Harmonic Load Calculator
The Harmonic Load Calculator assists the end users to model non-linear loads generating harmonics and perform harmonic evaluations at selected locations designated as service entrances or point of common coupling (PCC).
The software is delivered with a worksheet named “Home” and a main dialog window shown below:
There are two types of buttons in the main dialog window, Pale-blue colored buttons for the normal program users to perform harmonic modeling and analysis tasks, and Rose-colored buttons for the program administrators to manage important data protected from inadvertent changes that may occur during the normal program use.
In addition, a hidden worksheet named “LoadDefinitions”, which is accessible via a valid password by program administrators . The users can model a system by using the main dialog window and other supporting dialog/message boxes. The HLC creates worksheets to save user data and harmonic calculation results that are constantly updated without requiring any user action.
The Harmonic Load Calculator organizes harmonic data in a hierarchical structure. The software works with three model classes:
At the bottom of the hierarchy are load models, which contain data for harmonic generating loads. Data related to a particular load are arranged in an Excel worksheet, the name of which starts with “Load-“.
• Service Entry
A service entry is typically the metering point for a power customer with harmonic-generating loads. An Excel worksheet is created for each service entry where the combined effects of all loads for the customer are evaluated. Worksheets for service entries may be recognized by their names starting with “ServiceEntry-“.
• Point of Common Coupling (PCC)
If there are more than one customers served from a power supply point, this location may be modeled as a point of common coupling (PCC). An Excel worksheet is created for each PCC in which the combined effects of all loads from different customers are evaluated. Names of PCC worksheets start with “PCC-“. It is not necessary to have a PCC in the system under study.
Data Construction & Management
The user can perform following data construction and management tasks using the HLC software:
• Adding a case by defining a service entry or a PCC at which harmonic analysis is to be carried out
• Adding a (non-linear) load
• Managing the Excel worksheets already created.
For the software to be useful for particular utility environments, program administrators may perform following from the figure below, administrator tasks are all protected by password.
• Adding a new load type or deleting/modifying an existing load type.
• Setting coefficient of coherence that is used when harmonics from different sources are combined.
This software was created, modified, enhanced in project P11-8