MMC Simulator Using Equivalent Circuit Models for Real-Time Speed
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Solution Overview
Problem
Conventional simulators face challenges in achieving real-time simulation speed for modular multilevel converter (MMC) systems due to the complexity and computational demands of simulating thousands of switching devices, which results in time-consuming and difficult simulations.
Innovation Solution
The use of dual-diode-branch equivalent circuit models allows for parallel calculation and simulation of MMC systems, utilizing multiple computing units to increase simulation speed without sacrificing model detail or precision, by representing MMC valves with equivalent circuits that can be solved independently and in parallel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional simulators simulate thousands of switching devices in MMC systems, then model detail and precision are maintained, but simulation speed becomes too slow for real-time applications
Solution Approach 1:
The MMC system is divided into multiple independent valves, each valve into submodules (SMs), and each SM into switching devices. This hierarchical segmentation allows parallel simulation of independent units. The equivalent circuit model further segments the complex switching behavior into manageable voltage source representations that can be computed independently for each valve.
Solution Approach 2:
The patent creates equivalent circuit models that replicate the electrical behavior of complex MMC valves without simulating every switching device. The equivalent circuit copies the essential voltage and current characteristics while replacing thousands of detailed switching components with simplified voltage source representations, maintaining precision while enabling real-time computation.
2Measurement precision
If conventional simulators simulate all switching devices individually, then accurate device-level detail is achieved, but computational power requirements become prohibitively high
Solution Approach 1:
Multiple switching devices within each submodule are merged into a single equivalent voltage source representation. The patent combines the behavior of multiple IGBTs and diodes into unified voltage source models with associated impedance, dramatically reducing the number of computational elements from thousands of individual devices to a manageable number of equivalent circuits.
Solution Approach 2:
The equivalent circuit model serves multiple functions simultaneously: it represents the voltage output of the submodule, incorporates the effect of switching devices, models the capacitor voltage, and accounts for parasitic elements. This multi-functional approach eliminates the need for separate detailed models of each component while maintaining overall accuracy.
3Measurement precision
If conventional simulators use detailed switching device models, then accurate switching behavior is captured, but simulation complexity increases significantly
Solution Approach 1:
The patent transforms the simulation approach by changing from device-level parameters (individual IGBT, diode, capacitor parameters) to equivalent circuit parameters (voltage source magnitude, series impedance, parallel capacitance). This parameter transformation simplifies the mathematical models while preserving the essential electrical behavior through carefully derived equivalent parameters.
Data Source
AI summary
Method and apparatus for simulating a MMC system in an electronic simulator uses a computing unit and a connected input/output interface. The electronic simulator comprises a simulation model of a modular multilevel converter (MMC) system including at least one MMC valve, each MMC valve including a plurality of connected converter-submodules (SMs), each SM preferably comprising at least two controlled switches, a capacitor and auxiliary switches. The inventive approach replaces each MMC valve by an equivalent circuit whereby each SM in the valves may be solved separately. Multiple computing units are used to simulate those SMs in parallel, thus achieving fast or real-time simulation speed. The computing unit may comprise multiple computing means using CPU cores, FPGA or GPU cores and combinations thereof. The present inventive method keeps the model-detail including its precision, and enables a real time simulator to achieve fast or real-time speed for very large MMC system-simulations.