Asynchronous Generator Starting via Capacitor Excitation
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Solution Overview
Problem
Asynchronous generators face challenges in starting without a power supply for the inverter unit and require complex control arrangements, and existing systems like DFIG systems have maintenance issues with slip-ring brushes.
Innovation Solution
The use of capacitors for excitation during starting, eliminating the need for a power supply and control arrangement, and incorporating a converter system to convert voltages, with discharging resistors and switches for efficient operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an inverter unit with power supply and control arrangement is used to excite the asynchronous generator during starting, then the generator can be started, but the system complexity and cost increase
Solution Approach 1:
The patent extracts the excitation function from the complex inverter unit and power supply system, implementing it instead through a simpler capacitor-based excitation circuit. This removes the need for a dedicated power supply and control arrangement for excitation, significantly reducing system complexity while maintaining starting capability.
Solution Approach 2:
The asynchronous generator uses its own remanent magnetization to initiate the excitation process, eliminating the need for an external power supply. The system essentially excites itself using residual magnetic fields in the rotor, combined with capacitor banks to build up voltage during starting.
2Reliability
If a DFIG system with slip-ring brushes is used, then the asynchronous generator can be started and operated, but maintenance requirements increase
Solution Approach 1:
The patent removes the slip-ring brush assembly from the system entirely by using a squirrel-cage rotor design combined with capacitor-based excitation. This extraction of the problematic component eliminates the maintenance burden associated with brush wear and replacement while maintaining the generator's operational capabilities.
Solution Approach 2:
The patent employs a squirrel-cage rotor which is a robust, maintenance-free alternative to slip-ring rotors. The squirrel-cage design has no moving contacts or brushes that wear out, making it a durable, long-lasting component that eliminates the need for periodic maintenance of the excitation system.
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 cost-effective and maintenance-free starting of asynchronous generators without the need for a power supply or complex control systems, reducing maintenance needs and improving operational efficiency.
Implementation Method 1
The electrical energy supply system comprises capacitors (103) that are connected to the electrical terminals of the asynchronous generator (101) at least during starting of the asynchronous generator (101). The capacitors (103) are suitable for exciting the asynchronous generator (101) during the starting
Implementation Method 2
an asynchronous generator (101) that is driven by a prime mover (111) and comprises a stator and a rotor
Data Source
Figure 1
Figure 2
AI summary
An electrical energy supply system comprises at least one asynchronous generator (101) and a converter system (102) connected to the electrical terminals of the asynchronous generator. The converter system is configured to convert the voltages of the asynchronous generator into voltages suitable for an external system to be supplied by the electrical energy supply system. The electrical energy supply system further comprises capacitors (103) connected to the electrical terminals of the asynchronous generator at least during starting of the asynchronous generator. The capacitors are suitable for exciting the asynchronous generator during the starting. Thus, there is no need for a control arrangement for controlling the converter system to excite the asynchronous generator during the starting.