (%) Total System input MW 2.0429 2.0432 0.0001 Total System input MVAR 0.2903 0.2909 0.0020 Total System kW Loss 273.0490 267.8790 0.0190 Total System kVAR Loss 34.9990 34.8820 0.0030

4.2 VOLTAGE PROFILE VALIDATION

The voltage profile of selected nodes is provided in Table 6 for comparison.

Table 6. Comparison of Phase Voltage Magnitude & Angle between IEEE Results & XENDEE Simulation.

Node IEEE A-N

XENDEE A-N

IEEE B-N

XENDEE B-N

IEEE C-N

XENDEE C-N

IEEE Angles

XENDE Angles

800 1.0500 1.0500 1.0500 1.0500 1.0500 1.0500 0.0/-120.0/120.0 0.0/-120.0/120.0 802 1.0475 1.4750 1.0484 1.0485 1.0484 1.0485 -0.5/-120.1/119.9 -0.1/-120.1/119.9 806 1.0457 1.0458 1.0474 1.0475 1.0474 1.0475 -0.1/-120.1/119.9 -0.1/-120.1/119.9 808 1.0136 1.0141 1.0296 1.0300 1.0289 1.0293 -0.8/.120.9/119.3 -0.8/-121.0/119.3

The voltage profile at each node can be viewed within the annotation view in XENDEE. Moreover,

the professional report view in XENDEE can be used to check voltages at any node.

4.3 CURRENT FLOW VALIDATION

The magnitude of current through selected lines is provided in Table 7.

Table 7. Comparison of Phase Current Magnitude between IEEE Results & XENDEE Simulation.

Line From Node

To Node

IEEE Phase A

XENDEE Phase A

IEEE Phase B

XENDEE Phase B

IEEE Phase C

XENDEE Phase C

L14a 828 830 35.87 35.90 36.93 36.90 37.77 37.80 L17a 834 860 11.16 11.20 9.090 9.100 10.60 10.60

L22a 844 846 9.830 9.900 9.400 9.400 9.400 9.400

L24 850 816 48.47 48.50 40.04 40.00 38.17 38.20

The annotation view in XENDEE can also be used to view current values through individual lines

for each phase.

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5 ADDITIONAL NOTES We hope you have benefited from this step-by-step guide to creating an IEEE Test Feeder in

XENDEE. The full XENDEE results report can be generated by importing and simulating the

models referenced in this guide. The partnership with XENDEE has allowed our education and

research programs at Arizona State University to grow rapidly through the easy-to-use and

versatile user interface. You can find out more about our research, computational lab, micro-grid

test bed, and capacity building programs at http://faculty.engineering.asu.edu/nathanjohnson/

• Visit XENDEE at www.xendee.com to access the online simulation tool • Data for the IEEE 34 Node Test Feeder can be downloaded from the Web at

http://ewh.ieee.org/soc/pes/dsacom/testfeeders/index.html To learn OpenDSS visit http://smartgrid.epri.com/SimulationTool.aspx

http://faculty.engineering.asu.edu/nathanjohnson/

http://www.xendee.com/

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

http://smartgrid.epri.com/SimulationTool.aspx

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