This paper presents a thermal management framework for 120 kV hybrid commutated converter(HCC)valves,addressing critical cooling challenges in multi-hundred-MW power conversion systems.Power loss calculations under ra...This paper presents a thermal management framework for 120 kV hybrid commutated converter(HCC)valves,addressing critical cooling challenges in multi-hundred-MW power conversion systems.Power loss calculations under rated(1.0 p.u.)and overload(1.2 p.u.)conditions demonstrate that HCC valves achieve comparable loss levels to line commutated converter counterparts while enabling active turn-off control.Comparative analysis of radiator configurations identifies 2-parallel branch connections as optimal.Integrated thermal-fluid models combining 3D finite element analysis and computational fluid dynamics reveal significant temperature gradients and flow maldistribution in baseline designs.On this basis,this paper modifies the flow from equal flow resistance allocation to heat-based allocation and it reduces maximum integrated gate-commutated thyristor temperature rise by 7.3%at 1.2 p.u.with minimal pressure drop variation.Experimental validation confirms the proposed cooling strategy enhances valve safety margins through improved heat dissipation balance,providing a validated theoretical foundation for high-power converter thermal design.展开更多
UHVDC converter valves during operation may experience overvoltage,which come from the AC or DC systems to which they are connected.Therefore,building an equivalent circuit model(ECM)for the converter valve to analyze...UHVDC converter valves during operation may experience overvoltage,which come from the AC or DC systems to which they are connected.Therefore,building an equivalent circuit model(ECM)for the converter valve to analyze the interlayer transient voltage distribution characteristics has important engineering significance for safe and reasonable voltage equalization methods and improving the stability of the DC system.This paper proposes a two-port equivalent circuit model for ±1100 kV converter valve based on the structure of the valve and parameter extraction methods presented.In terms of lumped parameters,integrated ECMs for valve layers are built through impedance-frequency characteristic analysis;in terms of parasitic capacitance parameters,port equivalent parasitic capacitance parameters are obtained by terminal capacitance method and iterative equivalence methods proposed in this paper.By combining integrated ECMs of valve layers and port equivalent parasitic capacitances,the two-port ECM is obtained.Simulations are carried out to test the effectiveness of the twoport ECM.Using the ECM,the voltage transmission characteristics and their influencing factors are analyzed,depending on which corresponding voltage equalization method is proposed in this paper,and the effect of this method is verified through simulation.展开更多
The intermittent nature of wind and solar photovoltaic energy systems leads to the fluctuation of power generated due to the fact that the power output is highly dependent upon local weather conditions, which results ...The intermittent nature of wind and solar photovoltaic energy systems leads to the fluctuation of power generated due to the fact that the power output is highly dependent upon local weather conditions, which results to the load shading issue that led to the voltage and frequency instability. In additional to that, the high proportions of erratic renewable energy sources can lead to erratic frequency changes which affect the grid stability. In order to reduce this effect, the energy storage system is commonly used in most wind-solar energy systems to balance the voltage and frequency instability during load variations. One of the innovative energy storage systems is the compressed air energy storage system (CAES) for wind and solar hybrid energy system and this technology is the key focus in this research study. The aim of this research was to examine the system configuration of the CAES system through modelling and experimental approach with PID controller design for regulating the voltage and frequency under different load conditions. The essential elements and the entire system have been presented in this work as thorough modelling in the MATLAB/Simulink environment for different load conditions. The developed model was tested through an experimental workbench using the developed prototype of the compressed air storage in the Siemens Lab at DeKUT and explored the consequence of the working parameters on the system proficiency and the model accuracy. The performance of the system for the developed prototype of CAES system was validated using results from an experimental workbench with MATLAB/Simulink R2022b simulation. The modeling and experimental results, shows that the frequency fluctuation and voltage drop of the developed CAES system during load variations was governed by the I/P converter using a PID_Compact controller programed in the TIA Portal V17 software and downloaded into PLC S7 1200. Based on these results, the model can be applied as a basis for the performance assessment of the compressed air energy storage system so as to be included in current technology of wind and solar hybrid energy systems.展开更多
Pulse width modulated current-source converter(PWM-CSC)has great prospects in high voltage direct current transmission system(HVDC)due to its attractive features,such as flexible control characteristics,ability to avo...Pulse width modulated current-source converter(PWM-CSC)has great prospects in high voltage direct current transmission system(HVDC)due to its attractive features,such as flexible control characteristics,ability to avoid commutation failure,and lower cost.However,valve voltage of the PWM-CSC is the jump value between filter capacitors line-voltage and zero voltage due to its bypass operation,resulting in high peak voltage withstand by the converter for a rated HVDC system and high voltage ripper ratio.In order to solve these issues,an improved modulation method called specific carrier frequency of SPWM is proposed.After adopting the improved modulation method,the number of the reverse blocking integrated gate commutated thyristor(RB-IGCT)in series can reduce by 31.5%under unity power factor operation and the value of the dc choke can reduce by about 78.6%compared to traditional modulation methods,improving practicability of engineering application.Moreover,active power and reactive power operating range are derived under different modulation methods and the relationship of the power factor,modulation in q-axis and DC current are studied.Finally,effectiveness of the improved modulation method and comparisons of power operating range are verified in PSCAD/EMTDC.展开更多
基金National Key Research and Development Program,Grant/Award Number:2023YFB2405900。
文摘This paper presents a thermal management framework for 120 kV hybrid commutated converter(HCC)valves,addressing critical cooling challenges in multi-hundred-MW power conversion systems.Power loss calculations under rated(1.0 p.u.)and overload(1.2 p.u.)conditions demonstrate that HCC valves achieve comparable loss levels to line commutated converter counterparts while enabling active turn-off control.Comparative analysis of radiator configurations identifies 2-parallel branch connections as optimal.Integrated thermal-fluid models combining 3D finite element analysis and computational fluid dynamics reveal significant temperature gradients and flow maldistribution in baseline designs.On this basis,this paper modifies the flow from equal flow resistance allocation to heat-based allocation and it reduces maximum integrated gate-commutated thyristor temperature rise by 7.3%at 1.2 p.u.with minimal pressure drop variation.Experimental validation confirms the proposed cooling strategy enhances valve safety margins through improved heat dissipation balance,providing a validated theoretical foundation for high-power converter thermal design.
基金This work was supported by Science and Technology Project of the State Grid Corporation under Grant 5455ZS150004.
文摘UHVDC converter valves during operation may experience overvoltage,which come from the AC or DC systems to which they are connected.Therefore,building an equivalent circuit model(ECM)for the converter valve to analyze the interlayer transient voltage distribution characteristics has important engineering significance for safe and reasonable voltage equalization methods and improving the stability of the DC system.This paper proposes a two-port equivalent circuit model for ±1100 kV converter valve based on the structure of the valve and parameter extraction methods presented.In terms of lumped parameters,integrated ECMs for valve layers are built through impedance-frequency characteristic analysis;in terms of parasitic capacitance parameters,port equivalent parasitic capacitance parameters are obtained by terminal capacitance method and iterative equivalence methods proposed in this paper.By combining integrated ECMs of valve layers and port equivalent parasitic capacitances,the two-port ECM is obtained.Simulations are carried out to test the effectiveness of the twoport ECM.Using the ECM,the voltage transmission characteristics and their influencing factors are analyzed,depending on which corresponding voltage equalization method is proposed in this paper,and the effect of this method is verified through simulation.
文摘The intermittent nature of wind and solar photovoltaic energy systems leads to the fluctuation of power generated due to the fact that the power output is highly dependent upon local weather conditions, which results to the load shading issue that led to the voltage and frequency instability. In additional to that, the high proportions of erratic renewable energy sources can lead to erratic frequency changes which affect the grid stability. In order to reduce this effect, the energy storage system is commonly used in most wind-solar energy systems to balance the voltage and frequency instability during load variations. One of the innovative energy storage systems is the compressed air energy storage system (CAES) for wind and solar hybrid energy system and this technology is the key focus in this research study. The aim of this research was to examine the system configuration of the CAES system through modelling and experimental approach with PID controller design for regulating the voltage and frequency under different load conditions. The essential elements and the entire system have been presented in this work as thorough modelling in the MATLAB/Simulink environment for different load conditions. The developed model was tested through an experimental workbench using the developed prototype of the compressed air storage in the Siemens Lab at DeKUT and explored the consequence of the working parameters on the system proficiency and the model accuracy. The performance of the system for the developed prototype of CAES system was validated using results from an experimental workbench with MATLAB/Simulink R2022b simulation. The modeling and experimental results, shows that the frequency fluctuation and voltage drop of the developed CAES system during load variations was governed by the I/P converter using a PID_Compact controller programed in the TIA Portal V17 software and downloaded into PLC S7 1200. Based on these results, the model can be applied as a basis for the performance assessment of the compressed air energy storage system so as to be included in current technology of wind and solar hybrid energy systems.
基金supported in part by Science and Technology Project of State Grid Corporation of China(5500202058059A0000).
文摘Pulse width modulated current-source converter(PWM-CSC)has great prospects in high voltage direct current transmission system(HVDC)due to its attractive features,such as flexible control characteristics,ability to avoid commutation failure,and lower cost.However,valve voltage of the PWM-CSC is the jump value between filter capacitors line-voltage and zero voltage due to its bypass operation,resulting in high peak voltage withstand by the converter for a rated HVDC system and high voltage ripper ratio.In order to solve these issues,an improved modulation method called specific carrier frequency of SPWM is proposed.After adopting the improved modulation method,the number of the reverse blocking integrated gate commutated thyristor(RB-IGCT)in series can reduce by 31.5%under unity power factor operation and the value of the dc choke can reduce by about 78.6%compared to traditional modulation methods,improving practicability of engineering application.Moreover,active power and reactive power operating range are derived under different modulation methods and the relationship of the power factor,modulation in q-axis and DC current are studied.Finally,effectiveness of the improved modulation method and comparisons of power operating range are verified in PSCAD/EMTDC.
