PV Inverter Grid Observer for Stand-Alone Mode Control
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Solution Overview
Problem
Existing photovoltaic inverter systems for distributed generation are complex and costly due to the need for reliable communication systems and supervisory control to synchronize components in both grid-connected and stand-alone modes, often failing to produce power independently in stand-alone mode due to reactive power requirements.
Innovation Solution
A control system for photovoltaic panel coupled inverters that operates in current or voltage control modes based on grid connection and available energy sources, using a grid observer block, nonlinear hybrid controller, converter controller, phase shift modulator, and pulse width modulator to determine the optimal operating mode and provide active and reactive power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If intelligent circuit breakers with reliable communication are used to synchronize components in a micro-grid, then the reliability of grid connection is improved, but the device complexity and overall cost increase
Solution Approach 1:
The patent extracts the communication function from the synchronization process by using a grid observer block that passively monitors voltage at the point of common coupling. This eliminates the need for active communication between intelligent circuit breakers and inverters, reducing system complexity while maintaining synchronization reliability.
Solution Approach 2:
The inverter performs self-synchronization by autonomously detecting grid voltage characteristics through the grid observer block and automatically adjusting its operation. This self-service approach eliminates the need for external communication signals and supervisory control, simplifying the system architecture.
2Reliability
If supervisory control is used to manage power and harmonize components in stand-alone mode, then the power management reliability is improved, but the device complexity and communication requirements increase
Solution Approach 1:
The patent removes the supervisory control layer by enabling each inverter to independently determine its operating mode through the grid observer block. The inverter directly senses voltage at the point of common coupling and autonomously switches between grid-connected and stand-alone modes, eliminating the need for complex supervisory control and inter-component communication.
Solution Approach 2:
Each inverter performs self-management by autonomously detecting grid presence through voltage monitoring and independently controlling its own operation. This distributed self-service approach replaces centralized supervisory control, reducing system complexity while maintaining power management reliability.
3Adaptability or versatility
If microinverters operate in stand-alone mode without grid connection, then the energy independence is improved, but the ability to produce power is reduced due to reactive power requirements
Solution Approach 1:
The grid observer block provides continuous feedback on voltage at the point of common coupling, enabling the inverter to detect stand-alone mode conditions and automatically adjust its control strategy. This feedback mechanism allows the inverter to independently manage reactive power requirements and maintain full power production capability in stand-alone operation.
Solution Approach 2:
The inverter dynamically adapts its control mode based on real-time voltage detection. When stand-alone mode is detected, the inverter transitions from grid-following control to autonomous control, dynamically adjusting its output to satisfy both active and reactive power requirements and maintaining full power production capability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution simplifies micro-grid implementation by reducing complexity and cost, enabling seamless switching between on-grid and off-grid modes without external signals, and providing both active and reactive power, including during night-time when no active power is available from PV panels.
Implementation Method 1
PV panels using PV inverters. PV inverters convert the DC power to an AC power compatible with the utility grid
Implementation Method 2
The inverter is operated in either current control mode or in voltage control mode based on whether or not the inverter is coupled to a grid
Data Source
AI summary
Systems, methods, and devices relating to inverters. A control system for use with photovoltaic panel coupled inverters controls the function and operation of the inverter based on the voltage at the point of common coupling. The inverter is operated in either current control mode or in voltage control mode based on whether or not the inverter is coupled to a grid or whether other energy sources are available to control the voltage at the point of common coupling.