HYDROELECTRIC POWER PLANT (PLTA) OF PEUSANGAN 1 AND 2 4X22MW AT SUBSISTEM ACEH Ramdhan Hald Sregar 1, Syahrzal 2, Muhammad Arfa 3 1-3 Department of Electrcal Engneerng, Unverstas Syah Kuala, Banda Aceh, INDONESIA. ramdhan_hald@yahoo.com ABSTRACT Hydroelectrc power plant contrbutes much for modern people who use electrc equpment. Ths study ams to analyze the power flow of the 150kV Aceh Power System under maxmum loadng condtons before and after the entry of Peusangan hydropower n 2018. The addton of new power plants s one way to fulfll people's need for electrc energy so that a power flow study s needed to see the mpact of the addton. The problem of ths research s lmted to determnng the value of the substaton voltage, actve power flow and reactve power on varous channels and power losses before and after Peusangan hydropower comes. The method of power flow approach that wll be used n ths research s Gauss-Sedel method wth accuracy factor 0.0001 through smulaton wth the help of ETAP 12.6.0 software. The smulaton s done n two scenaros: 1) Power System of 150kV Aceh at present; and 2) Entrance of Peusangan Power Plant on Power System 150kV Aceh. The smulaton result shows that the Banda Aceh substaton s a substaton near the undervoltage lmt on the upcomng Aceh 2018 subsystem wth the value of the voltage s 137.14 kv or 91.43%. The hghest actve power and reactve power after the addton of the power plant are on the Lhokseumawe - Arun channel of 105,897 MW and 51,734 Mvar. The hghest power losses after the ncluson of new power plants occurred on the Sgl - Banda Aceh lne of 1,309 kw and 4,705 kvar. Keywords: Power Flow, ETAP, Interconnecton System, Aceh INTRODUCTION The avalablty of electrc energy especally n Aceh has become a serous publc ssue It s noted the modernty need electrcal energy and has become an nseparable part of human lfe. The growng number of people n Aceh and the development of the people's economy each year wll lead to an ncrease n the demand for electrcty n Aceh, so that the amount of electrc power must be ncreased n order to keep up wth the ncreasng needs of the communty. One way to ncrease the avalablty of electrc power s by addng new plants. Wth the ncluson of new plants nto the system that has been there before t wll have an mpact on the system. One of the power plants n Aceh that wll be planned for the addton s PLTA Peusangan 1 and 2. In prncple, ths hydroelectrc project has been started from 1995, but due to varous obstacles ths project was delayed for more than 12 years, then n 2011 hydropower development project Peusangan 1 and Peusangan 2 n Central Aceh Regency are seen to be resumed and targeted to strengthen the North Sumatera of electrcty system, especally n Aceh n 2018. Power flow study s one way that can be done to determne the effect caused by the addton of new generators n electrcal systems. One of the nformaton obtaned from the power flow study s the voltage and power flow of the power system after the addton of a new power Copyrght 2017 Leena and Luna Internatonal, Chkuse, Japan. 1 P a g e ( 株 ) リナアンドルナインターナショナル, 筑西市, 日本
plant. Ths nformaton can be used to evaluate the work of the electrc power system and analyze the generaton and loadng condtons. BASIC THEORY Power System Accordng to Stevenson (1983) electrcal system s a system that serves to generate, transmt, and dstrbute electrcal energy from power plants to consumers. The man components of the electrc power system are generatng, transmttng and dstrbutng. Generators generally produce electrcty wth a voltage of between 6-20 kv later, wth the help of a step-up transformer, the voltage s rased to 150-500 kv. It ams to reduce the losses that can occur durng the power transmsson process. Some power systems lower the voltage level, wth the help of a step-down transformer, nto a sub-transmsson voltage of 70 kv. Voltage reducton ams to reduce the rsk that can be caused by the voltage that s too hgh when the transmsson lne s nearng the settlement populaton. Ths voltage wll then be downgraded agan to a prmary dstrbuton voltage level of 20 kv, whch wll then be channeled to large consumers. After the electrcal energy s channeled through the prmary dstrbuton network, the voltage wll be lowered n the dstrbuton substatons nto low voltage wth a voltage of 380/220 Volts. The process of channelng electrcal energy through the generatng center to the consumer can be seen n the lne dagram n Fgure 1 below: Fgure 1. Dagram of one lne of power system In modelng a power system, the power system components are represented n the form of a multpler crcut, as they nclude: synchronous generator, power transformer, transmsson lne, shunt capactor, and load. On a balanced system, components such as power breakers, releases, governors and mpedances of neutral to ground relatons are not represented. Synchronous generators are usually connected drectly on rals or often through power transformers. Snce the purpose of ths analyss s to know the magntude of the ral voltage and the power flow, the synchronous generator s represented as an actve power source and the reactve power as shown n Fgure 2, and the voltage obtaned from ths analyss s the ral voltage at whch the generator s connected. Fgure 2. Representaton of synchronous generator The transformer n the power system serves to change the voltage so that n the power supply at hgh voltage wll reduce the losses. In the power transformer, the current flowng through the magnetzaton reactance (Xm) and the ron core loss (Rm) s much smaller than the current flowng to the load. So n the load flow study, the exctaton crcut of the transformer s gnored and represented only by reactance X only. www.ajsc.leena-luna.co.jp Leena and Luna Internatonal, Chkuse, Japan. Copyrght 2017 ( 株 ) リナアンドルナインターナショナル, 筑西市, 日本 P a g e 2
The transmsson lne s represented accordng to the transmsson class. Representaton of the transmsson lne s dvded nto 3 classes namely (Hutauruk, 1985): 1. Short transmssons 2. Medum transmsson 3. Long transmsson In ths case, the class dvson of the transmsson lne corresponds to the magntude of the channel capactance to the ground. Capacty to the ground s a functon of the dstance from the transmsson lne. For short transmsson lnes the magntude of the capactance to the ground can be neglected. For medum-szed channels the magntude of the capactance s not neglgble, but not so large that the capactance to the ground can be consdered centralzed. For long transmsson the magntude of the capactance prce can not be consdered centralzed but rather evenly dstrbuted along the channel. In analyzng electrc power systems, there are three ways to represent a load, such as: a. Representaton of load wth fxed power. In ths case the actve power (MW), as well as the reactve power (MVAR) are consdered constant. Ths load representaton s used for power flow studes. b. Representaton of loads wth fxed currents. c. Representaton of load wth fxed mpedance. To represent a load wth a fxed mpedance, the power absorbed by the load s converted nto a seres or parallel mpedance. The representaton of loads wth fxed mpedances s usually used n the stablty study of electrcal power systems. When real power (MW) and reactve (MVAR) are assumed to be known and the magntude s mantaned constant then the mpedance Z s calculated as follows: Z= V I = V 2 P jq (1) In the power system analyss besdes usng quanttes n electrc unts, t also uses quanttes that descrbe the value as a fracton of the reference value. The value that becomes a reference s usually a ratng or full load value. Ths quantty s called per unt (abbrevated p.u). The defnton of per unt s descrbed n the followng equaton. Per Unt = true value (electrc quantty) base or reference (same quantty) (2) Some practtoners descrbe the value per unt as a percentage of ts basc value. Interconnecton System The nterconnecton system s a power system consstng of several power plants and substatons (GIs) nterconnected (connected to each other) through transmsson lnes and servng the exstng load on the entre substaton (GI) (Marsud, 2005). In the nterconnecton system, all plants need to be coordnated n order to acheve mnmum cost of generaton, of course wth regard to qualty and relablty. The qualty and relablty of the supply of electrcty nvolves frequency, voltage and dsturbance. Smlarly, the ssue of power dstrbuton whch also needs to be observed n the nterconnecton system n order that there s no transmsson equpment that s overloaded. Copyrght 2017 Leena and Luna Internatonal, Chkuse, Japan. 3 P a g e ( 株 ) リナアンドルナインターナショナル, 筑西市, 日本
Power Flow Power flow study s a study conducted to obtan nformaton about the power flow or system voltage n steady operatng condtons. Ths nformaton s needed to evaluate the performance of the power system and to analyze the condtons of generaton and loadng (Cekdn, 2007). In the study of power flow, buses are dvded nto 3 types, namely: 1. Swng ral (swng or slack bus) Ths ral s used as a reference wheren known parameters are voltage magntude ( V ) and phase voltage angle ( ). Swng ral s requred on the system because the P and Q values for each ral can not be determned frst. Generally n the calculaton of power flow there s only one swng ral. 2. Ral load (P-Q bus) The parameters known n the load ral are actve power (P) and and reactve power (Q). The actve power and reactve power of the load are known from the load estmaton, whle the actve and reactve power of the generator (f any) has been determned. The pure load ral has a value of PG = 0 and QG = 0. 3. Ral control (P-Q bus) The known parameters are actve power (P) and voltage magntude ( V ), where P s determned and V kept constant wth reactve power njecton. In ths ral, the actve power and reactve power of the load are known from the load estmaton. Power flow studes are useful for: 1. Plannng and development of electrcty network of power flow studes provdes nformaton on the mpact of new load loadng, addng new generaton, addng transmsson lnes, nterconnectng wth other systems, and so on. 2. Determnaton of loadng of electrcal system equpment such as transmsson lne and transformer at present or future condton. 3. Determnaton of the best operatng condtons of electrc power system 4. Provde nput data for nose calculatons and stablty studes. Gauss-Sedell Method The Gauss-Sedel method s one of the methods used n power flow. The dgtal completon for ths load flow problem, wll follow a loopng process by settng approxmate values for unknown bus voltages and computng a new value for each bus voltage of the approxmate values obtaned from the prevous teraton process. So we get a new set of voltage values for each bus and then used to calculate the set of next teraton bus voltage. Each calculaton of a new set of voltages s called teraton. The teraton process s repeated contnuously untl the changes that occur on each bus are less than a mnmum value that has been determned (Mahendra, 2011). Modelng a ral of a power system n Fg. 3 s an mpedance n a system that has been converted nto a perunt (pu) admttance. www.ajsc.leena-luna.co.jp Leena and Luna Internatonal, Chkuse, Japan. Copyrght 2017 ( 株 ) リナアンドルナインターナショナル, 筑西市, 日本 P a g e 4
Fgure 3 Typcal bus n power system In the Gauss-Sedel method, to fnd the value s as follows: P sch jq sch (k) (k+1) V (k) + y j V j V y j j (3) If the equatons above are solved back to see P and Q, then the equaton s as follows: P (k+1) = R {V (k) [V (k) n n (k) j 0 y j j 1 y j V j ]} j (4) Q (k+1) = I {V (k) [V (k) n n (k) j 0 y j j 1 y j V j ]} j (5) The teraton process wll contnue f there s no tolerance value. The complete procedure of the Gauss Shedel method s as follows: a. Assume the value of V * and fnd the settlement to get V (1) b. If (V (1) V (0) ) the value of tolerance, the calculaton s stopped and V = V (1) c. Ths process contnues untl the bus ends. After the voltage values are obtaned, the next step s to calculate the power flow on the channel and the power loss on the channel. A channel connectng the two buses and j s shown n Fgure 4. The channel current I j,, measured on the bus and has a postve drecton. The current flowng from bus to bus j can be calculated by (Saadat, 1976): I j = I l + I 0 = y j (V - V j ) + y 0 V (6) Smlarly calculatng the current flowng from bus j to bus can be calculated by: I j = I l + I 0 = y j (V j - V ) + y j0 V j (7) Complex power (S j ) whch flows from bus to bus j and complex power (S_j) from bus j to bus can be calculated by: Copyrght 2017 Leena and Luna Internatonal, Chkuse, Japan. 5 P a g e ( 株 ) リナアンドルナインターナショナル, 筑西市, 日本
S j = V I j (8) S j = V j I j (9) The power loss at lne to j s the sum of the power flow from equaton (8) and equaton (9), so that t s obtaned: RESEARCH METHODS S L j = S j + S j (10) The study was conducted usng Gauss-Sedell method. The study was conducted n Aprl 2016 and for the locaton under consderaton was the 150kV Aceh power system. Ths research requres tools and materals that are as follows: 1. Laptop 2. ETAP Software 12.6.0 3. Data system of generator and dstrbutor of Aceh subsystem Fgure 4. Dagram of the research work flow www.ajsc.leena-luna.co.jp Leena and Luna Internatonal, Chkuse, Japan. Copyrght 2017 ( 株 ) リナアンドルナインターナショナル, 筑西市, 日本 P a g e 6
The research steps nclude: 1. Stage of Preparaton The purpose of the preparatory phase of the study s to prepare and collect nformaton n the form of data needed to perform the analyss. These data nclude the actve and reactve power of each load bus, the mpedance of the transmsson lne connectng each busbar, and a dagram of one lne of the 150kV Aceh power system. 2. Data Calculaton Phase The data calculaton s done usng softwareetap 12.6.0 to get ts power flow. The analyss s done wth two scenaros, the current condton and the ncluson of PLTA Peusangan n 2018. In the frst scenaro, the load value used s the peak load n Aprl of 2016. Whle n the second scenaro, the load value used s the peak load n 2018 because PLTA Peusangan s planned to enter nto the subsystem of Aceh n 2018. The results of the analyss are to look at and compare the values of voltage, actve power, reactve power, and network losses of the two scenaros. Fgure 4 shows the flowchart for the power flow calculaton process usng ETAP 12.6.0 software. RESULT AND ANALYSIS Results of Actve Power Flow Smulaton and Reactve Power From Fgure 5 t can be seen that the hghest actve current flow pror to the addton of the power plant s n the Lhokseumawe-Arun channel of 94.693 MW, and after the entry of the new generaton the hghest actve power flow s stll on the Lhokseumawe-Arun channel of 105.897 MW. Fgure 5. Chart comparson of channel power Fgure 6. Graphc comparson of channel reactve power From Fgure 6 t can be seen that the hghest reactve power flow pror to the addton of the plant s found n the Lhokseumawe-Arun channel of 44.56 Mvar, and after the entry of the new generaton the hghest reactve power flow s stll on the Lhokseumawe-Arun channel of 51.734 Mvar. Channel Power Loss Results From Fgure 7 t can be seen that the hghest actve loss before the addton of the plant s n the Lhokseumawe-Arun channel of 999 kw, and after the entry of the new generaton, the hghest actve power losses are found n the Sg-Banda Aceh channel of 1,309 kw. Copyrght 2017 Leena and Luna Internatonal, Chkuse, Japan. 7 P a g e ( 株 ) リナアンドルナインターナショナル, 筑西市, 日本
Fgure 7. Graphc comparson of actve power loss of channel Fgure 8. Graphc comparson of reactve power loss channels From Fgure 8 t can be seen that the hghest reactve power losses pror to the addton of the power plant are on the Nagan-Sgl channel of 5179 kvar, and after the entry of the new plant the hghest reactve power loss s stll n the Nagan-Sgl channel of 4981kvar. Voltage Results of each Substaton Fgure 9. Graph of the substaton comparson voltage From the graph of the voltage rato n fgure 9 above, t can be seen down the entry of PLTA Peusangan 1 and 2 nto the next subsystem of Aceh 2018 not too able to repar the exstng substatons voltage, ths s due to subsystem load growth of 15% n 2018. One of the substatons that ncreased the voltage s the substaton Breun prevously valued at 145.517 kv to 145.613 kv, ths s because the locaton of the substaton Breun drectly connected wth substatons powerhouse PLTA Peusangan. CONCLUSION 1. The addton of the 88 MW Peat Hydro Power Plant to the Aceh sub-system n 2018 wll reduce the power supply from the Pangkalan Brandan slack bus by 40.8 MW to 33.4 MW. 2. Hghest actve power and reactve power after Peusangan hydropower entry occurred on channel Lhokseumawe - Arun ytu for 105,897 MW and 51,734 Mvar. www.ajsc.leena-luna.co.jp Leena and Luna Internatonal, Chkuse, Japan. Copyrght 2017 ( 株 ) リナアンドルナインターナショナル, 筑西市, 日本 P a g e 8
3. Loss - the greatest loss of power at the tme pror to the entry of the Peusangan hydroelectrc power plant n the Aceh subdstrct of 2016 occurred n the Lhokseumawe - Arun channel of 999 kw and 3,591 kvar and the greatest losses at the tme of entry of the Peusangan hydro power plant on the Aceh subsystem n 2018 occurred on the Sgl - Banda Aceh lne of 1,309 kw and 4,705 kvar. 4. Substaton of Banda Aceh became the man substaton near the undervoltage lmt on the subsystem of Aceh 2018 wth the value of the voltage s 137.14 kv or 91.43%. REFERENCES [1]. Al-Shaalan, Abdullah M. (2013). Techncal and Economcal Merts of Power Systems Interconnecton. Journal of Power and Energy Engneerng, 1, 1-7. [2]. Cekdn, C. (2007). Power System, Sample Problem and Soluton Usng Matlab. And Yogyakarta, Yogyakarta. [3]. Jamal, Agus and Syahputra, Ramadon. (2014). Power Flow Control of Power Systems Usng UPFC Based on Adaptve Neuro Fuzzy. IPTEK, Journal of Proceedng Seres, 1, 218-224. [4]. Hutauruk, T. S. (1985). Power Transmsson. Erlangga. [5]. Marsud, D. (2005). Power Generaton. Erlangga, Jakarta. [6]. Meer, Alexandra von, (2006). Electrc Power Systems: A Conceptual Introducton. John Wley & Sons, Inc., Hoboken, New Jersey. Canada. [7]. Power Systems Engneerng Research Center (PSERC). (2007). The Electrc Power Industry and Clmate Change: Power Systems Research Possbltes. Regents of Arzona State Unversty. [8]. Saadat, H. (1999). Power system analyss. McGraw-Hll [9]. Stevenson, W. D. (1975). Elements of power system analyss. [10]. Wang, Xao-Png, Carlos J. Garc ıa-cervera, and Wenan. (2001). A Gauss Sedel Projecton Method for Mcromagnetcs Smulatons. Journal of Computatonal Physcs, 171, 357 372. Copyrght 2017 Leena and Luna Internatonal, Chkuse, Japan. 9 P a g e ( 株 ) リナアンドルナインターナショナル, 筑西市, 日本