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Results of cities electrosupply systems research, as an object of controll are given. Necessity of increase of automation level control by technical processes at its bottom levels is established. The expediency of application of booster transformers with thyristor control for complex automated control by voltage and reactive modes power is proved.
Modern cities are the largest consumers of electric energy (EE). Now their capacities are commensurable with capacity of the large industrial enterprises. In cities today not only lives over 60 % of the states population but also the most part of their industrial production is concentrated. And growth of cities quantity and a population in them has progressing nature. Processes of a urbanization last years were especially intensified in connection with rough development of trade, small and average business. As a result of city have turned to the large megacomplexes having ramified networks and consuming tens million of KW.h. of Electric energy in day. Thus the steady tendency of annual growth of extent of cities networks and a level of their power consumption is kept. It has caused significant a load increase on elements of a network and in the certain degree has worsened conditions of normal functioning of electrosupply systems, in one cases, or has made impossible work separate of them, in others. In connection with abovestated, now there was a question on revision of modes and SES parameters of many cities. However, as world experience testifies, the decision of this problem within the framework of the existing concept does not give positive results. It is connected to application of out of date criteria of estimation and methods a mode networks account parameters, methods and its control means.
As control object, SES of cities represent difficult multilevel developing systems with big number internal and field ties, speed and a continuity of change manufacture technological parameters process, transfer and distribution EE. Steady functioning of such systems, expenses for operation and damage to consumers in many respects are determined by a level of control automation in parameters technological process. In all variety of circuits and modes of cities SES operation in a flowsheet of supply with the electric power of consumers a number of the general processing steps may be allocated. Efficiency of performance of each of them in solving image influences technical and economic parameters of electrosupply systems and the electroreceivers connected them. The lowest is efficiency of operations on distribution EE between separate consumers. EE losses at this stage now in some times exceed losses on its transfer. According to [1,2] losses of capacity in networks of an average and low voltage of USA, England, Germany, Japan etc. make now 8 and 12%, accordingly, while losses of capacity in networks of upper voltage do not exceed 4 %. The CIS position in Ukraine and the states is even worse. Losses of capacity in networks of an average and lowest voltage achieve 15_20 % in average.
The analysis of the created reasons position specifies that the major direction of energy sawing in SES cities are improvement of energy quality level (QE) and increase of a indemnification of a reactive power in them. In the leading states of the world (USA, England, France, Germany, Japan) already for a long time the annual gain of a power consumption on 5_10 % is compensated not due to growth of generating capacities, and due to increase of technological efficiency process at various stages of power generation. The EE losses are several times lower, and EE technological charge of consumers is much smaller than in Ukraine, and CIS.
The estimation of real situation testifies that efficiency of course of technical processes in cities SES is influenced with the big number of factors: installation sites, capacity and a degree of the equipment loading, level automation processes circuits and parameters of networks, quality and a of regulation of a voltage and indemnification of a reactive power. Most the specified problems are solved at a stage perspective and routine planning of networks of modes operation [3]. However, a wide range in a combination to high_rate of change SES parameters mode the decision of a problem at a level operative or automatic control require. As analysis shows, automatic control of technological processes of manufacture, transfers and EE distributions in cities SES are carried out now practically only at its top levels.
Basically these are the automatic devices of local action which carry out only functions of automatic control of transformation ratio (АRКТ) of on load tap changing transformers or a reactive power of static condensers batteries, established on the centres of a meal (CENTRAL PROCESSING UNIT). On occassion on power objects special importance (mainly power plants, less often – substations) systems of automatic control normal (SAC NM) or emergency (SAC NE) are applied by modes. In most cases it is the centralized automatic control systems of regulatory type of frequency and reactive power (CSAFC), voltage (CSARV) or prevention of stability infringement (CSAIS). Recently in SES cities more and more systems of automated control have begun to receive a wide circulation. These are systems of the automated dispatching control (ASDC), less often – systems of automated control of technological processes (automated data management system TP).
At the bottom levels of cities SES systems of manual control are basically applied. Systems of discrete logic control are applied on occasion. At the same time, determining influence on an overall performance of SES cities are rendered with modes bottom level operation elements – distributive electrical networks of an average and low voltage which have the greatest extent and which the great bulk of consumers directly connected. Therefore the major direction of increase of efficiency of use EE in SES cities is automation of management by modes DN of average and, especially, a low voltage.
High grade operative controls of distributive electrical networks of cities are now essentially complicated in connection to their big extent and presence of significant number of lines and units. For this reason that part of distributive control modes problems electrical networks which concerns cycles with the big period of the reference of the information (perspective, year and short term planning [3] their same part which concerns cycles with a small cycle time of the information (operative and technological management) is solved only on an intuitive – empirical basis at a level discrete manual or automatic control of the equipment separate kinds. It is the reason of significant decrease of an overall networks performance and, the electroreceivers connected them. Thus the low level of automation, incompleteness and a low level of reliability of the initial information reduce quality of networks control and efficiency of EE use to great extend.
Control systems of the bottom level represent an independent layer which problem consists in stabilization of technological parameters of process near to there given value. Essential disadvantage of such systems, in view of rigid structure and the fixed meaning of automatic parameters adjustment regulators, is that for a long time they work without taking into account variability dynamic and direct current characteristic of technological object of management. Meanwhile, by researches it is established [4], that SES characteristics change over a wide range on fluctuations of daily, week or seasonal diagrams of loadings, and also under action of the big number of the operational factors shown during long work of the equipment and networks. Therefore adjustment of automatic systems and structures of regulators (P, PID, PI, etc.), Which were optimum in its initial period of operation, does not provide due regulator performance in his middle or in the end.
There are two ways elimination of this disadvantage. One is consists readjust to manually adjustments and structures of devices by results of expirience definition static and dynamic characteristics. Second – functions transfer on identification of object and account of adjustments to automatic devices. The manual way requires the big expenses of time and is ineffective, in feature at the big number of objects or variable modes of the equipment operation. Both factors simultaneously take place in cities SES operation. The decision of operation optimization modes problem SES with the help of automatic devices is effective than manual one, but requires some complication of a control system as a whole. The analysis of the researches dedicated to the problem, testifies the presence in world practice of control of modes of SES cities tendencies operation automation, which are necessary for taking into account at the decision of problems of management.
Thus, the carried out analysis testifies the presence of all data needed for technical and economic optimization of cities SES modes. The further increase of efficiency and quality of cities SES operation may be achieved due to increase of control automation level by networks of 6_10 and, especially, of 0,38 kV, and also the subsequent integration of automatic devices in existing monitoring systems and control of networks. Technical opportunities of modern information control systems promote its implementations. In this case cities SES transform in for information – measuring and control complex of cybernetic type, global purpose of which is functioning at its optimum performance as a single mechanism.