Forecasting daily gas off-take

FORECASTING DAILY GAS OFF-TAKE AT THE TRANSMISSION SYSTEM EXITS WHICH ARE ALSO THE ENTRIES INTO DISTRIBUTION SYSTEMS

Forecasting gas off-take is carried out by Plinacro, which, as the transmission system operator, has been appointed by the decision of the Agency to perform the tasks of the forecasting party.
The mathematical algorithm for calculating the forecasting of daily gas off-take at the transmission system exits, which are also the entries into distribution systems, is based on the study “Development of a unique standard consumption profile for non-daily metered custody metering points in the Republic of Croatia”, which was prepared for the Agency in 2017 by the Faculty of Mechanical Engineering, University of Maribor.
The mentioned study recommends that the dependence of daily gas consumption at distribution systems on the average daily air temperature for a gas day is described by a mathematical model of a function, the so called “sigmoid”. The sigmoid curve is slightly bent in the shape of the letter S and its characteristic is closest to the behaviour of temperature-dependent gas consumers with significant changes in consumption depending on the temperature in the middle part of the temperature range from -20°C to +30°C, and with almost constant amount in the area of extremely low and extremely high temperatures. The sigmoid function is already used to predict consumption in other member states of the Union (Germany, Slovenia).
Based on historical data on gas off-take by distribution systems and measured average daily temperatures, the mentioned study also calculates the parameters of the sigmoid model for 18 meteorological zones in the Republic of Croatia, assuming that the temperature dependence of consumption for all distribution systems in the same meteorological zone is equal (forecasting model parameter).
 

 
Figure 1 – a diagram of the sigmoid and the associated formula
 
Plinacro forecasts the daily off-take of each distribution system connected to the transmission system by including the standardized average daily gas off-take of the observed distribution system and the average daily temperature for a gas day, which Plinacro receives from the Croatian Meteorological and Hydrological Service (hereinafter: DHMZ), into the mathematical expression of parameter sigmoid that correspond to the meteorological zone (MZ) in which the observed distribution system is located. The list of 18 meteorological zones with corresponding exits towards the distribution systems and meteorological stations for metering and forecasting the temperature is given in the table below.

MZ	Transmission system exit	Meteorological station
MZ01	Bjelovar, Čepelovac- 2 bar - Čepelovac, Doljani - 3 bar – Doljani, Draganac - 4 bar – Draganac, Veliki Grđevac - 3 bar - Veliki Grđevac, Narta - 3 bar – Narta, Sirač - 4,5 bar - Kamenolom Sirač, Veliki Grđevac - 3 bar - Veliki Grđevac, Veliko Trojstvo - 3 bar - Veliko Trojstvo, Virje - 3 bar – Novigrad, Virje - 3 bar - Virje	Bjelovar
MZ02	Badljevina - 3 bar – Badljevina, Brezine - 3 bar – Brezine, Daruvar - 3 bar – Daruvar, Dobrovac - nova - 3 bar – Lipik, Dobrovac - nova - 3 bar - Poljoprivreda Lipik, Garešnica - 3 bar – Garešnica, Grubišno Polje - 3 bar - Grubišno Polje, Končanica - 3 bar – Končanica, Kukunjevac - 3 bar – Kukunjevac, Pakrac I - 3 bar – Pakrac, Pakračka Poljana - 3 bar - Pakračka Poljana, Sirač - 3 bar - Sirač	Daruvar
MZ03	Čabdin - 3,5 bar – Jastrebarsko, Karlovac - 4 bar - Karlovac	Karlovac
MZ04	Benkovac - 3,5 bar – Benkovac, Knin - 5 bar – Knin, Split - 3,5 bar - Split	Knin
MZ05	Bedekovčina - 3 bar – Bedekovčina, Dubrovčan - 3 bar – Dubrovčan, Klanjec - 3 bar – Klanjec, Konjščina, Konjščina - 25 bar - Zlatar Bistrica, Konjščina - 3 bar – Konjščina, Krapina - 3 bar – Krapina, Kumrovec - 3 bar – Kumrovec, Straža - 3 bar – Pregrada, Tuheljske Toplice - 3 bar - Tuheljske Toplice, Zabok - 10 bar - Donja Stubica, Zabok - 3 bar - Zabok	Krapina
MZ06	Gaj - 3 bar – Gaj, Gradec - 3 bar - Farma Gradec, Gradec - 3 bar – Gradec, Gradečki Pavlovac - 3 bar - Asfaltna baza, Haganj - 6 bar – Haganj, IP Kalinovac 5 - 3 bar – Sesvete, Kalinovac - 2 bar – Kalinovac, Koprivnica II - 6 bar – Koprivnica, Križevci - 3 bar – Križevci, Ladinec - 3 bar – Ladinec, Vrbovec - 6 bar – Vrbovec, Žabno - 3 bar - Žabno	Križevci
MZ07	Poreč - 4 bar – Poreč, Pula - 12 bar – Pula, Rovinj - 4 bar – Rovinj, Umag - 4 bar – Umag	Monte Cope
MZ08	Ogulin - 3 bar - Ogulin	Ogulin
MZ09	Kršan - 6 bar - Potpićan	Pazin
MZ10	Budrovac staklenici i - 2 bar – Staklenici Budrovac, Čađavica - 3 bar – Čađavica, Đolta - 3 bar - Sušare Đolta, Đurđevac - 2 bar – Đurđevac, Ferdinandovac - 2 bar – Ferdinandovac, Hampovica - 2 bar - Hampovica, Kloštar Podravski - 2 bar - Kloštar Podravski, Orahovica - 3 bar – Orahovica, Pitomača - 3 bar – Pitomača, Slatina, Suha žbuka - 4,5 bar - Suha žbuka, Suhopolje - 3 bar – Suhopolje, Virovitica - 6 bar - Virovitica	RC Bilogora
MZ11	Baranja, Belišće - 2,2 bar – Valpovo, Bokšić - 3 bar – Bokšić, Bokšić - 3 bar – Crnac, Čačinci - 3 bar – Čačinci, Donji Miholjac - 3 bar - Donji Miholjac, Đakovo,  Đurđenovac - 3 bar – Đurđenovac, Feričanci - 3 bar – Feričanci, Ivankovo - 3 bar – Ivankovo, 733 Magadenovac - 3 bar – Magadenovac, Marijanci - 3 bar – Marjanci, Našice grad - 3 bar – Našice, Negoslavci - 3 bar – Opatovac, Osijek, Viljevo - 3 bar – Viljevo, Vinkovci - 3 bar - Vinkovci i okolica, Vukovar	RC Osijek Čepin
MZ12	Rijeka Istok – 4 bar – Rijeka, Rijeka zapad - 16 bar – Rijeka, Rijeka zapad - 4 bar - Rijeka	Rijeka
MZ13	Kutina, Okoli - 3 bar – Okoli, Sisak - 6 bar – Sisak, Stružec – 3bar - Stružec	Sisak
MZ14	Donji Andrijevci - 3 bar - Donji Andrijevci, Ferovac - 3 bar – Pleternica, Nova Gradiška, Požega, Slavonski Brod - 3 bar - Sl. Brod, Strizivojna - 3 bar – Vrpolje, Županja - 3 bar – Gradište, Županja - 3 bar - Županja	Slavonski Brod
MZ15	Šibenik - 12 bar - Šibenik	Šibenik
MZ16	Cerje Tužno - 3 bar - Sela (IVKOM), Donje Međimurje - 12 bar – Prelog, Donje Međimurje - 3 bar - D.Dubrava, Gola - 3 bar – Gola, Ivanec - 3 bar – Ivanec, Legrad - 3 bar – Legrad, Međimurje, Novi Marof, Varaždin	Varaždin
MZ17	Biograd - 3,5 bar – Biograd, Zadar - 5 bar - Zadar srednji tlak	Zadar
MZ18	Dugo Selo, Ivanić Grad, Ivanja Reka - 6 bar - Iv. Reka, Sesvete, Jakovlje - 3 bar - Jakovlje, Sv. Ivan Zelina - 3 bar – Zelina, Zagreb, Zagreb zapad - 25 bar – Samobor, Zagreb zapad - 3,5 bar - Sv. Nedjelja, Zaprešić - 6 bar - Zaprešić	Zagreb Maksimir

 
In order to meet the provisions of BAL Regulation as regards information provision, the forecasting of daily off-take for gas day D will be carried out first time in the gas day D-1 and then it will be updated twice during the gas day D. Two mentioned forecast updates within the gas day D will be based on possibly modified forecast of average daily temperature for the gas day D delivered by the DHMZ.
In order to deliver to the transmission system users data on their expected off-take at the level of individual supplier in an individual balance group (hereinafter: SUPPLIER-BG), Plinacro will allocate the total daily off-takes at the distribution systems, calculated in a described manner, in proportion to the share that an individual SUPPLIER-BG had in the total energy volume input into the same distribution system on day D-3.
 
 The following figure shows the procedure of calculating the off-take forecast.
 

 
Figure 2 – procedure of calculating the off-take forecast 
 
Data on the forecast results will be delivered to suppliers and balance responsible parties via e-mail:

• In a gas day D-1, by 12:00 (noon) at the latest,
• In a gas day D, twice, at following times:

• First update no later than 13:00 hours
• Second update no later than 17:00 hours