Modeling and Simulation in XENDEE

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 shammya.saha@asu.edu Nathan Johnson Assistant Professor The Polytechnic School Ira A. Fulton School of Engineering Arizona State University nathanjohnson@asu.edu 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. 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.

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. 1 848 822 846 820 844 818 864 842 800 802 806 808 812 814 850 810 816 824 826 858 832 852 834 860 888 890 836 862 838 840 828 830 854 856 The below figure shows the one-line diagram of the IEEE 34 Node Test Feeder built in XENDEE.

2 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 IEEE_34_LVRauto.xpf IEEE_34_LVRtapsFixed.xpf Cap data.xls Transformer data.xls Distributed load data.xls Spot load data.xls Line Configurations.xls Line data.xls IEEE 34 Node Test Feeder.doc IEEE Test Feeder.pdf File Details XENDEE XML model with auto-adjusting regulators XENDEE XML model with fixed tap transformers Shunt capacitor data Transformer Parameters Distributed load data in kw, kvar, and power factor Spot load data in kw, kvar, and power factor Overhead wire model and pole configuration data Connectivity and configuration data for each segment IEEE Power Flow Results 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.

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

4 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 ACSR 1/0 ACSR #2 6/1 ACSR #4 6/1 Corresponding code word from XENDEE Catalogue IEEE8 IEEE11 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).

Transformer Data.xls Transformer model data. XENDEE requires ZZ% and XX % ratio for RR modeling a transformer as given in Table 3. Table 3. Transformer Parameters for IEEE 34 Node Test Feeder RR% XX% ZZ% = RR 22 + XX 22 (XX/RR)% Substation Transformer 1.00 8.00 8.062 8.000 Ignored in the IEEE results XFM-1 1.9 4.08 4.500 2.147 5 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 XX % RR of 1.001%. 3.4 LINE VOLTAGE REGULATOR MODELING Figure 3. Transformer with model (left) and power flow solution (right). 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.

6 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 AAAAAAAAAAAA TTTTTT iiii LLLLLL 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

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

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 (%). 8 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. Figure 6a. Distributed load schematic for IEEE test case. 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 6b. Distributed load schematic using one-half line length.

9 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. Figure 7. Distributed loads with model (left) and power flow solution (right). 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 8. Shunt capacitors with model (left) and power flow solution (right).

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. 10 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.

11 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