PV Storage Converter Control Without Inverter Communication
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Solution Overview
Problem
The existing control schemes for photovoltaic systems require additional sampling devices and complex communication protocols, leading to high costs, increased complexity, poor compatibility, and limited adaptability with third-party inverters.
Innovation Solution
A control method and device that directly manage the charging and discharging of energy storage devices within photovoltaic systems using a bidirectional power converter and switching network, without the need for additional sampling or communication with the grid-connected end, allowing for efficient control and compatibility with third-party inverters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If additional sampling devices or photovoltaic inverters are added to obtain photovoltaic generating power and grid-connected power data, then the control accuracy of energy storage charging/discharging is improved, but the system cost increases and device complexity increases
Solution Approach 1:
The patent extracts the control function from external sampling devices and inverters, and relocates it to the controller within the power converter. The controller directly acquires current and voltage signals from the power converter to calculate photovoltaic generating power and grid-connected power, eliminating the need for additional sampling devices and simplifying the system architecture.
Solution Approach 2:
The power converter is designed with multi-functionality, serving both as a power conversion device and as a measurement and control platform. The controller within the power converter performs multiple functions including acquiring electrical parameters, calculating power values, determining charging/discharging states, and controlling the bidirectional power converter, thereby eliminating the need for separate dedicated sampling devices.
2Ease of operation
If communication protocols are implemented to obtain parameters from photovoltaic inverters, then the control functionality is improved, but the ease of operation deteriorates due to poor compatibility with third-party inverters
Solution Approach 1:
The patent introduces the controller as an intermediary that directly interfaces with the power converter's electrical signals rather than requiring communication with external inverters. The controller acquires current and voltage signals directly from the power converter and performs all necessary calculations locally, serving as a mediator that eliminates the need for inverter communication protocols and thereby improving compatibility with third-party inverters.
Solution Approach 2:
The system performs self-service by having the controller within the power converter independently acquire all necessary electrical parameters and calculate both photovoltaic generating power and grid-connected power without requiring external inverter data. This self-contained approach eliminates dependency on specific inverter communication protocols and enhances adaptability.
3Reliability
If the control system requires communication with grid-connected end to obtain power data, then the reliability of power information is improved, but the productivity deteriorates due to complex control procedures
Solution Approach 1:
The patent segments the power measurement function into two independent calculation paths within the controller: one path calculates photovoltaic generating power using voltage and current signals from the photovoltaic side, and another path calculates grid-connected power using voltage and current signals from the grid side. This segmentation allows simultaneous independent calculation of both power values, improving control efficiency while maintaining information accuracy.
Solution Approach 2:
The controller continuously monitors and pre-calculates voltage and current signals from the power converter, maintaining ready-to-use electrical parameter data. When energy storage charging/discharging control is needed, the controller can immediately use these pre-acquired signals to calculate power values and execute control actions, eliminating the need for real-time communication delays and improving control responsiveness.
Data Source
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AI summary
The disclosure relates to the field of new energy technology and provides a control method and a control device of a photovoltaic system. The photovoltaic system includes a photovoltaic string (20), an energy storage device (30), a photovoltaic inverter (40), and a power converter (10). The method includes: obtaining a current time and an state of charge (SOC) of the energy storage device (30); checking whether the current time is in a preset charging period of the energy storage device (30), and checking whether the SOC of the energy storage device (30) meets a charging condition to control the power converter (10); checking whether the current time is in a preset discharging period of the energy storage device (30), and checking whether the SOC of the energy storage device (30) meets a discharging condition to control the power converter (10). The disclosure can directly implement the charging/discharging control of the energy storage device (30) without the need for a related apparatus to sample or communicate with a grid-connected end of the photovoltaic system, which is low in cost and simple in control. Moreover, since there is no information exchange with another apparatus, a third-party photovoltaic inverter apparatus can be better matched, and compatibility is strong.