RU2061186C1 - Hydraulic unit of smaller hydroelectric station - Google Patents

Abstract

FIELD: hydraulic engineering for generating electric power at small or microhydroelectric stations. SUBSTANCE: connected to main hydraulic turbine is pump having rotor provided with shaft and outlet branch pipe; connected to pump is auxiliary hydraulic turbine which has rotor provided with shaft and inlet branch pipe which is connected to electric current generator; pump shaft is connected with shaft of main hydraulic turbine; outlet branch pipe of pump is connected with inlet branch pipe of auxiliary hydraulic turbine; shaft of auxiliary hydraulic turbine is connected with shaft of electric current generator. Pump shaft may be connected with shaft of main hydraulic turbine through reduction gear. Maximum effect will be obtained if radial-axial hydraulic turbine developing speed of 80 to 145 r/min is used as auxiliary hydraulic turbine. EFFECT: enhanced reliability. 3 cl, 3 dwg

Description

 The invention relates to hydropower and can be used to generate electricity at small or micro-hydroelectric stations (SHPPs).

 When generating electricity at hydroelectric power plants, it is necessary to maintain the rotational speed of the rotor of a hydraulic unit, consisting of a hydraulic turbine and an electric current generator connected to it, in a given range. This requirement is due to the fact that the voltage and frequency of the electric current are functions of the rotational speed of the rotor of the generator. To solve this problem, it is necessary to maintain the equality of the capacities of the consumer of electric current and the power generated by the electric generator, which is a function of the power of the flow of water passing through the turbine. In practice, when working for an individual consumer, the deviation of the rotor speed of the hydraulic unit from the optimal value corresponding to the industrial frequency of the current should be no more than ± 20%. Often, consumers require a narrower range for maintaining the frequency of the generated electric current.

 A hydroelectric power plant is known, including an electric current generator containing a rotor with a shaft and a main hydraulic turbine containing a rotor with a shaft, which ensures the operation of a hydroelectric power station in a predetermined range of the rotational speed of the hydroelectric rotor by changing the power of the water flow entering the turbine. This hydraulic unit allows the efficient operation of hydroelectric power stations. However, this hydraulic unit includes expensive and difficult to operate special regulatory bodies at the entrance to the turbine, a guiding apparatus and a hydromechanical or electro-hydraulic regulator (Hydroelectric and auxiliary equipment of hydroelectric power plants. / Ed. By Yu.S. Vasiliev. M. Energoatomizdat, 1988, v. 1, p. 101).

 Closest to the proposed is the unit for small and micro hydroelectric power plants, including an electric current generator containing a rotor with a shaft and a main hydraulic turbine containing a rotor with a shaft. This hydraulic unit ensures operation in a predetermined range of the rotational speed of the hydraulic unit rotor using an adjustable electric ballast load connected to an electric current generator. Using such a ballast load, the braking torque on the hydraulic unit shaft is changed. In operating modes, the necessary opening of the guide vane is set, which corresponds to the optimal use of the watercourse, and all changes in the load of the consumer (below the optimum load of the hydraulic turbine) are compensated by the ballast load (for example, by electrical resistances for heating water or heating). Ballast load control can be carried out either by the rheostat method or by stepwise switching the constant load by thyristor switches (Small Hydropower. / Ed. By L.P. Mikhailov. M. Energoatomizdat, 1989, p. 120). The use of a guide vane in some cases can be completely ruled out, which is an advantage of this hydraulic unit.

 However, this hydraulic unit includes an electronic regulator and electric ballast, which reduces reliability and makes its use for small and micro hydroelectric plants very expensive.

 To eliminate these drawbacks, it is advisable to use the ability of some hydraulic turbines to self-regulate instead of the electronic frequency controller. The ability to self-regulate the greater, the less the rotational speed of the rotor of the hydraulic unit changes when the power of the electric load on the generator changes. The best self-regulating turbines, in which with an increase in electrical load automatically increases the power of the flow of water passing through them. This effect is due to the fact that when the electric load on the generator increases, the rotational speed of the hydraulic unit rotor changes and the turbine switches to a different operating mode with a different value of the reduced water flow through it. If this change in the reduced flow rate is positive, then the power of the flow of water passing through the turbine increases, and if it is negative, it decreases.

(1) где П параметр саморегулирования;
n_Ip', Q_Ip' приведенная частота вращения и приведенный расход при отключенной нагрузке (разгонные значения);
n_Iопт', Q_Iопт' приведенная частота вращения и приведенный расход при оптимальном режиме.Thus, the greatest effect of self-regulation is manifested in those turbines in which the power of the water flow passing through them automatically increases with increasing power of the electrical load, i.e. simulates the operation of the guide apparatus. Various hydroturbines have the ability to self-regulate to varying degrees. For a relative assessment of the ability of hydroturbines to self-regulate, it is convenient to introduce a special parameter
P

(1) where P is a self-regulation parameter;
n _Ip ', Q _Ip ' reduced speed and reduced flow at disconnected load (accelerating values);
n _Iopt ', Q _Iopt ' reduced speed and reduced flow rate in optimal mode.

(2)
Q

(3) где n частота вращения, об/мин;
D диаметр, м;
Н напор, м;
Q расход, м³/с.The given values of the rotational speed and flow rate are determined by well-known formulas (Orgo V.M. Gidroturbiny. L. 1975, p.233):
n

(2)
Q

(3) where n is the rotational speed, rpm;
D diameter, m;
N head, m;
Q flow rate, m ³ / s.

 From the above it follows that the larger the numerator in formula (1), the greater the ability of the turbine to self-regulate. Another important feature of a hydraulic turbine is its speed range when the load changes. The smaller this range, the better, since many consumers of electricity can only be successfully operated in a narrow range of current frequency changes, which is a function of the speed of the turbine. Thus, the smaller the denominator in formula (1), the greater the ability of the turbine to self-regulate. It follows that the larger the self-regulation parameter, the greater the ability of the turbine to self-regulation.

 Most of the radial-axial type hydraulic turbines have good self-regulation ability, however, this ability is most expressed in radial-axial hydraulic turbines with a speed from 80 to 145 rpm.

The results of processing test data of various hydraulic turbines of the radial-axial type, carried out by the authors, are presented in figure 1. Figure 1 shows the dependence of the self-regulation parameter P on the speed coefficient n _s .

(4) где n_Io' величина приведенных оборотов в оптимальной точке универсальной характеристики, об/мин;
Q_Io' величина приведенных расходов в оптимальной точке универсальной характеристики, м³/с;
η_To коэффициент полезного действия турбины в оптимальной точке характеристики.Turbine speed was calculated according to the well-known formula (Orgo V.M. Hydroturbines. L. 1975, p. 235):
n _s = 3.65 • n

(4) where n _Io 'is the magnitude of the reduced revolutions at the optimal point of the universal characteristic, rpm;
Q _Io 'the magnitude of the reduced costs at the optimal point of the universal characteristics, m ³ / s;
η _To turbine efficiency at the optimum point of the characteristic.

From figure 1 it is seen that the greatest ability for self-regulation is possessed by radial-axial type turbines at speeds from n _s 80 rpm to n _s 145 rpm.

 A hydroelectric unit of a small hydropower plant is proposed, including an electric current generator containing a rotor with a shaft, and a main hydraulic turbine containing a rotor with a shaft, characterized in that a pump containing a rotor with a shaft and an outlet pipe is connected to the main hydraulic turbine, and an auxiliary hydroturbine containing a rotor is connected to the pump with a shaft and an inlet pipe that is connected to an electric current generator, wherein the pump shaft is connected to the main turbine shaft, the pump outlet pipe is connected to the auxiliary inlet pipe Yelnia water turbine and the shaft of the auxiliary hydraulic turbine generator connected to the shaft of the electric current. The pump shaft can be connected to the shaft by the base of a hydraulic turbine through a gearbox. As an auxiliary hydroturbine, a radial-axial type turbine can be used with a speed of 80 to 145 rpm.

 Figure 2 shows a diagram of the proposed hydraulic unit. The hydraulic unit contains a main hydraulic turbine 1 having an inlet 5 and an outlet 2 nozzles to which water pipes 4 and 3 are connected, respectively. The hydraulic turbine includes a rotor with a shaft 6, which is connected by means of a coupling 7 to the shaft 8 of the pump rotor 9. The pump 9 has an inlet 10 and an outlet 12 nozzles, to which water pipes 11 and 13 are connected, respectively. The outlet pipe 12 of the pump 9 is connected via a pipe 13 to the inlet pipe 14 of the auxiliary turbine 17, which also has an outlet pipe 15 with an attached water pipe 16. The rotor shaft 18 of the auxiliary hydraulic turbine 17 is connected via the coupling 19 to the rotor shaft 20 of the electric current generator 21. Electric energy is removed from the electric current generator 21 by means of a cable 22. The shaft 8 of the pump 9 can be connected to the shaft 6 of the main hydraulic turbine 1 not directly by means of a coupling 7, but via a gearbox (not shown).

 The hydraulic unit operates as follows.

 The fluid flow from the river or other source is supplied through the water supply 4 and the inlet pipe 5 to the main low-pressure turbine 1, rotates the rotor with the shaft 6 and is diverted from the turbine through the outlet pipe 2 with the water pipe 3. The rotation of the shaft 6 is transmitted to the rotor shaft 8 by means of the coupling 7 pump 9, which also has a fluid flow from the river through the inlet pipe 10 with a water supply 11. The rotor of the pump 9 interacts with the fluid stream and feeds it under pressure through the pipe 13 and the inlet pipe 14 to the auxiliary rotor of the high-pressure hydraulic turbine 17, drives it and is diverted from the hydraulic turbine 17 through the outlet pipe 15 and the water supply 16. The rotor shaft 18 of the turbine 17 transmits the rotation by means of the coupling 19 to the shaft 20 of the rotor of the generator 21. During rotation of the rotor of the generator 21 of electric current, electricity is generated, which is allocated to the consumer via cable 22.

 Thus, the practical application of the proposed hydraulic unit allows the use of self-regulating high-pressure hydraulic turbines at HPPs with low pressures, which can dramatically increase the reliability of HPP equipment, reduce its cost and simplify maintenance. Particularly good results on the self-regulation of the hydraulic unit can be obtained by using a radial-axial type hydraulic turbine 17 as an auxiliary turbine with a speed of 80 to 145 rpm.

In practical use of the proposed hydraulic unit, it is convenient to use the dependences of the power of the hydraulic unit N _а on the pressure Н, constructed for different frequencies of the generated electric current f. The results of such processing of the data of experiments conducted by the authors on a hydraulic unit with an auxiliary turbine of radial-axial type with a speed of n _s 115 rpm are presented in FIG. 3.

H/H_о, где Н напор; Н_о максимальный напор при максимальной мощности. По нижней оси абсцисс отложены разгонные значения частоты тока f_р, т.е. значения частоты тока при электрической нагрузке, отключенной от генератора.The ordinate axis represents the relative power of the hydraulic unit N _a N _a / N _ao , where N _{a is the} power of the hydraulic unit; N _ao maximum power unit. Relative head is plotted on the top abscissa

H / H _about , where N pressure; N _{about the} maximum pressure at maximum power. Acceleration values of the current frequency f _{p are} plotted along the lower abscissa, i.e. current frequency values at an electric load disconnected from the generator.

 The practical application of the hydraulic unit is illustrated by the following example.

 PRI me R. Let the consumer demand that the hydraulic unit produce electrical energy with a current frequency of 55.5 to 47 Hz.

0,88 на верхней оси абсцисс. Следовательно, для того, чтобы частота тока не превышала значение f_р 55,5 Гц, необходимо установить на турбине напор, абсолютное значение которого равняется 88% от максимального для данного гидроагрегата. Если паспортный максимальный напор турбины Н_о 100 м, то эксплуатационный напор должен быть Н 88 м.From figure 3 we find on the lower axis of the abscissa the value of the acceleration speed f _p 55.5 Hz. This value of f _p corresponds to the value of the relative pressure

0.88 on the upper abscissa axis. Therefore, in order to ensure that the current frequency does not exceed the value of f _p 55.5 Hz, it is necessary to set the pressure on the turbine, the absolute value of which is 88% of the maximum for this hydraulic unit. If the passport maximum head of the turbine Н is _about 100 m, then the operational head should be Н 88 m.

0,88 с кривой f 47 Гц, и найдем соответствующее этой точке значение относительной полной мощности гидроагрегата

100. Следовательно, при подключении к генератору полезной электрической нагрузки, равной его минимальной мощности, частота вырабатываемого электрического тока будет не менее 47 Гц.Now we find the intersection of the vertical line connecting the values of f _p 55.5 Hz and

0.88 with a curve of f 47 Hz, and we find the value of the relative apparent power of the hydraulic unit corresponding to this point

100. Therefore, when connecting to the generator a useful electric load equal to its minimum power, the frequency of the generated electric current will be at least 47 Hz.

Thus, it was obtained that when operating a hydraulic unit at a pressure of 88% of the known maximum for a given turbine, when the useful electric load changes from zero to a maximum equal to the total maximum power of the hydraulic unit, the frequency of the generated electric current will be in a predetermined range from f _max 55 5 Hz to f _min 47 Hz. In this case, the hydraulic unit can be operated without any frequency control.

 With other permissible ranges of changes in the frequency of the electric current specified by the consumer, the pressure and load power values that provide the specified ranges of the frequency of the generated electric current are found similarly from the data shown in Fig. 3.

 The proposed hydraulic unit allows you to drastically reduce the cost of hydraulic units for small hydropower plants, reduce the cost of their operation and increase reliability.

Claims (3)

 1. The hydroelectric unit of a small hydroelectric power station, comprising an electric current generator containing a rotor with a shaft, and a main hydraulic turbine with a rotor and a shaft, characterized in that a pump containing a rotor with a shaft and an outlet pipe is connected to the main hydraulic turbine, and an auxiliary hydraulic turbine containing a rotor is connected to the pump with a shaft and an inlet pipe that is connected to an electric current generator, wherein the pump shaft is connected to the main turbine shaft, the pump outlet pipe is connected to the inlet pipe of the auxiliary hydraulic turbine And an auxiliary hydraulic turbine shaft connected to the shaft of the generator of electric current.  2. The hydraulic unit according to claim 1, characterized in that the pump shaft is connected to the main turbine shaft through a gearbox.  3. The hydraulic unit according to paragraphs. 1 and 2, characterized in that as an auxiliary hydraulic turbine use a radial-axial type hydraulic turbine with a speed of 60,145 rpm.

Images