Microgrid Inverter Control via Virtual Generator Latency
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Solution Overview
Problem
Microgrids face challenges in stable operation due to the complexity of coordinating between sources and loads, with central controllers being critical for stability, and their failure leading to microgrid failure.
Innovation Solution
A control system for power inverters comprising sensors and a controller that determines target power based on real power frequency droop information or power limits, and generates frequencies using a simulated generator's latency estimate to stabilize the microgrid, allowing for flexible operation modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a centralized control system is used to coordinate between all sources and loads, then the microgrid can operate stably, but the system complexity increases and a single point of failure is created
Solution Approach 1:
The patent divides the centralized control function into distributed control modules at each power inverter. Each inverter independently makes control decisions based on local measurements and simple peer-to-peer communication, eliminating the need for a complex centralized communication system while maintaining microgrid stability through coordinated autonomous operation.
Solution Approach 2:
The patent introduces a virtual synchronous generator model as an intermediary that simulates generator behavior at each inverter. This virtual model mediates between the power electronics and the grid, providing inertial response and frequency regulation without requiring complex centralized control, thus simplifying the overall system architecture.
2Reliability
If a centralized controller is used to coordinate sources and loads, then stable operation is achieved, but the failure of the central controller causes the entire microgrid to fail
Solution Approach 1:
The patent segments the control function across multiple independent inverters, each capable of autonomous operation. This eliminates the single point of failure by distributing control authority, so that if one inverter fails, the others can continue to maintain microgrid stability through their own local control algorithms.
Solution Approach 2:
Each power inverter is equipped with self-service control capabilities, including virtual synchronous generator modeling and adaptive impedance control. Each unit independently monitors its own operation and makes real-time adjustments without relying on external centralized control, ensuring continued stable operation even if other units fail.
3Ease of operation
If power inverters operate in grid-following mode with fixed control, then simplicity is maintained, but adaptability to different operating conditions is reduced
Solution Approach 1:
The patent implements dynamic control that automatically adapts between grid-following and grid-forming modes based on operating conditions. The virtual synchronous generator model provides dynamic inertial response and frequency regulation that adjusts in real-time to system conditions, maintaining both simplicity and adaptability through a unified dynamic control framework.
Solution Approach 2:
The patent changes key control parameters dynamically, including virtual inertia constants, damping coefficients, and impedance values. These parameter changes allow the inverter to adapt its behavior to different operating modes and system conditions while maintaining a relatively simple control structure, achieving versatility without excessive complexity.
Data Source
AI summary
The present invention provides control systems and methods for a power inverter. For example, a control system comprises a plurality of sensors and a controller. The plurality of sensors are configured to measure electrical signals that are indicative of output voltages and output currents of the power inverter. The controller, coupled to the power inverter, is configured to: determine a target power based on real power frequency droop information and a first frequency if the power inverter is in a voltage source mode; determine a target power based on a power limit and a predetermined power command if the power inverter is in a current source mode; and generate a second frequency based on the target power, a measured power, and a latency estimate of a simulated generator. The second frequency is used to control the output power of the power inverter.