Upgrade Cost Analysis

This chapter introduces the workflow for conducting upgrade cost analysis by using DISCO commands step by step or DISCO pipeline, where the pipeline chains the individual steps and runs upgrade cost analysis seamlessly. In the following two sections we will introduce the two methods separately.

There is a third method that bypasses the normal DISCO processes. This generic workflow allows you to run the upgrade simulations on existing, non-standardized OpenDSS models without any transformations.

The following commands run with default options. If you need any customization, please run --help on the commands to see the available options.

Step-by-Step Workflow

1. Transform Model

Prepare the model with PV deployments by using DISCO model transformation.

$ disco transform-model tests/data/smart-ds/substations upgrade -o upgrade-models

Load shape profiles for Load elements are not used by the upgrade module, and so we recommend that you remove them from the models in order to speed-up the simulations. Do so with this option:

$ disco transform-model tests/data/smart-ds/substations upgrade --exclude-load-profile -o upgrade-models

2. Create Config

With the transformed model, create the config.json file with submittable jobs.

$ disco config upgrade upgrade-models

DISCO will use default upgrade parameters if the option --params-file is not specified. If --params-file is specified, that file must contain all required parameters.

Here are optional parameters that you can customize in the same file:

[thermal_upgrade_params]
parallel_transformers_limit = 4
parallel_lines_limit = 4
upgrade_iteration_threshold = 5
timepoint_multipliers = {}

[voltage_upgrade_params]
capacitor_sweep_voltage_gap = 1.0
reg_control_bands = [1, 2]
reg_v_delta = 0.5
max_regulators = 4
place_new_regulators = true
use_ltc_placement = true
timepoint_multipliers = {}
capacitor_action_flag = true
existing_regulator_sweep_action = true

3. Submit Jobs

Submit jobs by using JADE and conduct upgrade cost analysis within each job. This command assumes that you are running on a local system. Please remove the option --local if you run on an HPC.

$ jade submit-jobs config.json --local

This step will generate the directory output, which contains all upgrade results.

4. Upgrade Analysis

Run post-processing to aggregate upgrade cost analysis results and create analysis CSV tables.

$ disco-internal make-upgrade-tables output

If everything succeeds, it produces aggregated json file: upgrade_summary.json

Pipeline Workflow

1. Create Template

Create a DISCO pipeline template file. By default, the output file is pipeline-template.toml.

$ disco create-pipeline template --task-name UpgradeTask --simulation-type upgrade --upgrade-analysis ~/Workspace/disco/tests/data/smart-ds/substations

Here, we need to enable the --upgrade-analysis option.

2. Config Pipeline

Update the pipeline template file for customization if needed. Then create the pipeline config file pipeline.json with this command.

$ disco create-pipeline config pipeline-template.toml

3. Submit Pipeline

Submit the pipeline with JADE

$ jade pipeline submit pipeline.json

If everything succeeds, it produces same aggregated upgrade tables in output-stage1.

Generic Workflow

Let’s assume that you have multiple networks defined in OpenDSS model files where each network has its own Master.dss.

• ./custom_models/model1/Master.dss

• ./custom_models/model2/Master.dss

Single Execution Mode

1. Configure the simulation parameters and in an input JSON file called upgrades.json. Refer to this file as an example. The JSON schemas are defined in Upgrade Cost Analysis JSON Schemas.

Each job represents one OpenDSS network and one upgrade simulation.

2. Run the simulation.

$ disco upgrade-cost-analysis run upgrades.json

Refer to disco upgrade-cost-analysis run --help for additional options.

Parallel Execution Mode through JADE

1. Configure upgrades.json as described in the previous step.

2. Create the JADE configuration file.

$ disco upgrade-cost-analysis config upgrades.json

3. Modify the generated config.json if necessary.

4. Run the jobs through JADE. This will aggregate results across all jobs. This example assumes local-mode execution.

jade submit-jobs --local config.json

Technical Details

The automated upgrades module consists of three components as shown in the figure: it performs traditional infrastructure upgrades to resolve both thermal and voltage violations, and then computes the costs associated with each of those upgrades.

A high level overview of thermal and voltage upgrades considerations is shown below:

1. Thermal Upgrades Workflow

In this sub-module, the thermal equipment (lines and transformers) violations are identified, and upgrades are determined as per the flowchart given below.

The technical equipment database is a catalog of available lines and transformers and can optionally be provided as an input. All the equipment in this database will be considered as available options while determining thermal upgrades. If this file is not provided, a technical database will be automatically generated from the given feeder model. This would provide the thermal upgrades module with a limited set of upgrade options. Refer to this sample technical equipment catalog for more information.

For an overloaded equipment, if a higher rated equipment of similar configuration is available in the technical catalog, that is considered as an upgrade and is chosen. Else, similar configuration equipment are added in parallel to resolve the observed violations. Sometimes, extreme thermal equipment overloaded can also cause voltage issues. So, it can be seen that thermal upgrades also resolve some undervoltage violations.

2. Voltage Upgrades Workflow

In this sub-module, the voltage violations present in the feeder are identified, and are resolved as shown in flowchart below:

a. Existing Capacitors:

• If capacitors are present

  • If capacitor control is present for a capacitor: correct capacitor control parameters i.e. PT ratio is checked and corrected (if needed)

  • If capacitor control is present, it is changed to voltage-controlled (if it is of any other kind)

  • If capacitor control is not present, voltage-controlled capacitor control is added and default control settings are applied to any newly added controller

• A settings sweep is performed through all capacitor settings, and setting with least number of violations is chosen. If initial settings are best, no changes are made. In the capacitor settings sweep method, same settings are applied to all capacitors.

b. Existing Regulators:

• If voltage regulators are present, regulator control parameters (like ptratio) are corrected (if needed), including for substation LTC.

• A settings sweep is performed for existing regulator control devices (excluding substation LTC).

  • In this settings sweep method, same settings are applied to all regulators

c. Add new Regulator:

• A new regulator is added by clustering nearby buses with violations and testing regulator placement (one at a time) on each of the common upstream nodes. The placement option with least number of violations is chosen.

3. Upgrades Cost computation A unit cost database is used to determine the total costs associated thermal and voltage upgrades determined through the workflows described above. Sample input cost database can be found here

Input parameters

In order to run this simulation, the following inputs are needed. For required fields, example inputs are provided, and for optional parameters, default inputs are shown.

1. Thermal Upgrade Inputs

The input parameters for thermal upgrades are shown in table below. For required fields, example inputs are provided, and for optional parameters, default inputs are shown.

Thermal Upgrade Inputs

Input Parameter	Type	Description	Required/Optional	Default/Example
transformer_upper_limit	float	Transformer upper limit in per unit	Required	1.25
line_upper_limit	float	Line upper limit in per unit	Required	1.25
line_design_pu	float	Line design in per unit	Required	0.75
transformer_design_pu	float	Transformer design in per unit	Required	0.75
voltage_upper_limit	float	Voltage upper limit in per unit	Required	1.05
voltage_lower_limit	float	Voltage lower limit in per unit	Required	0.95
read_external_catalog	bool	Flag to determine whether external catalog is to be used	Required	FALSE
external_catalog	str	Location to external upgrades technical catalog json file. Can be empty string, if read_external_catalog is False	Required	“”
create_plots	bool	Flag to enable or disable figure creation	Optional	TRUE
parallel_transformer_limit	int	Parallel transformer limit	Optional	4
parallel_lines_limit	int	Parallel lines limit	Optional	4
upgrade_iteration_threshold	int	Upgrade iteration threshold	Optional	5
timepoint_multipliers	dict	Dictionary to provide timepoint multipliers	Optional	None

2. Voltage Upgrade Inputs

The input parameters for voltage upgrades are shown in table below.

Voltage Upgrade Inputs

Input Parameter	Type	Description	Required/Optional	Default/Example
initial_upper_limit	float	Initial upper limit in per unit	Required	1.05
initial_lower_limit	float	Initial lower limit in per unit	Required	0.95
final_upper_limit	float	Final upper limit in per unit	Required	1.05
final_lower_limit	float	Final lower limit in per unit	Required	0.95
nominal_voltage	float	Nominal voltage (volts)	Required	120
create_plots	bool	Flag to enable or disable figure creation	Optional	TRUE
capacitor_sweep_voltage_gap	float	Capacitor sweep voltage gap	Optional	1
reg_control_bands	list(int)	Regulator control bands	Optional	[1,2]
reg_v_delta	float	Regulator voltage delta	Optional	0.5
max_regulators	int	Maximum number of new regulators that can be placed	Optional	4
place_new_regulators	bool	Flag to enable or disable new regulator placement	Optional	FALSE
use_ltc_placement	bool	Flag to enable or disable substation LTC upgrades module	Optional	FALSE
capacitor_action_flag	bool	Flag to enable or disable capacitor controls settings sweep module	Optional	TRUE
existing_regulator_sweep_action	bool	Flag to enable or disable existing regulator controls settings sweep module	Optional	TRUE
timepoint_multipliers	dict	Dictionary to provide timepoint multipliers	Optional	None

3. Simulation Input Parameters

In addition to the thermal and voltage input parameters, there are a few other simulation parameters which need to be provided.

Simulation input parameters

Input Parameter	Type	Description	Required/Optional	Default/Example
upgrade_cost_database	string	Final lower limit in per unit	Required
pydss_controllers	PyDSSControllerModel	If enable_pydss_controllers is True, these PyDSS controllers are applied to each corresponding element type	Required
enable_pydss_controllers	bool	Flag to enable/disable use of PyDSS controllers	Required	FALSE
include_pf1	bool	Include PF1 scenario (no controls) if pydss_controllers are defined.	Required	FALSE
dc_ac_ratio	float	Apply DC-AC ratio for PV Systems	Optional	None

Outputs

1. Costs

Output costs

Output Parameter	Type	Description
name	str	Job name
type	str	Equipment type
count	str	Count of upgraded equipment
total_cost_usd	float	Total cost in US dollars

2. Summary

Output summary

Output Parameter	Type	Description
name	str	Job name that produced the result
upgrade_type	str	Type of upgrade: thermal or voltage
scenario	str	Simulation scenario describing the controls being used
stage	str	Stage of upgrades: Initial (before upgrades) or Final (after upgrades)
simulation_time_s	float	Simulation time to perform upgrades (seconds). This will be present when stage=Final
thermal_violations_present	bool	Flag indicating whether thermal violations are present
voltage_violations_present	bool	Flag indicating whether voltage violations are present
max_bus_voltage	float	Maximum voltage recorded on any bus
min_bus_voltage	float	Minimum voltage recorded on any bus
num_voltage_violation_buses	int	Number of buses with voltage violations
num_overvoltage_violation_buses	int	Number of buses with voltage above voltage_upper_limit
voltage_upper_limit	float	Voltage upper limit, the threshold considered for determining overvoltages
num_undervoltage_violation_buses	int	Number of buses with voltage below voltage_lower_limit
voltage_lower_limit	float	Voltage lower limit, the threshold considered for determining undervoltages
max_line_loading	float	Maximum line loading
max_transformer_loading	float	Maximum transformer loading
num_line_violations	int	Number of lines with loading above line upper limit
line_upper_limit	float	Line upper limit, the threshold considered for determining line overloading
num_transformer_violations	int	Number of transformers with loading above transformer upper limit
transformer_upper_limit	float	Transformer upper limit, the threshold considered for determining transformer overloading

Example

For a feeder with thermal and voltage violations, the following figures show the violations in a feeder before and after upgrades.

1. Thermal Upgrades

The following figures show the thermal violations in a feeder before and after thermal upgrades:

The following figures show the voltage violations in a feeder before and after thermal upgrades:

2. Voltage Upgrades

The following figures show the voltage violations in a feeder before and after voltage upgrades: