Parallel Modular Switching for AC Load Flow Control
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Solution Overview
Problem
Existing devices for controlling load flow in alternating-voltage networks are either complex and expensive or cause interruptions in the network during startup, and they struggle to balance energy storage voltages without a line current.
Innovation Solution
A device with two modular series connections of double-pole switching modules connected in parallel, allowing for equalizing currents between them, which can balance energy storage voltages without affecting the network, and includes a protection device for safe startup and operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single modular series connection is used for load flow control, then the device structure is simple, but the energy storage voltages cannot be balanced without line current
Solution Approach 1:
The device divides the single modular series connection into two parallel modular series connections, each capable of independent operation. This segmentation allows the system to balance energy storage voltages by circulating equalizing currents between the two connections without requiring external line current, thereby resolving the contradiction between structural simplicity and voltage balancing capability.
Solution Approach 2:
The patent introduces equalizing currents as an intermediary mechanism that flows between the two parallel modular series connections. These equalizing currents serve as a mediator to transfer energy between the connections and balance their respective energy storage voltages, enabling reliable operation without external line current dependency.
2Loss of energy
If existing devices are used for load flow control, then the energy transmission efficiency is improved, but the network is interrupted during startup
Solution Approach 1:
The device performs preliminary balancing of energy storage voltages by circulating equalizing currents between the two parallel modular series connections before connecting to the network. This preliminary action ensures that the device is ready for immediate operation upon network connection, eliminating startup interruptions and maintaining continuous network operation.
3Power
If series transformers are used in load flow control devices, then the voltage control capability is improved, but the device cost increases significantly
Solution Approach 1:
The patent extracts and eliminates the expensive series transformer component from the load flow control device. By using two parallel modular series connections with equalizing currents, the system achieves voltage control capability without requiring traditional series transformers, thereby significantly reducing device cost while maintaining power control functionality.
Solution Approach 2:
The patent creates a substitute mechanism using two parallel modular series connections that replicates the voltage control function previously provided by series transformers. This copying approach uses semiconductor switching modules and energy storage elements to achieve similar voltage control capabilities through electronic means rather than electromagnetic transformation.
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
Enables reliable and cost-effective load flow control in alternating-voltage networks by balancing energy storage voltages without interrupting the network and eliminates the need for expensive series transformers, while providing protection against network faults.
Implementation Method 1
at least one switching module of each modular series connection has an energy store as well as semiconductor switches which can be switched on and off and which can be controlled in such a way that a switching module voltage can be generated at terminals of the switching module, which switching module voltage corresponds to a positive or negative energy storage voltage or to a zero voltage
Implementation Method 2
the control device is set up to generate an equalizing current between the modular series connections
Data Source
AI summary
A device for controlling a load flow in an alternating-voltage network includes first and second modular series connections of double-pole switching modules interconnected in a parallel circuit to be inserted in series into a phase line of the alternating-voltage network. At least one switching module of each connection has an energy store and semiconductor switches to be switched on and off. The semiconductor switches can be controlled in such a way that a switching module voltage can be generated at terminals of the switching module. The switching module voltage corresponds to a positive or negative storage voltage or a zero voltage. A control apparatus for controlling the switching modules is configured to generate an equalizing current between the modular series connections. A method for controlling a load flow by using the device is also provided.