PV DC Bus MPPT Handoff Control for Stable Power Sharing
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Solution Overview
Problem
Existing solar power systems face inefficiencies and high costs in power transmission and storage due to the inefficiencies of maximum power point tracking (MPPT) and the integration of energy storage systems, particularly when multiple DC/DC controllers with MPPT functionality simultaneously track the maximum power point, leading to system instability and poor performance.
Innovation Solution
Implementing a PV bus system with control mode handoff and adaptive ΔV MPPT control, where DC/DC controllers hand off MPPT control privileges after a predetermined duration or under specific conditions, and using power limiting control to manage power export, while a fixed DC bus system utilizes string-level MPPT controllers and a central inverter with MPPT functionality to eliminate multiple wiring runs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple DC/DC controllers with MPPT functionality simultaneously track the maximum power point, then power generation capability is improved, but system stability deteriorates
Solution Approach 1:
The patent segments the MPPT control function by designating one controller as the master MPPT controller while other slave controllers operate in voltage regulation mode. This segmentation prevents multiple controllers from simultaneously performing MPPT, thereby maintaining system stability while preserving overall power generation capability through coordinated control.
Solution Approach 2:
The patent introduces a master-slave control hierarchy where the master MPPT controller acts as an intermediary that coordinates the operation of all DC/DC controllers. The master controller determines the optimal operating point and communicates this information to slave controllers, which then regulate their output accordingly, preventing conflicts that would arise from simultaneous independent MPPT operations.
2Productivity
If multiple DC/DC controllers perform independent MPPT, then power extraction from PV arrays is improved, but control coordination becomes complex
Solution Approach 1:
The control functions are segmented into master and slave roles. The master controller handles the complex MPPT algorithm and decision-making, while slave controllers perform simpler voltage regulation tasks based on instructions from the master. This segmentation reduces the computational burden and control complexity for each individual controller while maintaining effective power extraction.
Solution Approach 2:
The master controller performs multiple functions: it executes the MPPT algorithm, determines optimal operating points, and communicates control signals to all slave controllers. This multi-functionality consolidates the complex control coordination into a single unit, simplifying the overall system architecture while maintaining efficient power extraction from PV arrays.
3Reliability
If distributed MPPT control is implemented across multiple controllers, then system reliability is improved through redundancy, but communication overhead increases
Solution Approach 1:
The control architecture is segmented such that only the master controller performs complex MPPT operations and maintains communication with the control system. Slave controllers operate autonomously in voltage regulation mode based on master instructions, minimizing communication requirements while preserving system reliability through the redundant presence of multiple functional controllers.
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
The proposed systems enhance system stability and efficiency by ensuring seamless power sharing and export limiting, reducing costs through simplified wiring and improved energy yield, while maintaining performance comparable to baseline systems.
Implementation Method 1
photovoltaic (PV) panels arranged in an array or string typically provide the means to convert solar energy into electrical energy
Data Source
AI summary
Solar power systems and methods utilize DC power transmission and centralized power inversion. The solar power systems include a photovoltaic (PV) bus system and a fixed bus system. The PV system utilizes a control mode handoff control method, which includes determining that a local maximum power point tracking (MPPT) control is enabled; in response to determining that the local MPPT control is enabled, starting an MPPT mode timer; performing local MPPT; determining that the MPPT mode timer is greater than a predetermined period; and, in response to determining that the MPPT mode timer is greater than a predetermined period, handing off MPPT control to the next MPPT controller. The distributed MPPT control method may include sequential MPPT control, adaptive ΔV MPPT control, and/or power limiting control. The fixed bus system includes PV string-level MPPT controllers and a fixed DC input central inverter or multiple fixed DC modular inverters.