PLC and LTE Interconnect for State Estimation in Distribution Grids

1 WSPLC15 PLC-LTE, 21.9.2015, Klagenfurt, Austria Project Grant agreement number: 619437 Radovan Sernec, TS

PLC and LTE Interconnect for State

Estimation in Distribution Grids

Radovan Sernec, Uros Droftina, Telekom Slovenije

Jurij Jurse, Elektro Primorska

Ziga Hribar, Bojan Milicic, Elektroservisi

Nermin Suljanovic, University of Tuzla


… or …

Why do we need advancedPLC comms in future

distribution smart grids?


Outline

1. Problem statement and objectives

2. State estimation background information

3. Measurements

4. Proposals & conclusion


Problem statement

1. Environment: distribution smart grid.

2. Configuration: dense network of distributedenergy generators (PV, wind, CHP) and activeconsumers (prosumers).

3. Current state: Virtually no real time measurabledata in distribution grid. Real time measurementmostly in main MV supply substations.

4. Goal: Observe whole (MV and LV) distributionpower grid behaviour in real time.

5. Solutions: Use state estimation as a tool towardsgoal.


Objectives

O2.1: Evaluation of existing DSO smart distribution grid communication solutions for converged networking in NAN/WAN with utility & telecom.

O2.2: Use of PLC comms and find optimal combinationwith other communication technologies for stateestimation in distribution grids.

O2.3: Aggregation of measured data via cellular/mobile 4G - LTE comms network.


State estimation for observability


Observability requirements

1. High number of phasor measurement units - PMU WAMS nodes is required for observable, distribution smart grid.

2. Alternatively, lower number of PMU WAMS nodes coupled with pseudo measurements from smart meters.

3. Reporting period from smart meters: 1 to 15 min.

4. At least 10 measurement quantities (9 + 1 event)


Need for pseudo measurements?

1. PMU (phasor measurement units) are expensive. All measurements time synchronised < 1 sec reporting period

2. Smart meters are already or pending deployment. At consumer / customer node in power grid Low reporting period: several hours

3. Much lower operating costs for utility to achieve goals.

4. But… Require good enough high speed PLC communication.


Field trial setup: Observability at tr.st. level


New use for enhanced smart meter

1. Decrease reporting period in real time 15 min, 1 min

2. Combine measuremenets in central PLC concentrator.

3. Relay in real time pseudo measurements via mobilenetwork, 4G LTE to utility network management.


Measurement setup

1. Lab tests

2. Equipment 34 smart meters (Landis+Gyr, IskraEmeco) PLC concentrator, G3 (Landis+Gyr) LTE modem/router (RUT550) Spectrum analyser (Tektronix)

3. No noise environment to establish comms upperbound

4. Noise environment, with Z = 0, to establish comms capabilities under poor SNR conditions


Measurement setup: S.m. - PLC c. II PMU WAMS - LTE


PLC comms setup

1. Up to 34 smart meters per single PLC concentrator

2. 10 measurement quantities

3. Reporting periods 15 min 10 min 5 min 3 min < 3 min not successful


Lab setup: Smart meters - PLC concentrator


Lab setup: PLC over LTE


Low noise environment


Low noise environment: PLC = ON


PLC comms preliminary results

1. Theoretically acheivable 1 min reporting period

2. Reality: > 2 min, for 34 meters Control sw overhead

3. High success rate on 1st transmission > 99 % (based on a sample of > 20.000 transmissions) 0,4 % in 2nd and 0,5 % in 3rd > 20.000 transmissions


Conclusions: PLC over LTE

1. LTE has enough bw for PLC concentrator uplink.

2. Ethernet port on PLC c. is used for modem/router-PLC c. interconnect.

3. Traffic from many PLC c. can be aggregated via singleLTE modem/router.


Conclusions: PLC for low reporting periods

1. Viable communication option

2. Needs sw adjustments in smart meter, PLC c., management sw

3. Sw was not designed for such purposes

4. Can be used for gathering real time pseudomeasurements for distribution grid state estimation.

5. New services will emerge that require real time PLC communication, e.g. 1 min gathering of gridobservability measurements.

Example: Per transformer station 200 smart meters for billing& 10 smart meters for 1 min grid observability reporting.


Proposals for enhanced PLC comms in smart meters

1. Reliable low reporting period communication << 1 min

2. Compound data packet of several measurementquantities

U, I, P, Q, cos, U, energy

3. Time stamp compound data packet

4. Allow for frequent time synchronisation NTPv4, IEEE1588v2 GPS option


We need something like this, but in PLC(Line coupling not included)

1. WiFi hot spot

2. MIMO capable (.n)

3. ARM processor integrated + 10 bit ADC + PWM + IO

4. < 3 € subsystem in low qty.

NOTE: WiFi Phy & MAC processing >> compute DSP mathintensive compared to post G3 PLC!


Acknowledgements

The laboratory and field trials are supported also by

Landis&Gyr smart meters and PLC equipment.

Their help and technical discussions is fully appreciated.


PLC and LTE Interconnect for State

Estimation in Distribution Grids

Uros Droftina, Radovan Sernec, [email protected]

Jurij Jurse, [email protected]

Ziga Hribar, Bojan Milicic, [email protected]

Nermin Suljanovic, [email protected]


Q & A


BACKUP SLIDES


Distribution power grid: Today


Smart distribution grid 1: Denser tomorrow


Smart distribution grid 2: Observability


Comms requirements: Protocols

1. IPv4 and IPv6

2. MPLS, GRE

3. Remote management: SNMPv3

4. IEC 61850-90-5 (Synchrophasor per IEEE C37.118)

5. Transparent to other IEC 61850 protocols

6. Clock synchronisation options, hw + sw solutions SNTPv4 In PMU today NTPv4 IEEE 1588v2 (IEC 61588) MAC must support it GPS


Time synchronisation: NTP realities

1. Jitter per node > 1 ms (example at Kromberk location). Max > 19 ms during 4 week observation

2. May influence WAMS node measurement errors.

3. Other approaches: IEEE1588v2, GPS.

Documents

PLC and LTE Interconnect for State Estimation in Distribution Grids