The transmission system is represented as an equivalent impedance and source as seen from the distribution system, downstream of any transformer or regulator. It is modeled as a 1.05 pu source behind a 0.4j Ω impedance bypassed by low impedance switches. The closed switches simulate normal operation. Opening a switch results in a lower voltage at the substation due to the higher source impedance. (The two switches with a node between is necessary for GridLAB-D since it does not allow two links between the same nodes.)
Three identical simple microgrids (MGs) are attached with switches as shown in the image. A short line connects the PCC to a central node and two longer, symmetrical, lines branch out to a load bus and a bus with inverter based resources (shown in green).
Two additional MGs are also attached via switches (negligible impedance). They have equivalent generation and load on a single node so that they do not import or export power. However, they are able to participate in support of the Bulk Power System (BPS).
- S_rated: 180 kVA per phase
- P_rated: 150 kW per phase
- P_Out: 0.5*P_rated = 75kW per phase
Loads are 1/2 of that specified by the powerdata.csv file.
The distribution system is a slightly modified IEEE 13-bus system. For simplicity, the loads are all converted to wye connected, constant PQ, spot loads. The bus numbers have also been renumbered, the image shows the new bus numbers in bold with the old bus names also shown. To simulate the distributed load, a node is added between 1/4 the way down the line between 632 and 671 (2 and 6) having 2/3 of the total distributed load. 1/3 of the distributed load is added to node 671 (6). See p. 56 of "Distribution System Modeling and Analysis" by Kersting. The original 13-bus system also has capacitors at 675 (12) and 611 (9). These are added to the loads instead.
- The description of each branch is found in branchdata.csv.
- Impedances are in p.u. on the base specified.
- The description of each bus, load, etc. is found in powerdata.csv.
- Columns PgA, PgB, and PgC specify the rated real power for the inverter on that phase. The apparent power rating is 1.2 times that value.
- Run the GridLAB-D model, demonstration.glm to get a simple demonstration.
- The bypass switch opens at t=45s to cause the voltage drop.
- Player files specify the reactive power output of the inverters as shown in the table below.
| time (s) | Q (kVar) |
|---|---|
| 0 | 0 |
| 60 | 100 |
| 70 | 125 |
| 80 | 150 |
- Real power output of inverters is set to 90kW per phase.
- The resulting substation voltage is shown in the plot below.
