MMC Energy Management for DC Voltage Stability Under Disturbances
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Solution Overview
Problem
Existing modular multi-level converters (MMC) lack robustness in controlling internal energy and maintaining stability of the DC power supply network, particularly in the presence of disturbances, and existing solutions are complex and resource-intensive.
Innovation Solution
A modular multi-level converter with a converter control module that includes a calculator and an energy management module to regulate internal energy by applying a function with an adjustable input parameter, allowing for virtual capacitance adjustment and decoupling between sub-module voltages and DC network voltage, thereby stabilizing the DC network.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing control methods are used for modular multi-level converters, then the converter can operate, but the internal energy control is not robust and DC network stability cannot be maintained under disturbances
Solution Approach 1:
The patent introduces an energy management module as an intermediary between the calculator and the submodule control systems. This module receives the internal power reference from the calculator and generates appropriate control signals for the submodules, effectively mediating the energy flow control and improving the robustness of internal energy control under disturbances.
Solution Approach 2:
The patent implements feedback mechanisms where the energy management module continuously monitors the actual energy state of the converter and compares it with the reference values generated by the calculator. Based on this feedback, the control system adjusts the submodule switching states to maintain desired energy levels and ensure DC network stability.
2Reliability
If existing control methods are used, then the converter can operate, but computational complexity is high and resources are intensive
Solution Approach 1:
The patent segments the control system into distinct functional modules: a calculator for generating internal power reference, an energy management module for coordinating energy flow, and individual submodule controllers. This segmentation allows each module to perform specialized functions with optimized computational requirements, reducing overall computational complexity while maintaining DC network stability.
Solution Approach 2:
The energy management module acts as an intermediary that simplifies the control architecture by handling the complex coordination between the calculator and submodule controllers. It translates high-level power references into specific submodule control commands, thereby reducing the computational burden on individual components and optimizing resource usage.
3Ease of operation
If sub-module voltages are directly coupled to DC network voltage, then voltage regulation is simplified, but the converter loses robustness under disturbances
Solution Approach 1:
The patent introduces an energy management module as an intermediary layer between the sub-module voltage control and the DC network voltage regulation. This module coordinates the energy exchange between submodules and the DC network, allowing independent optimization of both voltage regulation simplicity and converter robustness without direct coupling.
Solution Approach 2:
The control system is segmented into independent voltage regulation functions for submodules and DC network voltage control. The energy management module facilitates coordinated operation between these segmented control functions, allowing each to operate independently while maintaining overall system robustness under disturbances.
Data Source
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AI summary
The invention relates to a multi-level modular converter (10) provided with a control module (20) comprising a computer (22) to calculate an internal control setpoint of the converter and an energy management module (24) allowing a power setpoint to be determined that is to be transmitted to the alternating electrical power supply network (110), the control module being configured to regulate the voltage at the point of connection of the converter to the direct electrical power supply network (120) and to regulate the voltage at the terminals of each capacitor modelled as a function of the internal control setpoint and of the power setpoint to be transmitted to the alternating electrical power supply network.