SimpleDistributionPowerFlow.jl is a Julia language package for steady-state unbalanced radial distribution systems powerflow analysis focused on usage simplicity with reliable and fast results.
The simplicity of the package is based on the data entry and package usage:
The data entry is made with standard definition csv files. It identifies some input situations such as distributed loads, isolated segments, open/closed switches and works automatically according to such situations, per example adding auxiliar buses, purging segments and/or reordering buses. It accept some types of distributed generation also.
Two commands are provided: gridtopology() for topology verification only, and powerflow() for voltages, currents, power and losses evaluation.
Grid topology is discovered based on input line segments, transformers and the switches states information, and the graph is plotting even without bus_coords file or with missing bus location information. Power flow evaluation takes in account the discovered topology, spot and distributed loads and distributed generation if any.
julia> ]
pkg> add SimpleDistributionPowerFlow| filename | required | column names | comments |
|---|---|---|---|
| line_segments.csv | yes | bus1,bus2,length,unit,config | bus1 and bus 2: Int, unit: String (ft, mi, m, km only accepted) |
| line_configurations.csv | yes | config,unit, raa,xaa,rab,xab,rac,xac, rbb,xbb,rbc,xbc, rcc,xcc, baa,bab,bac,bbb,bbc,bcc |
unit: String represents ohm/unit or micro-siemens/unit (ft, mi, m, km only accepted) |
| substation.csv | yes | bus,kva,kv | kv: line-to-line voltage in kilovolts |
| spot_loads.csv | yes | bus,conn,type, kw_ph1,kvar_ph1, kw_ph2,kvar_ph2, kw_ph3,kvar_ph3 |
conn: Y/D, type: PQ/Z/I, ph1/2/3 represents A/B/C for Y connection, and A-B/B-C/C-A for D connection |
| distributed_loads.csv | optional | bus1,bus2,conn,type, kw_ph1,kvar_ph1, kw_ph2,kvar_ph2, kw_ph3,kvar_ph3 |
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| capacitors.csv | optional | bus,kvar_ph1,kvar_ph2,kvar_ph3 | |
| transformers.csv | optional | config,kva,phases, conn_high,conn_low, kv_high,kv_low, rpu,xpu |
currently only grY-grY, Y-D, D-grY and D-D three-phase step-down transformer configurations are accepted |
| switches.csv | optional | config,phases,state,resistance | phases: abc, resistance in ohms |
| bus_coords.csv | optional | bus,x_pos,y_pos | |
| regulators.csv | optional | config,phases,mode,tap_1,tap_2,tap_3 | mode: manual only |
| distributed_generation.csv | optional | bus,conn,mode,kw_set, kvar_set,kv_set,amp_set, kvar_min,kvar_max,xd |
bus, conn, mode and kw_set are mandatories, others params depends on distributed generation mode |
To load the package: using SimpleDistributionPowerFlow
For grid's topology discovery only: gridtopology()
| options | type | default | purpose/example |
|---|---|---|---|
| input | String | "" (pwd) |
input files location gridtopology(input = "examples/ieee-34") |
| output | String | "" (pwd) |
results files location gridtopology(output = "results") |
| save_topology | Bool | true | save in output directory a png file with the identified grid topology powerflow(display_topology = false) |
| display_topology | Bool | false | display in screen the identified grid topology gridtopology(display_topology = true) |
| timestamp | Bool | false | add a timestamp to results file names gridtopology(timestamp = true) |
| graph_title | String | "" (nothing) |
set a title in topology graph gridtopology(graph_title = "modified ieee-34 test feeder") |
| marker_size | Float | 1.5 | set the size of bus identifier in graph gridtopology(marker_size = 10) |
| verbose | Int | 0 | set the level of program verbosity (only 0 or 1 are available) powerflow(verbose = 1) |
For powerflow analysis: powerflow()
| options | type | default | purpose/example |
|---|---|---|---|
| input | String | "" (pwd) |
input files location powerflow(input = "examples/ieee-34") |
| output | String | "" (pwd) |
results files location powerflow(output = "results") |
| tolerance | Float | 1e-6 | maximum porcentual difference between calculated and nominal substation bus voltage powerflow(tolerance = 0.001) |
| max_iteration | Int | 30 | maximum number of iteration before procedure halt powerflow(max_iteration = 100) |
| display_summary | Bool | true | display in terminal screen a results summary powerflow(display_results = false) |
| save_topology | Bool | false | save in output directory a png file with the identified grid topology powerflow(display_topology = true) |
| display_topology | Bool | false | display in terminal screen the identified grid topology powerflow(display_topology = true) |
| timestamp | Bool | false | add a timestamp to results file names powerflow(timestamp = true) |
| graph_title | String | "" (nothing) | set a title in topology graph powerflow(graph_title = "modified ieee-34 test feeder") |
| marker_size | Float | 1.5 | set the size of bus identifier in graph powerflow(marker_size = 10) |
| verbose | Int | 0 | set the level of program verbosity (only 0 or 1 are available) powerflow(verbose = 1) |
Distributed Loads
If there are distributed loads, auxiliar buses are automatically added in the middle of segments (50% of segment lenght) with 100% of the load applied as spot load on them. These buses are retired and segments are restored after powerflow execution and before results are printed.
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Distributed Generation
To include DG in power flow analysis distributed_generation.csv file is needed. Currently following modes of DG in balanced three-phase operation are modeled: PQ (constant active and reactive power), PQV (constant active power, voltage dependant reactive power), and PI (constant active power and current). PQV is modeled as a synchronous generator.
Format of distributed_generation.csv file and required (req) values are shown in following table.
| bus | conn | mode | kw_set | kvar_set | kv_set | amp_set | kvar_min | kvar_max | xd |
|---|---|---|---|---|---|---|---|---|---|
| req | req | PQ | req | req | --- | --- | --- | --- | --- |
| req | req | PQV | req | --- | req | --- | req | req | req |
| req | req | PI | req | --- | --- | req | req | req | --- |
Topology graph
This package graphs the grid topology even if there is no bus_coords.csv file, it also calculates the graph in case of missing or duplicate bus information:
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Topology changes
If grid's topology is changed by opening and closing switches, the from-to buses relation in affected segments are adjusted before powerflow analysis. If a loop is detected, the procedure is halted (for now the package only works with radial topology).
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If line_segments.csv file has isolated segments by open switch or by error, they are pruned before powerflow analysis. Two graph are generated: input topology is the detected topology from input files, and working topology is the corrected one):
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Full configuration files for selected IEEE test feeders are in examples section.
Simplicity of SimpleDistributionPowerFlow.jl is based also on its low dependency of other packages. It only relies in DataFrames, Plots, GraphRecipes and CSV
- Regulators: different configurations and automatic tap operation (for now only works with 3-phase wye connection in manual mode).
- DERs: add more Distributed Generation modes, for now only works with PQ, PI and PQV (synchronous) DG.
- Transformers: add single-phase and open-delta transformers (for now only three-phase transformers are accepted)
- Isolated segments: for now isolated segments are pruned before powerflow analysis, in future releases they would be treated as islands
Contributions, issues, and feature requests are welcome!
See license