Power transmission and distribution (T&D) systems have evolved into vast interconnected power delivery networks that link multiple distributed power generators with different end user loads. A critical system requirement is to recover operation as quickly as possible whenever there is a fault condition that interrupts service. The system must monitor individual branches of the distribution grid, including overhead and underground power lines in urban and rural areas, and quickly locate a fault condition. This function, known primarily as fault indication (FI), and sometimes called line monitoring, faulting monitoring, or fault circuit indication, is growing because it is relatively easy to implement, achieves low cost, and requires little or no maintenance.
An FI system is composed of functional blocks such as energy harvesting, power management, processor, analog front-end (AFE) circuitry and communication interfaces. The most important requirements of an FI design are efficient energy harvesting and ultralow power consumption.
Design Considerations and Challenges
- Achieving very low power consumption (μA level) and meeting high efficiency for energy harvesting.
- Using a current transformer as both a sensor and a power source.
- Providing stable power delivery for the system by managing multiple power supplies and switching among them.
- Achieving long-term reliability over system lifetime while operating in a harsh field environment.
- Synchronizing wireless communication and networking while meeting low power.
The signal chain above is representative of a typical FI application design. The technical requirements of the blocks vary, but the products listed in the table on Page 3 are representative ADI’s solutions that meet some of those requirements.
ADI Solutions for Line Sensor and Fault Indicator Applications
ADI provides an integrated solution that implements a full signal chain, reduces design complexity, results in a small form factor, and achieves very low power consumption.
- A highly integrated ASIC implements efficient energy harvesting and manages multiple power sources, while reducing BOM cost and simplifying PCB design.
- Our solution achieves over 90% power conversion efficiency with optimized maximum power point tracking (MPPT).
- The low power op amp with a wide dynamic range and high slew rate supports Rogowski coil architecture and minimizes magnetic field interference with the current measurement accuracy.
- The high performance, ultralow power ARM® Cortex®-M3 processor provides a rich of set of peripherals and also supports security features that improve system safety and reliability.
- The integrated ISM band transceiver performs RF communication and supports sensor network protocol.
- Additional power supervision and voltage comparator solutions are available.
Analog Devices is the worldwide leader in mixed-signal processing technology and provides solutions for FI applications.
- ADI is an expert in energy measurement. Over half of all electrical grid equipment worldwide uses ADI converters.
- ADI enables ease of design, cost saving, and long-term system reliability by combining high integration with excellent system performance.
- ADI technology for energy harvesting and power management leads the industry.
- ADI offers precision signal measurement through highly accurate converters and amplifiers.
- A complete family of ADCs, processors, and wireless transceivers covers an entire ultralow power signal chain.
Main Products Introduction
|Part Number||Description||Key Features||Benefits|
|ADP5091||Ultralow power energy
|Input voltage: 80 mV to 3.3 V; fast cold start from 380mV; 150 mAregulated output from 1.5 V to 3.6 V;programmable voltage monitor ofcharging storage and backup cell battery||Boost regulator with maximum powerpointtracking; RFtransmission friendly|
rail-to-rail op amps
|Very low supply current: 13μA; low offset voltage:15μV maximum;offset voltage drift: 20 nV/C; VSUPPLY: 1.8 V to 5.5 V||Rail-to-rail input/output; unity-gain stable;extendedindustrial temperature range: −40°C to +125°C.|
|ADuCM302x||Ultralow power ARM
|Up to 26 MHz ARM Cortex-M3 core with 64 kB, 256kB flash, 4 kBcache; VSUPPLY: 1.8 V to 3.6 V; active < 38μA/MHz, hibernate < 750 nA;8-channel,1.8 MSPS, 12-bit SARADC; digitalcomparator; hardwarecrypto accelerator/CRC||Power supply monitor; LDO+ buck converter forimproved efficiency; user code protection; dynamic/SW clock and power gating|
|Ultralow power consumption ICC = 92 nA; voltage monitoring range:0.5 V to 4.63 V, ±1.3% threshold accuracy; optional watchdog timer||Manual reset input; active low, open-drainRESEToutput; power supply glitch immunity|
|ISM bands: 431 MHz to 435 MHz/862 MHz to 928 MHz; data ratessupported: 9.6 kbps to 300 kbps; VSUPPLY: 2.2 V to 3.6 V; automaticfrequency/gain control(AFC/AGC); 11.75μA autonomousRx sniff using smart wake mode(SWM)||Ultralow power sleep modes; digital received signalstrength indication(RSSI); highly linear/blocking/sensitivity; on-chip, 8-bitADC|
|ADCMP380||Ultralow power voltage
|Ultralow power consumption with ICC = 92 nA; enable input; 23μstypical propagation delay; open-drain type output||Comparator with on-chip reference;input glitch immunity|
|AD1582||Micropower, precisionseries modevoltage
|Low quiescent current: 70μA maximum;current output capability: ±5 mA; wide supply range: VIN= VOUT+ 200 mVto 12 V; wideband noise(10 Hz to 10kHz): 50μV rms||Patented temperature drift curvature correction design;industrial temperature range of −40°C to +125°C|
Reference Design/Demo Design
- EE-388, Power Optimization Guide for ADuCM302x Processors— www.analog.com/media/en/technical-documentation/application-notes/EE388v01.pdf
- EE-381, Using the ADuCM302x Processor Boot Kernel— www.analog.com/media/en/technical-documentation/application-notes/EE3881V01.pdf
- AN-1315, Autonomous IR Calibration on the ADF7024 www.analog.com/media/en/technical-documentation/application-notes/AN-1315.pdf
- AN-1317, Rolling Data Buffer on the ADF7024 www.analog.com/media/en/technical-documentation/application-notes/AN-1317.pdf