JP2019022309A - Power conversion device - Google Patents

Abstract

To provide a power conversion device capable of estimating temperature during an operation to prevent breakage of an element due to temperature rise.SOLUTION: A power conversion device is equipped with: a reactive power compensator; a sensor group which detects state data showing an operating state of the reactive power compensator; and a control panel 14 which calculates temperature based on output of the sensor group to control the reactive power compensator according to the calculated temperature. Thyristor valves 8U, 8X of the reactive power compensator are equipped with a plurality of thyristors 20to 20, 21to 21which are connected in series. A plurality of snubber circuits 22to 22and serial circuits of voltage dividing resistors 24to 24and voltage detectors 26to 26are connected in parallel with the plurality of thyristors, respectively. The control panel 14 calculates element bonding temperature of the thyristors, resistor line temperature of snubber resistors 28to 28, and resistor line temperature of the voltage dividing resistors, and controls operations of the thyristor valves according to calculation results.SELECTED DRAWING: Figure 2

Description

  Embodiments described herein relate generally to a power converter that can prevent damage to elements due to heat.

  A power converter that converts direct current to alternating current, alternating current to direct current, direct current to direct current, or alternating current to alternating current uses the switching action of the power semiconductor element. For example, the power converter includes a thyristor valve in which a large number of thyristors are connected in series. Each thyristor constituting the thyristor valve is provided with a snubber circuit in parallel. The snubber circuit is composed of a series circuit of a capacitor and a resistor, and suppresses spike-like high voltage generated at the time of on / off switching of the thyristor to prevent damage to the thyristor.

  Since power semiconductor elements such as thyristors may be damaged by heat generated due to loss, a cooling device is provided. However, since heat generation exceeding the cooling capacity may occur, the power conversion device estimates the temperature of the semiconductor element and performs processing such as stopping the device when the estimated temperature is equal to or higher than the threshold value.

JP 2005-124387 A

  The conventional power converter does not estimate the temperature of the element from the data representing the operating state during the operation of the device. Moreover, although resistance of peripheral circuits such as a snubber circuit also generates heat, the conventional power converter does not consider the temperature of the resistance.

  An object of the present invention is to provide a power conversion device capable of detecting a temperature rise that may cause damage to an element during operation and preventing the element from being damaged.

  According to one aspect of the present invention, a power conversion device calculates a temperature based on a thyristor converter, sensor means for detecting state data indicating an operation state of the thyristor converter, and an output of the sensor means. And a control means for controlling the thyristor converter according to the temperature. The thyristor valve of the thyristor converter includes a plurality of thyristors connected in series, a plurality of snubber resistors connected in parallel to the plurality of thyristors, and a plurality of voltage dividing resistors respectively connected in parallel to the plurality of thyristors. Are provided. The control means calculates the element junction temperature of the thyristor, the resistance line temperature of the snubber resistor, and the resistance line temperature of the voltage dividing resistor.

  According to the present invention, the temperature is estimated based on the data corresponding to the driving condition during operation, and the operation of the thyristor is controlled according to the estimated temperature, thereby preventing the element from being damaged due to the temperature rise. A power converter can be provided.

FIG. 1 is a diagram illustrating an example of the power conversion apparatus according to the first embodiment. FIG. 2 is a diagram illustrating an example of a thyristor valve of the reactive power compensator that constitutes the power converter according to the first embodiment. FIG. 3 is a diagram illustrating an example of a voltage detector that detects a forward voltage and a reverse voltage in the first embodiment. FIG. 4 is a diagram illustrating an example of a voltage detector that detects a forward voltage in the first embodiment. FIG. 5 is a diagram illustrating an example of the gate control device according to the first embodiment. FIG. 6 is a diagram illustrating an example of a cooling pipe provided in the power conversion device according to the first embodiment. FIG. 7 is a diagram illustrating an example of a cooling pipe provided in the power conversion device according to the second embodiment.

Embodiments of the present invention will be described below with reference to the drawings.
[First Embodiment]
FIG. 1 is a diagram illustrating an example of a power conversion apparatus 10 according to the first embodiment of the present invention.

  The power conversion device 6 includes a reactive power compensation device 8, a gate control device 10, a sensor group 12, and a control panel 14. The reactive power compensator 8 is connected to the gate controller 10 by an optical fiber cable (not shown). The reactive power compensator 8 has a function of converting three-phase AC power supplied from the three-phase AC power source 2 into DC power (also referred to as rectification) and a reactive power of the three-phase AC power supplied from the three-phase AC power source 2. It has a function to compensate. Here, the three-phase AC power is assumed to be composed of a U phase, a V phase, and a W phase. The reactive power compensator 8 is a static var compensator (SVC) that employs a thyristor controlled reactor (TCR) system. The reactive power compensator 8 opens and closes the thyristor valves 8U, 8V, 8W, 8X, 8Y, and 8Z as AC switches, adjusts the current flowing through the reactors R1 to R6, and compensates the reactive power.

  The reactive power compensator 8 is configured by delta connection of a UX phase circuit, a VY phase circuit, and a WZ phase circuit. The UX phase circuit compensates for reactive power between the UV phases of the power system. The VY phase circuit compensates for reactive power between the VW phases of the power system. The WZ phase circuit compensates for reactive power between the WU phases of the power system.

  The UX phase circuit includes two thyristor valves 8U and 8X and two reactors R1 and R2. The thyristor valves 8U and 8X are connected in parallel so that the direction in which the current flows is opposite. Reactors R1 and R2 are connected in series to thyristor valves 8U and 8X.

  The VY phase circuit includes two thyristor valves 8V and 8Y and two reactors R3 and R4. The thyristor valves 8V and 8Y are connected in parallel so that the direction of current flow is opposite. Reactors R3 and R4 are connected in series to thyristor valves 8V and 8Y.

  The WZ phase circuit includes two thyristor valves 8W and 8Z and two reactors R5 and R6. The thyristor valves 8W and 8Z are connected in parallel so that the direction in which the current flows is opposite. Reactors R5 and R6 are connected in series to thyristor valves 8W and 8Z.

  A reactor R1 of the UX phase circuit and a reactor R6 of the WZ phase circuit are connected, and this connection point becomes a U phase terminal Ta connected to the U phase of the power system. A reactor R2 of the UX phase circuit and a reactor R3 of the VY phase circuit are connected, and this connection point becomes a V phase terminal Tb connected to the V phase of the power system. A reactor R5 of the WZ-phase circuit and a reactor R4 of the VY-phase circuit are connected, and this connection point becomes a W-phase terminal Tc connected to the W-phase of the power system.

  FIG. 2 is a configuration diagram showing an example of the configuration of the thyristor valves 8U and 8X of the UX phase circuit according to the present embodiment. The thyristor valves 8V, 8Y; 8W, 8Z of the VY phase circuit and the WZ phase circuit are configured in the same manner. Therefore, here, the thyristor valves 8U, 8X of the UX phase circuit will be described as a representative.

The thyristor valves 8U and 8X have N thyristors 20 ₁ , 20 ₂ ,... 20 _N (arbitrary thyristors are referred to as thyristors 20) connected in series so that current flows from the terminal Ta to the terminal Tb. N thyristors 21 ₁ , 21 ₂ ,... 21 _N (arbitrary thyristors are referred to as thyristors 21) and N snubber circuits 22 ₁ connected in series so that current flows from the terminal Tb to the terminal Ta. , _{22 2,} 22 3, ..., 22 _N (optional snubber circuit is referred to as a snubber circuit 22) and, N-number of voltage dividing resistors _{24 1, 24 2, 24 3} , ..., 24 N ( arbitrary partial pressure The resistors are referred to as voltage dividing resistors 24) and N voltage detectors 26 ₁ , 26 ₂ , 26 ₃ ,..., 26 _N (any voltage detector is referred to as voltage detector 26). N is an integer of 2 or more.
The N thyristors 20 _{1 to} 20 _N and 21 _{1 to} 21 _N are all connected in series. The N thyristors 20 and the N thyristors 21 are connected in antiparallel to each other so as to correspond to each other. The N snubber circuits 22 are connected in parallel so as to correspond to each of the N sets of thyristors 20 and 21 connected in antiparallel. The snubber circuit 22 has a configuration in which a capacitor 30 and a resistor 28 are connected in series. The N voltage dividing resistors 24 _{1 to} 24 _N are connected in series to the _N voltage detectors 26 _{1 to} 26 _N , respectively. The _N circuits in which the voltage dividing resistors 24 _{1 to} 24 _N and the voltage detectors 26 _{1 to} 26 _N are connected in series are respectively connected in parallel with the _N thyristors 20 _{1 to} 20 _N and 21 _{1 to} 21 _N. Connected.

  The thyristors 20 and 21 are switching elements having a rectifying action. The thyristors 20 and 21 are driven (ignited) according to the gate pulse GP supplied from the gate control device 10 via the optical fiber cable. When the thyristors 20 and 21 are driven, AC power is converted to DC power.

Dividing resistors ₂₄ 1 to 24 _N is a thyristor valve 8U, with pressure uniformity partial DC voltage component applied to between poles of 8X, also serves the role of inhibition of the current flowing through the voltage detector ₂₆ 1 ~ 26 _N.

Snubber circuits ₂₂ 1 through 22 _N is a thyristor valve 8U, with pressure uniformity minute AC voltage component applied between 8X poles, each thyristor ₂₀ 1 _{to 20 N,} 21 thyristors ₂₀ 1 to 1 through 21 _N turn-on and during turn-off of the The thyristors 20 _{1 to} 20 _N and 21 _{1 to} 21 _N are protected from transient non-uniform voltage sharing applied to 20 _N and 21 _{1 to} 21 _N and overvoltage. The snubber circuits 22 _{1 to} 22 _N are provided to reduce power loss and perform stable switching with respect to the thyristors 20 _{1 to} 20 _N and 21 _{1 to} 21 _N , respectively. Each snubber circuit 22 _{1 to} 22 _N includes a snubber resistor 28 _{1 to} 28 _N (an arbitrary snubber resistor is referred to as a snubber resistor 28) and a capacitor 30 ₁ to 30 _N (an arbitrary capacitor is referred to as a capacitor 30). It consists of a series connection circuit.

Voltage detector ₂₆ 1 ~ 26 _N are each thyristor _{20 1 ~20 N, 21 1 ~21} N to the forward voltage (the voltage of the thyristor _{20 1 ~20 N, 21 1 ~21} N current flows in a direction) is applied Then, the forward voltage signals FV _{1 to} FV _N are output to the gate control device 10, respectively. In this way, the voltage detectors 26 _{1 to} 26 _N detect the forward voltage.

Some of the voltage detector, for example, three voltage detectors ₂₆ 1 to 26 ₃ each thyristor ₂₀ 1 _{to 20 3,} 21 1 to 21 ₃ in the reverse voltage (polarity opposite voltage forward voltage) is applied Then, the reverse voltage signals RV _{1 to} RV ₃ are output to the gate control device 10, respectively. In this manner, the voltage detector ₂₆ 1-26 ₃ detects the reverse voltage. That is, the three voltage detectors 26 _{1 to} 26 ₃ detect both the forward voltage and the reverse voltage.

  When the number of thyristors included in the thyristor valve is large, a thyristor valve may be configured by connecting a plurality of thyristor modules in series. In this case, each thyristor module is composed of a plurality of thyristors connected in series as shown in FIG.

The gate control device 10 generates a gate pulse GP based on various signals received from the control panel 14 and forward voltage signals FV _{1 to} FV _N or reverse voltage signals RV _{1 to} RV ₃ received from the thyristor valves 8U and 8X. . The gate control device 10 outputs a gate pulse GP to each thyristor 20 _{1 to} 20 _N and 21 _{1 to} 21 _N via an optical fiber cable, and drives each thyristor 20 _{1 to} 20 _N and 21 _{1 to} 21 _N. . Thereby, the thyristor valves 8U and 8X perform a power conversion operation.

  The sensor group 12 is composed of various sensors installed at various locations so as to detect the operating status of the thyristor valves 8U, 8X. The output of the sensor group 12 is input to the control panel 14. The control panel 14 calculates the element junction temperature of the thyristors 20 and 21, the resistance line temperature of the snubber resistor 28, and the resistance line temperature of the voltage dividing resistor 24. As an example, the sensor group 12 detects a cooling water incoming temperature, a valve voltage, a current flowing through a thyristor (element current), and the like, which will be described later, as an operation state.

  The control panel 14 includes, for example, a calculation unit 14a and a control unit 14b. However, the calculation unit 14a and the control unit 14b may be configured integrally.

  The calculation unit 14 a calculates the element junction temperature of the thyristors 20 and 21, the resistance line temperature of the snubber resistor 28, and the resistance line temperature of the voltage dividing resistor 24 based on the operation status of the thyristor valves 8 U and 8 X that are outputs of the sensor group 12. To do.

  The control unit 14b transmits and receives various signals to and from the gate control device 10 to control and monitor power conversion of the thyristor valves 8U and 8X. The control unit 14b controls the operation of the thyristor valves 8U and 8X according to the calculation result by the calculation unit 14a.

For example, the element junction temperature of the thyristors 20 _{1 to} 20 _N and 21 _{1 to} 21 _N , the resistance line temperature of the snubber resistors 28 _{1 to} 28 _N , and the resistance line temperature of the voltage dividing resistors 24 _{1 to} 24 _N calculated by the calculation unit 14a When at least one of the thresholds exceeds the threshold value, the control unit 14b sends a high temperature detection signal HT to the gate control device 10, and gate pulses GP from the gate control device 10 to the thyristors 20 _{1 to} 20 _N and 21 _{1 to} 21 _N Is stopped, and the operation of the thyristor valves 8U and 8X is stopped. Here, the threshold value of the element junction temperature of the thyristors 20 and 21, the threshold value of the resistance line temperature of the snubber resistor 28, and the threshold value of the resistance line temperature of the voltage dividing resistor 24 are not necessarily the same value.

  The gate control device 10 only needs to be able to prevent an increase in the element junction temperature of the thyristors 20 and 21, the resistance line temperature of the snubber resistor 28, and the resistance line temperature of the voltage dividing resistor 24. Not limited to any control. For example, a light load operation may be performed in which a gate pulse is continuously supplied to the gate of the thyristor so that a reverse voltage is not applied.

Figure 3 is a diagram showing an example of a voltage detector 26 ₁ configured to detect the forward voltage and reverse voltage. Here, also for the configuration of the voltage detector ₂₆ 2, 26 _3, is similar to the configuration of the voltage detector 26 _1, the description thereof is omitted.

Voltage detector 26 ₁ is provided with a Zener diode DZF, and DZR, the light emitting element LF, and LR, and a resistor RD.

Zener diode DZF is connected to the voltage dividing resistors 24 ₁ series. The Zener diode DZF is attached in a direction that prevents a current flowing due to a forward voltage. Zener diode DZF, when forward voltage is applied to the voltage detector 26 ₁ to apply a voltage for causing the light emitting element LF. The Zener diode DZF conducts in the direction in which this current flows when the current due to the forward voltage becomes excessive (when the overcurrent flows). Thereby, the Zener diode DZF protects the light emitting element LF from an excessive current.

Emitting element LF, when forward voltage is applied to the voltage detector 26 _1, emits light. When the light emitting element LF emits light, the forward voltage signal FV ₁ is output to the gate control device 10. The light emitting element LF is, for example, a light emitting diode (LED).

The Zener diode DZR is connected in series with the Zener diode DZF in the opposite direction to the Zener diode DZF. That is, the Zener diode DZR is attached in a direction that prevents a current flowing due to a reverse voltage. Zener diode DZR, when reverse voltage is applied to the voltage detector 26 ₁ to apply a voltage for causing the light emitting element LR. The Zener diode DZR conducts in the direction in which this current flows when the current due to the reverse voltage becomes excessive (when the overcurrent flows). Thus, the Zener diode DZR protects the light emitting element LR from overcurrent.

Emitting element LR, when reverse voltage is applied to the voltage detector 26 _1, emits light. When the light emitting element LR emits light, the light emitting element LR outputs a reverse voltage signal RV ₁ to the gate control device 10. The light emitting element LR is, for example, a light emitting diode.

  The resistor RD suppresses the current flowing through the light emitting elements LF and LR. As a result, the resistor RD causes a predetermined current to flow through the light emitting elements LF and LR.

Figure 4 is a diagram showing an example of the configuration of the voltage detector 26 ₄ for detecting the forward voltage. Here, also for the configuration of the voltage detector ₂₆ 5 ~ 26 _N, is the same as the configuration of the voltage detector 26 _4, the description thereof is omitted.

Current detector 26 _4, the voltage detector 26 ₁ shown in FIG. 3, a configuration obtained by removing the zener diode DZR and the light emitting element LR.

The Zener diode DZF prevents a voltage having a polarity opposite to that of the light emitting element LF from being applied. Other points, the voltage detector 26 _4, the same configuration as that of the voltage detector 26 ₁ shown in FIG.

  FIG. 5 is a diagram illustrating an example of the configuration of the gate control device 10.

  The gate control device 10 includes a majority circuit 42, a thyristor failure detection circuit 44, and a gate control circuit 46.

Majority circuit 42 receives a reverse voltage signal _RV 1 _{~RV 3} output from the three voltage detector ₂₆ 1-26 _3. The majority circuit 42 outputs the operation result of the received reverse voltage signals RV _{1 to} RV ₃ as the reverse voltage signal RV to the thyristor failure detection circuit 44 and the gate control circuit 46. When the majority circuit 42 receives two or more reverse voltage signals RV _{1 to} RV ₃ , it sets the reverse voltage signal RV to “1” and outputs it. When the majority circuit 42 receives one or less reverse voltage signals RV _{1 to} RV ₃ , it sets the reverse voltage signal RV to “0” and outputs it. That is, when receiving the reverse voltage signal from the voltage detector 26 _{1-26 3} majority (number of more than one-half), the majority circuit 42 outputs a reverse voltage signal RV which indicates "1". Otherwise, the majority circuit 42 outputs the reverse voltage signal RV indicating “0”.

The thyristor failure detection circuit 44 receives the forward voltage signals FV _{1 to} FV _N output from the voltage detectors 26 _{1 to} 26 _N and the reverse voltage signal RV output from the majority circuit 44, respectively. Based on the forward voltage signals FV _{1 to} FV _N and the reverse voltage signal RV, the thyristor failure detection circuit 44 detects the failure detection signals NG ₁ of the thyristors 20 _{1 to} 20 _N and 21 _{1 to} 21 _N of the thyristor valves 8U and 8X. ~ NG _N is detected. Thyristor failure detection circuit 44, forward voltage signals based on the _FV 1 _{~FV N} and reverse voltage signal RV, thyristor valves 8U, the gate control circuit forward voltage aggregate signal FV used to drive the thyristor 20, 21 of 8X 46 Output to.

  The gate control circuit 46 includes a phase control on timing signal ON which is a signal for making the thyristors 20 and 21 conductive, a gate block GB which suppresses the output of the gate pulse GP, a phase control on timing signal TON of the other phase to be commutated, and a thyristor. The forward voltage aggregate signal FV output from the element failure detection circuit 22, the reverse voltage signal RV output from the majority decision circuit 42, and the high temperature detection signal HT from the control unit 14b of the control panel 14 are input.

The gate control circuit 46 generates a gate pulse GP based on the phase control on timing signal ON and the forward voltage aggregate signal FV. The gate control circuit 46 outputs the generated gate pulse GP to the thyristors 20 _{1 to} 20 _N and 21 _{1 to} 21 _N of the thyristor valve 8U. As a result, the gate control circuit 46 fires the thyristors 20 _{1 to} 20 _N and 21 _{1 to} 21 _N. When the gate control circuit 46 detects the commutation failure of the thyristor valves 8U and 8X after outputting the gate pulse GP, the gate control circuit 46 outputs the commutation failure signal CFD. The gate control circuit 46 stops the output of the gate pulse GP based on the gate block GB, the phase control ON timing signal TON of the other phase to be commutated, and the reverse voltage signal RV. The gate control circuit 46 responds to the high temperature detection signal HT from the control unit 14b to stop the operation of the thyristor valves 8U and 8X or supply a gate pulse to the gate of the thyristor so that no reverse voltage is applied. Continue the light load operation. The power converter 6 includes a cooling device for processing heat generated due to loss of elements such as the thyristors 20 and 21 and the resistors 24 and 28 constituting the thyristor valves 8U and 8X. The thyristor is cooled by a heat sink. A water-cooled resistor is used as the resistors 24 and 28, and the resistance wire itself is cooled. Examples of the cooling medium include air, water, and alternative chlorofluorocarbon. For example, water is used. FIG. 6 shows an example of a cooling water piping system provided in the power converter 6. FIG. 6 shows a cooling water piping system of the thyristor valve 8U as an example. The piping system of the thyristor valves 8V, 8W, 8X, 8Y, and 8Z has a similar structure.
The heat sink _{62 1 ~62 N +} 1 (optional heat sink will be referred to as the heat sink 62) is arranged on both sides of the thyristor ₂₀ 1 to 20 _N. The heat sink _{62 1 ~62 N +} 1 of the water inlet is connected through a branch pipe to the cooling water inlet side header pipe 68, connected to the cooling Mizuide side main pipe 70 heat sink _{62 1 ~62 N +} 1 of the water outlet via the branch pipe Is done.

The water inlets of the water cooling resistors 64 ₁ to 64 _N constituting the snubber resistors 28 _{1 to} 28 _N (an arbitrary water cooling resistor is referred to as the water cooling resistor 64) are connected to the cooling water inlet side pipe 68 through the branch pipe. The water outlets of the water-cooled resistors 64 ₁ to 64 _N are connected to the cooling water outlet side main pipe 70 via branch pipes. The water inlets of the water-cooled resistors 66 _{1 to} 66 _N (arbitrary water-cooled resistors are referred to as the water-cooled resistors 66) constituting the voltage dividing resistors 24 _{1 to} 24 _N are connected to the cooling water inlet-side mother pipe 68 via the branch pipes. The water outlets of the water cooling resistors 66 _{1 to} 66 _N are connected to the cooling water outlet side main pipe 70 via branch pipes. Thus, the heat sinks 62 _{1 to} 62 _{N + 1} , the water-cooled resistors 64 ₁ to 64 _N , and the water-cooled resistors 66 _{1 to} 66 _N are arranged in parallel between the cooling water inlet side pipe 68 and the cooling water outlet side pipe 70. Placed in. Therefore, the cooling water injected into the cooling water inlet side main pipe 68 is injected in parallel with respect to the heat sinks 62 _{1 to} 62 _{N + 1} , the water cooling resistors 64 ₁ to 64 _N , and the water cooling resistors 66 _{1 to} 66 _N. The cooling water discharged from each of the heat sinks 62 _{1 to} 62 _{N + 1} , the water cooling resistors 64 ₁ to 64 _N , and the water cooling resistors 66 _{1 to} 66 _N is supplied to a cooling unit (not shown) via the cooling water outlet side main pipe 70. The The cooling water cooled in the cooling unit is supplied to the cooling water inlet side pipe 68, and the cooling water is circulated.

  Next, in order to prevent the destruction of the thyristor 20 and the resistors 64 and 66, the element junction temperature of the thyristor 20 and the resistance line temperature of the resistors 64 and 66 (or resistors 28 and 24) are estimated from the operating state of the thyristor valve 8U. The operation to be monitored will be described.

(1) Calculation of element junction temperature of thyristor 20
The calculation unit 14 a calculates the element junction temperature T _vj of the thyristor 20 based on the data acquired from the sensor group 12 using the following formula.
T _vj = (R _thy + R _fin ) P _thy + T _tin (1)
Here, T _tin is an incoming temperature (° C.) of the cooling water detected by a sensor installed in the water inlet of the heat sinks 62 _{1 to} 62 _{N + 1} adjacent to each thyristor.

R _thy is the thermal resistance of the thyristor 20, and R _fin is the thermal resistance of the heat sink 62, which can be expressed by the following equations. R _tn is the thermal resistance of the thyristor, R _fn is the thermal resistance of the heat sink, and τ _tn and τ _fn are time constants. The unit of thermal resistance is K / W.

  However, these thermal resistances are constants determined for each product. Actually, the thermal resistances may be used without being calculated using the equations (2) and (3).

In the expression (1), P _thy is an element loss. This element loss is calculated by the following equation using the energization loss P _cnd , the turn-on loss P _swon , and the turn-off loss P _swoff in the thyristor.

P _thy = P _cnd + P _swon + P _swoff (4)
Here, P _cnd , P _swon , and P _swoff are calculated by the following equations, respectively.

P _cnd = U _to × I _TAV + R _to × I ² _TRMS (5)
P _swon = 0.02P _cnd (di / dt ≤ 2 A / μs) (6)
= 0.035P _cnd (di / dt> 2 A / μus)

In equation (5), U _to is a threshold voltage (V), I _TAV is an average current (A), R _to is a slope resistance (Ω), and I _TRMS is an effective value current (A). The threshold voltage U _to and the slope resistance R _to are known, and the average current I _TAV and the effective value current I _TRMS are detected by a current sensor connected in series to the thyristor. In equation (6), di / dt is a time derivative of the device current. In equation (7), Q _rr is the reverse recovery charge (μQ), V _S is the valve voltage (V), α is the control angle (°), f is the frequency (Hz), and N is the number of thyristors in series. The series number N of thyristors, the reverse recovery charge Q _rr , the control angle α, and the frequency f are known, and the valve voltage V _S is detected by the voltage detector 26.

Calculation unit 14a calculates the element junction temperature _{T vj} thyristor 20 to 20 _N on the basis of the equation (1).

The element loss P _thy can be obtained by the following equation instead of the equation (4).

P _thy = (U _t + R _t × I _thy ) × I _thy (8)
Here, I _thy is a current (element current) (A) flowing through the thyristor, U _t is a threshold voltage (V) selected so as to match the actual element loss, and R _t matches the actual element loss. The selected slope resistance (Ω). The threshold voltage U _t and the slope resistance R _t are known values selected by substituting the formulas (5) to (7) into the formula (4) and the calculation results of the formula (8). The element current I _thy is detected by a sensor installed in the thyristor.

If the equation (8) is used to calculate the element loss P _thy , less data is required for the calculation than when the equations (4) to (7) are used.
(2) Calculation of resistance wire temperature of resistors 64 and 66
Calculation unit 14a, data acquired resistance wire temperature _{T r} of the resistor 64, 66 _N from the sensor group 12 to calculate the following equation based on. T _r = R _r · P _r + T _rin (9)
Here, T _rin is the temperature of the cooling water detected by a sensor installed at the water inlet of the resistors 64 and 66.

R _r is the thermal resistance of the resistors 64 and 66 and can be expressed by the following equation. The unit of thermal resistance is K / W.

P _r is that losses resulting resistance line, when calculating the temperature of the snubber resistor 64, the loss of snubber resistor (snubber loss) when the P _snb, calculating the temperature of the voltage dividing resistors 66 In this case, the loss _Pvd of the _{voltage dividing} resistor is used.

However, the thermal resistance R _{r is} also a constant determined for each product, and the constant is actually used without being calculated using the equation (10).

The snubber loss P _snb and the partial pressure loss P _vd can be expressed by the following equations, respectively.

f is the frequency, C _snb is the capacitance of the snubber circuit capacitor, V _S is the valve voltage, N is the number of snubber circuits in series, and R _vd is the voltage _dividing resistor (Ω). The frequency f, the capacitance C _{snb of} the snubber circuit capacitor, and the number of snubber circuits in series N are known, and the valve voltage V _S is detected by a sensor installed in the thyristor bubble. Calculation unit 14a calculates the resistance wire temperature _{T r} of (9) ₆₄ 1 ~64 N resistors based on _formula, 66 1 -66 _N.
The temperature calculated by the calculation unit 14a is supplied to the control unit 14b. The control unit 14b includes at least _one of the element junction temperature of the thyristors 20 _{1 to} 20 _N , the resistance line temperature of the snubber resistors 28 _{1 to} 28 _N , and the resistance line temperature of the voltage dividing resistors 24 _{1 to} 24 _N calculated by the calculation unit 14a. When the value exceeds the threshold, the operation of the thyristor valve 8U is controlled so that the generation of heat is reduced. For example, the operation of the thyristor valve 8U is stopped, or a light load operation is performed in which a gate pulse is continuously supplied to the gates of the thyristors 20 _{1 to} 20 _N so that a reverse voltage is not applied. Various characteristics of the thyristor, such as turn-off time and withstand voltage, depend on the temperature of the thyristor. If the temperature exceeds a predetermined value, the design performance cannot be maintained. The amount of heat generated by the thyristor depends on the energization current, and when the temperature exceeds a threshold value due to overload or the like, it is necessary to quickly decrease the energization current.

As described above, according to the embodiment, it is possible to calculate the element junction temperature and the resistance line temperature based on the data representing the operation state during the operation of the thyristor valve 8U, and monitor the temperature rise. Therefore, when the temperature becomes equal to or higher than the threshold value, the operation can be controlled to prevent the thyristor and the resistor from being damaged. The temperature calculation is not limited to the formulas (1) and (9), and other similar formulas may be used.
[Second Embodiment]
The first embodiment uses a cooling pipe in which a heat sink and a water-cooled resistor are connected in parallel. The calculation of temperature depends on the path of the cooling pipe. A second embodiment using a cooling pipe having a path different from that in FIG. 6 will be described. In the second embodiment, as shown in FIG. 7, the heat sink and the water-cooled resistor are connected in series.

  FIG. 7 shows a cooling pipe of a portion for cooling the two thyristor valves 8U, 8X. Since the thyristor valves 8V and 8Y and the thyristor valves 8W and 8Z are the same as the thyristor valves 8U and 8X, illustration is omitted.

In the thyristor valve 8U, the heat sinks 62 _{1 to} 62 _{N + 1} are arranged on both sides of the thyristors 20 _{1 to} 20 _N , as in the embodiment of FIG. The heat sink _{62 1 ~62 N +} 1 of the water inlet is connected through a branch pipe to the cooling water inlet side header pipe 68, the heat sink _{62 1 ~62 N +} 1 of the water outlet is connected to a water cooled resistor _{72 1 ~72 N +} 1 of the water inlet The The water outlets of the water cooling resistors 72 _{1 to} 72 _{N + 1} are connected to the cooling water outlet side main pipe 70 through branch pipes. The water-cooled resistors 72 are not all the same resistance value, but have different resistance values every other one. The odd-numbered water-cooled resistors 72 ₁ , 72 ₃ ,... Include two independent resistance lines 76, 78 a, and the even-numbered water-cooled resistors 72 ₂ , 72 ₄ ,. The resistance line 76 constitutes the voltage dividing resistor 24, and the series connection of the two resistance lines 78 a and 78 b constitutes the snubber resistor 28.

In the thyristor valve 8X, the heat sinks 62 _{1 to} 62 _{N + 1} are arranged on both sides of the thyristors 20 _{1 to} 20 _N , as in the embodiment of FIG. The heat sink _{62 1 ~62 N +} 1 of the water inlet is connected through a branch pipe to the cooling water inlet side header pipe 68, the heat sink _{62 1 ~62 N +} 1 of the water outlet is connected to a water cooled resistor _{72 1 ~72 N +} 1 of the water inlet The The water outlets of the water cooling resistors 72 _{1 to} 72 _{N + 1} are connected to the cooling water outlet side main pipe 70 through branch pipes. The water-cooled resistors 72 are not all the same resistance value, but have different resistance values every other one. The even-numbered water-cooled resistors 72 ₂ , 72 ₄ ,... Include two independent resistance lines 76, 78 a, and the odd-numbered water-cooled resistors 72 ₃ , 72 ₅ ,. The resistance line 76 constitutes the voltage dividing resistor 24, and the series connection of the two resistance lines 78 a and 78 b constitutes the snubber resistor 28. Since the number of cooling paths is one more than the number of siris, one of the first and last water-cooled resistors 72 ₁ , 72 _{N + 1} is used to balance the flow path with and without the water-cooled resistors. A dummy resistance line 80 is included. In this way, the series connection of the heat sinks 62 _{1 to} 62 _{N + 1} and the water-cooled resistors 72 _{1 to} 72 _{N + 1} is arranged in parallel between the cooling water inlet side pipe 68 and the cooling water outlet side pipe 70.

In the case of FIG. 6, the cooling water supplied from the cooling water inlet side main pipe 68 is injected in parallel to the heat sinks 62 _{1 to} 62 _{N + 1} and the water cooling resistors 64 ₁ to 64 _N and 66 ₁ to 66 _N. in the case of FIG. 7, not cooling water supplied from the cooling water inlet side header pipe 68 is directly injected into the water-cooled resistor _{64 1 ~64 N + 1, 66} 1 ~66 N + 1, the water temperature at the heat sink ₆₂ 1 _{through 62 N +} within ₁ The cooling water having risen is injected into the water-cooled resistors 64 ₁ to 64 _{N + 1} and 66 _{1 to} 66 _{N + 1} . For this reason, when calculating the resistance line temperatures of the snubber resistor 28 and the voltage dividing resistor 24, it is necessary to consider the increase in the temperature of the cooling water.

In the second embodiment, the calculation unit 14a calculates the water temperature increase ΔT in the heat sinks 62 _{1 to} 62 _{N + 1} , and corrects the equation (9) using the result to calculate the resistance line temperature.

  The temperature rise ΔT of the cooling water is calculated by the following formula.

ΔT = P / (ρ × c × Q) (13)
P is the calorific value, Q is the flow rate of cooling water (L / min), ρ is the density of cooling water (kg / m), and c is the specific heat of cooling water (kJ / (kg · K)). The element loss P _thy is used as the heat generation amount. The flow rate Q of the cooling water is detected by the sensor group 12, and the density ρ of the cooling water and the specific heat c of the cooling water are known.

The calculation unit 14a calculates the resistance line temperatures of the snubber resistor 28 and the voltage dividing resistor 24 by replacing the _incoming water temperature T _{rin in} equation (9) with T _rin + ΔT. The calculation unit 14a calculates the element junction temperature of the thyristors 20 and 21 according to the equation (1) as in the case of FIG.
In FIG. 7, when the heat sink and the water-cooled resistor are connected in series, the heat sink is connected to the cooling water inlet-side mother pipe 68, and cooling water through the heat sink is injected into the water-cooled resistor. The connection may be reversed. That is, a water-cooled resistor may be connected to the cooling water inlet-side mother pipe 68, and cooling water via the water-cooled resistor may be injected into the heat sink.

In this case, calculation unit 14a, as the heating value by using the loss P _r generated in the resistance wire (13) the temperature rise ΔT of the cooling water calculated by formula, the incoming water temperature T _tin of (1) T The element coupling temperature of the thyristor 20 is calculated by replacing with _tin + ΔT. Note that the calculation unit 14a calculates the resistance line temperatures of the snubber resistor 28 and the voltage dividing resistor 24 by the equation (9) as in the case of FIG. Although 2nd Embodiment showed the example of the cooling piping by which the serial connection which consists of one heat sink and one water-cooling resistor was connected in parallel, the example of piping is arbitrary. For example, a heat sink, a heat sink, a water-cooled resistor, and a water-cooled resistor may be connected in series from the cooling water inlet side mother pipe 68. In any case, the device junction temperature and the resistance wire temperature can be calculated by calculating the temperature rise of the equation (13) and correcting the water intake temperature of the equation (1) or (9) based on the calculated temperature rise.
Thus, as shown in FIG. 7, even when the cooling water is not injected into the heat sink and the water cooling resistor at the same time, and the temperature of the cooling water rises by the heat sink or the water cooling resistor, the equations (1) and (9) The element junction temperature or the resistance wire temperature can be calculated correctly. According to the embodiment described above, the element junction temperature of the thyristor and the resistance line temperature of the resistor can be estimated by performing calculations using the equations (1) and (9). Further, by monitoring the element junction temperature and resistance wire temperature of the thyristor and controlling the operation of the thyristor valve, it is possible to prevent the thyristor and the resistor from being damaged. Further, even in a cooling pipe configuration in which a heat sink and a water-cooled resistor are connected in series, an increase in the temperature of the cooling water is calculated by the equation (13), and by using the result, the element junction temperature of the thyristor, And the temperature of the resistance wire can be calculated.

  In addition, although some embodiment of this invention was described, these embodiment is shown as an example and is not intending limiting the range of invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 6 ... Power converter device, 8 ... Reactive power compensation device, 10 ... Gate control device, 12 ... Sensor group, 14 ... Control panel, 20, 21 ... Thyristor, 22 ... Snubber circuit, 24 ... Voltage dividing resistor, 26 ... Voltage detection 28 ... Snubber resistor, 30 ... Capacitor, 62 ... Heat sink, 64, 66, 72 ... Water-cooled resistor.

Claims (8)

A reactive power compensator comprising a plurality of thyristor valves;
Sensor means for detecting state data indicating an operating state of the reactive power compensator;
Control means for calculating a temperature based on the output of the sensor means, and controlling the reactive power compensator according to the calculated temperature,
The thyristor valve is
A plurality of thyristors connected in series;
A plurality of snubber resistors respectively connected in parallel to the plurality of thyristors;
A plurality of voltage dividing resistors respectively connected in parallel to the plurality of thyristors,
The control means is a power converter that calculates element junction temperatures of the plurality of thyristors, resistance line temperatures of the plurality of snubber resistors, and resistance line temperatures of the plurality of voltage dividing resistors. A plurality of heat sinks for cooling the plurality of thyristors;
Further comprising a plurality of snubber resistors and a plurality of water-cooled resistors constituting the plurality of voltage dividing resistors,
The control means includes
Based on the thermal resistance of the plurality of thyristors, the thermal resistance of the plurality of heat sinks, the element loss of the plurality of thyristors, and the incoming temperature of the cooling water injected into the plurality of heat sinks, Calculate the device junction temperature,
Based on the thermal resistance of the plurality of snubber resistors, the loss generated in the plurality of snubber resistors, and the incoming temperature of the cooling water injected into the plurality of water-cooled resistors constituting the plurality of snubber resistors, Calculate the resistance wire temperature of the snubber resistor,
Based on the thermal resistance of the plurality of voltage dividing resistors, the loss generated in the plurality of voltage dividing resistors, and the incoming temperature of the cooling water injected into the plurality of water cooling resistors constituting the plurality of voltage dividing resistors, The power converter according to claim 1, wherein resistance line temperatures of the plurality of voltage dividing resistors are calculated. The plurality of water-cooled resistors include a plurality of first water-cooled resistors that configure the plurality of snubber resistors, and a plurality of second water-cooled resistors that configure the plurality of voltage dividing resistors,
Each of the plurality of thyristor valves includes the plurality of first water-cooled resistors, the plurality of second water-cooled resistors, and the plurality of seat sinks,
The plurality of first water-cooled resistors, the plurality of second water-cooled resistors, and the plurality of heat sinks are arranged in parallel between a cooling water inlet end and a cooling water outlet end. The power conversion device according to claim 2. Each of the plurality of snubber resistors is divided into a first resistor and a second resistor;
The plurality of water-cooled resistors include a plurality of first water-cooled resistors that constitute the first resistors of the plurality of voltage dividing resistors and the plurality of snubber resistors, and a plurality of that constitute the second resistors of the plurality of snubber resistors. A second water-cooled resistor;
Each of the plurality of thyristor valves includes the plurality of first water-cooled resistors, the plurality of second water-cooled resistors, and the plurality of seat sinks,
The plurality of heat sinks are connected in series with the plurality of first water-cooled resistors or the plurality of second water-cooled resistors,
The series circuit of the plurality of heat sinks and the plurality of first water-cooled resistors or the plurality of second water-cooled resistors is arranged in parallel between the cooling water inlet side end and the cooling water outlet side end. The power converter according to claim 1 or 2 arranged.   The power conversion device according to claim 4, wherein the cooling water discharged from the plurality of heat sinks is injected into the plurality of first water cooling resistors or the plurality of second water cooling resistors.   The power converter according to claim 4, wherein cooling water discharged from the plurality of first water cooling resistors or the plurality of second water cooling resistors is injected into the plurality of heat sinks.   The reactive power compensator is configured when at least one of an element junction temperature of the plurality of thyristors, a resistance line temperature of the plurality of snubber resistors, and a resistance line temperature of the plurality of voltage dividing resistors is equal to or greater than a threshold value. The power converter device according to any one of claims 1 to 6, wherein the power converter is stopped or operated at a low load. A reactive power compensator comprising a plurality of thyristor valves;
Sensor means for detecting state data indicating an operating state of the reactive power compensator;
Control means for calculating the temperature based on the output of the sensor means, and controlling the reactive power compensator according to the calculated temperature,
The thyristor valve is
A plurality of thyristors connected in series;
A plurality of snubber resistors respectively connected in parallel to the plurality of thyristors;
A plurality of voltage dividing resistors respectively connected in parallel to the plurality of thyristors,
The plurality of thyristors are cooled by a plurality of heat sinks,
The plurality of snubber resistors are constituted by a plurality of first water-cooled resistors,
The plurality of voltage dividing resistors is a temperature monitoring method for a power conversion device including a plurality of second water-cooled resistors,
The plurality of thyristor elements based on the thermal resistance of the plurality of thyristors, the thermal resistance of the plurality of heat sinks, the element loss of the plurality of thyristors, and the incoming temperature of cooling water injected into the plurality of heat sinks Calculate the junction temperature
The resistance line temperature of the plurality of snubber resistors is calculated based on the thermal resistance of the plurality of snubber resistors, the loss generated in the plurality of snubber resistors, and the incoming water temperature of the cooling water of the plurality of first cooling resistors. And
The resistance lines of the plurality of voltage dividing resistors based on the thermal resistance of the plurality of voltage dividing resistors, the loss generated in the plurality of voltage dividing resistors, and the incoming water temperature of the cooling water of the plurality of second water cooling resistors. A temperature monitoring method that calculates temperature.

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