Micro-grid Voltage Control via Local Reactive Power Regulation
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Solution Overview
Problem
Micro-grids connected to power distribution systems face challenges in maintaining stable voltage supply due to load and generation variations, which complicates their integration and reduces plug-and-play capabilities, as existing control methods require complex power flow computations and additional burdens on the power distribution system.
Innovation Solution
A system and method for controlling micro-grids using local information, such as power flow measurements, to determine the parameters of a model that ensures exponential stability of voltage at the point of common coupling, allowing for the regulation of reactive power to maintain constant voltage, even with load changes, through a combination of primary droop control and secondary stabilization control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If PDS controls micro-grids by adding compensation signal to voltage regulator and emulating voltage source, then voltage stability is improved, but device complexity and computational burden increase
Solution Approach 1:
The patent extracts the voltage control function from the centralized PDS and implements it locally within the micro-grid through autonomous voltage regulation. The micro-grid controller independently measures local voltage and adjusts reactive power output to maintain voltage stability, removing the need for complex centralized compensation signals and power flow computations.
Solution Approach 2:
The micro-grid system performs self-voltage regulation by autonomously measuring its own voltage output and adjusting its reactive power generation accordingly. This self-service mechanism eliminates the need for PDS to provide complex control signals, enabling plug-and-play capability while maintaining voltage stability.
2Measurement precision
If PDS performs sophisticated measurements of power flow on entire PDS and micro-grid, then voltage control precision is improved, but measurement complexity and operational burden increase
Solution Approach 1:
The patent implements local voltage measurement and control at the micro-grid level rather than requiring sophisticated measurements across the entire PDS. The micro-grid controller measures only the voltage at its own output terminals and uses this local information to regulate reactive power, simplifying the measurement system while maintaining adequate control precision.
3Ease of operation
If droop controllers are used in micro-grids, then power sharing is improved, but voltage control capability and power quality prediction deteriorate
Solution Approach 1:
The patent merges the power sharing function of droop controllers with the voltage regulation function of reactive power control. The controller combines droop-based reactive power allocation with autonomous voltage measurement and adjustment, achieving both easy power sharing among distributed generators and stable voltage control at the point of common coupling.
Data Source
AI summary
A method controls a micro-grid connected to a power distribution system. The method determines parameters of a model of dynamics of the micro-grid using measurements of power flow at a point of common coupling (PCC) of the micro-grid with the power distribution system. The model is exponentially stable on a voltage set-point at the PCC and the method determines, using the parameters of the model, an amount of reactive power required to maintain the voltage at the PCC asymptotically stable on the voltage set-point. Next, the method controls a generator of the micro-grid to produce the amount of reactive power.