Virtual Synchronous Generator Control for Grid Voltage Fluctuations
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Solution Overview
Problem
Voltage-controlled power converters with virtual synchronous generator control experience phase differences leading to AC voltage fluctuations, causing overvoltage and potential shutdown when connected to power systems, especially with small-capacity power sources.
Innovation Solution
A power conversion device and control device that simulates synchronous generator behavior by adjusting inertia and damping constants based on AC voltage fluctuations, using a power storage element, power converter, and control device to stabilize operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the power converter operates as a voltage source with virtual synchronous generator control, then it can simulate synchronous generator behavior and provide inertial energy compensation, but phase differences are generated during system accidents causing AC voltage fluctuations and overvoltage that lead to shutdown
Solution Approach 1:
The inertia constant and damping constant are made dynamically adjustable rather than fixed. The control device changes these constants based on real-time detection of AC voltage fluctuation magnitude, allowing the power converter to adapt its response characteristics to different disturbance conditions and prevent overvoltage-induced shutdown
Solution Approach 2:
The invention changes the parameters (inertia constant and damping constant) of the virtual synchronous generator control based on the detected voltage fluctuation magnitude. By adjusting these parameters dynamically, the system optimizes its response to different disturbance levels, preventing harmful phase differences and overvoltage conditions
2Device complexity
If the power storage element has small capacity, then the device complexity is reduced, but the DC voltage fluctuates significantly during active power input/output changes causing overvoltage and shutdown
Solution Approach 1:
Instead of increasing power storage capacity, the invention changes the control parameters (inertia constant and damping constant) to compensate for the limited energy buffer. By adjusting these parameters based on voltage fluctuation magnitude, the system maintains DC voltage stability even with small-capacity storage elements
Data Source
AI summary
A power conversion device includes a power storage element, a power converter, and a control device. The control device includes: a power generator simulation unit to simulate characteristics of a synchronous power generator based on an active power command value and active power, to generate an angular frequency deviation; a constant setting unit to set at least one of an inertia constant and a damping constant of the synchronous power generator; a phase generation unit to generate a reference phase, based on the angular frequency deviation and a reference angular frequency; and a signal generation unit to generate a control signal, based on the reference phase and a reference voltage command value. When the AC voltage of the power system fluctuates, the constant setting unit sets at least one of the inertia constant and the damping constant such that active power to be inputted and outputted decreases.Buchanan