CC BY
4УДК 621.75 Mammadova G. V., Valizade J.
Mammadova G.V.
Associate professor Azerbaijan State Oil and Industry University (Baku, Azerbaijan)
Valizade J.
Master student Azerbaijan State Oil and Industry University (Baku, Azerbaijan)
ANALYSIS OF REACTIVE POWER IN ELECTRICAL NETWORK
Аннотация: power system is a typical non-linear system. Along with social progress and economic development, all the population's demandfor electricity has also increased, which has led to the rapid development of the modern electricity system. Traditional reactive power compensation equipment can meet a number of reactive power compensation requirements, but it is slow to respond, unable to support difficulties and other shortcomings. The static reactive compensator has made great progress in recent years and is widely used to compensate long-distance transmissions, as well as to compensate large numbers of reactive loads. The main issue of managing the mode of the electric network is to ensure that the quality indicators of the voltage level at the points of demand meet the standards specified in the DST and the favorable mode of the electricity supply.
Ключевые слова: reactive power, compensation, efficiency, voltage, useful work factor.
For each network, economic efficiency should be ensured due to reactive power compensation, and as a result, the voltage level at the node loads will also improve. If this improvement is not enough in different modes, then it is necessary to use adjustable reactive power sources and adjustable transformers under load. However, if we take into account that it is more important to ensure the voltage level
in the nodal loads, then the issue of reactive power compensation should be solved on the condition that the voltage level is ensured, and then the economic efficiency should be paid. At this time, the lowest voltage node where the reactive power compensating device (RGK) should be installed in the network is determined, then the next low voltage node is determined and the compensating device is installed, this is continued until the voltage at all nodes is at the required level Then, in the second stage, from the point of view of economic efficiency, that is, to reduce the loss of electrical energy, it is determined whether it is appropriate to additionally compensate the reactive power. There are natural and artificial methods of reactive power compensation. Special events held in natural road enterprises, saving electricity, etc. measures.
Artificial compensation is mainly used. For this purpose, synchronous compensator or adjustable capacitor batteries are mostly used. Capacitors differ from synchronous compensators in many advantages, which is why capacitors are used in most cases to solve compensation problems. In most foreign countries, the value of cos^ is 0.95. In Belgium it is between 0.9+- 0.97, in France and Bulgaria it is 0.93. Between 0.9^1.0 in Canada, 0.9 in 3 countries (Denmark, Greece and Italy), up to 0.92^0.97 in Hungary, 0.92 in Portugal. Reactive power required by electric machines and other electrical equipment working on the principle of electromagnetic induction from the network along with active power creates additional active power losses in energy transmission and distribution systems due to the heating of their wires, starting from generators, passing through transformers, transmission and distribution lines.
At the same time, the high voltage drop caused by the reactive currents in the network elements causes a decrease in the voltage in the clamps of the operators and, as a result, the quality indicators of the electric energy deviate from the established norm limits. This also worsens the technical and economic indicators characterizing the operation of the electric power system, in other words, loading power plant generators with reactive current increases fuel consumption, power losses in transmission and distribution networks, as well as voltage drop [3-5].
Therefore, the development of the methodology for evaluating the technical and economic indicators of the use of reactive energy and the creation of an
appropriate legal framework based on it should be considered as one of the most important issues. In order to solve issues related to reactive power or energy, first of all, technical conditions for reactive power for consumers connected to the energy system normative tg< =0.22 for 110 kV and lower voltage levels for the purpose of differentiation it is necessary to determine the values of It should be noted that the normative values of the reactive power coefficient have been set for the energy systems of many foreign countries and To determine the normative values of tg< =0.2 for the energy system of Azerbaijan the need has arisen.
In Japan and European countries, as well as in the United States until recently, the reactive power coefficient was accepted as tg< = 0.2...0.4, depending on the class of the network. However, in recent years, distribution networks in many systems have zero-value tg9 at maximum loads with ( cos< = 1), and individual lines work even with a preventive reactive current [6]. Currently, the rates of billing for active energy in the republic have been set by the Tariff Council, and payment for the active energy used is made accordingly. Reactive energy required by consumer devices is not billed and therefore the cost of this energy used by each consumer is not paid, but it should be clarified to what extent active energy is taken into account in the established tariff. In most foreign countries (Russia, Ukraine, USA, Japan, etc.) payments are provided for reactive energy consumed. Thus, taking into account the reactive power (energy) demanded by consumers, it is necessary to revise the normative values of reactive power coefficient (effective reactive power) and reactive power (energy) calculation methodology for different voltage levels in order to calculate payments for electricity.
Methodology of determination of effective reactive power (energy) on the energy system. In order to evaluate the normative reactive power factor, economically justified effective reactive power values for voltage levels should be determined. Reactive power in order to stimulate compensation (RGK). Qsm price of RGK devices can be determined from the billing conditions based on installation costs and reactive energy used (Figure 1).
Figure 1. Cost change curves
o = tsrn ■ P
OTsm max
Technical and economic justification of normative values of the reactive power factor. As it is known, the controlled KQ applied to maintain the voltage in the power system, reduce the losses, increase the output capacity of the system and reduce the costs, also provides the required level of the reactive power factor [6,7,10]. In order to solve this problem, first of all, appropriate reports should be made to determine the power of the RGM, the installation location, the management method and the type of connection. Currently, the multi-objective fuzzy optimization method, which is considered a promising method, can be considered the most objective method for the placement of CG in distribution power networks (PESH) [3, 11]. The method is based on the application of fuzzy set theory . For the technical-economic justification of the issue, regime reports were made for the real electric network of the energy system. The following is provided here: the network works at design capacity 55% of the time, maximum load (110% of rated load) covers 25% of the time and minimum load (30% of rated load) covers 20% of the time. The values of the reactive power factor for other voltage steps were determined by similar reports and the results are given in table 1.
Figure 2. Dependence curves of annual costs on tg^ - dependence curves.
Table 1.
Gsrginlik pillssi, kV tgf-nin qiymstlsri
110 0,46
35 0,38
6-10 0,31
0,4 0,23
Conclusion. The results of the studies conducted for the evaluation of the reactive power (energy) in the energy system were given and appropriate proposals were made with the methodology developed based on reference to the normative documents in foreign countries. The results obtained for different voltage levels of the power system on the calculation of the reactive power factor and reactive energy are preliminary estimates, and additional research is needed in this direction.
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