SimpleDistributionPowerFlow.jl

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.

Installation

julia> ]
pkg> add SimpleDistributionPowerFlow

Configuration files

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
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

Usage

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)

Special features

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.

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:

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).

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):

Examples

Full configuration files for selected IEEE test feeders are in examples section.

Minimun Dependency

Simplicity of SimpleDistributionPowerFlow.jl is based also on its low dependency of other packages. It only relies in DataFrames, Plots, GraphRecipes and CSV

Future Updates

• 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

Support

Contributions, issues, and feature requests are welcome!

License

See license