Variable Frequency Transformer Damping Controller for Power System Oscillation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for suppressing low frequency oscillation in power systems, such as adding power system stabilizers and using HVDC or FACTS devices, are limited by high complexity, operational challenges, and dependence on system configuration, necessitating a more adaptive and computationally efficient solution.
Innovation Solution
A method utilizing a Variable Frequency Transformer (VFT) to determine system transfer functions and optimize damping controller parameters using the Prony method and root locus analysis, allowing for dynamic suppression of low frequency oscillations without requiring detailed system knowledge or complex calculations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If power system stabilizers are added in generator excitation systems to suppress low frequency oscillation, then damping effect is improved, but device complexity and operational complexity increase significantly
Solution Approach 1:
The patent extracts the oscillation suppression function from individual generator excitation systems and concentrates it in a centralized control system that processes power flow measurements from PMUs. Instead of distributing stabilizers across all generators, the system extracts oscillation information from phasor measurements and applies suppression through centralized control of interconnection ties, significantly reducing the number of devices needed while maintaining damping effectiveness.
Solution Approach 2:
The centralized control system serves multiple functions: it monitors power flow across interconnections, identifies oscillation modes through spectral analysis, calculates suppression signals, and controls multiple tie-lines simultaneously. This multi-functional approach replaces numerous individual stabilizers with a single system that handles detection, analysis, and suppression across the entire interconnection.
2Reliability
If HVDC power regulation or FACTS devices are applied to suppress low frequency oscillation, then damping capability is improved, but device complexity and cost increase
Solution Approach 1:
The patent introduces PMUs (phasor measurement units) as intermediary devices that provide synchronized measurement of voltage and current phasors across the interconnection. These measurements serve as the foundation for identifying oscillation modes and generating suppression signals. The PMUs act as intermediaries between the physical power system and the control system, enabling precise detection without requiring complex modeling of the entire system.
Solution Approach 2:
The system implements closed-loop feedback by continuously monitoring power flow through PMUs, comparing measured values with reference values, identifying oscillation components through spectral analysis, and adjusting tie-line power flow in response to detected oscillations. The feedback signal is generated real-time based on the difference between measured and reference power flow, enabling dynamic suppression of oscillations as they occur.
3Reliability
If traditional parameter design methods are used for power system stabilizers, then initial damping effect is achieved, but adaptability to system configuration changes is reduced
Solution Approach 1:
The patent transitions from static, pre-configured stabilizer parameters to dynamic, real-time parameter adjustment. The control system continuously updates suppression signals based on current operating conditions by performing spectral analysis on measured power flow data. This dynamic approach allows the system to adapt to changing system configurations, loading conditions, and oscillation modes without requiring manual reconfiguration or retuning of stabilizer parameters.
Solution Approach 2:
The system performs preliminary identification of oscillation modes and suppression signal generation before oscillations become problematic. By continuously monitoring power flow and maintaining a library of suppression strategies for different oscillation modes, the system is prepared to respond immediately when oscillations are detected, rather than requiring time-consuming analysis and configuration changes when problems arise.
Data Source
AI summary
A method, apparatus and system for suppressing low frequency oscillation in a power system. The method includes determining a system transfer function of an interconnected power system section in which a variable frequency transformer (VFT) is located; determining a damping controller parameters according to the system transfer function; and suppressing low frequency oscillation of the power system by means of the VFT based on the damping controller parameter. The objects of the method, apparatus and system are definite: optimizing the damping controller parameter can be achieved by simply tracking and analyzing the response of the system to disturbance, without the need to understand the configuration and parameters of the system or solve complicated power system equations, which has a better effect in suppressing low frequency oscillation in the power system and is advantageous for improving the safety and stability level of the power grid.