Len Schaller Prepayment (Smart Payment) Technology Manager, South Africa

Transcription

1 Len Schaller Prepayment (Smart Payment) Technology Manager, South Africa

2 PLC Technology in Metering: Challenges of and Solutions to Communicating into the customer home Agenda 1. What is split metering? 2. What MCU to CIU communication technology options exist? 3. What are the challenges in the PLC environment? 4. A journey to a solution 5. Conclusion

3 Integrated vs Split Metering Integrated meter: Metrology, switch, keypad and LCD all in one housing. Meter must be installed where consumer has access, to allow token entry. Integrated Meter Split meter: Metrology and switch in a housing (MCU). Keypad and LCD in a separate housing (CIU). Communication link required between MCU and CIU. Only the CIU is in consumer premises MCU is out of reach of consumer in utility controlled area, in a secure enclosure. Split Meter

4 MCU to CIU Communication Options Hard wired Low cost Point to point (Low risk of interference) Polarity independent Can be extended range >150m Requires dedicated pilot wires in addition to the mains conductors to the load/installation (extra cost)

5 MCU to CIU communication options RF Multiple technologies available Point to point Meshed Multiple protocols available Proprietary (normally for point to point) Zigbee WiFi/WiMax Bluetooth Susceptible to environmental and external interference Radio Frequency regulations vary per area Power requirements can be high to achieve desired range

6 MCU to CIU communication options PLC Multiple modulation technologies available Frequency Shift Keying (FSK) Phase Shift Keying (PSK) Orthogonal Frequency Division Multiplexing Differential Code Shift Keying Multiple protocols available Proprietary Prime 3G ITU G.9955 IEEE1901.2

7 Challenges to Using PLC Mains power cables are designed for power transfer not digital communications Optimised for 50Hz-60Hz operation Non linear attenuation characteristics Appliances connected to the mains network influence impedance Triac based light dimmers and motor controls introduce switching noise typically at 2x line frequency (cyclostationary noise) Switch mode power supplies and AC/DC to DC converters can inject noise onto the mains. Loads switching on and off introduce sporadic noise

8 Challenges to Using PLC Source: Noise and multipath characteristics of power line communication channels Hasan Basri Çelebi University of South Florida

9 Challenges to Using PLC Source: Noise and multipath characteristics of power line communication channels Hasan Basri Çelebi University of South Florida

10 Challenges to Using PLC Source: Noise and multipath characteristics of power line communication channels Hasan Basri Çelebi University of South Florida

11 Challenges to Using PLC Source: Noise and multipath characteristics of power line communication channels Hasan Basri Çelebi University of South Florida

12 Challenges to Using PLC Setting up for field measurements Burnt red phase-out from the meter

13 Challenges to Using PLC Measurement at a rural site Measurement at a block of flats in an urban environment

14 Toward a Solution Factors to bear in mind Regulations demand very low output levels for PLC (EN ) Metering specifications have strict limits on the power burden a meter may present to the network (IEC ) The cost of the solution is paramount to make it affordable in the prepayment meter environment Interference to other technologies and spectrum users such as radio amateurs must be avoided Bandwidth requirements are not so high for metering, but reliability of the communication link is critical

15 Toward a Solution Single carrier vs Multi Carrier Single carrier is susceptible to narrow band noise and cyclostationary impulse noise Single carrier is lower cost and generally has lower power requirements than multi carrier Multicarrier is more complex to implement and is generally more costly then single carrier Multicarrier offers significant advantages in the face of impulse noise Multicarrier offers great opportunities for exploiting the advances in digital signal processing to aid robustness and data throughput

16 Toward a Solution Analogous representation of S-FSK vs OFDM First Generation PLC Latest Generation PLC

17 Toward a Solution

18 Toward a Solution

19 Conclusion The PLC environment has many challenges to effective communication for metering applications Impulse noise, both synchronous and asynchronous are significant challenges to overcome due to their dynamic nature and power content By using multi carrier technologies such as OFDM and exploiting the advances in DSP technology a cost effective and highly robust PLC solution can be implemented for the link between MCU and CIU