SU1728924A1 - Method of distributing reactive load between ac generators operating in parallel - Google Patents

Abstract

SUMMARY OF THE INVENTION: In a method for distributing reactive loads between parallel-running alternators, voltage is measured on the generator buses and the reactive load of each of the parallel generators, summarizes the reactive load of all parallel generators, and on each of the parallel generators maintain a reactive power value the optimal value according to the generalized criterion of reduced costs for the distribution of reactive load. 2 Il.

Description

The invention relates to power engineering and can be used in power plants with synchronous and asynchronized or synchronous generators operating in parallel.

There is a known method for distributing reactive loads between parallel-running synchronous generators, based on measuring the mode parameters (voltage on the generator buses, reactive loads of each of the parallel-running generators), comparing the distribution parameter with a given value and changing the excitation current depending on the error signal, reactive power level on all generators in all modes of operation.

The disadvantage of this method is that the alignment of reactive power leads to different reliability of parallel generators, which reduces the reliability of the power plant as a whole. The minimum loss of active power occurs if the characteristics of the generators are identical. In addition, the method is applied only to synchronous generators.

The closest to the technical essence of the invention is a method of distributing a reactive load between parallel-running synchronous generators, in which the mode parameters are measured, the distribution parameter is compared with the set value, and the excitation current is changed depending on the error signal, and

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generators are maintained equal ratios. between the current and maximum permissible values of reactive power.

For this, the active load of each generator is measured, the value of the maximum permissible reactive load corresponding to it is determined, this value is multiplied by the voltage on the generator buses, and the resulting signal is used as a power setting signal. However, with equal ratios of current and maximum allowable values of reactive power of all generators, a generator with lower active power has greater reactive power, which in the consumption mode leads to a sharp deterioration in the dynamic stability of a synchronous generator, and therefore, the reliability of the generator decreases according to dynamic stability conditions. Therefore, a generator with lower active power in the mode of reactive power consumption has lower reliability, i.e. the alignment of the relations between the current and maximum allowable values of the reactive power of all generators leads to different reliability of parallel generators, which reduces the reliability of the power plant as a whole. The maximum reliability of the power plant is achieved at equal levels of reliability of all of its generators, and the most favorable distribution, providing an increase in efficiency, taking into account the losses of active power and reliability under the conditions of dynamic stability and thermal state. In addition, the disadvantages of the known method include the fact that it is applied only to synchronous generators operating in parallel.

The aim of the invention is to increase the reliability and cost-effectiveness of work, as well as to expand the use of the system of parallel-running alternators by optimizing the reduced cost of reactive load distribution by the generalized criterion by maintaining it on each generator at the optimum value.

According to the method of distributing reactive loads between parallel-running alternators, according to which the voltage on the generator buses is measured, the reactive load of each of the parallel-running generators is compared with its power setting signal and the excitation current is varied depending on the error signal. the load of all parallel generators, are determined by the known dependencies corresponding to the total load value of the relative increase in spending, which determines the optimal value of the reactive power of each generator, multiplies this value by the voltage on the generator buses and the resulting signal is used as a signal to set the power for each generator.

Using the proposed method of reactive load distribution provides an increase in the level of reliability and efficiency of the system of parallel operating alternators and the power plant as a whole compared to maintaining equal ratios of current and maximum allowable values of reactive power at different values of the active, expanding the field of use, since the method is applicable not only for parallel synchronous

generators, but also for parallel-running synchronous and asynchronized generators.

Since the mode of operation of the generator by reactive power affects the losses of active power, dynamic stability and thermal state, the optimization of the distribution of reactive load is carried out according to a generalized criterion of reduced costs

3 | 3p + 3d + 3t.

where 3i is the reduced cost of compensation for active power losses; Rear - reduced costs of damage from reduced reliability under the conditions of dynamic stability;

Zm - reduced costs of damage from reduced reliability under the conditions of thermal state;

H1.2n is the generator serial number.

Goal equation has the form

50

H

Lt

mm

and the condition of optimality is

 eZp 0Qi 302 QQn

or

 . . . cjn.

where qi, q2Qn are relative increments

costs.

On., Fig. Figure 1 shows a diagram of the process of distributing reactive loads between station generators; in fig. 2 is a functional block diagram of a device implementing the proposed method.

FIG. Figure 1 shows the order of the optimal distribution of the total reactive load. It is between parallel generators, performed according to previously calculated in the operating range of changes in active loads, and then averaged for these loads, the characteristics of the relative increase in costs of the synchronous generator qc, asynchronous generator qa and load qH. As can be seen from FIG. 1, functional dependency scale It is formed by summing the reactive powers of synchronous Qc and asynchronized Qa generators with equal relative cost increases.

The circuit (Fig. 2) is given for two generators, with a larger number of them, the number of individual blocks increases accordingly. The scheme contains central elements; bus voltage regulator 1 2, functional converter 3, adder 4 and individual aggregate elements: generators 6 reactive power sensors 5, functional converters 7, multiplication units 8, equalization units 9, executive units 10.

The output of the central regulator 1 of the busbar voltage 2 is connected to the inputs of the multiplication units 8. The other inputs of block 8 are connected to the outputs of individual functional converters 7. The inputs of which are connected to the output of the central functional converter 3, the input of which is connected to an adder 4, the inputs of which are connected to the outputs of individual sensors 5 of the reactive power of the generators 6. In individual functional converters 7 the dependences of the relative increments of the costs of the generators 6 on the reactive power, and in the central functional transducer 3 - the dependence of the relative cost irosta costs load from the total reactive load. The outputs of the units 8 and other outputs of the individual reactive power sensors 5 are connected to the comparison unit 9, the outputs of which are connected to the inputs of the execution units 10.

The method is carried out as follows.

With the help of the central regulator 1, the voltage is measured on the buses 2 of the generator 5 and 6 and is converted into the same signals that are fed to the inputs of the blocks 8. The output signals of the individual reactive power sensors 5 are summed in the adder 4 and converted depending on the relative value the increase in the cost of the load in the output signal of the central functional converter 3. The output signal of the central functional converter supplies 5 s to the inputs of the individual functional converters 7 and zuets depending on the optimal values of the reactive power generators in output signals of individual

0 functional converters 7.

In blocks 8, the signals from the central controller 1 and the individual functional transducers 7 are multiplied and the outputs of the blocks 8 receive signals

5 assignments of reactive power of generators 6. The assignment signals and output signals of individual sensors 5 of the reactive power of generators enter the comparison units 9, where the signals are of current value

0, the reactive power of each of the generators is compared with the reference signal, and the resulting difference in the form of control signals is sent to the executive units 10, designed to match their type and level with the design and circuit features of specific generator excitation systems. As a result, a predetermined reactive power is established on the generators 6.

0 In this case, the values of given reactive powers are optimal based on the generalized criterion of reduced costs for the distribution of reactive power between parallel

5 operating generators (loss of active power, reliability under the conditions of dynamic stability, reliability under the conditions of thermal state). The efficiency and reliability of the system of parallel operating generators increases, and the range of use expands.

Claims (1)

Invention Formula A method for distributing reactive loads between parallel-running alternators, according to which the voltage on the generator buses, the reactive load of each is measured from parallel generators, compare it with the power reference signal and vary the excitation current depending on the error signal, differing in that. that, in order to increase reliability and cost-effectiveness, as well as expanding the field of use, the reactive load of all parallel generators is summed up 0 With the known dependencies, the value of the relative increase in costs corresponding to the total load determines the optimal value of the reactive power of each generator, multiplies this value by the voltage on the generator buses, and the resulting signal is used as a power setting signal for each generator. 1