Control Admittance Tuning for Neutral Point Voltage Imbalance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The neutral point voltage in three-phase resonant-earthed electric networks is often nonoptimal due to varying admittance imbalances, which can affect earth fault detection and phase voltage symmetry, and existing solutions like power electronics-based methods increase cost and complexity.
Innovation Solution
A method and apparatus that determine a target neutral point voltage and calculate phase-specific control admittances to adjust the neutral point voltage to the target value, using components like capacitors and inductors to balance admittance imbalances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If power electronics-based methods are used to raise neutral point voltage for coil tuning, then coil tuning capability is improved, but cost and device complexity increase
Solution Approach 1:
The patent uses simple, passive admittance elements (resistors, capacitors, inductors) instead of expensive power electronics-based active elements. These passive components are inexpensive, reliable, and sufficient for the intended purpose of raising neutral point voltage during coil tuning, eliminating the need for complex power electronics equipment.
Solution Approach 2:
The patent extracts and utilizes the natural admittance imbalance already present in the network to raise the neutral point voltage. By calculating and applying a compensating admittance based on the existing imbalance, the method converts a potentially problematic condition (admittance imbalance) into a useful resource for achieving the desired voltage level during tuning.
2Manufacturing precision
If high admittance imbalance compensation is implemented, then neutral point voltage control is improved, but device complexity and cost increase
Solution Approach 1:
The patent changes the admittance parameters of the network by adding controlled admittance elements (resistors, capacitors, inductors) to compensate for the natural admittance imbalance. This parameter adjustment raises the neutral point voltage to an optimal level, improving voltage control precision without requiring complex active compensation systems.
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
Achieves a desirable neutral point voltage level regardless of admittance unbalance, improving earth fault detection and reducing the need for complex, costly tuning methods.
Implementation Method 1
The idea of the resonant earthing is to form a parallel resonance circuit with the network admittances. The resulting resonance circuit is essentially an RLC-parallel resonance circuit, where R is essentially due to network shunt losses (e.g. losses of conductors and coils), L is essentially due to the inductance of the arc suppression device and C is essentially due to the phase-to-earth capacitance of the conductors in the network.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A method and apparatus for controlling a neutral point voltage of a three-phase resonant-earthed electric network, the apparatus comprising determining means (31) configured to determine a target value for the neutral point voltage of the three-phase resonant-earthed electric network (20), calculating means (31) configured to calculate at least one phase-specific control admittance or a neutral point specific control admittance required for controlling the neutral point voltage of the three-phase resonant-earthed electric network (20) from a prevailing value to the determined target value, and admittance means (30) configured to add the calculated at least one phase-specific control admittance between a ground and a respective phase (A, B, C) of the three-phase resonant-earthed electric network (20) or the calculated neutral point specific control admittance between the ground and a neutral point (21) of the three-phase resonant-earthed electric network (20).