The OpenRESV is an open-source Modelica-based library that is focused on modeling and validation of WECC-based renewable energy models. It was built using the Modelica language, leveraging the Modelica Standard Library. The library includes the newly developed customized renewable energy source models (validated against PHIL experiments), and a bare minimum of power system components sourced from the OpenIPSL library. The choice to separate OpenRESV from OpenIPSL was made to lower the entry barrier into Modelica modeling. Additionally, it aims to encourage the concept of developing open-source renewable colaboration between researchers. If the user is interested in knowing more about the OpenIPSL library, follow this link: OpenIPSL.
This Modelica Library explores the potential of Power Hardware-in-the-Loop (PHIL) setups for model validation, comparing an actual inverter with generic renewable energy source (RES) models from the Western Electricity Coordinating Council (WECC). Utilizing PHIL experimental data, the study not only validates and tests WECC models but also proposes enhancements to improve real-world inverter representation. The suggested improvements include three features: a voltage ride-through logic, an irradiance-to-active-power module, and an update to the voltage proportional control logic. The first two additions are extra components, preserving the original structure of WECC RES models and respecting the efforts of the modeling team. The last feature slightly modifies the model to enhance the reactive power response for a better match with experimental data. The upgraded models were implemented using the open-source Modelica language and the OpenIPSL Modelica Library, encouraging collaborative contributions for accelerated model development. To round everything off, a comprehensive comparison and validation against a real PV inverter in laboratory settings, offering an extensive set of simulations and comparisons to existing literature.
We have submitted a paper to the IEEE Transactions on Energy Conversion, which we would welcome you to cite as:
Fachini, Fernando, et al. "Customized Open-Source Renewable Energy Models Validated through PHIL Lab Experiments" IEEE Transactions on Energy Conversion (2024)
PHIL testing, particularly for power electronics systems like smart inverters, has gained popularity due to its advantages over traditional testing methods. The ALSETLab research team at Rensselaer Polytechnic Institute established the ALSETLab Volta Facility to facilitate research and development in power electronics systems. This power hardware-in-the-loop laboratory is designed for testing inverter functionality at a 15 kW capacity, utilizing Opal-RT simulators and a 4-quadrant bi-directional controllable power converter from Opal-RT. The PHIL setup was conceptualized such the researcher is capable of testing the inverter in different control modes, such as volt-var mode and constant power factor (PF) mode. The figure bellow illustrates the electrical design schematic of the lab, showcasing the components that make up the equipment setup: Power Inverter, Transformer, and Grid Simulation.
The Sunny Highpower SHP-150-20 inverter is located in the Power Inverter group, thus power flows from the power inverter in direction to the grid simulation group, passing through a 30 kVA 125 Maddox three-phase dry-type auto-transformer. The SEL-735 PQ Meter is the meter used by the authors to collect experiment data for the purpose of the inverter model validation. The power amplifier (OP8100 4-Quadrant power amplifier) has been employed with a capability to absorb or inject 15 kVA of power. This amplifier serves as a power grid emulator for the connected PV inverter. A common method for providing DC voltage/current to the smart inverter and replicating the behavior of a photovoltaic (PV) array during equipment testing is to utilize a DC power supply. The lab setup utilizes a Magna-Power programmable DC power supply, which provides programmable voltage, current, protection settings, and accurate measurements. The recreation of a photovoltaic power profile is conducted utilizing a photovoltaic power profile emulator (PPPE). The PPPE software automatically produces solar array voltage and current profiles according to predefined parameters. These profiles are then sequentially provided to the Magna-Power supply for emulation.
In case the reader would like to read more about the Volta Facility, folder contains additional information.
The library is structured into five sub-packages (illustrated in Figure shown below): Examples, NonMultiDomain, MultiDomain, Controls, and Functions.
- RES_Model_vs_PHIL_Inverter_Examples: contains Modelica model examples of all the validation tests conducted on the ALSETLab Volta PHIL Setup.
- Electrical: contains the bare minimum electrical components (from the OpenIPSL library) necessary for running the simulations.
- NonElectrical: contains the bare minimum nonelectrical components (from the OpenIPSL library) necessary for running the simulations.
- Types: contains variable types created in OpenIPSL and extended in this library.
- Interfaces: interfaces used in the models.
OpenModelica is an open-source and free Modelica-based modeling and simulation environment intended for industrial and academic usage. To download the latest version of the software, click on: Windows Version or Linux Version.
In order to load OpenRESV, you have to know the folder where you downloaded the library. You should go to File>Open Model/Library File(s) and search for the folder where you downloaded OpenRESV. Once you have found the folder, you must load the package.mo file.
Now that you have loaded OpenRESV, we can start running some examples.
Under Libraries Browser, click on OpenRESV>RES_Model_vs_PHIL_Inverter_Examples>VoltageRideThrough>CircuitBreakerLogic. You should expect to see the screen below. On the right-hand side of the figure below is the Documentation Browser, where the user can read more about the selected example.
Next step is to click on Simulate.
To display the simulation results, you must type the name of the variable you wish to plot.
As an example, let's compare the experiment Active Power data against the simulation generated Active Power.
Under Variable Browser, type pwLine1.P12 (this variable is the active power flowing through line pwLine1 that is being generated by the simulation model) and select the variable so that it can be plotted.
Now, search for the variable P_experiment_per_phase.y (this variable comes from a table in the model that contains active power data generated in the Voltage Ride-Through PHIL experiment) and select the variable to be plotted.
The user can now compare in the same plot the active power output generated by the PHIL and the simulation model.
OpenRESV: Copyright February 2024 - current, Fernando Fachini and Luigi Vanfretti, ALSETLab, Rensselaer Polytechnic Institute, Troy, NY.
The authors can be contacted by email: emaildofachini@gmail.com.
This Source Code Form is subject to the terms of the 3-Clause BSD license.
The development of the OpenRESV library is based upon work supported by the U.S. Department of Energy’s Office of Energy Efficiency and Renewable Energy (EERE) under the Advanced Manufacturing Office, Award Number DE-EE0009139.