The resilience impact computes how much of the system’s load can be met by a microgrid consisting of Photovoltaics and batteries with or without a back-up generator. The impact calculation leverages the open-source software tool Microgrid Component Optimization for Resilience (MCOR), which can be downloaded here. It then calculates several metrics to illustrate how the selected microgrid can improve system resilience.
About MCOR
MCOR is a Python-based, open-source software tool that generates microgrid configurations (combinations of Photovoltaic, battery and generator capacities) to meet a site’s critical load during a power outage. It includes a statistical model that produces hundreds of outage scenarios to allow simulation of microgrid behavior under a large range of weather conditions. The scenarios include hourly solar parameters (GHI, DNI, DHI), cloud cover, temperature, and site load. The model uses data from NSRDB for the given project location (based on the Photovoltaic system weather station). A detailed explanation of this model and the overall MCOR methodology can be found here. MCOR simulates microgrid behavior during each of these outage scenarios and computes several metrics aggregated across the scenarios.
Application to GridPIQ
A slightly modified version of the MCOR tool is leveraged in GridPIQ. The open-source version of MCOR outputs microgrid configurations that can meet 100% of the site’s load during an outage of the user-specified length; the version used in GridPIQ takes in a microgrid configuration specified by the user and calculates how much of the load can be met for a user-specified outage length across the various simulated scenarios. While the MCOR tool is described in terms of meeting a given site’s load, in the context of GridPIQ, the “site” is defined as the region associated with the Pre-project Load Profile. This could be as small as an individual building or campus, or as large as an ISO’s territory or even the entire U.S.
In addition, the open-source version of MCOR allows for customization of the simulation with dozens of input parameters, whereas GridPIQ assumes default values for most of these to allow a user to run a resilience simulation quickly without needing to gather a large amount of detailed information. The information that is needed from the GridPIQ user includes:
- Pre-project load profile and maximum system load
- Resilience goal
- Back-up generation system parameters (if included)
- Photovoltaic capacity, weather station, project grid location, and (optionally) Photovoltaic system specifications
- Battery system objective, energy and power capacity, efficiency, and project grid location
Resilience Calculation
Based on the outage scenarios generated by MCOR’s statistical algorithm and the Photovoltaic, battery and back-up generator information supplied by the user, MCOR simulates how each microgrid component is dispatched to meet the system load for each of the scenarios according to the following order:
- If Photovoltaic generation is available, it is used until either the load is met or no more generation is available. Any excess generation not used to meet the load is charged into the battery, subject to state of charge and battery power rating limits.
- The battery is discharged to meet remaining load, until either the load is met or no more battery capacity is available. During the day, the battery can discharge at up to its power rating and at night, the battery is discharged at a dynamic rate such that it can continue to discharge at a nearly constant rate for the entirety of the night.
- Any remaining load is met by the backup generator(s) up to the capacity limit. Several different generator models can be specified and are dispatched according to their user-specified designation as “prime” or “not-prime”.
Several different metrics are calculated across the scenarios and displayed on the Results page. These include:
- Likelihood of meeting the resilience goal
- Fuel storage capacity
- Percentage of load not met
- Total load not met
- Peak load not met
For each of these metrics, results are shown for three types of microgrid configurations:
- Generator only
- Microgrid (PV + battery) without the generator
- Microgrid (PV + battery) with the generator
In addition, for each metric and type of configuration, both an aggregated number is shown for all outage scenarios as well as a graph showing the distribution of the parameter across outage scenarios. An example is shown below for Likelihood of meeting the resilience goal:
