System with a merging unit for variably controlling and synchronizing sampling frequency of a secondary converter
A system with a merging unit for variably controlling and synchronizing a sampling frequency of a secondary converter is provided. The system facilitates the setting of sampling frequencies according to the types of various voltage/current transformers and stably collects sampling outputs of different sampling frequencies of various voltage/current transformers without collisions. The system for variably controlling the sampling frequency includes: a secondary converter, which collects analog data from a first sensor and converts the analog data into digital data; and a merging unit which collects analog data from a second sensor and converts the analog data into digital data while collecting the output of the secondary converter.
1 . A system for variably controlling and synchronizing a sampling frequency, the system comprising:
a secondary converter configured to collect first analog data from a first sensor and convert the first analog data to first digital data; and
a merging unit configured to collect second analog data from a second sensor and convert the second analog data to second digital data while collecting an output of the secondary converter,
wherein the secondary converter includes:
a first analog/digital (A/D) converter configured to perform A/D conversion on a measurement sample signal for measuring a current state of a voltage transformer (VT) or a current transformer (CT) to generate the first digital data;
a second A/D converter configured to perform the A/D conversion on a protection sample signal based on a measurement range set according to equipment protection standards for the VT or the CT to generate the first digital data;
a multiplexer configured to selectively collect an output of the first A/D converter and an output of the second A/D converter and transmit the collected output to the merging unit; and
a buffer configured to perform buffering on a latter output among the output of the first A/D converter and the output of the second A/D converter and transmit the buffered output to the multiplexer, and
wherein the first A/D converter and the second A/D converter divide a reference clock synchronized with a reference signal to generate the sampling frequency, and perform redistribution to be synchronized with an AC synchronization signal when a reference clock frequency is not a multiple of the sampling frequency, the AC synchronization signal being an AC signal used in at least one of the first sensor or the second sensor.
2 . The system of claim 1 , wherein the first A/D converter performs the A/D conversion on the measurement sample signal with the sampling frequency transmitted from the merging unit.
3 . The system of claim 1 , wherein the second A/D converter performs the A/D conversion on the protection sample signal with the sampling frequency transmitted from the merging unit.
4 . The system of claim 1 , wherein the buffer stores the latter output when the output of the first A/D converter and the output of the second A/D converter collide, and the output stored in the buffer is sent to the multiplexer and transmitted to the merging unit after data of the first output is collected in the multiplexer and transmitted to the merging unit.
5 . The system of claim 4 , wherein, in the buffer, data to be output first is selected according to a priority set by a user when the output of the first A/D converter and the output of the second A/D converter are output with completely the same time clock.
6 . The system of claim 1 , wherein the first A/D converter and the second A/D converter perform the A/D conversion in synchronization with a reference signal transmitted from the merging unit.
7 . The system of claim 1 , wherein each of the first sensor and the second sensor includes at least one of the VT or the CT.