WO2014146422A1

WO2014146422A1 - Method for measuring and calculating temperature of rotor winding of large-sized water turbine generator set

Info

Publication number: WO2014146422A1
Application number: PCT/CN2013/084963
Authority: WO
Inventors: 许其品; 袁亚洲; 刘光权; 耿敏彪; 朱宏超; 徐其质; 安宁; 王亚婧; 万泉; 仇志刚
Original assignee: 国电南瑞科技股份有限公司
Priority date: 2013-03-18
Filing date: 2013-10-10
Publication date: 2014-09-25
Also published as: CN103267587A

Abstract

A method for measuring and calculating a temperature of a rotor winding of a large-sized water turbine generator set comprises the following steps: (1) separately measuring a temperature of a rotor winding in a halting state and a no-load state, of a generator as well as the rotor winding, and calculating to obtain the temperature of the rotor winding and a linear coefficient of a resistor; (2) obtaining, by using sampling, real-time sampling values of an exciting voltage and an exciting current to obtain a resistance value of the rotor winding; and (3) multiplying a real-time resistance value of the rotor winding by the temperature of the rotor winding and the linear coefficient of the resistor, and subtracting a zero resistance temperature to obtain the temperature of the rotor winding. The measurement of a rotor voltage and a rotor current has a filtering function and a fault-tolerant mechanism, and a linear coefficient calculation method of a rotor resistance and a rotor temperature is optimized and the calculation of the resistance value of the rotor winding is closer to an actual value; in addition, the influence of a slip ring pressure drop and a bus pressure drop on the calculation of a rotor temperature are considered to enable the calculated temperature of the rotor to be closer to an actual temperature, thereby improving the accuracy of the temperature measurement and calculation of a rotor.

Description

Instruction manual

Calculation of rotor winding temperature of large hydro-generator set 3⁄43⁄4

The invention provides a method for improving the calculation accuracy of the resistance of the rotor winding by optimizing the linear coefficient of the resistance of the rotor winding and the temperature, reasonably selecting the measuring point, considering the influencing factors of the outer loop, and considering the rotor voltage and the rotor current. The sampling is performed by filtering and fault tolerance, and belongs to the field of electrical engineering.

Background technique

The temperature of the large generator rotor is an important monitoring parameter for the safe operation of the generator. The measurement methods include direct measurement method and indirect measurement method. The direct measurement method is more reliable, but the implementation is more difficult, and the equipment is safely operated and repaired. Adding new difficulties. The basic principle of the indirect measurement method is based on the resistance temperature characteristics of the copper conductor. Since the real-time monitoring values of the excitation voltage and the excitation current are required, the method of using the excitation software to calculate the rotor winding temperature has been widely used, and its implementation is relatively easy. No special maintenance is required.

The implementation of this method requires a linear coefficient of resistance and temperature, as well as real-time samples of the excitation voltage and excitation current, where the calculation of the linear coefficient is mostly achieved by absolute zero and the maximum temperature of the winding or the resistance at full load. The sampling, algorithm, and output link errors all cause inaccurate temperature calculations. Therefore, improving the accuracy of sampling, calculation, and output is related to accurate measurement of rotor winding temperature.

Summary of the invention

The technical problem to be solved by the invention is to improve from sampling, algorithm and output simultaneously. The accuracy of the rotor winding temperature measurement.

In order to solve the above problems, the technical solution adopted by the present invention is:

A method for calculating a rotor winding temperature of a large hydroelectric generating set, characterized in that: the following steps are included:

(1) Calculate the linear coefficient of rotor winding temperature and resistance by measuring the temperature of the rotor winding of the generator and the temperature and rotor winding in the no-load state, and then determining the slope of the line by two points;

(2) obtaining the real-time sampling value of the excitation voltage and the excitation current by sampling, and dividing the excitation voltage by the excitation current to obtain the resistance of the rotor winding;

(3) The real-time resistance of the rotor winding is multiplied by the linear coefficient of the rotor winding temperature and the resistance. Then the zero resistance temperature is subtracted to obtain the rotor winding temperature.

The foregoing method for calculating the rotor winding temperature of a large hydro-generator set is characterized in that: in the step (1): pre-measuring the rotor rotor winding shutdown state temperature ⁷ ^ port idling temperature ^ and the corresponding rotor resistance Value and, using the measured value according to the formula _κ _ Τ ₂ _ Ί

^{1 R} 2 _ ^R 1 Calculate the linearity of the winding temperature and resistance. In order to make the calculation of the coefficient unaffected by the external circuit, the rotor resistance required for the calculation needs to be measured from the connection between the slip ring and the rotor winding.

The foregoing method for calculating the rotor winding temperature of a large hydro-generator set is characterized in that: in the step (2): the resistance value of the rotor is calculated by sampling the excitation voltage and the excitation current, and is subtracted in the calculation. The external loop resistance.

The foregoing method for calculating the rotor winding temperature of a large hydro-generator set is characterized in that: the excitation phase of the rotor excitation voltage and the excitation current of the rotor are fault-tolerant, and the rotor is excited. The voltage is calculated by the trigger angle and the anode voltage. The voltage is sampled three times in one sampling period, and the third time is used as a referee function. The first and second samples are fault-tolerant, and the third time is selected. The value of the rotor excitation voltage needs to be filtered to avoid the instantaneous jitter of the rotor voltage during operation or the interference jitter of the measurement link, which brings errors to the measurement of the rotor resistance; the current sampling fault tolerance is to compare whether the two measurement channels are similar. If it is not similar, it is compared with the theoretical value, and if it is close to the theoretical value, the theoretical value is calculated by the active reactive power and the terminal voltage.

The foregoing method for calculating the rotor winding temperature of a large hydro-generator set is characterized in that: when measuring the rotor resistance of the rotor winding of the generator, the resistance of the rotor winding of the generator is measured at the connection between the slip ring and the rotor winding, On the outgoing side of the generator DC magnetic circuit breaker

D

Measure the resistance of the rotor winding of the generator with external circuit ^{( ?} i + ), where ^Z is the resistance of the external circuit, and then the actual values of the excitation voltage and the excitation current are S, and the rotor resistance can be obtained.

.

The foregoing method for calculating the rotor winding temperature of a large hydro-generator set is characterized in that: in the step (3): theoretically, the critical temperature of copper entering the superconducting state is close to an absolute zero-273 ° C, but actually -234. The resistance of the copper conductor is very small at 5 °C, so the industrial calculation takes -234. 5 °C is the zero resistance temperature of the copper conductor, that is, the intersection of the linear extension line and the abscissa in Figure 1, by the rotor winding The zero-resistance temperature determined by the material copper is 234.5, but considering the existence of the slip ring contact resistance, the calculated rotor temperature ⁷ ^ is slightly higher than the actual value, so take =- ²³⁵ · ¹ to offset this error.

The foregoing method for calculating the rotor winding temperature of a large hydro-generator set, characterized by In the step (3): according to the linear relationship between the rotor winding temperature and the resistance,

T _f = K _x R _f -K ₂ (D where ^ - rotor winding temperature

- linearity of winding temperature and resistance

^R f - rotor winding resistance

- Zero resistance temperature determined by the rotor winding material.

The beneficial effects of the invention are:

1. According to the sampling point of the excitation voltage and the excitation current in the loop, the calculation of the resistance of the rotor winding takes into account the influence of the external loop, and the calculation is more accurate.

2. The resistance of the rotor winding at normal temperature is measured from the connection of the rotor slip ring. The calculation of the linear coefficient of the rotor winding temperature and resistance is more accurate. The rotor temperature at ambient temperature and no-load state is selected to calculate the coefficient.

3. The influence of slip ring pressure drop and busbar voltage drop is considered in the calculation of rotor winding temperature.

4. The measurement of excitation voltage and excitation current of the rotor has filtering and fault tolerance. At the same time, the output result also needs to be fault-tolerant. If it does not meet the linear ratio, if the deviation of the temperature and current set by the parameter is too much, re-pair The voltage and current are sampled or rounded off.

In summary, the present invention corrects the fault-tolerant and calculation method for calculating the rotor temperature-related parameters, so that the rotor winding temperature is closer to the actual value, reflecting the actual heat generation of the rotor winding.

DRAWINGS Figure 1 is a graph showing the relationship between copper conductor resistance and temperature in the present invention.

Figure 2 is a schematic diagram of the rotor circuit of the present invention.

Figure 3 is a logic diagram of rotor voltage sampling tolerance and filtering.

Concrete implementation

The present invention will be further described in detail below with reference to the accompanying drawings in conjunction with examples. However, the invention is not limited to the embodiments given.

Figure 1 is a graph showing the relationship between the resistance of a copper conductor and its temperature. It can be seen that at normal temperature (except for high temperature and very low temperature), the resistance of the copper conductor has a good linear relationship with its temperature, which is approximately straight, and its slope depends on copper. The size and structure of the conductor. The characteristics of the copper material determine that the resistance temperature characteristic line of any copper conductor passes through the point ₍ ^_234 · ⁵ , 0) in Figure 1 ₍ according to the relationship diagram of Figure 1, as long as the slope of the rotor winding resistance temperature characteristic line is obtained, Calculate the resistance value of the rotor at a certain temperature, and then calculate the corresponding rotor temperature value.

The temperature of the rotor in the normal temperature state and the operating state and its corresponding resistance value and the resistance value are measured, that is, the two points and the slope of the temperature characteristic line in Fig. 1 can be determined. According to the equal slope, other points on the characteristic line ( ⁷ , ^ are satisfied:

R ₂ —R, Rf - Ri

Can be drawn

According to the above, the calculation of ^Α ' can enter the rotor winding temperature and resistance through the normal temperature state. The calculation of the line measurement to achieve, the need to remove the effect of the loop resistance.

Figure 2 shows the rotor circuit schematic:

Among them, 1-rotor winding; 2-slip ring; 3-carbon brush; 4-excitation resistance; 5-excitation resistance retract switch; 6-DC magnetic field circuit breaker; 7-shunt; 8-part pressure plate; - rotor current transmitter; 10-rotor voltage transmitter; 11-rectifier cabinet. It is necessary to measure the temperature of the normal temperature state ⁷ ^ and the resistance of the motor of the normal temperature state, including the resistance value measured from the connection of the slip ring and the resistance value of the external circuit. Because the resistance of the rotor is small, the instrument required for measurement is required. Higher precision.

Before the measurement, the excitation regulator is added with a millivolt signal generator to calibrate the excitation voltage and the excitation current respectively. When the generator is stopped, the DC magnetic circuit breaker of the generator is disconnected, and the cable at point A is uncoupled to disconnect the de-excitation resistor. Two WHM-5 type digital display wet and dry thermometers are placed on the rotor pole of the generator upper wind tunnel, and the average temperature is taken as the generator rotor winding ambient temperature. JYR-10 type transformer DC resistance fast tester is used in the slip ring and rotor winding. The connection point (ie, points B and C in Figure 2) is used to measure the resistance of the generator rotor winding. The generator with the external circuit is measured on the outgoing side of the generator DC magnetic circuit breaker (ie, at points 0 and E in Figure 2). Rotor winding resistance ^{+ Rl} . The rotor is heated by the excitation and excitation method. The temperature of the rotor end is measured from the top of the generator rotor by the infrared point temperature gun. When the temperature reaches (between 50 and 70 degrees), the excitation current is removed, and the excitation current is immediately removed. The power cabinet outlet measures the rotor loop resistance ^; Similarly, the same method can be used to measure another temperature measurement point as redundant fault tolerance. The linear coefficient of temperature and resistance is determined by the two points of the loop resistance at normal temperature and the normal state of the shutdown state. The two points are determined by a line, and the contact resistance of the slip ring is opposite to the rotor. -20 ° C ~ 100 ° C, the minimum division of 1 ° C. JYR-10 transformer DC resistance fast tester resolution 0.1μ Ω, measuring range 1μ Ω~2Ω, measurement accuracy ±0.2%, test current 10Α.

Theoretically, the critical temperature of copper entering the superconducting state is close to the absolute zero -273 ° C, but in fact the resistance of the copper conductor has been extremely small at -234.5 ° C, so in the industrial calculation, take -234.5 ° C as the zero resistance of the copper conductor. The temperature, that is, the intersection of the linear extension line and the abscissa in Figure 1, the zero resistance temperature determined by the copper material of the rotor winding is 234.5, but considering the existence of the contact resistance of the slip ring, the calculated rotor temperature is slightly smaller than the actual value. High, so take ^^ ²³⁵ · ¹ to offset this error.

As shown in Figure 3, the rotor excitation voltage is obtained: Ul, U2, U3 are three rotor excitation voltages taken within 20ms of one sampling period. The first two acquisitions of the excitation voltage Ul, U2, when the difference does not exceed 5% U1, U1 is selected and then used as the rotor voltage after the filtering step. The first two acquisitions of the excitation voltage Ul, U2 in the case of a difference of more than 5% U1, select the voltage in Ul, U2 and the third sample U3 and then pass the filter step as the rotor voltage. The rotor excitation current sampling tolerance and filtering are the same as the rotor excitation voltage.

The actual values of the excitation voltage and the excitation current sampled at this time are ^U f and

U _f -I _f *R,

κ ■ Ί -T,

, = R

I

'i and ^l f are substituted into (1)

The basic principles, main features and advantages of the present invention have been shown and described above. It should be understood by those skilled in the art that the present invention is not limited by the foregoing embodiments, and that the present invention is described in the foregoing embodiments and the description of the present invention, and the present invention may be practiced without departing from the spirit and scope of the invention. Various changes and modifications are intended to fall within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and their equivalents.

Claims

claims

1. A method for measuring the temperature of the rotor winding of a large hydroelectric generator set, which is characterized by: including the following steps:

(1), respectively measure the temperature and rotor winding of the generator rotor winding in the shutdown state and no-load state, and then calculate the linear coefficient of the rotor winding temperature and resistance by determining the slope of a straight line from two points;

(2) Obtain the real-time sampling values of the excitation voltage and excitation current through sampling, and divide the excitation voltage by the excitation current to obtain the rotor winding resistance;

(3) Multiply the real-time resistance of the rotor winding by the linear coefficient of the rotor winding temperature and resistance, and then subtract the zero resistance temperature to get the rotor winding temperature.

2. A method for measuring the temperature of the rotor winding of a large hydroelectric generator set according to claim 1, characterized in that: in the step (1): the generator rotor winding shutdown state temperature ⁷ and the no-load state are measured in advance Temperature and corresponding rotor resistance sum ^, measured with κ _ Τ ₂ _ Ί\

The value is calculated according to the formula ¹ ^ _ to calculate the linear coefficient of winding temperature and resistance. In order to make the calculation of the coefficient not affected by the external loop, the rotor resistance required for calculation needs to be measured from the connection between the slip ring and the rotor winding.

3. A method for measuring the temperature of the rotor winding of a large hydroelectric generator set according to claim 2, characterized in that: in the step (2): the rotor resistance is calculated by sampling the excitation voltage and excitation current. , this external loop resistance needs to be subtracted when calculating.

4. A method for measuring the temperature of the rotor winding of a large hydroelectric generator set according to claim 3, characterized in that: the sampling link of the rotor excitation voltage and the rotor excitation current For fault tolerance, the rotor excitation voltage is calculated through the trigger angle and the anode voltage. In one water sampling cycle, the program will perform three voltage samplings, and the third time serves as a referee function to perform fault tolerance on the first and second sampling. Select a value close to the third time; and the sampling of the rotor excitation voltage needs to go through the filtering link to avoid the instantaneous jitter of the rotor voltage during operation or the interference jitter of the measurement link, which will bring errors to the rotor resistance it ί:; Current sampling capacity, is Compare the two waters: whether the channels are similar. If not, compare with the theoretical value and choose the one close to the theoretical value. The theoretical value is calculated through active and reactive power and machine terminal voltage.

5. A method for measuring the temperature of the rotor winding of a large hydroelectric generator set according to claim 4, characterized in that: when measuring the rotor resistance of the generator rotor winding in the shutdown state, the resistance is measured at the connection between the slip ring and the rotor winding. Generator rotor winding resistance, the generator rotor winding resistance with external loop ( ⁺ ) is measured on the outlet side of the generator DC magnetic field circuit breaker, where is the external loop resistance, and then the actual values of the excitation voltage and excitation current are sampled, respectively.

U _f -I *R,

is and /, then the rotor resistance can be obtained.

6. A method for measuring the temperature of the rotor winding of a large hydroelectric generator set according to claim 5, characterized in that: in the step (3): in industrial calculations, -234.5°C is taken as the zero value of the copper conductor. Resistance temperature, the zero resistance temperature determined by the rotor winding material copper is 234.5.

7. A method for measuring the temperature of the rotor winding of a large hydroelectric generator set according to claim 6, characterized in that: in step (3): According to the linear relationship between the temperature of the rotor winding and the resistance, it can be obtained where f—rotor winding temperature

^Κ ι—linear coefficient of winding temperature and resistance

^R f - rotor winding resistance