Solid state valve thermal protection for HVDC power converters
First Claim
1. A thermal protection system for solid state valve means that includes at least one representative thyristor having a junction and a heat sink system for transferring heat from said junction to cooling fluid flowing past said heat sink system, said protection system comprising:
- (a) a solid state valve thermal analog model comprising an electrical network whose dynamic electrical operating characteristics are analogous to the thermal characteristics of said solid state valve means for a given value of instantaneous D.C. load current supplied through said solid state valve means, which thermal characteristics include the heat transfer to cooling fluid capability characteristics of said representative thyristor including its heat sink system,(b) means for deriving a first electrical signal representative of the value of the D.C. load current,(c) D.C. current to heat generation simulation network means responsive to said first electrical signal for deriving an output electrical power dissipation signal representative of the instantaneous value of the power dissipation within the junction of said representative thyristor for a given value of load current flowing through said junction,(d) means for applying said power dissipation signal to said thermal analog model,(e) output means connected to said thermal analog model for deriving an output junction temperature signal representative of the temperature of said thyristor junction, and(f) means for applying to said thermal model an additional electrical signal representative of the instantaneous temperature value of the cooling fluid flowing over said valve means and said heat sink system in such a way that said output junction temperature signal is modified by said additional signal.
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Accused Products
Abstract
A thermal protection system is provided for a solid state valve that includes at least one representative thyristor having a junction and a heat sink system. The protection system comprises a thermal analog model whose electrical network dynamic electrical operating characteristics are electrically analogous to the thermal characteristics of the solid state valve for any given value of instantaneous load current supplied through the valve, which thermal characteristics include the heat transfer to cooling fluid capability characteristics of said representative thyristor including its heat sink system. A first electrical signal is derived which is representative of the value of the D.C. load current through said valve. A D.C. current to watts generation simulation network responsive to the first electric signal is provided for deriving an output electrical signal representative of the instantaneous value of the watts being dissipated within the junction of said representative thyristor for a given value of load current flowing through said junction. The watts-being-generated signal is applied to said thermal analog model and an output electric signal is derived from said thermal analog model which is representative of the temperature of said thyristor junction.
The thermal analog model comprises an RC ladder network having the signal from the simulation network applied to one of its terminals. To another terminal of the ladder network is applied an electric signal representative of the instantaneous temperature value of the cooling fluid flowing over said solid state valve means and said heat sink system.
24 Citations
21 Claims
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1. A thermal protection system for solid state valve means that includes at least one representative thyristor having a junction and a heat sink system for transferring heat from said junction to cooling fluid flowing past said heat sink system, said protection system comprising:
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(a) a solid state valve thermal analog model comprising an electrical network whose dynamic electrical operating characteristics are analogous to the thermal characteristics of said solid state valve means for a given value of instantaneous D.C. load current supplied through said solid state valve means, which thermal characteristics include the heat transfer to cooling fluid capability characteristics of said representative thyristor including its heat sink system, (b) means for deriving a first electrical signal representative of the value of the D.C. load current, (c) D.C. current to heat generation simulation network means responsive to said first electrical signal for deriving an output electrical power dissipation signal representative of the instantaneous value of the power dissipation within the junction of said representative thyristor for a given value of load current flowing through said junction, (d) means for applying said power dissipation signal to said thermal analog model, (e) output means connected to said thermal analog model for deriving an output junction temperature signal representative of the temperature of said thyristor junction, and (f) means for applying to said thermal model an additional electrical signal representative of the instantaneous temperature value of the cooling fluid flowing over said valve means and said heat sink system in such a way that said output junction temperature signal is modified by said additional signal. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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6. A thermal protection system according to claim 4 wherein said means for applying to the said other terminal of the RC ladder network an electrical signal representative of the instantaneous temperature value of the cooling fluid flowing over said thyristor heat sink system comprises:
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(a) at least two thermo-electric temperature sensing means disposed in the flow path of the cooling fluid passing over said heat sink system for sensing the ambient temperature of the cooling fluid and deriving at least two output electric signals representative of the cooling fluid ambient temperature after passing over said heat sink system, and (b) voting circuit means responsive to the output from said at least two thermo-electric temperature sensing means for selectively supplying that electric signal representative of the highest sensed ambient cooling fluid temperature to the valve thermal analog model.
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7. A thermal protection system according to claim 6 in combination with means for increasing automatically the magnitude of the power dissipation signal derived from the output from said current to heat generation simulation network means in accordance with increases in duty placed on said solid state valve means.
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8. A thermal protection system for solid state valve means that includes at least one representative thyristor having a junction and a heat sink system for transferring heat from said junction to cooling fluid flowing past said heat sink system, said protection system comprising:
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(a) a solid state valve thermal analog model comprising an electrical network whose dynamic electrical operating characteristics are analogous to the thermal characteristics of said solid state valve means for a given value of instantaneous D.C. load current supplied through said solid state valve means, which thermal characteristics include the heat transfer to cooling fluid capability characteristics of said representative thyristor including its heat sink system, (b) means for deriving a first electrical signal representative of the value of the D.C. load current, (c) D.C. current to heat generation simulation network means responsive to said first electrical signal for deriving an output electrical power dissipation signal representative of the instantaneous value of the power dissipation within the junction of said representative thyristor for a given value of load current flowing through said junction, (d) means for applying said power dissipation signal to said thermal analog model, (e) output means connected to said thermal analog model for deriving an output junction temperature signal representative of the temperature of said thyristor junction, and (f) means for automatically modifying even at a given load current the magnitude of the power dissipation signal derived from the output from said current to heat generation simulation network means in accordance with modifications in mode of operation of the solid state valve means being monitored. - View Dependent Claims (9, 10)
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11. A thermal protection system for solid state valve means that includes at least one representative thyristor having a junction and a heat sink system for transferring heat from said junction to cooling fluid flowing past said heat sink system, said protection system comprising:
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(a) a solid state valve thermal analog model comprising an electrical network whose dynamic electrical operating characteristics are analogous to the thermal characteristics of said solid state valve means for a given value of instantaneous D.C. load current supplied through said solid state valve means, which thermal characteristics include the heat transfer to cooling fluid capability characteristics of said representative thyristor including its heat sink system, (b) means for deriving a first electrical signal representative of the value of the D.C. load current, (c) D.C. current to heat generation simulation network means responsive to said first electrical signal for deriving an output electrical power dissipation signal representative of the instantaneous value of the power dissipation within the junction of said representative thyristor for a given value of load current flowing through said junction, (d) means for applying said power dissipation signal to said thermal analog model, (e) output means connected to said thermal analog model for deriving an output junction temperature signal representative of the temperature of said thyristor junction, and (f) said means for deriving a first electrical signal representative of the value of the load current comprises a load current sensor for sensing the actual value of the magnitude of the D.C. load current flowing through said solid state valve means, (g) current to voltage converting means is provided for converting the sensed current value to a voltage signal representative of the load current magnitude, (h) a first voltage to current converter means is provided responsive to the output from said current to voltage converter means and having its output current supplied to the current to heat generation simulation network means, (i) said current to heat generation simulation network means comprises an interconnected resistor-diode network having a non-linear impedance for providing an output voltage signal proportional to the product of said non-linear impedance and the value of a current signal supplied thereto from said first voltage to current converter means, (j) and second voltage to current converter means responsive to the voltage output from said resistor-diode network for converting the output voltage signal to a controlled current signal representative of the power dissipation within the junction of said representative thyristor for supply to said thermal analog model. - View Dependent Claims (12, 13, 14, 15, 16, 17)
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18. A thermal protection system for solid state valve means included in a High Voltage D.C. transmission system including a plurality of power sources capable of supplying current to the valve means, said valve means including;
- at least one representative thyristor having a junction and a heat sink system for transferring heat from said junction to cooling fluid flowing past said heat sink system, said protection system comprising;
(a) a solid state valve thermal analog model comprising an electrical network whose dynamic electrical operating characteristics are analogous to the thermal characteristics of said solid state valve means for a given value of instantaneous D.C. load current supplied through said solid state valve means, which thermal characteristics include the heat transfer to cooling fluid capability characteristics of said representative thyristor including its heat sink system, (b) means for deriving a first electrical signal representative of the value of the D.C. load current, (c) D.C. current to heat generation simulation network means responsive to said first electrical signal for deriving an output electrical power dissipation signal representative of the instantaneous value of the power dissipation within the junction of said representative thyristor for a given value of load current flowing through said junction, (d) means for applying said power dissipation signal to said thermal analog model, (e) output means connected to said thermal analog model for deriving an output junction temperature signal representative of the temperature of said thyristor junction, and (f) output signal level sensing circuit means responsive to said output means for comparing the output junction temperature signal level derived from said thermal analog model to a plurality of different reference signal level values and deriving a plurality of different priority action output alarm signals in the event one or more of the reference signal level values is exceeded by said output junction temperature signal, (g) means for signaling a warning when a first one of said reference signal level values is exceeded, (h) means for automatically reducing the current order of the D.C. system that includes said valve means when a second one of said reference signal level values is exceeded, (i) and means for establishing a bypass around said valve means when a third one of said reference signal level values is exceeded. - View Dependent Claims (19, 20)
- at least one representative thyristor having a junction and a heat sink system for transferring heat from said junction to cooling fluid flowing past said heat sink system, said protection system comprising;
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21. A thermal protection system for solid state valve means that includes at least one representative thyristor having a junction and a heat sink system for transferring heat from said junction to cooling fluid flowing past said heat sink system, said protection system comprising:
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(a) a solid state valve thermal analog model comprising an electrical network whose dynamic electrical operating characteristics are analogous to the thermal characteristics of said solid state valve means for a given value of instantaneous D.C. load current supplied through said solid state valve means, which thermal characteristics include the heat transfer to cooling fluid capability characteristics of said representative thyristor including its heat sink system, (b) means for deriving a first electrical signal representative of the value of the D.C. load current, (c) D.C. current to heat generation simulation network means responsive to said first electrical signal for deriving an output electrical power dissipation signal representative of the instantaneous value of the power dissipation within the junction of said representative thyristor for a given value of load current flowing through said junction, (d) means for applying said power dissipation signal to said thermal analog model, (e) output means connected to said thermal analog model for deriving an output junction temperature signal representative of the temperature of said thyristor junction, and (f) valve thermal protection system monitor means coupled to said thermal analog model for monitoring the performance of the valve thermal protection system and for deriving output indications of at least the maximum value of the heat sink system cooling fluid ambient temperature, the difference between the maximum and minimum sensed values of heat sink system cooling fluid ambient temperature, the maximum value of the thyristor junction temperature and the difference between the maximum and minimum sensed values of said thyristor junction temperature.
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Specification