The objectives and questions you want to answer will determine the power system model or models you need. As you are selecting your model or models, be sure to pay attention to the costs or effort required to secure the model, data requirements, and your team’s modeling capacity.
What You Need to Know
Grid integration studies typically use one or more of the following power system models: capacity expansion, production cost, and/or power flow.
The model or models you choose depends on your objectives, or the questions you are trying to answer. But you may find that securing the model requires purchasing commercial software or modifying open-source models to meet your needs. In some cases, the MWG may need to build its own model. Securing models can be a time-intensive process and should start as quickly as possible.
Your MWG may need training on how to use the model.
First, Consider the Questions a Capacity Expansion Model Can Answer
Use the objectives developed with the TRC in step 5 to select the model or models to use in your study. Compare your objectives to the questions in the lists below.
You will want to select a capacity expansion model if you need to answer the following questions:
Where, when, how much, and what types of infrastructure (generation and/or transmission) would achieve variable RE targets at least cost?
How will factors such as new policies, technological advancement, fuel prices, and electricity demand growth affect planning for generation and transmission infrastructure in the future?
What are the system wide capital costs associated with different variable RE targets?
How will different variable RE penetration scenarios impact economic development indicators?
What are the expected air emissions reductions associated with various RE scenarios?
What types of generation and transmission infrastructure can protect the power sector against unexpected disruptions to the normal operations of a system?
If you decide to run a capacity expansion model, you can use several different tools and software that are either open access, including the TIMES and ENGAGE models, or commercial packages, like PLEXOS.
Capacity Expansion Model Table developed with NREL.
Now, Consider the Questions a Product Cost Model Can Answer
You will want to select a production cost model if you need to answer the following questions.
What are the impacts of variable RE penetration scenarios on bulk power scheduling and economic dispatch?
What are the expected variable RE curtailment levels, GHG emissions, generator ramps, plant load factors, reserve requirements, transmission constraints, and other generator-level impacts under different variable RE scenarios?
What are the relative systemwide operating impacts associated with different variable RE expansion scenarios (such as different levels of variable RE, siting of variable RE in best resource sites versus close to transmission lines)?
What are the cost-effective mechanisms to access flexibility (e.g., from institutional measures such as forecasting or new infrastructure such as transmission) under high variable RE penetration levels?
If you decide to run a production cost model, you can select from open access tools, like the Scalable Integration Infrastructure Planning Model (SIIP), or commercial packages, including the PROMOD and ORDENA models.
Production Cost Model Table developed with NREL.
Next, Consider the Questions a Power Flow Model Can Answer
You will want to select a power flow model if you need to answer the following questions:
How do high penetrations of wind and solar impact the transient stability and frequency response of the electric power system?
Do various RE scenarios meet the security or reliability criteria for the power system?
Can the power system sustain and recover from temporary and significant disturbances and with high levels of nonsynchronous generation?
Will various RE deployment scenarios meet grid code requirements? If not, what interventions may be necessary?
How does the power system respond to a real-time disturbance such as an unplanned generator and/or transmission line outages under various variable RE deployment scenarios?
What is the expected system recovery time (i.e., magnitude and duration of frequency deviation following a disturbance) under various variable RE deployment scenarios?
Next, Read About Procuring Available Models for Your Analysis
The availability of commercial and open-source software varies by model, as does the cost and level of effort needed to use the model or apply it to your needs. In some cases, your MWG may need to develop its own model.
Read Excerpt: Pages 24-25 of Variable Renewable Energy Grid Integration Studies Guide: A Guidebook for Practitioners by NREL.
Finally, Consider Your or Your Team’s Modeling Skills
Your selection of modeling tools and software should carefully consider your available budget, data resources, and modeling skills and capacity. Many of these models will require expert modelers with strong technical backgrounds to manage inputs, run the model, and interpret outputs.
Modeling Team Requirements
The MWG team is comprised of technical staff from power system operators, energy agencies, and other organizations with expertise in power systems or electrical engineering, power flow modeling, and the mechanisms that drive electricity markets.
Desired qualifications of team members include:
1. Electrical or power systems engineering
2. Modeling experience in power flow studies
3. Knowledge of power systems operation, including unit commitment and economic dispatch
4. Understanding of electricity market mechanisms.
Time commitment: Team members are expected to devote at least 10 h/week/person, which may vary depending on the stage of the project.
With your MWG, select and begin securing (or developing) the model or model(s) suggested by your study’s objectives.
After you have selected your model(s), review the tables provided above and compare the available tools and software. What model software best meets your budget and team’s capacity?
Consider enhancing the MWG’s capacity to run the model. Do you have the experience and expertise needed? Do you need external support? Review the example training and resources provided in the tables above for the model(s) you have chosen. Most commercial software vendors offer their own training packages for their products.
Many organizations offer power system modeling training to support the analyses required for capacity expansion, production cost, power flow models and more. WatchEnergy Modeling 101 by the National Association of State Energy Officials for a review of all three power system models and read IRENA’s power system modeling and analysis overview.