Accurate models of power system resources are fundamental to the power system’s reliability, stability, and long-term planning. Model Quality Testing (MQT) is a critical process for developers and system operators to ensure that these models are accurate and validated for power system stability and interconnection approval. An automated approach to MQT can deliver more accurate and transparent results faster than conventional approaches.
Standard MQT procedures involve rigorous testing, including flat start, frequency disturbance, and fault response tests, to confirm model reliability across different simulation environments. However, conventional manual approaches can lead to errors and inconsistencies, which risk costly interconnection delays.
On the other hand, PSC’s automated approach to MQT ensures accuracy, efficiency, and transparency. This eliminates human error, speeds up testing, ensures accuracy, transparency, and compliance. With PSC’s MQT services, developers avoid costly interconnection delays, utilities and grid operators receive highly accurate, validated models, and system operators benefit from efficient validation processes. The end result is the smooth addition to power generation projects while maintaining a stable and reliable grid.
Model Quality Testing: Purpose and Procedure
MQT is a crucial process for ensuring that the dynamic models of power system resources accurately reflect real-world behavior across various operating conditions. For independent system operators (ISOs), MQT is a mandatory step in the interconnection process, requiring developers to repeatedly demonstrate that their models perform correctly before receiving interconnection approval.
Why is MQT Needed?
Accurate and validated models are fundamental to power system reliability, stability, and long-term planning. ISOs depend on these models to conduct reliable grid studies and prevent potential disruptions in power grids.
Typically, Original Equipment Manufacturers (OEMs) conduct type tests in a controlled laboratory environment using Hardware-in-the-Loop (HIL) methods to verify the Electromagnetic Transient (EMT) model of each unit, often using PSCAD software. However, in the case of Inverter-Based Resources (IBRs), MQT becomes significantly more complex because of their intricate control systems and diverse interactions with the grid.
A complete IBR plant consists of multiple components that need validation in both EMT and Root Mean Square (RMS) simulation environments such as PSS®E or PowerFactory. ISOs utilize various simulation tools to analyze different grid phenomena, ensuring that electricity remains reliable, high-quality, and cost-effective. Each of these simulations requires highly accurate resource models, making MQT an essential part of the interconnection process. Ensuring consistency across EMT and RMS models, aligning them with field measurements, and validating them against laboratory tests is the key purpose of MQT.
Standard Procedures for MQT
MQT follows standardized validation procedures established by ISOs and regulatory bodies. For example, ERCOT’s Dynamics Working Group Procedural Manual outlines specific model validation requirements, while industry-wide guidelines such as NERC MOD-026/027 and IEEE 2800 set high-level compliance standards for IBR interconnection studies.
MQT involves a series of tests to evaluate model behavior under different grid conditions, including:
- Flat Start Test: Verifies the model’s ability to initialize correctly in steady-state conditions.
- Small Frequency Disturbance Test: Assesses the model’s response to minor deviations in system frequency.
- Small Voltage Disturbance Test: Evaluates how the model reacts to slight voltage variations.
- Large Voltage Disturbance Test: Tests the model’s performance under significant voltage dips or surges.
- Fault Response and Short Circuit Ratio (SCR) Test: Validates the plant’s dynamic behavior during grid faults and assesses stability in weak grid conditions.
These tests serve two primary objectives:
- Ensuring power plants and their controllers respond correctly to real-world disturbances, maintaining grid stability and compliance with interconnection requirements.
- Validating consistency between different simulation environments (EMT and RMS) and the actual plant, ensuring that models behave realistically across various software platforms.
Human Errors Can Lead to Interconnection Delays
Conventional MQT approaches rely heavily on manual processes, making them prone to human error. Many developers and ISOs manually execute multiple tests, adjusting settings in different simulation environments. The issue arises when changes made in one model are not correctly implemented across other platforms, leading to inconsistencies. Minor misconfigurations that go undetected can result in inaccurate test results, requiring developers to redo the process and causing unnecessary and costly delays. Worse yet, prolonged delays can lead to project withdrawals.
For example, a large-scale battery storage project (e.g., 100 MW) must pass MQT within strict deadlines to sync with the system operator’s interconnection schedule. If a model fails MQT and requires corrections, the project may have to wait an additional three months for the next available interconnection window. This delay can be costly, as postponing synchronization for even one week can have significant financial implications.
PSC’s Approach to MQT
At PSC, we enhance traditional MQT methods by integrating automation, leveraging combined EMT-RMS benchmarks, and improving model validation workflows. We conduct RMS simulations using PSLF software, as well as EMT simulations, and overlay these results to ensure model accuracy across platforms.
Our approach reduces manual intervention, accelerates testing, minimizes errors, and ensures model consistency across different simulation environments. By incorporating data-driven analysis and streamlined compliance checks aligned with regulatory standards, we enhance confidence in model performance while expediting interconnection studies.
How Stakeholders Benefit from PSC’s Approach
PSC provides MQT services at various project stages, including planning, as-built verification, and operational validation. The accuracy and transparency of PSC’s methods significantly reduce human error. By identifying potential problems before submission to the system operator, we help clients avoid costly rework and lengthy waiting periods. Unlike conventional MQT, where errors are often discovered post-submission, our approach ensures readiness before the submission deadline.
By using PSC’s MQT services:
- Developers can avoid interconnection delays, ensuring their models meet system operator requirements before submission.
- Utilities and grid operators receive highly accurate, validated models, improving their ability to conduct reliable grid planning and operations.
- ISOs benefit from efficient validation processes, ensuring compliance and accuracy without unnecessary rework.
ISO areas in which PSC has deep technical knowledge include ERCOT, SPP, WECC, ISO-NE, FRCC, and PJM. By streamlining the MQT process, PSC helps developers and ISOs maintain reliable, secure, and efficient grid operations, ultimately advancing the integration of renewable energy resources into the power system.
Please find out more about our Power Networks capabilities and contact us to talk about first steps.