Power Network Synchronization via Kirchhoff Current Analysis
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Solution Overview
Problem
Existing synchronization techniques in electrical power networks, such as GPS-based and Ping-Pong methods, are costly and prone to mal-operation due to communication time delays, especially when GPS signals are lost or in switched networks, leading to inaccurate differential protection.
Innovation Solution
A method that calculates communication time delays by selecting a calculation node, calculating node currents from local and remote terminals, equating these currents to zero according to Kirchhoff's first law, and extracting the time delay from the equated sum, allowing for accurate synchronization and reducing errors in differential current calculations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If GPS-based synchronization is used, then synchronization accuracy is improved, but cost increases and reliability deteriorates when GPS signals are lost
Solution Approach 1:
The patent introduces an intermediary method (Ping-Pong technique) that uses communication between terminals to establish synchronization without relying on external GPS signals. The local terminal sends a synchronization request, the remote terminal responds with a timestamp, and the local terminal calculates the time delay based on the round-trip communication, thereby mediating the synchronization process independently of GPS.
Solution Approach 2:
The system performs self-synchronization by having terminals exchange timing information and calculate delays autonomously. Each terminal uses the communication timestamps received from the other terminal to compute the time delay and adjust its own timing, enabling the system to synchronize itself without external assistance.
2Reliability
If Ping-Pong synchronization method is used, then cost is reduced and GPS signal loss is handled, but communication time delays cause mal-operation
Solution Approach 1:
The patent replaces the traditional mechanical/time-based synchronization approach with an electrical signal-based method. By using current samples and Kirchhoff's current law, the system substitutes physical time measurement with electrical signal analysis, where the sum of currents at a calculation node is used to directly determine communication time delays without relying on timestamp exchanges.
Solution Approach 2:
The patent changes the parameter used for synchronization from time stamps (in Ping-Pong method) to current samples. By analyzing the phase and magnitude of current samples at the calculation node and applying Kirchhoff's current law, the system extracts time delay information from the electrical domain rather than the time domain, improving accuracy under communication delays.
3Device complexity
If traditional synchronization methods are used, then device complexity is reduced, but measurement precision of time delay deteriorates
Solution Approach 1:
The patent makes the existing protection system multi-functional by using the same current samples and calculation nodes for both protection calculations and time delay measurement. The calculation node, already necessary for differential protection, is additionally used to measure communication time delays by analyzing current sums, thereby achieving dual functionality without adding separate synchronization hardware.
Solution Approach 2:
The protection system performs its own synchronization function by utilizing its existing current measurement capability. The same current samples used for differential protection calculations are also used to determine communication time delays through Kirchhoff's current law analysis, allowing the system to self-synchronize without external synchronization equipment.
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
This method provides accurate synchronization, reduces errors in differential current calculations, and ensures reliable operation of differential protection schemes by accounting for communication time delays, thereby enhancing the reliability of fault detection in electrical power networks.
Implementation Method 1
equating, in respect of the or each remote terminal, a sum of node currents flowing into the corresponding calculation node to zero according to Kirchhoff's first law
Data Source
AI summary
A method of determining a communication time delay in a communication network between a local terminal and one or more remote terminals within an electrical power network includes: selecting, in respect of the or each remote terminal a calculation node in the electrical power network; calculating respective node currents flowing into the corresponding calculation node from the local terminal and the or each remote terminal; equating, in respect of the or each remote terminal, a sum of node currents flowing into the corresponding calculation node to zero according to Kirchhoff's first law; and extracting, in respect of the or each remote terminal, a communication time delay between the local terminal and the said respective remote terminal from a corresponding equated sum of node currents.