Point on Wave Switching Using Slow-Speed Controllers
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Solution Overview
Problem
Current point on wave (POW) switching systems require high-speed processing to avoid damaging reactive devices due to random switching, leading to transient disturbances and noise in electrical power systems, which can be stressful and damaging to equipment.
Innovation Solution
The system determines an implementation period and strategically issues a switch command at an integer multiple of implementation periods before the objective POW, accounting for processor delay, stack priority, and mechanical delay, allowing for accurate POW switching even with relatively slow-speed controllers, and is applicable to three-phase power systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high-speed processing is used to achieve accurate POW switching, then switching precision is improved, but system complexity and cost increase
Solution Approach 1:
The system determines the implementation period in advance and strategically issues the switch command at an integer multiple of implementation periods before the objective POW. This preliminary timing calculation allows slow-speed controllers to achieve accurate POW switching without requiring high processing speeds, as the command is issued at the optimal moment considering all delays.
2Object-affected harmful factors
If high-speed processing is used to achieve accurate POW switching, then transient disturbances are reduced, but processing cost and complexity increase
Solution Approach 1:
By calculating the implementation period that accounts for processor delay, stack priority, and mechanical delay in advance, the system issues the switch command at the optimal timing (integer multiple of implementation periods before objective POW). This ensures switching occurs at the precise moment needed to minimize transient disturbances, over-voltage transients, and inrush currents without requiring high-speed processing hardware.
3Device complexity
If slow-speed controllers are used for POW switching, then system cost is reduced, but switching accuracy deteriorates
Solution Approach 1:
The system determines the implementation period in advance, which represents the number of processor cycles between issuing the switch command and when the switch command is completed. By issuing the command at an integer multiple of implementation periods before the objective POW, the system compensates for the slow processing speed and achieves accurate switching at the desired point on the wave.
Solution Approach 2:
The system accounts for processor delay, stack priority, and mechanical delay when determining the implementation period. This feedback mechanism allows the system to calculate the optimal command issuance timing that compensates for known delays in slow-speed controllers, maintaining switching accuracy despite reduced processing speed.
Data Source
AI summary
An intelligent electronic device (IED) may provide point on wave switching. The IED may receive a control operation request, and determine when to issue a control command to cause a switch to change positions. The actuation of the switch may occur at a target point on an alternating current. An IED may have a processor that is too slow to implement a switch when a desired point on an alternating current first occurs. Accordingly, some embodiments may compensate for the processing speed of an IED by determining a number of processor cycles needed (in advance) to issue a control command so that the resulting action results in the desired point on wave open or close.