Intermittent new energy delivery requires increasing the flexibility of ultra-high voltage direct current(DC)power adjustment.Based on a converter steady-state model and a DC power model,the control angle constraints ...Intermittent new energy delivery requires increasing the flexibility of ultra-high voltage direct current(DC)power adjustment.Based on a converter steady-state model and a DC power model,the control angle constraints of a converter valve are relaxed for power regulation.In this paper,a flexible DC power control method based on a fixed tap changer position is proposed.The initial ratio of the converter transformer is optimized.The effects of the fixed-tap changer position control on the control angle,reactive power compensation,and commutation failure are analyzed.The new control method allows a DC system to operate at a large angle and increase the additional reactive power loss while improving the commutation security margin.Steady-state and electromagnetic transient simulations in the CIGRE test system verify the validity of the method proposed in this paper and the correctness of the analysis conclusions.展开更多
AC / DC converter is a kind of devices applicable to reactive power compensation. Three parameters including losses, Total Harmonic Distortion （THD） and compensation capacity have important role in designing procedu...AC / DC converter is a kind of devices applicable to reactive power compensation. Three parameters including losses, Total Harmonic Distortion （THD） and compensation capacity have important role in designing procedure that these parameters are affected by the firing angle. Consideration trade of between these parameters can cause be selected suitable firing angle for optimal working of the compensator. In this paper is defined an objective function which includes the above parameters. This objective function is optimized through appropriate weighting factor for any parameters and the optimal firing angle will be obtained. So, the mention parameters can be selected optimally.展开更多
The mitigation of commutation failure(CF)depends on the accuracy of CF prediction.In terms of the large error of the existing extinction angle(EA)calculation during the fault transient period,a method for CF predictio...The mitigation of commutation failure(CF)depends on the accuracy of CF prediction.In terms of the large error of the existing extinction angle(EA)calculation during the fault transient period,a method for CF prediction and mitigation is proposed.Variations in both DC current and overlap angle(OA)are considered in the proposed method to predict the EA rapidly.In addition,variations in critical EA and the effect of firing angle(FA)on both DC current and OA are considered in the proposed method to obtain the accurate FA order for the control system.The proposed method can achieve good performance in terms of CF mitigation and reduce reactive consumption at the inverter side when a fault occurs.Simulation results based on the PSCAD/EMTDC show that the proposed method predicts CF rapidly and exhibits good performance in terms of CF mitigation.展开更多
基金an independent research project from the Shandong Electric Power Research Institute,“Research on the control method of DC power under fixed converter transformer tap-changer position”(ZY-2020-01)Based on the achievement,a national invention patent(No.2020112240143)has been applied.
文摘Intermittent new energy delivery requires increasing the flexibility of ultra-high voltage direct current(DC)power adjustment.Based on a converter steady-state model and a DC power model,the control angle constraints of a converter valve are relaxed for power regulation.In this paper,a flexible DC power control method based on a fixed tap changer position is proposed.The initial ratio of the converter transformer is optimized.The effects of the fixed-tap changer position control on the control angle,reactive power compensation,and commutation failure are analyzed.The new control method allows a DC system to operate at a large angle and increase the additional reactive power loss while improving the commutation security margin.Steady-state and electromagnetic transient simulations in the CIGRE test system verify the validity of the method proposed in this paper and the correctness of the analysis conclusions.
文摘AC / DC converter is a kind of devices applicable to reactive power compensation. Three parameters including losses, Total Harmonic Distortion （THD） and compensation capacity have important role in designing procedure that these parameters are affected by the firing angle. Consideration trade of between these parameters can cause be selected suitable firing angle for optimal working of the compensator. In this paper is defined an objective function which includes the above parameters. This objective function is optimized through appropriate weighting factor for any parameters and the optimal firing angle will be obtained. So, the mention parameters can be selected optimally.
基金supported by the National Natural Science Foundation of China(No.51907058)Project of Hunan Power Co.,Ltd.of the State Grid Corporation of China(No.SGTYHT/18-JS-206)Natural Science Foundation of Hunan Province(No.2020JJ5081)。
文摘The mitigation of commutation failure(CF)depends on the accuracy of CF prediction.In terms of the large error of the existing extinction angle(EA)calculation during the fault transient period,a method for CF prediction and mitigation is proposed.Variations in both DC current and overlap angle(OA)are considered in the proposed method to predict the EA rapidly.In addition,variations in critical EA and the effect of firing angle(FA)on both DC current and OA are considered in the proposed method to obtain the accurate FA order for the control system.The proposed method can achieve good performance in terms of CF mitigation and reduce reactive consumption at the inverter side when a fault occurs.Simulation results based on the PSCAD/EMTDC show that the proposed method predicts CF rapidly and exhibits good performance in terms of CF mitigation.
