Методи та засоби аналізу якості електропостачання та електромагнітної сумісності електротехнічних комплексів та систем

Abstract

Дисертація на здобуття наукового ступеня доктора технічних наук за спеціальністю 05.09.03 – Електротехнічні комплекси та системи. – Національний технічний університет "Харківський політехнічний інститут", Харків, 2019. У роботі міститься вирішення актуальної наукової проблеми аналізу якості електропостачання та електромагнітної сумісності електротехнічних комплексів та систем. Ця проблема полягає у відсутності математичної бази та, відповідно, нормативної бази оцінювання впливу окремого електротехнічного комплексу або системи споживача на якість електроенергії. Діючи норми покладають усю відповідальність за низьку якість електропостачання на безпосередньо постачальну організацію у вигляді штрафів, що, як показує досвід, не сприяє побудові оптимальних систем електропостачання. В роботі запропоновано оцінку якості електропостачання шляхом порівняння режиму електроспоживання діючого електротехнічного комплексу з еталонним споживачем у вигляді числових коефіцієнтів потужності та втрат. Отримані розрахункові формули для однофазних, трифазних трипровідних та чотирьохпровідних систем електропостачання. Запропоновано розподіл загальних втрат на втрати від несиметрії, не лінійності, реактивності та нестаціонарності. Запропоновано та досліджено концепції еталонного реактивного споживача та усередненого реактивного споживача. Запропоновано методику врахування якості електроспоживання при розрахунках за спожиту електроенергію, яка створює економічний стимул для підвищення ефективності енергорежимів споживача. Запропоновано методику оцінки порушення споживачем норм споживання за величиною потужності і гармонійних складових, що потенційно здатні викликати вихід показників якості електричної енергії за допустимі межі. Надано основи методики побудови штрафних санкцій щодо споживача у разі перевищення допустимих параметрів електроспоживання, а також штрафних санкцій щодо постачальника електричної енергії у разі низької якості електричної енергії та відсутності порушень з боку споживача.The dissertation on achieving the scientific degree Doctor of Technical Sciences by specialty 05.09.03 – "Electrotechnical complexes and systems" - National Technical University "Kharkiv Polytechnic Institute", Kharkiv, 2020. The paper contains the solution of the actual scientific problem of the analysis of quality of power supply and electromagnetic compatibility of electrotechnical complexes and systems. This problem is the lack of a mathematical basis and, accordingly, a regulatory framework for assessing the impact of a particular electrical complex or consumer system on the quality of electricity. The current regulations place all responsibility for the low quality of electricity supply directly on the supply organization in the form of fines, which, as experience shows, does not contribute to the construction of optimal power supply systems. The paper analyzes the compatibility of the existing regulatory framework (including IEEE519, EN50160) and evaluates the effectiveness of the proposed methods of determining responsibility using computer simulations. The analysis showed that the existing methods have significant limitations, as a result of which they are not suitable for practical application. The paper proposes an assessment of the quality of power supply by comparing the mode of power consumption of the existing electrical complex with the reference consumer in the form of numerical coefficients of power and losses. Calculation formulas for single-phase, three-phase three-wire and four-wire power supply systems are obtained. Three-phase three-wire system the reference consumer, regardless of the voltage parameters, is a symmetrical triangle of constant active resistance is shown. Three-phase four-wire system the reference consumer, regardless of voltage parameters, is a combination of a symmetric triangle of constant active resistances and a symmetrical star, the resistance in the branches of which is as many times more than the resistance of the triangle is shown. It is noted that the general assessment of the loss ratio is not informative enough about the reasons for the deterioration of electricity quality. To solve this problem, the division of total losses into losses from asymmetry, nonlinearity, reactivity and nonstationarity is proposed. The concept of the reference reactive consumer is offered, and conclusions concerning possibility and expediency of its use are made. A method for determining the reactivity coefficient by volumes of energy flowing in the forward and reverse directions is proposed. The concept of the average reactive consumer is offered. The paper proposes to build an assessment of the contribution of a separate electrical complex or consumer system in the deterioration of power supply on the basis of power values specified in the contract and the establishment of normalized resistance of the power supply system. Based on these values, a mathematical apparatus is proposed, which allows not only to determine the fact of violation of the limits of electromagnetic compatibility but also to quantify the amount of electricity that has been damaged. It is proposed to determine the coefficient of losses from asymmetry using a reference consumer. This coefficient is calculated as the ratio between the power loss of three independent single-phase reference consumers to the losses of the reference three-phase consumer. This solution avoids the influence of such factors as nonlinearity and reactivity. In addition, the device of symmetrical components is not used, which is inconvenient in the case of non-sinusoidal voltages and currents. It is proposed to select individual coefficients of losses from reactivity and nonlinearity, which are calculated by dividing the harmonic components of the distortion current by the power direction. The method of calculation of losses from nonstationarity is calculated, which is calculated as the ratio of total losses of reference consumers on several "short" intervals, and losses of the reference consumer on a long interval that includes all "short". The analysis of character of complex resistance of an electric network depending on parameters of its elements for typical cases of connection of consumers of various character on voltage of 10 KV is carried out. The obtained dependence allows us to talk about the possible use of normalized values to estimate network bandwidth. An empirical method for calculating the normalized resistance is proposed. A method for measuring the parameters of the electrical network mode is proposed, which allows to implement algorithms for assessing the quality of power consumption, the advantages of which are self-synchronization, calculation of values strictly for one period of the main voltage harmonic, absence of gaps and overlays of observation intervals. A method for measuring the current values of currents and voltages on their discrete images is proposed, taking into account the discrepancy between the moments of the initial and final readings of the digital image of the signal with the moments of the beginning and end of the measurement period. A method of taking into account the quality of electricity consumption in the calculations for the consumed electricity is proposed, which creates an economic incentive to increase the efficiency of energy regimes of the consumer. The method of estimation of infringement by the consumer of norms of consumption on size of power and harmonic components which are potentially capable to cause an exit of indicators of quality of electric energy beyond admissible limits is offered. The basics of the method of construction of penalties against the consumer in case of exceeding the allowable parameters of electricity consumption, as well as penalties against the supplier of electricity in case of low quality of electricity and the absence of violations by the consumer. In the experimental part of the work the application of the offered mathematical devices on the examples of test mathematical models and oscillograms obtained on real objects is tested. The experiment allowed to confirm the effectiveness of the proposed methods, in addition to the method of comparison with the reference medium-reactive consumer, which has not proved to be an effective tool for analysis and does not seem promising. Also in the work the hardware realization in the form of the electric energy meter taking into account its quality is offered.