PV Single-Stage Inverter Control for Microgrid Power Sharing
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Solution Overview
Problem
Conventional power grids face inefficiencies and reliability issues due to centralized generation, high power losses, and the integration of renewable energy sources like PV systems, which are limited by generation capacity and operational complexity, particularly in micro-grids.
Innovation Solution
A micro-grid controller with a power sharing unit using a robust current droop controller and quasi-proportional resonant regulator, a DC-link voltage regulation unit, and a PLL-less SSM control scheme to manage power distribution among photovoltaic arrays, ensuring seamless operation in grid-connected and islanded modes, and avoiding resonance phenomena.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional centralized generation systems are used, then power transmission and distribution can be maintained, but system reliability deteriorates due to complete black-out risk upon failure
Solution Approach 1:
The patent divides the centralized power generation system into multiple distributed generator units (PV arrays with independent control). Each DG unit operates autonomously and can independently supply power to loads, eliminating the single point of failure problem in centralized systems while maintaining overall system reliability.
Solution Approach 2:
The patent changes the control parameter from centralized voltage control to distributed current control mode. This parameter change enables each DG unit to independently regulate its output current based on power sharing ratios, improving system reliability while simplifying the control structure through standardized current-controlled voltage source inverter modules.
2Power
If power network expansion is implemented to meet load growth, then power supply capacity is improved, but cost and feasibility deteriorate due to expensive transmission lines and transformers
Solution Approach 1:
The patent enables distributed generator units to self-regulate their power output based on local load conditions and power sharing ratios. Each DG unit automatically adjusts its current output without requiring centralized coordination or expensive grid expansion infrastructure, making the system feasible for remote rural areas and islands.
Solution Approach 2:
The patent designs a universal current-controlled voltage source inverter module that can be replicated and scaled to meet varying power demands. This standardized module serves multiple functions: power generation, voltage regulation, and adaptive load sharing, eliminating the need for customized expensive transmission infrastructure.
3Productivity
If fossil fuel-based power stations operate during light or zero load conditions, then power generation continues, but efficiency deteriorates and power losses increase
Solution Approach 1:
The patent implements dynamic power sharing control where distributed generator units automatically adjust their output based on real-time load conditions and power capacity ratios. This dynamic adaptation allows the system to maintain continuous power generation while optimizing efficiency by matching output to actual demand, avoiding the inefficiency of fixed-output fossil fuel plants during light load conditions.
4Power
If multiple PV arrays are integrated into micro-grids, then renewable energy capacity is improved, but operational complexity deteriorates due to control coordination challenges
Solution Approach 1:
The patent simplifies control coordination by changing the control parameter from voltage to current for all DG units. This unified current control approach, combined with power sharing ratios based on rated powers, creates a standardized control framework that scales linearly with the number of PV arrays, avoiding exponential complexity increases.
Solution Approach 2:
The patent implements a feedback mechanism where each DG unit continuously monitors its own current output and adjusts based on the power sharing ratio. This decentralized feedback control eliminates the need for complex centralized coordination while maintaining synchronous operation and stable power sharing among multiple PV arrays.
Data Source
AI summary
A microgrid (MG) controller can control a plurality of distributed generators (DGs) of photovoltaic (PV) arrays. The MG controller can include a power sharing unit configured to share power proportionally in a single current controlled mode (CCM) between the plurality of DGs based on a power capacity for each DG. The power sharing unit can include a robust current droop controller (RCDC) configured to provide proportional active current shared between the plurality of DGs. The power sharing unit can also include a quasi-proportional resonant (QPR) regulator coupled to the RCDC within a unified architecture. The QPR regulator can be configured to regulate a reference current signal.