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DETERMINATION OF THE MAXIMUM VOLTAGE AT THE PHOTOVOLTAIC POWER PLANT CONNECTION POINT

Mykola Volodymyrovych Bazylevych

2021
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Bulletin of the National Technical University "KhPI". Series: Energy: Reliability and Energy Efficiency
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The modes of the electrical network have not been calculated for the photovoltaic power plants if they are used for small and medium-sized applications. It is known that the voltage at the point of installation of a photovoltaics power plant may exceed the critical limit voltage and as a result it may cause the emergency with the electrical equipment. According to the existing methods, it is possible to find the voltage only by full electrical network modes calculating. In practice such
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... ion is not convenient, especially for 0.4 kV distribution networks. The suggestion is to find the most probable limit voltage at the point of installation of a photovoltaic power plant without calculating the mode of the electrical network using instead the information about the voltage value in the power supply centre. The voltage at the installation point of the photovoltaic power plant mainly depends on the generated power of the photovoltaics power plant, line resistance, load power connected to a voltage of 0.4 kV and bus voltages of 0.4 kV of the power supply. The voltage hardly depends on the power of the power transformer, the parameters of 10 kV lines and the parameters of 0.4 kV lines, except for the line "power centre–photovoltaic power plant". The highest voltage at the point of installation of the photovoltaics power plant will be in the case when the load on the line is absent. The suggested methods allow finding analytically the maximum value of voltage at the point of installation of a photovoltaic power plant without using of the successive approximations methods. As a rule the photovoltaics power plant operates in the mode of delivery of the maximum active power. By the range of various analytical formulas, the value of voltage at the point of installation of a photovoltaic power plant has been determined. The accuracy of finding the voltage by different formulas has also been determined. It is established that in order to achieve the required accuracy, the dependence of the current at the output of the photovoltaics power plant on the voltage at the connection point should be taken into account. Modification of formulas for the purpose of simplification of their application is considered. The conditions for finding the maximum possible voltage value at the point of installation of a photovoltaics power plant are considered. This requires that the argument of the voltage drop vector on the line be equal to the argument of the voltage vector on the busbars of the power supply. This is achieved by the fact that the photovoltaic power plant generates active and reactive power in a certain ratio. It is shown the inexpediency of finding the maximum possible voltage value at the point of installation of a photovoltaic power plant due to a small difference with the most possible voltage value with a significant complication of calculations.

doi:10.20998/2224-0349.2021.01.02
fatcat:5vsuia2ryrd7vjckkdqztdnive