Coordinated Voltage Control for Power Grid Stability
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Solution Overview
Problem
Existing power grid systems face challenges in maintaining optimal voltage control and minimizing interactions between voltage control modules, which can lead to system instability and increased costs due to inefficient reactive power distribution.
Innovation Solution
A method of coordinated voltage control using On Load Tap Changers and Automatic Voltage Regulators, employing a Proportional-Integral-Derivative control algorithm to regulate voltage across turbo generators, adjust set points with a correction coefficient, and balance reactive power load rates, while limiting reactive power exchange with the grid through a flow rate parameter and OLTC control mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple voltage control modules are deployed across different substations, then voltage control coverage is improved, but interaction and instability between modules increases
Solution Approach 1:
The patent segments the voltage control system into hierarchical levels (transmission level and distribution level) with independent control modules at each level. Each substation's voltage control module operates semi-autonomously within its designated voltage range and authority, reducing cross-interactions while maintaining comprehensive coverage across the power system.
2Loss of energy
If reactive power distribution is optimized across the grid, then system efficiency is improved, but control complexity increases
Solution Approach 1:
The patent implements dynamic reactive power optimization where control parameters, setpoints, and authority distributions are adjusted in real-time based on system conditions. The voltage control modules dynamically adapt their operating ranges and coordination strategies according to load conditions, generation availability, and system state, enabling efficient reactive power distribution without requiring overly complex static control structures.
3Extent of automation
If voltage control authority is distributed across multiple substations, then system autonomy is improved, but coordination difficulty increases
Solution Approach 1:
The patent divides voltage control authority into distinct segments with clear boundaries between transmission-level and distribution-level substations. Each segment operates with defined autonomy within its voltage range and operational scope, while hierarchical coordination protocols manage interactions between segments, reducing overall coordination complexity despite distributed autonomy.
Solution Approach 2:
The patent introduces a hierarchical dimension to voltage control coordination, organizing substations into multiple levels (transmission and distribution) with different control authorities. This dimensional organization transforms the coordination problem from a flat, complex multi-substation interaction into a structured hierarchical system where coordination follows clear vertical and horizontal protocols across levels.
Data Source
AI summary
A method and apparatus of coordinated voltage control for electric power systems with at least two substations and at least one load, a method of controlling distribution of reactive power between substations within a power system of similar parameters, and a method of reduction of interaction between voltage control modules in the said power system are disclosed. The purpose of coordinated control is to maintain acceptable voltage with minimal deviation from the set point across all elements of the power system. Disclosed coordinated control is accomplished via each substation's transformers equipped with on load tap changers (OLTC) and electrical generators Automatic Voltage Regulators (AVR) using proportional-integral-derivative control embedded in coordinated master controllers. The purpose of controlling the distribution of reactive power is to minimize power losses, maintain each busbar voltage in accordance to selected set point, maintain active and reactive power reserves, and minimizing the reactive power drawn from the transmission system by manipulating transformer's OLTC, generator's AVR, and energizing capacitors and inductors. Control of reactive power flow through the network is accomplished by the following steps:Sensing and measuring active and reactive power flow rates, and all controlled busbars voltages.Computing each voltage/reactive power controller set point and controlled variable.Using PID algorithm to compute each controller output to maintain network voltages and reactive power flows in accordance to defined set points.Implementing control actions based on computed output values.Finally, reducing the interaction between various voltage control mechanisms. It is important to ensure smooth system operation. This is accomplished by counteracting potentially destabilizing interactions between high and low level substations and corresponding control modules using specialized set point correction coefficients.