Inverter Control Device Dynamic DC Voltage Limit
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Solution Overview
Problem
Inverters in solar power generation systems face limitations in controlling direct current voltage below a preset lower limit, restricting maximum power point tracking and thus reducing the range of electrical power output.
Innovation Solution
A control device for the inverter that includes a system voltage sensing part, a direct current voltage control part, a lower limit determination part, and a reactive power control part, which adjusts the lower limit of direct current voltage based on system voltage and controls reactive power output to prevent reverse current flow and maintain waveform integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the lower limit of direct current voltage is preset to ensure safe operation, then the inverter can operate reliably, but the range of maximum power point tracking is restricted
Solution Approach 1:
The lower limit voltage is changed from a fixed preset value to a dynamic value that adjusts based on system voltage conditions. When system voltage is high, the lower limit is reduced to expand MPPT range; when system voltage is low, the lower limit is increased to maintain safe operation margins.
Solution Approach 2:
The control device changes the parameter of lower limit voltage based on system voltage conditions. By monitoring system voltage and adjusting the lower limit threshold accordingly, the system optimizes both safety and power extraction capability under different operating conditions.
2Productivity
If the lower limit of direct current voltage is reduced to expand control range, then maximum power point tracking efficiency improves, but the risk of reverse current flow increases
Solution Approach 1:
The control device continuously monitors system voltage and uses this feedback to dynamically adjust the lower limit voltage threshold. This closed-loop control ensures that the lower limit is appropriately set based on real-time system conditions, preventing reverse current while maximizing power extraction.
Solution Approach 2:
By proactively adjusting the lower limit voltage based on predicted system voltage conditions, the control device prevents reverse current flow before it can occur. The system anticipates potential harmful conditions and takes preventive action by setting appropriate voltage thresholds.
Data Source
AI summary
A control device (2) of an inverter converts electrical power generated by a solar cell (3) into alternating current power connecting to an electric power system (7). The control device includes: an alternating current voltage sensor (14) sensing a system voltage (Vr) of the electric power system; an MPPT executer (23) controlling a direct current voltage (Vdc) applied to the inverter (1) to cause the electrical power output from the solar cell (3) to be a maximum when the direct current voltage (Vdc) is higher than a lower limit (VL); a direct current voltage lower limit calculator 22 reducing the lower limit (VL) when the system voltage (Vr) is lower than a predetermined voltage; and an electrical power controller (25) controlling reactive power based on the system voltage (Vr), the reactive power being output from the inverter (1).