JP2016158341A - Cooling fan driver in power conversion device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cooling fan driver in a power conversion device, capable of driving a cooling fan by estimating a temperature without providing a temperature sensor.SOLUTION: A cooling fan driver in a power conversion device includes, in the power conversion device's board 100: a transformer temperature operation unit 14 that includes a first data table including a load loss corresponding to a load current and a thermal calculation equivalent circuit to which thermal capacity of each part of a transformer and a thermal resistance value between respective parts are set as parameters, acquires a load loss corresponding to a taken-in load current of the power conversion device from the first data table, and estimates a temperature of the transformer 12 by using the load loss and the thermal calculation equivalent circuit; and an after-cooling-time setting unit 15 that includes a second data table including a fan drive time, which corresponds to a temperature and is for suppressing a rise in in-board temperature after stop of the device, and acquires a fan drive time corresponding to the transformer's temperature estimated by the operation unit 14 to output the drive time. The cooling fan driver in the power conversion device drives a fan 16 for the fan drive time.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a driving device for a cooling fan provided in a power converter.

  For example, a photovoltaic power generation system that generates power from natural energy converts DC power generated by a solar panel into AC power by a power conditioner (hereinafter referred to as “PCS”) as a power converter. doing.

  An inverter (power converter), a transformer (main transformer), a cooling fan, and the like are installed in the power conditioner panel.

  The relationship between the operation time (PCS operation time) of a solar power generation system power conditioner and its output current (solar PCS output current corresponding to the amount of power generated by the solar panel), for example, as shown in FIG. As shown, the transition of the solar PCS output current varies depending on the situation of one day and one day (varies depending on the day).

  As a power conditioner (power conversion device), it operates in the daytime and stops at night, but the temperature of the transformer installed in the panel rises due to the device operation in the daytime. Therefore, if the cooling fan is stopped after stopping the equipment, the heat inside the transformer appears on the surface and causes the temperature in the panel to rise, so after-cooling is necessary (the cooling fan in the panel must be kept running for a certain period of time) There).

  Conventionally, a temperature sensor is provided at a specific location of the transformer, and the fan drive is controlled and operated until a predetermined temperature is reached based on the detected temperature.

  Conventionally, a technique for controlling the driving of a fan by an output signal of an abnormal temperature detector is described in Patent Document 1, for example.

  In addition, in the present invention, a thermal calculation equivalent circuit used when estimating the temperature of the transformer is described in Non-Patent Document 1, for example.

JP 2002-66738 A

Yoshinobu Mizutani and 3 others, “Calculation method of transient temperature rise during overload operation of distribution transformer”, Central Research Institute of Electric Power, October 2003, Report of Central Research Laboratory of Electric Power Research report: W03001, pp.1 -12

  In the conventional method of performing after cooling with a cooling fan based on the temperature detected by the temperature sensor, the mounting location of the temperature sensor is restricted, and the structure in the power converter panel (power conditioner panel) needs to be examined. There is a problem.

  For example, there is a place where it is difficult to attach the sensing part of the temperature sensor at a specific place of the transformer (for example, winding, insulating oil, tank surface, etc.).

  Further, by providing the temperature sensor, the number of electrical components is increased, and the cost and failure rate are increased.

  The present invention solves the above-described problems, and an object of the present invention is to provide a cooling fan driving device in a power conversion device that can drive a cooling fan by estimating temperature without providing a temperature sensor. is there.

The fan driving device for cooling in the power conversion device according to claim 1 for solving the above-described problem is provided.
A cooling fan driving device in a power converter in which a power converter, a transformer and a cooling fan are installed in the same panel,
A first data table in which load loss data corresponding to no-load loss and load current is tabulated, and a heat calculation equivalent circuit in which the heat capacity of each part of the transformer and the thermal resistance value between each part of the transformer are set as parameters A load current output from the power conversion device is acquired, a load loss corresponding to the acquired load current is acquired from the first data table, and the acquired load loss and the thermal calculation equivalent circuit are used. A transformer temperature calculation unit that calculates the temperature rise of the transformer and estimates the temperature of the transformer,
Transformer having a second data table in which fan driving time data for suppressing temperature rise in the panel after stopping the power converter corresponding to the temperature is tabulated and estimated by the transformer temperature calculation unit An after-cooling time setting unit that acquires and outputs the fan driving time corresponding to the captured temperature from the second data table,
The cooling fan is driven for the fan driving time output from the after cooling time setting unit.

Moreover, the cooling fan drive device in the power converter according to claim 2 is:
In Claim 1, the thermal resistance value between each part of the transformer in the said heat calculation equivalent circuit is set by measuring the temperature of each part of a transformer when the load loss by load current is generated, The said heat calculation The heat capacity of each part of the transformer in the equivalent circuit is characterized in that it is set by measuring the transient temperature of the transformer when a pulse-like load loss is generated.

  According to the above configuration, the temperature can be estimated and the cooling fan can be driven without providing a temperature sensor. As a result, it is not necessary to examine the structure in the power conversion device panel for providing the temperature sensor, the number of parts is reduced, and the cost and failure rate can be reduced.

  According to the present invention, it is possible to drive the cooling fan without providing a temperature sensor, making it unnecessary to examine the structure in the power conversion device panel for providing the temperature sensor, reducing the number of parts, cost, and The failure rate can be lowered.

The block diagram which shows one embodiment of this invention. The circuit diagram of the thermal calculation equivalent circuit utilized by this invention. The characteristic view of the data of temperature vs. after-cooling time set in the after-cooling time setting unit in the embodiment of the present invention. The characteristic view which shows an example of transition of the output current with respect to the operation time of a power conditioner in a solar power generation system.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the following embodiments. Below, the Example which applied this invention to the solar energy power generation system is described.

  In FIG. 1, 1 is a solar panel, 100 is a power converter panel (power conditioner panel). The power conversion device panel 100 includes a power converter (inverter) 11, a transformer (main transformer) 12, a control device 13, a transformer temperature calculation unit 14, an after cooling time setting unit 15, a fan (cooling fan) 16, and the like. Is installed.

  The DC power generated by the solar panel 1 is converted to AC power by the power converter 11 and output to the off-board power system via the transformer 12.

  The control device 13 takes in the secondary side voltage of the transformer 12, the secondary side current, and the operation (PCS operation) information of the power converter 11 and controls the operation of the power converter 11. Note that an instrument transformer for detecting the secondary side voltage (load voltage) of the transformer 12 and a current transformer for detecting the secondary side current (load current) are not shown.

  The transformer temperature calculation unit 14 includes a first data table in which load loss data corresponding to no-load loss and load current is tabulated, a heat capacity of each part of the transformer 12, and a thermal resistance value between each part of the transformer 12. Is a thermal calculation equivalent circuit set as a parameter, takes in the load current (secondary current of the transformer 12) output from the power converter, and sets the load loss corresponding to the taken load current to the first The temperature of the transformer 12 is estimated using the acquired load loss and the thermal calculation equivalent circuit.

  The after-cooling time setting unit 15 is a second table in which fan driving time data for suppressing temperature rise in the power conversion device panel 100 after the power conversion device (power converter 11) is stopped corresponding to the temperature is tabulated. The transformer temperature estimated by the transformer temperature calculation unit 14 is fetched, and the fan driving time corresponding to the fetched temperature is acquired from the second data table and output.

  Then, based on the stop information of the power converter 11 in the PCS operation information input to the control device 13 (after the operation stop time), the control device 13 or the drive unit (not shown) outputs from the after cooling time setting unit 15. The fan 16 is driven for the fan driving time.

  An example of the second data table held by the after cooling time setting unit 15 is shown in FIG. The vertical axis in FIG. 3 represents temperature, and the horizontal axis represents after-cooling time (fan drive time after stopping the device). In the example of FIG. 3, the after-cooling time is set longer with a predetermined elongation as the temperature rises. ing.

  According to the above configuration, the fan 16 can be driven without providing a temperature sensor as in the prior art, and the examination of the structure inside the power conversion device panel 100 for providing the temperature sensor becomes unnecessary. Further, the number of parts can be reduced, and the cost and failure rate can be reduced.

  Next, details of the transformer temperature calculation unit 14 will be described. The heat generated by the transformer is divided into no-load loss and load loss. The no-load loss is iron loss, copper loss due to no-load current, and dielectric loss, which are almost fixed values. It is known that the load loss is a copper loss due to the winding due to the load current and a floating load loss, and varies depending on the temperature. In recent years, transformer transient temperature analysis technology has advanced, and an equivalent circuit for loss and heat calculation has been proposed and verified. For example, Non-Patent Document 1 discloses “Method for calculating transient temperature rise during overload operation of distribution transformer”. ing.

  In the transformer temperature calculation unit 14 of the present embodiment, the temperature of a predetermined portion of the transformer is estimated by the following procedure using the technique of Non-Patent Document 1.

  First, the following preparations are made in advance.

  (1) Measure the no-load loss of the transformer 12 and the load loss when a load current flows, and create a data table (first data table). If there is temperature dependence, estimate by calculation.

  (2) The setting of the thermal calculation equivalent circuit and the setting of the circuit constant are performed using, for example, the thermal calculation equivalent circuit of Non-Patent Document 1 shown in FIG.

  Fig. 2 shows an equivalent circuit for thermal calculation of a ground-mounted transformer in which a transformer tank is housed in an outer box, and two different-capacity windings for power and light are connected in the transformer tank. Yes.

  FIG. 2 (a) is a four-stage RC ladder circuit that calculates the temperature rise of the target transformer due to heat generation of the target winding among the power dedicated transformer and the lighting common transformer, and FIG. Is a four-stage RC ladder circuit that calculates the temperature rise of the target transformer due to heat generated by other windings.

In the equivalent circuit of FIG. 2, R _th (R _{th11 to} R _th14 , R _{th21 to} R _th24 ) is between each part (between each part of the transformer; for example, between the winding and the insulating oil, between the insulating oil and the tank surface, C (C _{11 to} C ₁₄ , C _{21 to} C ₂₄ ) represents the heat capacity of each part (for example, winding, insulating oil, tank surface). T ₀ (t) is the ambient temperature (voltage source), W ₁ (t) and W ₂ (t) are generated heat sources (current sources), and T _n (T _{1 to} T ₄ ) is the calculated temperature of the target winding. , ΔT _n (ΔT _{1 to} ΔT ₄ ) is the calculated temperature of the other winding, and T _n + ΔT _n is the temperature of each part of the target winding.

(2-1) Generate a specified load loss due to the load current, measure the temperature of each part of the transformer at that time, and set the thermal resistance (R _th ) between each part (between each part of the transformer).

  (2-2) A pulse-like load loss is generated, and the heat capacity (C) of each part is determined by measuring the transient temperature at that time.

  Thus, the thermal calculation equivalent circuit and the constants of the equivalent circuit are determined.

  (3) The after cooling time setting unit 15 is set. A data table (second data table) of the temperature at the designated location and the after-cooling time (fan driving time after the apparatus is stopped) is created as shown in FIG. 3, for example.

  The above is the preparation to be performed in advance.

  (4) When the power converter (device of FIG. 1) is driven, the transformer temperature calculation unit 14 constantly monitors (loads) the load current and acquires the load loss corresponding to the load current from the first data table. Then, using this load loss and the thermal calculation equivalent circuit of FIG. 2, the temperature rise of the transformer 12 is calculated and the temperature of the transformer 12 is estimated.

At this time, if the ambient temperature (T ₀ (t)) has been measured, this value is added to estimate the temperature at the designated location. Further, the loss having temperature dependence is calculated and then corrected. If the ambient temperature is not measured, a value that is not a measured value is used instead of a predetermined value.

  With the above procedure, the temperature can be estimated without providing a temperature sensor.

  (5) The after cooling time setting unit 15 acquires and outputs the after cooling time corresponding to the temperature estimated by the transformer temperature calculation unit 14 with reference to the table of FIG. Thus, after the apparatus is stopped, the fan 16 is driven for the after cooling time.

DESCRIPTION OF SYMBOLS 1 ... Solar power panel 11 ... Power converter 12 ... Transformer 13 ... Control apparatus 14 ... Transformer temperature calculation part 15 ... After cooling time setting part 16 ... Fan 100 ... Power converter board

Claims (2)

A cooling fan driving device in a power converter in which a power converter, a transformer and a cooling fan are installed in the same panel,
A first data table in which load loss data corresponding to no-load loss and load current is tabulated, and a heat calculation equivalent circuit in which the heat capacity of each part of the transformer and the thermal resistance value between each part of the transformer are set as parameters A load current output from the power conversion device is acquired, a load loss corresponding to the acquired load current is acquired from the first data table, and the acquired load loss and the thermal calculation equivalent circuit are used. A transformer temperature calculation unit that calculates the temperature rise of the transformer and estimates the temperature of the transformer,
Transformer having a second data table in which fan driving time data for suppressing temperature rise in the panel after stopping the power converter corresponding to the temperature is tabulated and estimated by the transformer temperature calculation unit An after-cooling time setting unit that acquires and outputs the fan driving time corresponding to the captured temperature from the second data table,
The cooling fan driving device in the power converter, wherein the cooling fan is driven for the fan driving time output from the after cooling time setting unit.   The thermal resistance value between each part of the transformer in the thermal calculation equivalent circuit is set by measuring the temperature of each part of the transformer when load loss due to load current is generated, and the transformer in the thermal calculation equivalent circuit 2. The cooling fan in the power converter according to claim 1, wherein the heat capacity of each part is set by measuring a transient temperature of the transformer when a pulse-like load loss is generated. Drive device.

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