Bidirectional Inverter Power Factor Control for Stable Distribution
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Solution Overview
Problem
Conventional distributed power source systems with storage batteries face instability in power supply due to inability to swiftly and appropriately respond to changes in load current power factor, leading to reactive power compensation issues.
Innovation Solution
A distributed power source system with a storage battery, featuring a bidirectional inverter, unidirectional converter, and bidirectional converter, along with a control section that controls the power factor of inverter output current to match the load current power factor, enabling stable power supply and reactive power compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If reactive power compensation is performed based on system current power factor detection, then reactive power can be compensated, but the system cannot swiftly and appropriately respond to changes in load current power factor
Solution Approach 1:
The control section implements feedback control by continuously detecting the power factor of load current and adjusting the inverter output current accordingly. This closed-loop feedback mechanism enables the system to swiftly respond to changes in load current power factor, ensuring stable power supply while maintaining accurate reactive power compensation.
2Loss of energy
If reactive current is increased based on system current power factor, then reactive power compensation is achieved, but a difference occurs between system current power factor and load current power factor
Solution Approach 1:
The control section acts as an intermediary that detects the power factor of load current directly and uses this information to control the inverter output current. This intermediary approach eliminates the discrepancy between system current and load current power factor measurements, enabling precise reactive power compensation without measurement errors.
3Reliability
If inverter output current is controlled to match load current power factor, then stable power supply is achieved, but the control complexity increases
Solution Approach 1:
The control section autonomously controls the inverter output current to match the power factor of load current without requiring external intervention or complex coordination with other system components. This self-service approach simplifies the overall control architecture while achieving stable power supply through direct power factor matching.
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 system ensures stable power supply and effective reactive power compensation by synchronizing the power factor of inverter output current with load current, even during changes, thereby preventing power instability and harmonic current issues.
Implementation Method 1
a bidirectional inverter (7) having a smoothing capacitor (6) on a DC side and configured to perform bidirectional conversion between DC power outputted from the distributed power source (2) and/or the storage battery (4), and AC power interconnected to a commercial power system (8)
Implementation Method 2
a unidirectional converter (3) provided between the distributed power source (2) and the bidirectional inverter (7) and configured to perform DC conversion of DC power of the distributed power source (2)
Implementation Method 3
a bidirectional converter (5) provided between the storage battery (4) and the bidirectional inverter (7) and configured to perform bidirectional DC conversion of DC power of the storage battery (4)
Implementation Method 4
a bidirectional inverter (7) having a smoothing capacitor (6) on a DC side
Data Source
AI summary
The present system 1 includes a distributed power source 2, a storage battery 4, a bidirectional inverter 7 having a smoothing capacitor 6 on its DC side, and a control section 10 for controlling the entire system, and supplies AC power to a load 9 while being interconnected with a power system 8. When active power supplied from the distributed power source 2 and/or the storage battery 4 to the smoothing capacitor 6 is equal to or greater than active power of load power, the control section 10 controls a power factor of inverter output current outputted from the bidirectional inverter 7 so as to coincide with a power factor of load current flowing to the load 9.