Grid-Forming Inverter Overload Ride-Through via System-Level Coordination
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Solution Overview
Problem
Conventional grid-forming inverter-based resources face challenges in transient power-limiting during disturbances, leading to potential cascading instability and loss of synchronism due to unclear activation of virtual impedance and insufficient power reserve, with existing control systems being locally focused and not accounting for additional grid-forming resources.
Innovation Solution
A system-level overload ride-through control strategy employing online system-level analysis and control actions, including preemptive transmission of modified parameter sets to inverter-based resources for rapid re-parameterization during disturbances, ensuring stability and optimality through self-protection, stability, and optimality objectives.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional local control strategies are used during disturbances, then device complexity is reduced, but system stability deteriorates due to cascading instability and loss of synchronism
Solution Approach 1:
The control system is segmented into two levels: local control (at each inverter-based resource) and system-level control (centralized coordination). Local controllers execute simple reactive power adjustments based on frequency deviations, while the system-level controller coordinates these actions across multiple resources to maintain overall stability, preventing cascading failures.
Solution Approach 2:
A system-level controller acts as an intermediary between individual inverter-based resources and the grid. This intermediary coordinates the collective behavior of multiple resources, enabling them to work together as a unified system that maintains stability during disturbances, while each individual resource maintains relatively simple local control logic.
2Quantity of substance
If virtual impedance is activated during disturbances, then power reserve is increased, but device complexity increases due to unclear activation timing and parameters
Solution Approach 1:
The system pre-calculates and stores optimal virtual impedance parameters for various disturbance scenarios before disturbances occur. When a disturbance is detected, the system-level controller quickly retrieves and applies the appropriate pre-determined parameters, avoiding the complexity of real-time parameter optimization while ensuring adequate power reserve is available.
Solution Approach 2:
The system dynamically adjusts virtual impedance parameters based on the severity and type of disturbance detected. The system-level controller modifies reactive power setpoints and virtual impedance values in response to frequency deviations, enabling the inverter-based resources to provide appropriate power reserve without requiring complex real-time parameter synthesis.
Data Source
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AI summary
A method for controlling a network of inverter-based resources (IBRs) during a disturbance includes, in response to a start of the disturbance, employing a system-level overload ride-through (SLORT) algorithm among the network of IBRs. The SLORT algorithm includes determining, via a SLORT control module, a modified parameter set for one or more of the IBRs using regularly-updated system-level analyses, transmitting, via the SLORT control module, the modified parameter set to the IBRs, and automatically activating, via one or more local controllers of the IBRs, the modified parameter set, wherein automatically activating the modified parameter set comprises rapidly re-parameterizing one or more parameters of the one or more of the IBRs for a duration of and for a time period after the disturbance so as to transition the network of IBRs from a pre-disturbance stable state to a post-disturbance stable state.