Energy efficiency strategy in public electric transport an implemented practical case of a trollleybus operator in Gdynia Marta Woronowicz, Mikołaj Bartłomiejczyk (PKT GDYNIA)
THE CITY OF GDYNIA AND ITS PUBLIC TRANSPORT FACTS OVERVIEW One of the three cities (together with Gdansk and Sopot) forming 1 million inhabitants Tricity agglomeration on the Baltic Sea coast in the north of Poland 250.000 inhabitants Length of public roads: ca. 400 km Length of public transport routes: ca. 250 km Motorization rate: 500 cars/ 1000 inhabitants Transport modes market share: 56%/43% individual transport and public transport; only ca. 1% covered by cycling
2014 EU REGIOSTARS AWARD for Gdynia trolleybus transport GDYNIA: Very good quality of public transport services managed by Gdynia Public Transport Authority 2013 UITP AWARD for excellent public transport organization 4 municipal public transport operators ( 2 bus, 1 long distance bus and 1 trolleybus operator) and 3 private bus operators 77% of all Gdynia inhabitants live within a 5 min. walk from a bus/trolleybus stop - districts very well connected by PT
GDYNIA TROLLEYBUS TRANSPORT FACTS 12 day trolleybus lines 93 trolleybuses (75 trolleys in daily operation) 90 km of trolleybus traction mileage of over 5 milion vehicle km a year 385 employees, incl. 250 drivers only 3 trolleybus cities in Poland (Gdynia, Lublin, Tychy) 15 in the past ELECTRIC vs DIESEL PT MARKET SHARE Trolleybus transport covers ca. 30% of the whole public transport in Gdynia and neighbouring spa resort city Sopot (which does not have poblic transport of iits own), mainly in central areas of both cities.
Regular off traction courses by trolley battery hybrids - an innovation introduced by CIVITAS DYN@MO and ELIPTIC project Line 21 a line extended by 2 km to a Gdynia landmark street Skwer Kościuszki - runs from May 2015 - DYN@MO Line 29 a line extended by 4 km to Fikakowo densely populated housing estate - runs from December 2016-ELIPTIC Automatic lowering and raising of current collectors due to special devices docking stations placed on the overhead grid
Origins of trolley battery hybrids in Gdynia In 2008 - PKT s preparation to the fleet modernization co-financed by EU funds Basic requirement auxiliary drive allowing for autonomous operation in trolleybuses Diesel drive long distatance flexibility popular solution Battery promising technology zero emission easy maintenance ( all electric ) Decision makers
Battery drives currently used in Gdynia trolleys Ni-Cd battery capacity: 6-16 kwh range: 3-5 km no of vehicles: 41 Li-Ion battery capacity: 27 i 69 kwh range: ok.15 i 30 km no of vehicles: 3 + 3 LiFePO4 battery capacity: 40 kwh range: ok. 20 km no of vehicles: 1
Energy efficiency strategy and solutions introduced Optimised braking energy recovery in the trolleybus network due to: implementation of a dual power supply system in the trolleybus grid installation of an energy storage supercapacitor on one of the substations ongoing procurement of the state-of-the art trolleybuses and gradually heading to 100% energy recuperation system equipped fleet
Optimised braking energy recovery in trolleybus network - use cases implemented Trolleybus network is supplied by 10 traction substations Substations power: 13,6 MVA Network voltage: 600 V Substation in Sopot One of the substations (Wielkopolska) is equipped with braking energy supercapacitor a storage device which captures and stores unused braking energy and saves ca. 12% of energy on this network section
Wielkopolska Substation - location of a supercapacitor energy bank This substation was predisposed for supercapacitor installation due to the hilly terrain of the power supply area there are more occurrences of trolleybuses braking and giving recuperative energy back to the traction network. Supercapacitor catches this energy and stores it for later use by other trolleybuses.
Results recuperation of energy in 2017 in vehicles before and after SC installation
Supercapacitor technical data Nominal input voltage Max. input current General data 600 V DC 500 A Max. input power 400 kw/20 s. Data of SC bank The range of voltage during operation Max. current Capacitance Energy capacitance 187-375 V 1000 A 104.15 F 1.56 kwh Number of modules 15: 5 branches x 3 modules The range of voltage during operation 187-375 V
Optimised braking energy recovery in trolleybus network use cases implemented Power is centrally managed from 24 h Substations Control Centre placed in one of the substations (Redłowo) Further optimization of the network introduced within ELIPTIC project: Smart grid in practice implementation of bidirectional (dual) energy supply in two spots of Gdynia trolleybus network
Optimised braking energy recovery in trolleybus network Billateral supply increasing energy recuperation by optimizing energy balance in the network An improved way of recuperated energy flow by balancing it and levelling off voltage drops - currently on 2 places of the network: bilateral supply links 2 pairs of substations: Sopot & Sopot I and Grabówek & Dworzec
Smart grid in practice implementation of bidirectional energy supply in Gdynia trolleybus system - results Unilateral supply Sopot Sopot I Bilateral supply Recovery effectiveness 2,5% 10% Transmission losses 4,6% 3,2% Voltage drops <550 V 0,23% 0% Voltage drops <500 V 0,01% 0% Dworzec - Grabówek Recovery effectiveness 19% 22% Transmission losses 11,2% 7,1% Voltage drops <550 V 0,93% 0,01% Voltage drops <500 V 0,38% 0,09%
Smart grid in practice implementation of bilateral energy supply in Gdynia trolleybus system Grabówek - Dworzec Improved spread of voltage Grabówek Dworzec Sopot Sopot I Sopot connection Sopot Reja connection
Main findings: Bilateral supply system and supercaps on substations bring positive energy management and savings results Reduction of energy consumption (2 5 % - dual power supply and ca. 12 % - supercapacitors) Reduction of voltage drops balancing the grid Plans for extending these solutions to further spots on the network Gradual phase out of trolleys without energy recuperation systems and replacing them with state-of-the art. vehicles with best available battery cells (by the end of 2020 ca. 100% of vehicles with regenerative braking and 65% of trolley hybrids)
Why In Motion Charging is the best solution for us? Traffic congestion problem for stationary charging Stationary charging: losing time for charging Traffic congestion: arrival delay not enough time to charge in stationary charging IMC: better time usage better flexiblity Time is money! IMC no problem with delays! Delay arrival not enought time to fully charge
Why IMC? IMC: way of reducing of battery capacitance ebus IMC
How much infrastructure do we need? Energy balance of In Motion Charging Energy consumption Length of off-wire distance Discharging efficiency Charging power Time of ride in wire mode Charging efficiency
How much infrastructure do we need? Minimal covering rate by overhead wires
Distance covered Energy consumption in short and all day period scale Energy consumption in short scale: minimall battery capacitance Energy consumption in long scale: charging power
Requirements for vehicles Vehicle equipment - facts Bigger battery capacity greater costs Charging power: bigger power faster charging less infrastructure but charging power is limited by: Infrastructruce (OHL, supply system): 50 500 kw Current collectors: 250 300 kw, but it could be better Charging DC/DC converter the main limitation (150 kw?)
Requirements for vehicles Issue of charging power Charging power according max short time energy consumption Lower charging power not enough time to fully charge Charging power according max all day energy consumption Lower charging power deeper discharge
Perspectives Tips for future: Improvement of DC/DC power converter now 150 kw, future:? Impovement of current collectors: now 600 A, future 1000 A? Ideal for ebrt
PLANS FOR THE NEAR FUTURE -photovoltaic power plant on the roof of the depot (5000 m2, 500 kw, 5% of solar power in the traction network) -new Solaris fleet coming this year - 30 trolley battery hybrids (16 of 18M and 14 of 12M) -6 in-motion charged e-buses to be purchased in 2019 -exchange of Ni-Cd batteries in 21 trolleys - further line extensions already approved by Public Transport Authority
Tips for future: mini inverter station:
Tips for future: PV system + double supply smart grid
Thank you for your attention! Marta Woronowicz Mikołaj Bartłomiejczyk PKT Gdynia Emails: m.woronowicz@ pktgdynia.pl mikolaj.bartlomiejczyk@ pg.edu.pl