Switchgear Priority Control for Grid Frequency Load Shedding
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Solution Overview
Problem
Current power distribution systems face challenges in managing sudden changes in power supply and demand, leading to potential system power outages due to simultaneous operation of under frequency relays and over frequency relays, and planned power outages may not be timely in cases of unexpected supply and demand fluctuations.
Innovation Solution
A power distribution system with a power system operating system that sets unique operation conditions for switchgear units based on priority orders assigned to power distribution areas, allowing for controlled power supply cutoffs when frequency thresholds or change rates are exceeded, thereby preventing simultaneous switchgear unit operation and minimizing power outages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If set values for under frequency relays in multiple substations are set to be the same, then the response to frequency reduction is uniform, but loads are shed simultaneously causing power supply to exceed demand and triggering over frequency relay operation
Solution Approach 1:
The patent applies local quality by setting different operation set values for under frequency relays in different substations based on their local characteristics and priority levels. Instead of using a uniform set value across all substations, each substation is configured with customized set values that reflect its specific role and importance in the power system, thereby preventing simultaneous load shedding while maintaining system stability.
Solution Approach 2:
The patent segments the power distribution system into multiple priority groups with different operation set values. By dividing substations into distinct segments with hierarchical priority levels, the system ensures that load shedding occurs in a controlled sequence rather than simultaneously across all areas, preventing the power supply excess condition that triggers over frequency relay operation.
2Ease of operation
If planned power outage is performed by dividing power distribution area into groups, then systematic load management is achieved, but unexpected supply and demand tightness due to disaster may not be responded to in time
Solution Approach 1:
The patent implements dynamics by making the under frequency relay operation set values adjustable and modifiable based on real-time system conditions. The set values are not fixed but can be dynamically changed according to the current power supply and demand situation, allowing the system to respond quickly to unexpected tightness caused by disasters while maintaining the structured approach of grouped power distribution areas.
Solution Approach 2:
The patent applies parameter changes by modifying the operation set values of under frequency relays according to different operational scenarios. The set values can be adjusted to reflect changing system conditions, enabling both planned power outages under normal conditions and rapid response to unexpected tightness during disasters, thus resolving the contradiction between systematic control and response speed.
Data Source
AI summary
According to one embodiment, a power distribution system includes switchgear units. The switchgear units are interposed between a feeder and power distribution areas. Each of the switchgear unit cuts off a power supply path when a frequency of power on the feeder falls below the allowable frequency in a case where the allowable frequency has been set, cuts off the power supply path when a frequency change rate of power on the feeder exceeds the allowable frequency change rate in a case where the allowable frequency change rate has been set, and cuts off the power supply path when an elapsed time since a state in which the power supply path between the feeder and the power distribution area is to be cut off is formed exceeds the allowable response time in a case where the allowable response time has been set.