DSP-based digital integrator
A key component enabling smart-grid power analytics is the integrator, which detects the 50- or 60-Hz rms-current from a current sensor device, such as a Rogowski coil. The advantage of a Rogowski coil is the current can be measured without having to make an incision onto the power cable, as it is normally being done when using current transformers (CT).
A DSP-based digital integrator performs better than an analog-based integrator in low frequency noise rejection, minimum phase error over the entire frequency band, and providing wide dynamic range.
Power line communication (PLC)
PLC is the preferred method for service providers to communicate with the electric meters installed at the remote sites because the advanced metering infrastructure only requires a moderate data rate to service a large number of residences and businesses. One of the biggest concerns is interference with other wireless networks.
The number one advantage that DSP-based PLC designs have over other implementations, such as an application-specific integrated circuit (ASIC), is that standards vary from country to country, so it is crucial to have a design that supports many different formats and protocols.
Accurate measurements of electrical systems are essential to the development and stability of the smart grid. These measurements are used to detect symptoms of poor power quality in the grid. Phenomena can lead to false tripping of relays, blown fuses, and failure of electrical equipment, among other problems. Moreover, identifying and eliminating poor power quality can lead to a significant reduction in revenue waste.
Electric metrology involves the measurement of parameters such as rms current and voltage, reactive, active and apparent power components and the frequency of a power signal. Often, the calculation of these metrology parameters involves the use of several multiply-and-accumulate operations.
More applications are now requiring higher precision and faster response times meaning a floating-point DSP is better suited for the task.
A power-quality monitor system must be capable of detecting abnormalities such as voltage swells and dips, surges and transients, short interruptions, and harmonics. The presence of harmonics can lead to overheated transformers, false tripping of relays and even lighting flicker detectable by the human eye. One method of identifying the harmonics present in a power signal is through the use of discrete fast-Fourier transforms (DFT) or FFT.
When an FFT or DFT is applied to the input power signal, its output can be used to identify the different frequencies that are present in the input signal. A DSP is very efficient at performing FFTs and DFTs due to its specialized multiply-and-accumulate instructions.