KR101096147B1 - Apparatus and method for controlling transformer temperature using load factor - Google Patents

Abstract

Disclosed are a temperature predictive cooling control apparatus and a method using a load ratio of a power transformer. The temperature predictive cooling control device includes an outside temperature measuring unit, a winding temperature measuring unit, a current measuring unit, a winding peak temperature calculating unit, and a cooling device control unit. The outside temperature measuring unit measures the outside temperature of the transformer, the winding temperature measuring unit measures the winding temperature of the transformer, and the current measuring unit measures the load supply current of the transformer. The winding peak temperature calculation unit calculates the winding peak temperature of the transformer using the measured ambient temperature, the winding temperature, and the load factor of the transformer calculated from the measured load supply current, and the cooling device controller calculates the winding peak temperature calculated. When the reference value exceeds a preset reference value, the cooling device of the transformer is driven. By such a configuration, by predicting and controlling the winding peak temperature of the power transformer, it is possible to lower the deterioration rate of the power transformer, thereby prolonging its life, and more efficiently performing the preventive diagnosis of the transformer.

Power transformer, load factor, winding temperature

Description

Apparatus and method for controlling transformer temperature using load factor

The present invention relates to a temperature prediction cooling control device using the load ratio of the power transformer and a control method thereof. More specifically, the relationship between the load ratio of the power transformer and the winding temperature of the power transformer is related to the current of the power transformer, Derived based on winding temperature, outside temperature, power transformer operation database, and predicting and controlling the winding peak temperature of power transformer according to load change rate based on the correlation equation to reduce the deterioration rate of power transformer for extended life and preventive diagnosis. It relates to a device for.

Power transformer consists of conductor, insulating paper, iron core and structure through which electric current flows, and heat is generated by Joule hand during operation. At this time, the generated heat increases the temperature of the winding part and the insulator, and as the temperature increases, the deterioration of the insulator is accelerated and the life of the transformer is shortened. The life of a transformer is determined by the temperature value of a specific part rather than the overall thermal characteristics of the internal part.In particular, when the hot spot temperature rises above the allowable value, the life of the transformer decreases drastically due to a decrease in dielectric strength. do.

In recent years, power transformers have been reduced in size and weight according to the trend of high efficiency and miniaturization, and as a result, heat generation rate per unit volume of the winding is increasing, requiring more detailed and precise information in cooling design and temperature characteristics. Many resources should be invested in the processing and grasping of information. In particular, the conventional cooling control method based on load rate and temperature measurement only controls hysteresis to perform ON and OFF at a specific temperature without sufficiently reflecting the temperature characteristic curve of the power transformer. Is difficult.

In addition, the temperature control of the conventional power transformer has a limit in precise temperature prediction control by controlling the temperature by calculating the winding peak temperature based on the insulating oil temperature and the load amount.

The present invention has been made to solve the above-described problems, the relationship between the load factor of the power transformer and the winding temperature of the power transformer, the current, winding temperature, ambient temperature, power transformer operation database of the power transformer The purpose of the present invention is to provide a device for extending the life and preventing diagnosis by lowering the deterioration rate of the power transformer by predicting and controlling the winding peak temperature of the power transformer according to the load change rate based on the correlation derived based on the equation.

In order to achieve the above object, the temperature predicted cooling control apparatus using the load ratio of the power transformer according to the present invention includes an outside temperature measuring unit, winding temperature measuring unit, current measuring unit, winding peak temperature calculating unit, and cooling device control unit. do. The outside temperature measuring unit measures the outside temperature of the transformer, the winding temperature measuring unit measures the winding temperature of the transformer, and the current measuring unit measures the load supply current of the transformer. The winding peak temperature calculation unit calculates the winding peak temperature of the transformer using the measured ambient temperature, the winding temperature, and the load factor of the transformer calculated from the measured load supply current, and the cooling device controller calculates the winding peak temperature calculated. When the reference value exceeds a preset reference value, the cooling device of the transformer is driven.

By such a configuration, by predicting and controlling the winding peak temperature of the power transformer, it is possible to lower the deterioration rate of the power transformer, thereby prolonging its life, and more efficiently performing the preventive diagnosis of the transformer.

The winding peak temperature calculation unit is the following equation

는 변압기의 권선 최고점 온도, (

The winding peak temperature of the transformer,

, 여기서, A는 미리 설정된 상수,

,

, K는 부하율,

, Where A is a preset constant,

,

, K is the load factor,

, 여기서,

는 변압기 외기 온도,

는 변압기 탑-오일 온도의 변화량,

는 변압기 권선 최고점 온도의 변화량) 을 이용하여 상기 변압기의 권선 최고점 온도를 산출할 수 있다.

, here,

The transformer outside temperature,

The amount of change in the transformer tower-oil temperature,

Can calculate the winding peak temperature of the transformer using the amount of change in the transformer winding peak temperature.

In addition, the value of A may be set by user input. With such a configuration, the user can use both the conventional control method and the control method according to the present invention in controlling the cooling control device.

In addition, the invention embodying the apparatus in the form of a method is also disclosed.

According to the present invention, by predicting and controlling the winding peak temperature of the power transformer, the degradation rate of the power transformer can be lowered, thereby prolonging the service life and more efficiently performing the preventive diagnosis of the transformer.

The present invention automatically optimizes the correlation between the load rate and the winding temperature by using the load factor, winding temperature, ambient temperature, power transformer operation information of the power transformer, and predicts the winding temperature of the power transformer to control the temperature of the power transformer. Cooling control device for controlling the control method and a control method thereof, the temperature prediction cooling control device using the load factor of the power transformer according to the present invention uses the load ratio, winding temperature, ambient temperature, power transformer operation information for power A central processing unit for controlling the temperature control FAN of a transformer and controlling an input / output device, a current measuring unit for providing the central processing unit with current information of a power transformer for load factor calculation, and the central processing unit. Winding temperature measuring unit for providing the winding temperature information of the power transformer to the device, and the winding on 4 to 20 mA output unit for receiving analog information of 4 to 20 mA to the outside receiving digital information corresponding to the winding temperature of the power transformer measured by the measuring unit to the outside, and the outside temperature to the central processing unit An outside temperature measurement unit for providing information, a FAN control driver for controlling and driving a temperature control FAN of a power transformer by receiving winding temperature information on the load ratio of the power transformer predicted by the central processing unit, and the central Signal input unit for transmitting external digital and analog signals to the processing unit, Signal output unit for transmitting digital and analog signals from the central processing unit to the outside, Communication for communication between the central processing unit and an external device And a database unit for storing information calculated by the central processing unit.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

4 is a schematic block diagram of an embodiment of a power transformer according to the present invention.

In FIG. 4, the cooling device is implemented as a FAN, and the winding peak temperature calculator and the cooling device controller are each implemented as a central processing unit 201 and a FAN control driver 206.

The temperature prediction cooling control device using the load factor of the power transformer is based on the current, winding temperature, ambient temperature, power transformer operation database of the power transformer based on the correlation between the load factor of the power transformer and the winding temperature of the power transformer. The central processing unit 201 for driving the temperature control FAN of the power transformer and controlling the input / output device by predicting the winding peak temperature of the power transformer according to the load change rate based on the correlation equation. A current measuring unit 202 for providing current information of a power transformer required for load factor calculation to 201, and a winding temperature measuring unit 203 for providing winding temperature information of the power transformer to the central processing unit 201. ) And digital information corresponding to the winding temperature of the power transformer measured by the winding temperature measuring unit 203 in the central processing unit 201. 4-20 mA output unit 204 for providing analog information of 4-20 mA to the outside and outside air temperature measuring unit 205 for providing outside temperature information to the central processing unit 201, and the center. The FAN control driver 206 for controlling and controlling the FAN for controlling the temperature of the power transformer by receiving the winding temperature information about the load ratio of the power transformer predicted by the processing device 201 and external to the central processing unit 201. A signal input unit 207 for transmitting digital and analog signals, a signal output unit 208 for transmitting digital and analog signals from the central processing unit 201 to the outside, and the central processing unit 201 And a communication unit 209 for communicating with an external device and a database unit 210 for storing information calculated by the central processing unit 201.

The current measuring unit 202 is a component for measuring the current of the power transformer, and transmits the current amount measured using a current transformer, an amplifier circuit, a filter circuit, and an analog-to-digital converter (ADC) to the central processing unit 201. . The winding temperature measuring unit 203 heats the insulating oil flowing into the insulating oil thermometer according to the amount of current by using a current transformer (separate from the current transformer attached to the current measuring unit 202) to the power transformer as shown in FIG. Is to measure the value of the winding thermometer of the power transformer providing an analog value corresponding to the temperature close to the winding temperature of the power transformer to provide to the central processing unit 201, consisting of an amplifier circuit, filter circuit, ADC circuit do. The outside temperature measuring unit 205 measures the external temperature of the power transformer and measures the value of the PT100 thermometer and provides it to the central processing unit 201 and includes an amplifying circuit, a filter circuit, and an ADC circuit.

)를 식(1)과 같이 계산하고, 식(2)와 같은 가중치함수(W: Weight Function)를 두어 팬 제어 시작 시점을 전력용 변압기의 최적 운전조 건에 맞도록 상시 연산하는 기능을 소프트웨어로 구현한다.The central processing unit 201 refers to the information of the current measuring unit 202, the winding temperature measuring unit 203, and the outside air temperature measuring unit 205 and the design specifications of the power transformer. Temperature(

) Is calculated as in Equation (1), and the weight function (W) as in Equation (2) is used to calculate the start point of fan control at all times in accordance with the optimal operating conditions of the power transformer. Implement

In practice, it is difficult to directly measure the winding maximum temperature of the power transformer, so the international standard (IEEE Std C57.91-1995, hereinafter referred to as the international standard) measures the oil temperature to obtain the winding maximum temperature and control the fan. It is defined. Obtaining the winding maximum temperature from the international standard is defined as equation (1).

(1)

(One)

는 권선최고점온도,

는 현재 외기온도,

는 탑-오일 온도의 변화량,

는 권선최고점온도의 변화량을 의미한다. 기존에는 식(1)에서 계산된 권선최고점온도를 기준으로 팬 구동 및 종료를 제어하고 있으나, 국제규격에서 제안한 식(1)에 의해 오일온도, 현재 외기온도를 측정하여 권선최고점온도를 계산하는 것은 식(1)에 반영되지 않은 비정규적인 외란(전력용 변압기의 상시 부하율의 높을 때, 부하변동이 심할 때, 열화가 많이 진행되었을 때, 제작 결함이 있을 때, 설치시 변형이 발생 되었을 때)으로 인한 오차가 발생한다. 이와 같은 오차는 전력용 변압기의 최적운전을 저해하여 열화를 빨라지게 하여 전력용 변압기의 수명을 단축시킨다. 전력용 변압기의 최적 운전조건을 자동으로 연산하기 위하여 식(2)의 가중치 함수를 도입하여 부하율과 전력용 변압기 운전환경에 맞는 새로운 최적화 권선최고점온도를 찾아낸다.In equation (1),

The winding peak temperature,

Is the current outside temperature,

Is the amount of change in top-oil temperature,

Is the amount of change in the winding peak temperature. Conventionally, fan driving and shutdown are controlled based on the winding maximum temperature calculated in Equation (1) .However, calculating the winding maximum temperature by measuring the oil temperature and the current ambient temperature by Equation (1) proposed by the International Standard As an irregular disturbance not reflected in Equation (1) (when the constant load factor of the power transformer is high, when the load fluctuates severely, when a lot of deterioration proceeds, when there is a manufacturing defect, or when deformation occurs during installation) Error occurs. This error hinders the optimal operation of the power transformer and accelerates deterioration, thereby shortening the life of the power transformer. In order to automatically calculate the optimal operating conditions of the power transformer, the weight function of Equation (2) is introduced to find the new optimal winding maximum temperature for the load factor and the operating environment of the power transformer.

(2)

(2)

는 최적화 권선최고점온도이며, W는 가중치함수(Weight Function)이며, 식(3)와 같은 비선형 함수이다.In equation (2),

Is the optimum winding maximum temperature, W is the weight function, and is a nonlinear function such as Eq. (3).

(3)

(3)

In Equation (3), A, B, and C are optimization constants, and e is an exponent. In Eq. (3), A is an initial user-defined constant. If A> 1, the fan control start time will be faster.If A <1, fan control start time will be slow. Based on the unit function, the fan control start time is adjusted by referring to the change in load ratio and winding peak temperature. B is formula (4), C is the same as formula (5).

(4)

(4)

이며,

는 1차 미분을 의미한다.In Eq. (4), K means load factor,

,

Means the first derivative.

(5)

(5)

은 2차 미분을 의미한다.In equation (5)

Means second derivative.

는 식(1)의 권선최고점온도

와 같다. 여기서 설명하는 단위함수는 전력용 변압기가 국제규격에 맞게 이상적으로 제작, 설치되었을 때를 의미하며, 실제로는 심한 부하변동, 높은 열화율, 제작 결함, 설치시 변형으로 전력용 변압기의 오일온도를 참조하여 권선최고점온도를 계산한다는 것은 불가능하다. 또한, 도 3과 도 7을 참조하면, 부하에 변화에 대하여 오일온도의 변화는 둔감하다. 이는 전력용 변압기의 권선 온도가 측정부까지 전이되는 시간이 긴 것을 의미 한다. 기존에 전력용 변압기 온도제어를 위하여 오일온도를 기준으로 권선최고점온도를 계산하여 이용하는 방법에 의한 전력용 변압기의 권선 온도 및 오일온도를 도 8에 도시하였다. 이때 이미 전력용 변압기의 권선 온도는 정상상태에 도달한 후가 되므로 권선 주변에는 열화가 진행된다.Referring to Figures 4 to 10, the initial value is set to A = 1, B = 0, C = 0 before A, B, C in the initial database and equation (3) is optimized and built, which is the fan control start time. Means to control linearly with temperature. Optimum winding maximum temperature at this time

Is the maximum temperature of the winding in equation (1)

Same as The unit function described here refers to when the power transformer is ideally manufactured and installed in accordance with international standards, and actually refers to the oil temperature of the power transformer due to severe load fluctuations, high deterioration rate, manufacturing defects, and deformation during installation. It is not possible to calculate the winding peak temperature. 3 and 7, the change in oil temperature is insensitive to the change in load. This means that the time taken for the winding temperature of the power transformer to transition to the measuring unit is long. 8 shows the winding temperature and the oil temperature of the power transformer by the method of calculating the winding maximum point temperature based on the oil temperature for temperature control of the power transformer. At this time, since the winding temperature of the power transformer reaches a steady state, deterioration proceeds around the winding.

In the present invention, B (load variation per unit time, winding maximum temperature variation) and C (acceleration of load variation per unit time) of Equation (3) are applied to irregular disturbances and changes in winding maximum temperature not reflected in Equation (1). By applying W (weighting function) to sensitively react to the load fluctuations, the optimum winding maximum temperature is obtained. At this time, the winding temperature and the oil temperature of the power transformer can be controlled as shown in FIG. Referring to FIG. 10, it can be seen that the cooling method according to the present invention can effectively control the winding temperature and the winding peak temperature than the conventional general cooling method.

The 4-20 mA output unit 204 is to be applied to a power transformer that is installed and operated in the prior art whether the temperature of the winding is used in the temperature control device of the existing power transformer according to an embodiment of the present invention Winding temperature of the power transformer from the central processing unit 201 in order to prevent the information from being blocked by utilizing the temperature prediction cooling control device using the load ratio of the power transformer, and to use the existing power transformer and the temperature control unit jointly. It receives the information and provides it externally as an analog signal of 4 ~ 20mA. The FAN control driver 206 receives the optimum temperature control information of the power transformer calculated by the central processing unit 201 and turns on and off the temperature control fan of the power transformer installed in plural. When the CPU 201 turns on the fan by using the A, B, and C terms of the weight function according to the user's setting, the central processing unit 201 is weighted according to the user's setting and B, C is the load change amount. When the fan is turned off, the conventional general fan control (A = 1, B = 0, C = 0) can be used.

The signal input unit 207 is to provide the central processing unit 201 with analog and digital information provided outside the temperature prediction cooling controller using the load factor of the power transformer according to an embodiment of the present invention. It consists of circuit, photo-coupler circuit, voltage divider circuit, filter circuit, and DC-DC converter for input / output isolation. The signal output unit 208 is for providing analog and digital information provided from the central processing unit 201 to an external device. The signal output unit 208 provides a switch circuit, a digital to analog converter (DAC) circuit, an overvoltage, an overcurrent protection circuit, and an input / output isolation. It is composed of DC-DC converter. The communication unit 209 is for communication between the central processing unit 201 and an external device, and is composed of an RS232 circuit, an RS485 circuit, a LAN circuit, an Optical-LAN circuit, a CAN communication circuit, and an I2C circuit. The database unit 210 stores the winding temperature, the insulating oil temperature, the outside temperature, the operation information, the load ratio, the fan driving information, the deterioration rate, the specification, and the signal input / output information of the external power transformer collected by the central processing unit 201. It consists of a data memory circuit.

Although the present invention has been described in terms of some preferred embodiments, the scope of the present invention should not be limited thereby, but should be construed as modifications or improvements of the embodiments supported by the claims.

The temperature prediction cooling control device using the load ratio of the power transformer according to the present invention and the control method thereof have a relationship between the load ratio of the power transformer and the winding temperature of the power transformer, the current, winding temperature, ambient temperature, A central processing unit for driving the temperature control fan of the power transformer and controlling the input / output device by estimating the winding peak temperature of the power transformer according to the load change rate based on the correlation equation derived from the power transformer operation database; A current measuring unit for providing current information of a power transformer necessary for calculating a load ratio to the central processing unit, a winding temperature measuring unit for providing winding temperature information of a power transformer to the central processing unit, and measuring the winding temperature Digital information corresponding to the winding temperature of the power transformer measured in the 4-20mA output unit for providing analog information of 4-20mA to the outside received from the outside, an outside temperature measuring unit for providing outside temperature information to the central processing unit, and a power transformer predicted by the central processing unit A FAN control driver for controlling and controlling a temperature control fan of a power transformer by receiving winding temperature information of a load ratio of a load factor, a signal input unit for transmitting external digital and analog signals to the central processing unit, and the central processing unit And a signal output unit for transmitting digital and analog signals to the outside, a communication unit for communicating with the central processing unit and an external device, and a database unit for storing information calculated by the central processing unit.

In addition, the temperature prediction cooling control method using the load ratio of the power transformer according to the present invention is calculated by calculating the load ratio, winding peak temperature, deterioration rate, overload capacity by receiving the winding temperature, current, ambient temperature of the power transformer It calculates the correlation between the load rate and the winding temperature change amount by referring to the operation database of the over-power transformer, and predicts the start time and the end time of fan operation by feeding back the winding temperature of the power transformer for each unit time. The winding temperature change is calculated and the winding temperature of the power transformer is optimized in the entire range from the minimum load to the maximum load of the power transformer so that the calculated load ratio and the winding temperature change are proportional to each other.

1 is a graph illustrating a transformer temperature characteristic and a fan driving according to a conventional power transformer temperature control.

2 is a hysteresis temperature control graph of a conventional power transformer.

3 is a graph showing the relationship between the load current and the top-oil temperature of the power transformer.

4 is a schematic block diagram of an embodiment of a temperature predictive cooling control apparatus using a load ratio of a power transformer according to the present invention;

5 is a graph for explaining a weight function according to an embodiment of the present invention.

6 is a graph illustrating a fan control start time by a weight function according to an embodiment of the present invention.

7 is a graph illustrating the relationship between the winding temperature and the oil temperature, the load ratio, the temperature, and the time of the power transformer.

8 is a graph illustrating a relationship between winding temperature, oil temperature, load rate, temperature, and time according to a temperature control method of a conventional power transformer.

9 is a graph illustrating a relationship between a winding temperature and an oil temperature, a load rate, a temperature, and a time of a temperature control method of a power transformer according to an embodiment of the present invention.

10 is a graph for explaining the effect of the temperature control method of the power transformer according to an embodiment of the present invention.

11 is a reference diagram for explaining a winding temperature measuring method of a power transformer.

12 is a schematic flowchart of an embodiment of a temperature predictive cooling control method using a load ratio of a power transformer according to the present invention;

Claims (6)

delete An outside air temperature measuring unit measuring an outside air temperature of the transformer; Winding temperature measuring unit for measuring the winding temperature of the transformer; A current measuring unit measuring a load supply current of the transformer; A winding peak temperature calculator configured to calculate a winding peak temperature of the transformer using the measured outside temperature, the winding temperature, and the load factor of the transformer calculated from the measured load supply current; And A temperature predictive cooling control device using a load factor of a power transformer including a cooling device controller for driving a cooling device of the transformer when the calculated winding peak temperature exceeds a preset reference value. The winding peak temperature calculation unit is the following equation

(

The winding peak temperature of the transformer,

, Where A is a preset constant, ,

, K is the load factor,

, here,

The transformer outside temperature,

The amount of change in the transformer tower-oil temperature,

Is a change amount of the transformer winding peak temperature) to calculate the winding peak temperature of the transformer using the load factor of the power transformer, the temperature prediction cooling control device. 3. The method of claim 2, The value of A can be set by the user's input temperature prediction cooling control apparatus using the load ratio of the power transformer. delete An outside temperature measuring step of measuring the outside temperature of the transformer; A winding temperature measuring step of measuring a winding temperature of the transformer; A current measuring step of measuring a load supply current of the transformer; A winding peak temperature calculating step of calculating the winding peak temperature of the transformer using the measured outside temperature, the winding temperature, and the load factor of the transformer calculated from the measured load supply current; And A temperature predictive cooling control method using a load factor of a power transformer comprising a cooling device control step of driving a cooling device of the transformer when the calculated winding peak temperature exceeds a preset reference value. The winding peak temperature calculating step is the following equation

(

The winding peak temperature of the transformer,

, Where A is a preset constant,

,

, K is the load factor,

, here,

The transformer outside temperature,

The amount of change in the transformer tower-oil temperature,

(B) calculates the winding peak temperature of the transformer by using the amount of change in the transformer winding peak temperature). The method of claim 5, The value of A can be set by a user input, temperature prediction cooling control method using the load ratio of the power transformer.

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