Generator Fault Current Reduction via Excitation Control
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Solution Overview
Problem
The increasing fault current levels in electrical power distribution networks due to additional generators exceed the rated capacity of switchgear, leading to costly upgrades and impediments to expanding power production.
Innovation Solution
A system comprising a generator with a field winding, a generator step-up transformer, and an excitation system compensator that regulates field excitation current to reduce fault current contribution by adjusting output voltage and reactive power, utilizing a high impedance transformer and maximum tap selection to increase impedance and control voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If additional generators are added to the electrical power distribution network to serve electrical loads, then the power supply capacity is improved, but the fault current level increases beyond the rated capacity of the switchgear
Solution Approach 1:
The invention changes the operating parameters of the generator by adjusting the excitation system to operate in an under-excited mode, which reduces the generator's contribution to fault current. This allows additional generators to be added to increase power supply capacity while maintaining fault current levels within switchgear ratings.
Solution Approach 2:
The invention implements dynamic control of the generator's excitation system through an excitation system compensator that adjusts field excitation current based on system conditions. This dynamic adjustment enables the generator to adapt its fault current contribution in real-time, allowing network expansion without exceeding switchgear capacity.
2Reliability
If switchgear is upgraded or replaced to allow higher fault levels, then the fault level capacity is improved, but the cost and complexity of the system increases
Solution Approach 1:
The invention converts the potentially harmful high fault current into a beneficial control parameter by using excitation system adjustment to deliberately reduce fault current contribution. This eliminates the need for expensive switchgear upgrades while maintaining system reliability through controlled fault levels.
3Stability of the object's composition
If the generator increases its output current to maintain output voltage at rated value during fault, then the voltage stability is improved, but the fault current contribution increases
Solution Approach 1:
The invention changes the excitation parameter to operate in under-excited mode, which fundamentally alters the generator's response to faults. Instead of increasing current to maintain voltage, the controlled reduction in excitation current reduces fault contribution while the transformer and network impedance maintain voltage stability.
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 the electrical power distribution network to accommodate additional power plants without upgrading switchgear, provides enhanced fault ride-through capabilities, and supports grid code compliance by reducing fault currents and increasing critical clearing times.
Implementation Method 1
a generator (105) including a field winding (110) that is configured to generate a magnetic field in response to receiving a field excitation current
Implementation Method 2
A generator step-up transformer, coupled to the generator terminal of the generator, is configured to adjust the output voltage generated from the generator terminal
Data Source
AI summary
An approach for reduction in generator-sourced fault current contribution is disclosed. In one aspect, automatic excitation control of a generator is coordinated with a generator step-up transformer operating on maximized tap selection to reduce generator fault current contribution to an electrical power distribution network.