Grid-Forming Inverter Control for Constrained Inertial Power Deviations
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Solution Overview
Problem
Grid-forming inverter-based resources face challenges in maintaining stable power output during rapid grid-induced frequency and phase changes, leading to potential equipment overloads, trips, or instabilities due to their inertial response characteristics.
Innovation Solution
A method and system that determine dynamic power change limits and inertial power regulator references based on upper and lower power boundaries, applied to an inertial power regulator in an inverter-based resource, to constrain grid-induced power deviations and prevent undesirable oscillations and overloads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If grid-forming inverter-based resources provide inertial response to support grid frequency, then grid stability is improved, but power output deviations and equipment overload risks increase during rapid grid-induced frequency changes
Solution Approach 1:
The patent introduces an intermediate control layer (power deviation constraint mechanism) between the inertial response generator and the grid connection point. This intermediary monitors power output deviations in real-time and applies corrective control actions to limit excessive power fluctuations while preserving the beneficial inertial response characteristics, thus resolving the contradiction between grid stability support and power deviation control
Solution Approach 2:
The patent implements dynamic adjustment of power output limits based on real-time grid conditions and equipment status. The control system continuously adapts the acceptable power deviation boundaries according to the current operating state, allowing maximum inertial response during normal conditions while automatically constraining power deviations during abnormal grid events to prevent equipment overload
2Speed
If grid-forming inverters operate without power deviation constraints during grid disturbances, then rapid frequency response is achieved, but equipment overload and trip risks increase
Solution Approach 1:
The patent pre-configures power deviation constraints and protection thresholds before grid disturbances occur. The control system is prepared with predetermined safe operating boundaries and response protocols, enabling it to immediately enforce equipment protection limits during rapid frequency changes without waiting for overload conditions to develop, thus maintaining both fast response and equipment safety
3Device complexity
If conventional current source control is used in weak grids, then simple control structure is maintained, but PLL stability and current control performance deteriorate due to power fluctuations
Solution Approach 1:
The patent implements a feedback mechanism that monitors grid voltage and frequency conditions and adjusts the current reference signals accordingly. The system continuously measures actual power output and compares it with constrained reference values, using the error signals to correct PLL operation and maintain current control stability even in weak grid conditions, thereby improving reliability while adding minimal complexity
Data Source
AI summary
A method for providing grid-forming control of an inverter-based resource includes receiving, via a controller, a power reference signal. The method also includes determining a dynamic power change limit. Further, the method includes determining, via the controller, an upper power boundary and a lower power boundary for grid-induced power deviations from a desired power operating point based on the power reference signal. Moreover, the method includes determining, via the controller, limits for an inertial power regulator reference based, at least in part, on the upper and lower power boundaries and the dynamic power change limit. In addition, the method includes applying, via the controller, the limits to the inertial power regulator reference in an inertial power regulator of the inverter-based resource.