Virtual Synchronous Generator Inverter Control
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Solution Overview
Problem
As renewable energy sources like wind and solar power become a majority of the grid power, they require high-efficiency energy storage and appropriate control to stabilize frequency and output, mimicking conventional synchronous generators to ensure reliable power supply and system stability, which is challenging with current inverter control methods.
Innovation Solution
A control device for inverters that models a synchronous generator, using virtual rotor position, speed, and inertia to regulate frequency and power output, implementing feedback loops to adjust drive torque and produce AC outputs akin to a virtual synchronous generator, allowing inverters to behave like conventional generators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If inverters are used to convert DC to AC for distributed energy sources, then integration of renewable energy sources is enabled, but the inverters cannot naturally provide frequency stability and load sharing capabilities like conventional synchronous generators
Solution Approach 1:
The patent applies the copying principle by creating a virtual model of a synchronous generator's rotor dynamics within the inverter control system. The control device implements mathematical models that replicate the inertial and damping characteristics of physical synchronous generators, allowing the inverter to mimic their frequency stability and load sharing behaviors without requiring actual rotating machinery. This enables distributed energy sources to contribute to grid stability while maintaining their static, non-rotating nature.
2Productivity
If current inverter control methods are used, then power conversion is achieved, but frequency regulation and inertial response are insufficient
Solution Approach 1:
The patent applies the dynamics principle by introducing dynamic virtual inertia and damping coefficients that can be adjusted in real-time. The control system continuously calculates virtual rotor acceleration based on frequency deviations and applies adaptive torque references that dynamically respond to grid conditions. This allows the inverter to provide inertial response and frequency regulation that adapts to changing system requirements, transforming a static power converter into a dynamically responsive frequency regulator.
3Ease of operation
If inverters operate without mimicking synchronous generator behavior, then control simplicity is maintained, but load sharing and stability control during faults are compromised
Solution Approach 1:
The patent applies the feedback principle by implementing closed-loop control that continuously monitors grid frequency and voltage conditions. The virtual synchronous generator model includes feedback mechanisms where frequency deviations generate virtual rotor acceleration signals, and voltage sags trigger fault ride-through responses. This feedback-based control enables the inverter to automatically adjust its output to maintain stability and share loads, achieving synchronous generator-like reliability while keeping the control architecture unified and manageable.
Data Source
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AI summary
The invention is concerned with a device and a method for controlling an inverter associated with a power source, which typically will be a distributed power source. The role of an inverter is to modulate the electrical power output, e.g. to provide a three phase AC electrical output at suitable voltage, where the output is to be supplied to a conventional power distribution, grid. The invention involves modelling the behaviour of a synchronous electrical generator. Variables represent the angular position and rotational speed of the virtual rotor (14) of this virtual synchronous generator. The torque electromagnetically exerted on the rotor is calculated from a measured inverter output current, and from a variable representing excitation current in the rotor. Allowing for this and for a notional drive torque applied to the virtual rotor (which in the physical analogue would be supplied by some prime mover such as an engine), as well as for the virtual inertia of the rotor, the angular speed of the virtual rotor is calculated, Using the angular position and rotational speed of the virtual rotor, and allowing for the aforementioned excitation current, it is possible to obtain the cmf induced in stators of the virtual generator. On this basis a control signal is generated which causes the inverter to produce an AC output corresponding to that which would be provided by the virtual synchronous generator. A synchronous generator must be regulated, as too must the virtual synchronous generator of the present invention. To this end, the invention provides a feedback loop in which deviation of the rotational speed of the virtual generator rotor from a reference angular speed is detected and is used to adjust the virtual drive torque, thereby to regulate the rotational speed of the rotor and hence the frequency of the AC output and the real power supplied by it.