Method for automated active control of electric energy quality coefficients
FIELD: electric engineering.
SUBSTANCE: method includes estimation of quality coefficients of electric energy in electric energy system, determining degree of matching of these coefficients to normal values, forming of control signal for correcting devices and predicting electric energy characteristics expected after effect of these devices. On basis of analysis of predicted characteristics quality coefficients are newly estimated and if necessary control signals for correction devices are formed. Estimation of not only voltage and frequency is provided, but also current. Whole cycle is repeated for each node of electric energy system.
EFFECT: higher efficiency.
The invention relates to electrical engineering and can be used in the process of operation of modern power systems, which differ in electrical energy, which tends to decrease its quality.
In accordance with the requirements of the existing interstate standard GOST 13109-97 “Rules of electric power quality in electrical systems General purpose” installed to use the following indicators of quality of electric energy:
- steady-state voltage deviation;
- peak-to-peak voltage (the magnitude of the spike voltage in the area of ±10% of nominal voltage);
- dose flicker (accumulation effects of surges in voltage swings that occurred during the predetermined standard time interval);
- the duration of the voltage SAG (momentary voltage dip per level -10%);
- THD voltage;
factor ν-the harmonic component of voltage;
- asymmetry coefficient voltage reverse order;
the asymmetry coefficient for zero-sequence;
- coefficient of temporary overvoltage;
the frequency deviation.
By this standard are evaluated only two specifications electrical the practical energy - voltage and frequency. For objective assessment of the quality of electric energy is not enough. In some cases, required such an assessment of the current. Indeed, if satisfactory terms of standard indicators of the quality of electric energy, but with increasing numerical values of the same indicators relative to the current one cannot make a statement about the high quality of this energy.
Known methods for the automated control of the quality of electrical energy. Created a Park tools such control. This measuring and computing complexes “Quality”, “Eris-CA”, “Resource-UF”, “Parma RC-605”, “Omsk” and others. These tools are described in many publications. For example, . But these methods only passive control. And this type of control, as it is known, requires only the registration of these quality indicators, the assessment of their compliance with their normative values and does not provide for their improvement.
Development of methods and means of active influence on the quality of the electrical energy turned out to be a separate task, which is currently quite successfully solved, but for each indicator of the quality separately.
But as already noted, and this is confirmed by simple logical conclusions that changing any single indicator cachestatistics energy invariably leads to changes in a number of other indicators. And indeed: the change in the spectral content of the voltage and current (the change in the level of nonsinusoidal respective curves) will inevitably result in a change in the level of asymmetry of the same characteristics of electric energy, if we are talking about a multiphase systems; change the level of voltage fluctuations, if we are talking about short-term changes of voltage and current; the frequency deviation, voltage and current, if we are talking about significant changes in the spectral composition of the above-mentioned characteristics, and so forth. Such facts can be distributed on almost all indicators of quality of electrical energy. This means that it is impossible to consider and plan for the adjustment of one indicator of the quality of electric energy as a purely local operation in isolation from other SCE. This can lead to negative results.
Thus, the problem of stabilization of the electric power quality can only be solved comprehensively. It is in any case can not be solved by considering the possibility of adjustment of one and the most obvious indicator of the quality of electric energy. This is a comprehensive approach to active effect on the quality of electric energy, which is taken into account when creating automated way active control display of the indicators of quality of electrical energy.
The closest technical solution to the proposed method is the description of the automated system for active monitoring of the quality of electrical energy .
The objective of the invention is the formation method of automated control of the quality of electrical energy.
The technical result is achieved by active control of the quality of electrical energy involves not only obtaining information about these indicators, but the possibility of their correction, as well as the fact that the algorithm steps of the automated control of the quality of electrical energy involves the prediction of their status after appropriate adjustments not only in any one particular node power system, but also in the neighboring nodes of this system, besides the fact that the basis of the proposed algorithm is a comprehensive approach to the analysis of the quality of electrical energy, so all these figures are considered in close relationship. When this control should be subjected to not only the quality of electrical energy, specified by the interstate standard GOST 13109-97, but additional, namely:
- steady-state deflection current;
the range of change of current (led the rank of a sharp rise of current in the zone of ±10% of nominal current);
- dose flicker current (accumulation effects of surges in current with different swings that occurred within a specified earlier time interval);
- the duration of the failure current (short-landing of a current for the level - 10%);
- THD current;
factor ν-the harmonic current component;
- coefficient of asymmetry of the currents in the reverse order;
- asymmetry coefficient current zero-sequence;
- pulse current;
the coefficient of time over-current.
In other words, the proposed active control of the quality of electrical energy involves the control of deviations of voltage and current levels nonsinusoidal voltage and current levels of unbalance voltages and currents, pulse voltages and currents, fluctuations of voltages and currents, dips voltage and current, overvoltage and overcurrent.
The drawing shows a graphical representation of the structural scheme of the method for automated control of the quality of electrical energy.
According to this scheme, information about the main characteristics of the investigated power system in the form of analog signals fed to devices (sensors), where these signals are communicated to acceptable to you is ikitelli engineering units. For signals, which carry information about the timing charts of the voltage, as such sensors are useful in existing power systems transformers voltage and signals, which carry information about the current - shunt. The main requirement for these sensors is the constant form of time diagrams of voltage and current. If it is impossible for strict compliance with this requirement should be used by the relevant schedules of amendments.
From the interface units corresponding to the signals on the input terminals of the analog-to-digital Converter (ADC), where the analog signal is converted to discrete.
For analysis of power system DC or single-phase alternating current rather two signals: voltage and current. Therefore, in this case, only two-channel ADC.
For the analysis of three-phase power system required ADC containing at least nine channels, so as to analyze such a system must, as a minimum, nine signals: three line voltage, three phase voltage, three linear current.
For power systems with a large number of phases must ADC with a large number of channels.
For active control of the quality of electrical energy can be used and the model produced the e domestic and foreign industry ADC. The only other multi-channel, demand - responsiveness. This is necessary to ensure the efficiency of active control.
The digital signals from the ADC are received in block 0, where, if necessary, introduced the amendment described above in the values of these signals. This is necessary to compensate for possible distortion of signals in the device pairing. And only after that starts the processing of the received devices pairing and ADC information for the purpose of obtaining quantitative assessment of the quality of electric energy in the investigated area power system with the subsequent formation of control signals corrective devices.
For the successful implementation of active control it is important to assess all indicators of quality of electrical energy. But to start this procedure follows from the quality indicator for the evaluation of which can be obtained with the information needed to identify other indicators of quality of electrical energy, all of which the researcher is interested indicators of quality of electrical energy. These are indicators that assess the level of nonsinusoidal.
In unit 1, and performs the evaluation of these indicators of quality of electrical energy. Its purpose is to obtain qualitative characteristics of these indexes.
In the Loka 2, which is defined as the unit of comparison, it is verified that the actual quantitative characteristics in this case the level of nonsinusoidal their normative values. These normative values can be set or state standard or specific technical requirements to the appropriate equipment.
If the actual quantitative characteristics of the level of nonsinusoidal voltage does not meet the established requirements, the block 3 is formed of discrete control signal for the corresponding corrective devices, which may be different types of filters. Here is a prediction already corrected spectral content of the voltage and current. In the analysis of multiphase systems such prediction should be performed for phase and line values of currents and voltages. On the basis of this prediction are specified discrete values of the respective voltages and currents, by means of which the unit 4 analyzes the next indicator of the quality of electric power.
If the actual quantitative characteristics satisfy previously established requirements, based on the former received from the ADC, the discrete values of voltages and currents in unit 4 analyzes the following group pokazatel the th quality, which of the importance of their quantitative characteristics for the subject industrial region usually takes the leading place. Often for modern industrial regions are the indicators of quality of electric energy, assessing the level of asymmetry of voltages and currents.
Next, in block 4 highlights the quantitative characteristics of these indicators, and in block 5 assesses their compliance with applicable regulatory requirements. When discovering this discrepancy between the unit 6 is determined by the control signal for correcting these quality indicators, and forecasting the updated characteristics of the electrical energy. And only then proceed to block 7 to the analysis of the following groups of indicators of quality of electrical energy.
And so on. Until you have exhausted all scheduled for this analysis the indicators of quality of electrical energy.
In blocks a, b and C performed the analysis, evaluation and formation control of the latter group, the quality of electrical energy.
Next, in block D, it turns out, was there during the last part of the algorithm is the need to adjust any of the SCE. If such had taken place, a clear need to re-check all indicators of the quality of their regulatory requirements in sootvetstvuyuschayatrebovaniyam discrete values of voltages and currents. In this case, the procedure of evaluation of the quality of electric power is performed again, starting with block 1.
There is the possibility of a “loop” algorithm analysis of electric power quality in a given area (node) power system. To avoid this, in block R should be set to the maximum number of cycles of analysis of the quality of electrical energy in this node power system, after which you can choose the best option to improve the quality of electrical energy from the assumed previously (either from the alleged technical solutions that provide quantitative characteristics of quality indicators that are closest to the applicable regulatory requirements, or from the condition of minimizing the reduction of costs) and then in block S to find recommendations for change modes or patterns of energy consumption with the aim of ensuring optimal quality of electrical energy. Moreover, these recommendations may be directed to the technological processes of interest, which are powerful sources of distortion power quality on the changing structure of the electricity system or other events of a similar type and destination.
If in block D found that in the process of conducting all pre is striding procedures to find the optimal technical solution, ensuring regulatory compliance of all quality parameters of electric energy in this node power system, it does not mean the completion of the implementation of active control of these parameters.
The fact that any change in the mode of consumption, and especially the adjustment of the quality of electrical energy in any node in the power system will inevitably lead to a redistribution of electrical energy, and hence to change the state of its quality in other areas controlled power system. Therefore stipulated in case there is an urgent need for such analysis of the quality of electrical energy across the electric power system or at least its nodes.
To do this, perform the prediction of the quantitative characteristics of electrical energy in the other nodes of the power system. This procedure must be carried out in accordance with the following recommendations.
As a result of recent actions to neighboring investigated nodes of the power system can be obtained (to predict) discrete values of phase and line currents and voltages. This prediction should be performed taking into account the recommendations provided in the Patent for sabreena No. 2210154 “a method for predicting the distribution of harmonic components of the electric energy unbranched parts of the electricity system” (applicant Bratsk state technical University registered 10.08.2003 year).
Based on the thus obtained data for the nearest neighboring node repeats the whole procedure of analysis of all indicators of quality of electric energy for the corresponding node power system, similar to that which was carried out in blocks 1, 2, 3, 4, 5, 6, 7, 8, 9,..., A, B, C, D, P. All of this happens in block I.
If the last examined node identified the need for correction of any indicator of the quality of electric energy and has been forecasting the values of voltages and currents acting on the node power system (block II, block III is the formation of the corresponding signal for correcting devices, and then predicting discrete values of phase and line currents and voltages in the initial node of the investigated system and the entire process of analysis of electric power quality, starting with block 1 is repeated.
If in the described node power system the need for correction of the quality of electrical energy is not detected (block II), then in block IV repeats this cycle of operations for the next node.
If necessary, correction of the quality of electrical energy in this node (block V block VI predicted discrete value is of phase and line voltages and currents in the following order: first predicted voltages and currents in the interim, located near the last towards the home node; then the next and next until the start. And then it all repeats from block 1.
If this need is not found, you can proceed to the analysis described above following distance from the starting node (blocks VII, VIII and IX).
And so on.
The last node of the analyzed power system in this way is treated in blocks of IaIIaand IIIa.
If, finally, found even if some compromise solution for all interested researcher plots power system, you can go to the related active control of the quality of electrical energy objectives. This is the challenge of maintaining static and dynamic stability of power system, reliability, energy consumption, optimal loading of electrical equipment, ensuring optimal power factor and a number of others. “Vtorostepenno” these problems quite conditional and valid here only focus on the quality of electrical energy. The definition of appropriate criteria directly in the block K. Moreover, these criteria are evaluated here, if necessary, for the sun is x number of nodes of the electricity system. In the case of matching these criteria regulatory requirements (block L) analysis of the quality of electrical energy ends and are mounted in blocks 3, 6, 9,..., S, To the control signals corresponding corrective devices are used as intended (see drawing).
If in block L there is a discrepancy criteria for optimal power consumption with their normative values, in block M should determine the presence of other acceptable options to achieve target values of indicators of quality of electrical energy. If there is, it makes sense to repeat the whole procedure for the analysis of electric power quality again. If not, then it is necessary to restrict recommendations to ensure acceptable conditions of power consumption in a particular node of the power system. It can be recommendations on the redesign of this system, replacement of one or other electrical equipment on a more rational under the circumstances, changing consumption patterns, and can be, and technologies relevant consumers of electrical energy.
Thus can be implemented by way of an automated active control of the quality of electrical energy into existing power systems.
The sources of information is AI
1. Kurbatskiy VG Information-measuring software quality control electricity. Izvestiya vuzov. Energy, 1997, №1-2. - P.44-48
2. Emtsev, A.N., Balsamin GA Automated system for active monitoring of power quality. The study of power quality in complex electrical systems: proceedings of the. Bratsk: brie, 1990. - C.34-41.
The method of automated control of the quality of electrical energy, including assessment of the quality of electrical energy in the node power system, the source data is an analog type signals of the main characteristics of electrical energy, which is converted into an analog-to-digital Converter in a discrete type of signals, find out the level of these nonsinusoidal signals, check the conformity of the level of normative values, obtain information needed to identify other indicators of power quality, quantify the remaining indicators power quality, find out the degree of consistency of these indicators appropriate normative values, characterized in that the quality of electrical energy provide not only the voltage and frequency but power, in violation of the normative values of the CSO or other indicator of the quality of electrical energy form the control signal corresponding corrective devices and predict expected after the action of these devices electrical characteristics energy, and then based on the analysis of the predicted characteristics re-evaluate the quality of electrical energy and, if necessary, generate control signals corresponding corrective devices, after adjusting of the quality of electrical energy in a single node power system cycle of operations is repeated for the next node power system, after the control nodes of the electricity system and define criteria of its work to resolve the problems of maintaining static and dynamic stability of power system, reliability, energy consumption, optimal loading of electrical equipment, optimum power factor, provide assessment and active influence on these criteria the operation of the electricity system.