Inverter VSG Control for Accurate Distributed Power Sharing
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Solution Overview
Problem
Existing methods for controlling virtual synchronous generators in power grids fail to ensure accurate power allocation among distributed power sources during load and power generation fluctuations, leading to imbalances in power distribution.
Innovation Solution
A power conversion device equipped with an inverter and a controller that generates control parameters for virtual synchronous generator control, including speed adjustment rates and damping coefficients, based on power target values and system information, to maintain optimal power allocation ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If control parameters for virtual synchronous generator are set based only on grid inertial force requirements, then the inertial force of the grid is ensured, but the power allocation ratio among distributed power sources deviates from the intended operation plan
Solution Approach 1:
The patent changes the control parameters (speed adjustment rate and damping coefficient) of the virtual synchronous generator based on both the grid inertial force requirement and the intended power allocation ratio. By adjusting these parameters dynamically, the system ensures that distributed power sources allocate power according to their operation plan while maintaining the required grid inertial force, thus resolving the contradiction between reliability and precision.
2Ease of operation
If the same control parameters are used for all distributed power sources, then the control is simplified, but the power allocation during load fluctuations does not match the intended ratio
Solution Approach 1:
The patent applies local quality by setting different control parameters for each distributed power source based on its specific characteristics and intended power allocation ratio. Instead of using uniform parameters for all sources, each source receives customized parameters that reflect its local role in the system, enabling accurate power allocation while maintaining operational simplicity through automated parameter generation.
3Loss of energy
If thermal power plants are closed to reduce power generation costs, then the power generation costs including management costs are reduced, but the stability of power grids deteriorates due to loss of synchronous generator functions
Solution Approach 1:
The patent replaces the mechanical synchronous generator system with a virtual synchronous generator implemented through control algorithms in static inverters. This substitution allows the system to maintain the stabilizing functions of synchronous generators (inertial force and synchronization force) without requiring physical thermal power plants, thereby reducing power generation costs while preserving grid stability.
Data Source
AI summary
A control circuit includes a virtual synchronous generator control circuit to impart a transient characteristic of a synchronous generator to the inverter, a control parameter generating circuit to generate a control parameter for controlling the virtual synchronous generator control circuit, an inverter voltage control circuit to control the inverter as a voltage source, based on AC system voltage information input from the virtual synchronous generator control circuit, and a communication circuit to receive, from a management device that manages the distributed power source, a power target value of the distributed power source and information necessary for generating the control parameter. The control parameter generating circuit generates at least one of a speed adjustment rate and a damping coefficient to be used in the virtual synchronous generator control circuit, based on the power target value and the information necessary for generating the control parameter received by the communication circuit.