Capacitive Power Taking Off from High Voltage Transmission Lines

2018 International Theoretical and Practical Conference on Alternative and Smart Energy (TPCASE 2018) ISBN: 978-1-60595-617-6 Capacitive Power Taking Off From High Voltage Transmission Lines Marina Rozhina, Nadezhda Buryanina, Yury Korolyuk and Anna-Mariia Timofeeva ABSTRACT A complex infrastructure and transport scheme of fuel supply, long and busy power lines, extreme continental climate with temperature changes from -50 to +45 ºС - all these factors have a negative impact on the quality of electricity. There is high probability of accidents due to the unreliability of electrical networks. This paper describes a method of power supply to remote consumers of "low" power without the construction of high-power transformer substations and the use of diesel generators. INTRODUCTION The Russian Federation is the largest country in the world by area. It occupies a huge area of 17.1 million square kilometers. Most of its territory is concentrated in the North. The energy problems of the Republic of Sakha (Yakutia) are due to its territory and non-settlement. Occupying the sixth part of Russian territory, the population of Yakutia is only about one million. Yakutia is divided into 4 energy areas—Central, Western, South Yakutian and Northern. More than 900 thousand people live in these four energy areas. The research considers the Northern energy area, which occupies 2/3 of the territory of the whole Yakutia (2.2 million square kilometers). The total installed capacity is 184.9 MW (electricity) and 92.4 Gcal/h (heat). The main sources of heat and electricity are diesel power plants, but in addition, 19 solar power plants ____________ Marina Rozhina, North-Eastern Federal University, 808 Office, 50 Kulakovskogo Street, Yakutsk, Russia Nadezhda Buryanina, Yury Korolyuk, Anna-Mariia Timofeeva, Chukotka branch of North- Eastern Federal University, 4-106 Office, 3 Studencheskaya Street, Anadyr, Russia 253 with a total capacity of 1.6 MW operatein the Northern part of Yakutia, which are the largest in the Arctic, and 2 wind power plants (290 kW). Because ofthe large number of diesel power plants (120), the problem of fuel delivery is acute, and the cost of electricity is accordingly high. Fuel is delivered to 23 Northern regions of Yakutia on the rivers and the Northern sea route. Every year supply of fuel and energy resources for the needs of the Northern and Arctic regions becomes more difficult. A technological consumption of electricity for its transport is about 13% of the electricity released into a network [1]. All power districts are not connected by electric networks by now. Now the construction of large inter-system power lines is going on: VL-220 kV "Chernyshevsky-Mirny-Lensk-Peleduy" and VL-220 kV "Nizhny Kuranakh– Tommot–Maya", which will connect the disparate energy areas into a single power system. In the future, we should also take into account the connection of Yakutian electric networks to Magadan ones. PRACTICAL PART Electricity supply to the Northern territories is a serious problem due to remoteness of facilities, mainly small settlements, often limited to several houses. The territory of the Russian Federation is huge, which explains the presence of a large number of long overhead power lines. Power transmission lines of 110 – 220 kV are laid along roads, on which there are settlements of a few houses, geological party, agricultural lands, and wood processing plants. It is not economically feasible to build substations with transformers taking into account their operation. Therefore, such settlements are supplied with electricity from small diesel generators. As a rule, there is no qualified service. That's why blackouts are frequent. At Physics and Technology Institute of North-Eastern Federal University at the Department of Power Supply and its Chukotka branch, research is being conducted that will improve the reliability of electrical networks of existing power lines. An alternative solution to the problem of the power supply without the construction of high-power transformer substations and using of diesel generators is capacitive power taking off from the power transmission line. There are several options for capacitive power taking off. The classical scheme of capacitive power taking off [2] is shown in Figure 1. The design schemes of substitution of capacitive power taking off are shown in Figure 2. 254 VL 110 kV Load Figure 1. Classical scheme of capacitive power taking off. VL 110 kV a VL 110 kV b Transformer Transformer Y12 Transformer Load Load Y12 Y12 Figure 2. Design scheme of the capacitive power taking -off: a) taking -off from the latest transformer; b) with inclusion of capacitors across transformers. The conductivity of the U-shaped equivalent circuit of the transformer is calculated as: 2 1− 푘푡 푘푡 −1 푘푡 푌1 = + 푌푥푥 ; 푌2 = ; 푌12 = , (1) 푍푡 푍푡 푍푡 where 푘푡- the transformer transformation ratio as the ratio of high voltage to a low voltage; 푍푡 – the resistance of the transformer, converted to a high voltage; 푌푥푥- the conductivity due to no-load current (generally accepted designations), which is described as: 255 2 2 ∆푃푥푥 퐼푥푥% 푆푛표푚 ∆푃푥푥 푌푥푥 = 2 − 푗√( ∙ 2 ) − ( 2 ) . (2) 푈푣 100 푈푣 푈푣 The nominal low voltage 푈푛표푚 on the conductivity 푌2 is 0.38 kV. Figure 3a shows two dependences of a voltage on a load 푆 (in relative units) with a power ratio of 0.8. Curve 1 (Figure 3a) shows the dependence of a voltage on a load with a linear change in the power of additional capacitors to maintain voltage levels within the specified limits (from 0.95 to 1.05 푈푛표푚). The required power is 1.3 times more than the reactive power (dependence 1 in Figure 3b). For linear changes in a power of additional capacitors is characterized by an increase in voltage in the range of minimum loads, and the more power capacitors relative to reactive power, a voltage level is higher. In this example, the voltage at low loads reaches 1.07 푈푛표푚, and the voltage at the full load is reduced to 0.95 푈푛표푚. At higher power capacitors both voltages increase, and if the full load voltage is equal to the nominal, at low loads it will exceed 1.1 푈푛표푚. Therefore, this method of voltage regulation should be considered inappropriate. Therefore, it is necessary to pay attention to voltage regulation by a non- linear change of capacitors power depending on a load change. Figure 3a shows the dependence of voltage on the load (curve 2) of the non-linearly variable capacitor power (Figure 3b, curve 2). From idle to max load the voltage varies from 1.05푈푛표푚 up to the nominal. The given dependence of voltage leads to the conclusion that it is enough to control the voltage level and maintain it within the specified limits by changing a power of capacitors without adhering to any specific law or regulation. Figure 3. a) dependence of voltages at the load from capacitors power, which are included to maintain the voltage levels; b) the corresponding capacity of capacitors. CONCLUSION A serious problem that needs to be solved is the disconnection of capacitive power taking off from the line. A switch setting is expensive. Therefore, the 256 disconnection of capacitive power taking off from disconnector is considered. At the voltage of 110 kV when the distance between the poles of 3.5 m in accordance with the Rules of Electrical device installations charging currents of a line can be disabled. Charging currents of a line, as currents of capacitive power taking off, are capacitive, so the above rule also applies for deactivation of a current of capacitive power taking off in idle mode. It is guaranteed that the idle current can be switched off at a power of three-phase taking off of 150 kVA. The shutdown current will be 3 A. The load has to be disabled first, which can be done by load switch. ACKNOWLEDGMENTS The research was carried out with the financial support of RFFI and constituent entity of the Russian Federation-the Republic of Sakha (Yakutia) #18- 48-140 010 REFERENCES 1. “About a Strategic Planning in the Russian Federation” in Federal law of June 28, 2014 № 172-FZ The energy strategy of Russia for the period up to 2035. 2. Korolyuk, Y.F., N.S. Buryanina, E.V. Lesnykh, and M.A. Rozhina. 2016. “Device of Capacitive Power Taking off from Power Transmission Line,” patent of the Russian Federation #2594890. 257 .

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