Considerations Regarding the Reconductoring Opportunity Analysis of 220 kv OHL D.C. Porţile de Fier Reşiţa

Transcription

1 Considerations Regarding the Reconductoring Opportunity Analysis of 220 kv OHL D.C. Porţile de Fier I. Ardelean, N. Chiosa, B. Sinca and M. Mihai Abstract-- This paper is a study case for considering whether reconductoring of OHL 220 kv dc Porţile de Fier - Resita, in order to reduce energy losses (CPT). Although this line has the largest contribution to total energy losses of ST Timisoara outline, reconductoring not prove a feasible solution in anticipation of transition to 400 kv of Portile de Fier - Resita - Timisoara - Arad axis and building a new 400 kv interconnection line with Serbia, Resita - Pancevo. Index Terms-- overhead electricity line, electricity system, uprating, HTLS, the maximum allowable current, increasing transport capacity, reconductoring. I. NOMENCLATURE HTLS high temperature low sag LEA d.c. double circuit overhead electricity line SEE electro-energetic power system CHE hydroelectric power plant CEE wind power plant CPT own technological consumption ATR technical advice for connection CTES Economic and Scientific-Technical Commission (of approval in Transelectrica) II. INTRODUCTION HL 220 kv d.c. Portile de Fier - Resita is the only power O evacuation line of 220 kv from Portile de Fier 1 node, this beeing accomplished towards the west of the country. Portile de Fier 1 node is a very strong node, with power surplus, having a local production of more than 1000 MW, which collects the surplus power from the CHE Portile de Fier 2 area, approx. 200 MW and CET Halânga, approx. 150 MW. At this junction, the power groups are connected at the voltage of 220 kv, into a with double bus-bar system and transfer bus-bar, recently repaired. OHL 220 kv d.c. Portile de Fier - Resita is built on metallic, double circuit posts (422 posts) and was completely repaired during the This is the most loaded line between those in the management of ST Timisoara and has the largest contribution to total energy losses in branch s outline. The maximum dr.ing. Ilie ARDELEAN, dr.ing. Nicolae CHIOSA, ing. Bogdan SINCA, ing. Marian MIHAI - CNTEE Transelectrica S.A. Timişoara Transport Branch transport capacity of this line is about 600 MW, required by the static stability criteria. In 2008 it commenced the transition to 400 kv Portile de Fier - Resita - Timisoara Arad axis, in conjunction with building a new 400 kv OHL interconnection with Serbia. In the year 2008, Fichtner Engineering SA prepared and CTES Transelectrica approved, an SPF seeking to achieve the two objectives above. After taking those steps, a potential investor, Wind A3 Eolica Trade Bucharest, asked Transelectrica a technical issue opinion of connection to system (ATR), for an EEC 600 MW, located in the Socol. This request requires a new analysis of SPF aforementioned solutions and hence delay the action started in In this context, S.T. Timisoara management called Technical Service to make an analysis on OHL 220 kv d.c. Portile de Fier Resita reconductoring, in order to reduce energy losses (CPT) and increase its transport capacity [2]. III. LOCATION AND CONSTRUCTIVE CHARACTERISTICS OF THE LINE 220 kv OHL Portile de Fier - Resita route crosses almost the entire length a hill region. From Portile de Fier Power Station the line follows a N-NW direction, crossing in 1-2 opening DN 6 and electrified Drobeta Turnu Severin Orsova railroad, overcome Verbunului peak and cross Slatinicului, Vodiţa and Bahnei valleys. Next, line route cross Baldovin top, Balabanului peak, Predediul Mic and Padesului peaks and after Stragierul hill go down the Cerna Valley near the confluence with the river Belareca. In the opening 39 to 40, OHL crosses DC Bahna - Ilovita. In the opening 92 to 93 the line crosses the river Cerna. In the opening the OHL cross DN 67 Orsova - Tg. Jiu. In the opening 96 to 97 the line crosses DJ towards Băile Herculane and Belareca river, and in openings and crosses again Belareca river. Further, it aims Belareca valley to S of Mehadia, which passes east, continuing to Plugova village. North of Plugova, the line crosses the Belareca river in 149 to 150 opening and enter into the hill zone, in the area of Cornea, Domaşnea, Feneş şi Sat Bătrân villages. Next line bound for NV, across the opening 277 to 278 crosses electrified railroad Slatina-Timiş Caransebes, in the opening crosses DN 6 and the opening 279 to 280 passes across the Timis river. North of S Slatina-Timiş, the line bound for Bucoşniţa and Petroşniţa villages keeping N direction to Prisian village. It continue to NW by Rugi village, then west to Delineşti. Passes near 24

2 Apadia, heading the direction of SV to Tarnova, after that entering the 220 kv Resita. The line was build under the ISPE design project no. 6727/1968, based on LI 1 67 norm. Calculation parameters considered when designing the line, are Meteorological area 2 nd ; t max. +40[ C] t min. -30[ C] t frost formation -5[ C] wind max. 40[m/s] wind + frost 20[m/s] frost thickness 25[mm] Constructive characteristics of the line are: putting into operation year 1971 line length 116,5 km total no. of posts 428 pcs. active wire Al/Ol 2x(3x450/75) mm 2 protection wire OPGW 160/95 mm and posts, OPGW 95 mm posts, Al/Ol 1x450/75 mm posts, OlZn 1x95 mm şi posts; insulation CTS 120-2p şi posts, composite 1-89 şi posts. IV. IMPORTANT OFFICIAL EVENTS JOURNAL 1971 replacing IN post from 212 terminal, with a pole type ICN , which due to heavy frost deposits led to deformation of the lower segment of the pole; 1978 protection wire ALOLS 160/95 mm 2, was replaced with a 95 mm 2 conductor type OLZn between posts, due to inadequate reaction to mechanical loads; 1980 due to landslides in the pillar 32 area, it was moved 45 m in line to the terminal 33 and the existing pole was replaced with a pole type Sc sc - M1; due to landslides in the pillar 154 area, a modified route was done; K3 insulation type was replaced with CTS 120-2p and PSG 12 A type insulation; 1985 after heavy frost deposits the active conductor was deteriorated and was replaced in panel , S-phase; 1993 due to mechanical overload, top-cap of pillar 25 broke, being replaced; 1995 due to mechanical overload, thrusts console terminal 237, phase T was strengthend. V. RECONDUCTORING SOLUTIONS AND TYPES OF CONDUCTORS USED Replacing conductors is one of the most common techniques for increasing the carrying capacity of the OHL. Different variants are possible, consisting of installing a conductor or a bundle of conductors, having a larger transport capacity and, if possible, with a higher ratio H/w (obtained by increasing horizontal pressure into conductor, or by decreasing conductor unit weight). There are two possible approaches: replacing existing conductors with new ones, all conventional, but with a larger section and/or higher conductivity, which operate at the same temperature, or compact conductors having a higher cross-section, but without increasing the beam diameter exposed to the wind; replacing existing conductors with special conductive HTLS (High Temperature Low Sag), capable of operating at higher temperatures without increasing the arrows, with a lower thermal expansion coefficient. There are many types of HTLS conductors that can be used to increase the transmission capacity of an OHL. Choosing the most appropriate type for specific cases, depends on initial conditions for sizing the line. Overhead power lines in Romania with rated voltage of 220 kv are equipped, with few exceptions, with Al/Ol 450/75 mm 2 conductors, one conductor per phase. The inclusion of Romania in the European transport network, on the one hand and the implementation of wind turbines in large groups on the other hand, involves the growth of transport capacity in some lines, forced to evacuate or to carry power over existing capacity. Table 1 shows both the type of conductor used in fitting conventional overhead power lines and conductors with increased transmission capacity, achieved through optimization of the geometry, the use of new materials, or by increasing the operating temperature of the conductor [5], [6] [7], [8]. Maximum capacity of transport for non-conventional conductors, is reported at the conventional type ACSR conductor, whose capacity is considered 100 [%]. Addressing increasing transport capacity is different from new lines to existing lines. at new lines, increasing transport capacity is made either by increasing the aluminum section or by increasing the number of conductors beam. There are also possible some solutions fitting the line with HTLS conductors, optimal approach beeing based on technical-economic analysis; for existing lines, increasing the transmission capacity can be achieved successfully at present, through the process of uprating. Uprating means increased transport capacity of the OHL, by increasing the current or voltage, or by increasing the values of both sizes [1]. Increase current value is achieved either by increasing the temperature of existing conductors or by replacing them with new ones, capable of operating at high temperatures. Increasing the amount of voltage involves increasing the insulation level of the OHL (corresponding to a new stage of voltage), increasing the distances between phases and ground gauge. On existing lines, when reconductoring using unconventional conductive type HTLS, in order to maintain safety in its operation, there must be followed the next restrictions: the new conductor diameter must be less than or equal to the existing conductor (29.25 mm); maximal horizontal thrust for new conductor, must not exceed the existing one (Tmax = 5362 dan), in order to reduce the impact on the pillars and foundations; The final arrow of the new conductor, at the maximum operating temperature should be limited to the final arrow for the existing ACSR conductor 450/75 type; breaking force for the new conductor, must be greater or at least equal to that of the existing conductor AlOl 450/75 mm 2 type; 25

3 electrical distances must be maintained. S.C. Fichtner Engineering S.A developed for C.N. "Transelectrica" SA a SF phase documentation regarding the 220 kv d.c. OHL Bucuresti Sud-Fundeni reconductoring and 220 kv d.c. OHL Lacul Sărat-Fileşti-Barboşi Focşani [3],[4]. Calculation of the carrying capacity of conductors was carried out with a design and verification software PLS-CADD for overhead power lines. This program is widely used worldwide, the calculation of the maximum allowable current is in accordance with IEEE Std After technical and economic analysis, was proposed for reconductoring ACSS conductor type [3]. Inside S.T. Timişoara, due to absence of dedicated software for performing such technical-economic analisys, we did consider the opportunity of reconductoring the 220 kv d.c. OHL Porţile de Fier [2], taking into account the ACSS conductor type, proposed by Fichtner Engineering in SF study on the 220 kv OHL Bucuresti- Fundeni reconductoring [3]. Hypothesis is correct because both lines were designed under the same regulatory, LI TABLE I Characteristics No. Conductor type Material View Temperature [ C] Max. transport capacity [% from ACSR] 1 ACSR Al + Steel 75 C 100% 2 ACSR/ACS Al + ACS 75 C 107% 3 SLAC/ACS Al + SBAl + ACS 113% 4 ACSR/TW TW + ACS/St 115% 5 AeroZ ZW + ACS/steel 75 C 116% 6 TACSR/AS TAl + ACS 150 C 150% 7 60% ZTACIR/ACS ZTAl + IR (ACS) 8 58% ZTACIR/ACS 9 XTACIR/ACS XTAl + IR(AS) 230 C 200% 10 60% ZTACEIR/ACS 11 58% ZTACEIR/ACS SBZTAl / IR (AS) 230 C 200% 12 XTACEIR/ACS SBXTAl / IR(AS) 230 C 200% 13 GTACSR TAl + TZ + EST 150 C 150% 14 GZTACSR ZTAl + TZ + EST 120 C 180% 15 ACCC Al (1350) + Composite 200 C 150% (without structure change) 16 3 M ACCR Al+Zr melt, + Composite 210 C 200% 17 ACSS Al (1350) + steel 250 C 200% VI. CALCULATION OF ENERGY LOSSES (CPT) For calculation of lost energy for 220 kv OHL Portile de Fier-Resita, for a comparative analysis between the situation with conductors OlAl 450/75 mm 2 and the variant of equipping it with ACSS type conductors, were considered following simplifying assumptions [2]: there will be taken into account only the losses by Joule effect, others are neglected; it is considered a constant voltage i.e. 220 kv on the line (neglecting the voltage drop between the ends of the line); line resistance at ambient temperature of 20 C (neglecting the resistance change with conductors temperature, and also with the load and weather conditions) 26

4 Analysis of energy losses for 220 kv d.c. OHL Portile de Fier-Resita, was made for one year respectively September 2008-August As input data were used: active and reactive energy measured monthly in Portile de Fier, active and reactive energy measured monthly in Resita, the maximum active and reactive powers. For comparison was retained the average energy losses calculated with measured quantities of end s. Calculation relations used are: 2 S med ΔW a =R T 2 U where: ΔW a - active power losses, R line resistance, T operating time, U line voltage, S med average apparent power. W 2 2 a + Wr S med = T where: W a active energy, W r reactive energy For the same line load, for all types of conductors, energy losses amount depends on the value of resistance of conductors. In Table 2 are presented energy losses calculated for the circuit 1 of the 220 kv d.c. OHL Portile de Fier-Resita, in the existing situation and in the variant of reconductoring. In Table 3 are the same calculations for circuit 2, and in Table 4 are presented cumulative losses on the two circuits. TABLE II Calculated ACSR existing conductor ACSS proposed conductor losses [MWh] Month, ΔWa ΔWa ΔWa ΔWa ΔWa ΔWa Year average average September October November December January February March April May June July August TOTAL Calculated losses [MWh] TABLE III ACSR - existing conductor ACSS - proposed conductor P. de Fier ΔWa ΔWa ΔWa ΔWa ΔWa ΔWa Month, Year calculated calculated average calculated calculated average September October November December January February March April May June July August TOTAL

5 TABLE IV Calculated ACSR - existing conductor ACSS - proposed conductor losses [MWh] Month, ΔWa ΔWa ΔWa ΔWa ΔWa ΔWa Year calculated calculated average calculated calculated average September October November December January February March April May June July August TOTAL VII. ECONOMIC ANALYSIS Economic analysis refers to the calculation efficiency of reconductoring action upon 220 kv d.c. OHL Portile de Fier- Resita, that the length of payback. There are estimated direct total costs and annual cost of lost energy. VII.1 DIRECT TOTAL COST Direct total costs C C+M, result from the estimating the following categories of expenses: C P - the direct cost of purchasing the conductors and their accessories C i - cost of labor for installation of conductors and accessories C m - cost of maintenance, after mounting the conductors on the line Therefore: C C+M = C P + C i + C m Note that C P and C i are costs made in the new conductor installation year, and C m are annual maintenance costs. This last ones costs C m, beeing approximately equal to the existing ACSR conductor and new ACSS conductor, were not considered. Evaluation of total direct costs was done with average prices [euro/km] used by Fichtner in SF study regarding reconductoring 220 kv d.c. OHL Bucureşti Sud- Fundeni [3]. In Fig. 1 are shown the costs to purchase the conductor and in Fig. 2 are given installation labor costs. Using specific costs shown in Fig. 1 and Fig. 2, for reconductoring 220 kv d.c. OHL Portile de Fier- Resita, result the following charges: conductor procurement costs x (116, ,5) = euro cost for installing the conductor 3000 x (116, ,5) = euro total direct costs = euro Costul procurării Euro/ (km si circuit) ACSS ZTACIR GZTACSR ACCR ACCC/TW Conductor Fig. 1 Costul instalării (Euro/km) ACSS ZTACIR GZTACSR ACCR ACCC/TW Conductor Fig.2 VII.2 ANNUAL COST OF ELECTRICITY LOSSES Now, to cover energy losses (CPT) in RET, Transelectrica buy energy at a rate imposed by ANRE, 250 lei/mwh. At a rate of 4,15 lei/euro, results a fee for lost power at 60,24 euro/mwh. By reconductoring energy losses became lower, in accordance with Table 4, from ,40 MWh/year at ,69 MWh/year, i.e ,71 MWh/year. In cost terms, this economy means: 2 195,71 x 60,24 = euro/year. Length of payback time for reconductoring, only by the bases of difference of losses, is: 28

6 : = 53 years VIII. CONCLUSIONS kv d.c. OHL Porţile de Fier reconductoring, designed only to reduce energy losses, is not a feasible solution, the payback period of the investment beeing very high; kv d.c. OHL Porţile de Fier reconductoring in order to increase transport capacity and reduce energy losses would be a feasible solution if switching to 400 kv voltage of Porţile de Fier Timişoara Arad axis would be a long distance perspective; 3. According to SF Upgrading 220 kv d.c. OHL Bucuresti Sud Fundeni and strengthen it by using conductors with larger capacity, reconductoring has maximum efficiency at OHL with lengths of up to 50 km because of voltage losses; 4. ACSS conductor, to the other conductors with increased load capacity, has the advantage of the lowest direct costs (procurement + installation + maintenance); 5. ACSS conductorul to ACSR conductor has also an environmental advantage, in that of having a smaller diameter, the visual impact is lower. IX. REFERENCES 1. Propunere privind reconductorarea lea 220 kv Iernut-Baia Mare 3, utilizând tehnologii de LST,., Florea G., Oltean M., Mateescu E., Mărginean D., Kilyeni S., Bărbulescu C; [1] Ardelean I et.all. Propunere privind reconductorarea lea 220 kv Iernut- Baia Mare 3, utilizând tehnologii de LST. [2] Ardelean I., Şinca B., Mihai M., Notă tehnică privind analiza oportunităţii de reconductorare a LEA 220 kv d.c. Porţile de Fier. Serviciul Tehnic, S.T. Timişoara, oct. 2009; [3] ***, Modernizarea LEA 220 kv d.c. Bucuresti Sud Fundeni şi întărirea acesteia prin utilizarea de conductoare cu capacitate mărită, Studiu de Fezabilitate elaborat de S.C. Fichtner Engineering S.A. pentru C.N. Transelectrica S.A; [4] ***, Reconductorarea LEA 220 kv d.c. Lacul Sărat - Fileşti-Barboşi Focşani, Studiu de Fezabilitate elaborat de S.C. Fichtner Engineering S.A. pentru C.N. Transelectrica S.A; [5] ***, Conductors for the Uprating of Overhead Lines, WG B2.12, CIGRE, Technical Brochure No. 244, April 2004; [6] Peter Reichmeider et.all. Experience With New Methods For Live-Line Conductor Replacement, CIGRE 2008; [7] ***, How on lines are re-designed for uprating/ upgrading, WG B2.06, CIGRE, Technical Brochure No. 294, June 2006; [8] ***, Conductors for the Uprating of Overhead Lines, WG B2.12, CIGRE Technical Brochure No. 244, April