Frequency Estimation in Power Systems Using Multi-Node Merging
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current frequency estimation methods in three-phase power systems are inefficient due to high computational complexity and inaccuracies in unbalanced conditions, particularly when dealing with non-circular signals and harmonics, which can lead to incorrect frequency calculations and system instability.
Innovation Solution
A method that determines the current frequency of an electrical signal by combining information from multiple nodes in a network, using a widely linear filter and state space models to account for both the signal and its complex conjugate, thereby improving accuracy and reducing computational complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If frequency is determined from each of the three signals in a three-phase system, then measurement precision is improved, but device complexity increases due to high computational complexity
Solution Approach 1:
The patent combines frequency estimation results from multiple nodes (at least two nodes) to produce a current combined function for frequency estimation. This merging approach improves measurement precision by utilizing information from multiple sources while distributing the computational burden across nodes, thereby reducing the complexity burden on any single processing unit.
Solution Approach 2:
The system segments the frequency estimation task across multiple nodes in the network. Each node independently determines frequency from local measurements and shares results with other nodes. This segmentation allows parallel processing of frequency estimation, reducing the computational complexity burden on any single node while maintaining high measurement precision through combination of results.
2Ease of operation
If standard complex linear adaptive filters are used for frequency tracking, then ease of operation is improved, but measurement precision deteriorates due to modelling error from negative sequences in unbalanced conditions
Solution Approach 1:
The patent employs a composite estimation approach that combines results from multiple nodes, each using adaptive filtering. This composite method integrates multiple estimation functions (including both linear and conjugate components) to create a more robust frequency estimation that maintains algorithmic simplicity while improving accuracy in unbalanced conditions by compensating for individual filter limitations.
Solution Approach 2:
The system uses feedback from multiple nodes where each node determines frequency from local measurements and shares this information with other nodes. The current combined function is determined based on frequency estimates from at least two nodes, creating a feedback mechanism that improves measurement precision by allowing each node to correct for its own modelling errors using information from other nodes.
3Productivity
If frequency estimation is performed in real-time to detect system imbalances and faults, then productivity is improved, but reliability may worsen due to incorrect frequency estimates from harmonics and non-circular signals
Solution Approach 1:
The patent merges frequency estimation results from multiple nodes to produce a combined frequency estimate. This combining approach improves reliability by reducing the impact of harmonics and non-circular signal effects on any single node, as the aggregation of multiple independent estimates provides a more robust result that better withstands adverse signal conditions while maintaining real-time response capability.
Solution Approach 2:
The system implements feedback where frequency estimates from multiple nodes are continuously exchanged and combined. This feedback mechanism enhances reliability by allowing the network to detect and correct erroneous estimates caused by harmonics or non-circular signals, as incorrect estimates from one node can be compensated by accurate estimates from other nodes, maintaining both real-time response and high reliability.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A method and an apparatus for estimating a frequency are disclosed. In one method, the frequency of an electrical signal at a node in an electrical system having a plurality of nodes is estimated. The method comprises determining a current function indicative of the one or more properties of the electrical signal at the node at the current instant in time in accordance with at least one determined property of the electrical signal at the node at the current instant in time, a previous function indicative of the one or more properties of the electrical signal at the node at a previous instant in time, and a function of the error in the previous frequency estimation. A current function indicative of one or more properties of an electrical signal at the at least one other node at the current instant in time is received from at least one other node of the plurality of nodes. The current function indicative of one or more properties of the electrical signal at the node and the current function indicative of one or more properties of the electrical signal at the at least one other node are then combined to produce a current combined function indicative of one or more properties of the electrical signal at the node at the current instant in time. Finally, a current frequency of the electrical signal at the node is estimated in accordance with the current combined function.