新一代大容量调相机已成功应用于特高压直流送、受端换流站。新一代调相机属于同步电动机,挂网运行时,消耗电网能量以维持额定转速运行;启动过程中,采用静止变频器SFC(Static Frequency Converter)实现0转速至1.05倍额定转速全速范围内...新一代大容量调相机已成功应用于特高压直流送、受端换流站。新一代调相机属于同步电动机,挂网运行时,消耗电网能量以维持额定转速运行;启动过程中,采用静止变频器SFC(Static Frequency Converter)实现0转速至1.05倍额定转速全速范围内升速。本文基于国网扎鲁特换流站调相机本体电气拓扑结构,研究了新一代调相机的启动控制策略,详细分析了在调相机启动过程中关联开关变位时序。同时,研制PLC实现进口SFC一拖二功能。最后,基于扎鲁特站现场调相机实际启动情况,验证本文提出的新一代大容量调相机启动控制策略的正确性。展开更多
Transient electromagnetic method(TEM)has been widely used in the field of medium and shallow underground detection due to its high detection efficiency and large detection depth.However,due to the long turn-off time o...Transient electromagnetic method(TEM)has been widely used in the field of medium and shallow underground detection due to its high detection efficiency and large detection depth.However,due to the long turn-off time of the transmitting current caused by the inductive characteristics of the transmitting coil,the early signals will be overwhelmed by primary field.Since the early signals contain most of shallow geological signals,it is necessary to reduce the long turn-off time to get shallow layer signal.Due to lack of a reliable and effective clamping method for high-power transmission at present,we design a TEM transmitter fast turn-off circuit,combining self-resonant zero-voltage switching technology with the corresponding timing control circuit to solve this problem effectively.A transient electromagnetic transmitter based on self-resonant constant voltage clamping technology was fabricated to charge the clamping capacitor.The rated transmitting current of the transmitter is 20 A,and the turn-off time is continuously adjustable from 550-50μs.Moreover,the current drop process is approximately linear rather than exponential attenuation.Compared with the existing clamping methods,the proposed clamping method solves the problems that transient voltage suppressor(TVS)clamping cannot be used in high-power occasions and has a high failure rate.It also solves the problem of long pre-charge time in traditional capacitor clamping methods due to insufficient inductance of the small size transmitting coil.The proposed method can provide a reference for fast shutdown of large current.展开更多
In medium voltage-high power(MV-HP)applications,the high switching frequency of power converter will result in unnecessary energy losses,which directly affect efficiency.To resolve this issue,a novel finite control se...In medium voltage-high power(MV-HP)applications,the high switching frequency of power converter will result in unnecessary energy losses,which directly affect efficiency.To resolve this issue,a novel finite control set-model predictive control(FCS-MPC)with low switching frequency for three-level neutral point clamped-active front-end converters(NPC-AFEs)is proposed.With this approach,the prediction model of three-level NPC-AFEs is established inα-βreference frame,and the control objective of low average switching frequency is introduced into a cost function.The proposed method not only achieves the desired control performance under low switching frequency,but also performs the efficient operation for the three-level NPC-AFEs.The simulation results are provided to verify the effectiveness of proposed control scheme.展开更多
文摘新一代大容量调相机已成功应用于特高压直流送、受端换流站。新一代调相机属于同步电动机,挂网运行时,消耗电网能量以维持额定转速运行;启动过程中,采用静止变频器SFC(Static Frequency Converter)实现0转速至1.05倍额定转速全速范围内升速。本文基于国网扎鲁特换流站调相机本体电气拓扑结构,研究了新一代调相机的启动控制策略,详细分析了在调相机启动过程中关联开关变位时序。同时,研制PLC实现进口SFC一拖二功能。最后,基于扎鲁特站现场调相机实际启动情况,验证本文提出的新一代大容量调相机启动控制策略的正确性。
文摘Transient electromagnetic method(TEM)has been widely used in the field of medium and shallow underground detection due to its high detection efficiency and large detection depth.However,due to the long turn-off time of the transmitting current caused by the inductive characteristics of the transmitting coil,the early signals will be overwhelmed by primary field.Since the early signals contain most of shallow geological signals,it is necessary to reduce the long turn-off time to get shallow layer signal.Due to lack of a reliable and effective clamping method for high-power transmission at present,we design a TEM transmitter fast turn-off circuit,combining self-resonant zero-voltage switching technology with the corresponding timing control circuit to solve this problem effectively.A transient electromagnetic transmitter based on self-resonant constant voltage clamping technology was fabricated to charge the clamping capacitor.The rated transmitting current of the transmitter is 20 A,and the turn-off time is continuously adjustable from 550-50μs.Moreover,the current drop process is approximately linear rather than exponential attenuation.Compared with the existing clamping methods,the proposed clamping method solves the problems that transient voltage suppressor(TVS)clamping cannot be used in high-power occasions and has a high failure rate.It also solves the problem of long pre-charge time in traditional capacitor clamping methods due to insufficient inductance of the small size transmitting coil.The proposed method can provide a reference for fast shutdown of large current.
文摘In medium voltage-high power(MV-HP)applications,the high switching frequency of power converter will result in unnecessary energy losses,which directly affect efficiency.To resolve this issue,a novel finite control set-model predictive control(FCS-MPC)with low switching frequency for three-level neutral point clamped-active front-end converters(NPC-AFEs)is proposed.With this approach,the prediction model of three-level NPC-AFEs is established inα-βreference frame,and the control objective of low average switching frequency is introduced into a cost function.The proposed method not only achieves the desired control performance under low switching frequency,but also performs the efficient operation for the three-level NPC-AFEs.The simulation results are provided to verify the effectiveness of proposed control scheme.
