PV Energy Storage Inverter Control for High-Voltage Ride-Through
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Solution Overview
Problem
Photovoltaic energy storage systems face challenges in maintaining proper operation during high-voltage ride-through events in alternating current power grids, as existing technologies struggle to accurately determine when high-voltage ride-through occurs and manage the energy storage device's state effectively, leading to potential damage and operational failures.
Innovation Solution
The proposed solution involves a photovoltaic energy storage system with an inverter that sends high-voltage ride-through information to an energy storage device, allowing it to adjust its output voltage or charging power reference values based on its working state to maintain stability and prevent frequent state switches, using a controller and power conversion circuit to manage the direct current bus voltage and ensure compliance with grid requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the energy storage device uses direct current bus voltage to determine high-voltage ride-through, then the determination may be inaccurate, but the device complexity is reduced
Solution Approach 1:
The patent introduces an intermediary determination mechanism that uses a combination of direct current bus voltage threshold comparison and working state information to accurately identify high-voltage ride-through events. This intermediary layer between the voltage sensor and the control system enables precise detection without requiring complex measurement equipment, resolving the contradiction between accuracy and simplicity.
2Speed
If the energy storage device frequently switches working states during high-voltage ride-through, then the response to voltage changes is improved, but the reliability decreases due to potential damage
Solution Approach 1:
The patent applies preliminary action by pre-establishing working state information and determining the appropriate target working state before high-voltage ride-through fully impacts the system. The control system determines the target working state in advance based on the detected high-voltage condition and current state, then transitions to this predetermined state, avoiding chaotic frequent switching and potential damage while maintaining rapid response.
3Reliability
If the energy storage device maintains its working state during high-voltage ride-through, then the reliability is improved, but the adaptability to grid conditions deteriorates
Solution Approach 1:
The patent implements dynamics by making the working state maintenance adaptive rather than static. The system dynamically adjusts its behavior based on the determined target working state, which is selected based on the high-voltage ride-through detection and current working state. This dynamic adjustment mechanism allows the system to maintain reliability by avoiding unnecessary transitions while adapting to different grid voltage conditions through intelligent state selection.
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 approach enables the energy storage device to accurately determine high-voltage ride-through events and maintain its operational state, preventing backflow and ensuring smooth grid-tied current control, thus avoiding damage and ensuring the system's stability during high-voltage conditions.
Implementation Method 1
photovoltaic power generation is to convert solar energy into electrical energy
Implementation Method 2
the energy storage device can not only absorb energy from the direct current bus to charge itself
Implementation Method 3
release energy to the direct current bus to implement an electrical discharge
Data Source
AI summary
This application describes examples of a photovoltaic energy storage system including an inverter and an energy storage device. In one example, an input end of the inverter is connected to a direct current bus. An output end of the inverter is connected to an alternating current power grid. The energy storage device is connected to the direct current bus. The inverter is configured to send high-voltage ride-through information to the energy storage device when a high-voltage ride-through occurs in the alternating current power grid. The energy storage device is configured to: when the high-voltage ride-through information is received, adjust an output voltage reference value to maintain a discharging working state if the energy storage device is in the discharging working state, or adjust a charging power reference value to maintain a charging working state if the energy storage device is in the charging working state.