Reliability level of HVDC power transmission systems becomes an important factor impacting the entire power grid.The author analyzes the reliability of HVDC power transmission systems owned by SGCC since 2003 in respe...Reliability level of HVDC power transmission systems becomes an important factor impacting the entire power grid.The author analyzes the reliability of HVDC power transmission systems owned by SGCC since 2003 in respect of forced outage times,forced energy unavailability,scheduled energy unavailability and energy utilization eff iciency.The results show that the reliability level of HVDC power transmission systems owned by SGCC is improving.By analyzing different reliability indices of HVDC power transmission system,the maximum asset benef its of power grid can be achieved through building a scientif ic and reasonable reliability evaluation system.展开更多
Recently, introduction of renewable energy sources like wind power generation and photovoltaic power generation has been increasing from the viewpoint of environmental problems. However, renewable energy power supplie...Recently, introduction of renewable energy sources like wind power generation and photovoltaic power generation has been increasing from the viewpoint of environmental problems. However, renewable energy power supplies have unstable output due to the influence of weather conditions such as wind speed variations, which may cause fluctuations of voltage and frequency in the power system. This paper proposes fuzzy PD based virtual inertia control system to decrease frequency fluctuations in power system caused by fluctuating output of renewable energy sources. The proposed new method is based on the coordinated control of HVDC interconnection line and battery, and energy balancing control is also incorporated in it. Finally, it is concluded that the proposed system is very effective for suppressing the frequency fluctuations of the power system due to the large-scale wind power generation and solar power generation and also for keeping the energy balancing in the HVDC transmission line.展开更多
Power sharing among multiterminal high voltage direct current terminals(MT-HVDC)is mainly developed based on a priority or sequential manners,which uses to prevent the problem of overloading due to a predefined contro...Power sharing among multiterminal high voltage direct current terminals(MT-HVDC)is mainly developed based on a priority or sequential manners,which uses to prevent the problem of overloading due to a predefined controller coefficient.Furthermore,fixed power sharing control also suffers from an inability to identify power availability at a rectification station.There is a need for a controller that ensures an efficient power sharing among the MT-HVDC terminals,prevents the possibility of overloading,and utilizes the available power sharing.A new adaptive wireless control for active power sharing among multiterminal(MT-HVDC)systems,including power availability and power management policy,is proposed in this paper.The proposed control strategy solves these issues and,this proposed controller strategy is a generic method that can be applied for unlimited number of converter stations.The rational of this proposed controller is to increase the system reliability by avoiding the necessity of fast communication links.The test system in this paper consists of four converter stations based on three phase-two AC voltage levels.The proposed control strategy for a multiterminal HVDC system is conducted in the power systems computer aided design/electromagnetic transient design and control(PSCAD/EMTDC)simulation environment.The simulation results significantly show the flexibility and usefulness of the proposed power sharing control provided by the new adaptive wireless method.展开更多
Renewable energy transmission by high-voltage direct current(HVDC)has attracted increasing attention for the development and utilization of large-scale renewable energy under the Carbon Peak and Carbon Neutrality Stra...Renewable energy transmission by high-voltage direct current(HVDC)has attracted increasing attention for the development and utilization of large-scale renewable energy under the Carbon Peak and Carbon Neutrality Strategy in China.High-penetration power electronic systems(HPPESs)have gradually formed at the sending end of HVDC transmission.The operation of such systems has undergone profound changes compared with traditional power systems dominated by synchronous generators.New stability issues,such as broadband oscillation and transient over-voltage,have emerged,causing tripping accidents in large-scale renewable energy plants.The analysis methods and design principles of traditional power systems are no longer suitable for HPPESs.In this paper,the mechanisms of broadband oscillation and transient over-voltage are revealed,and analytical methods are proposed for HPPESs,including small-signal impedance analysis and electromagnetic transient simulation.Validation of the theoretical research has been accomplished through its application in several practical projects in north,northwest,and northeast region of China.Finally,suggestions for the construction and operation of the future renewable-energy-dominated power system are put forward.展开更多
随着近年来高压直流输电的快速发展,换流变压器有载分接开关频繁动作导致故障数量明显增加,直接影响了直流工程的可靠性与电网的安全运行。运用(modular multilevel converter,MMC)模块化多电平可控电压源技术和基本原理,提出了一种新...随着近年来高压直流输电的快速发展,换流变压器有载分接开关频繁动作导致故障数量明显增加,直接影响了直流工程的可靠性与电网的安全运行。运用(modular multilevel converter,MMC)模块化多电平可控电压源技术和基本原理,提出了一种新型具备有载调压功能的(line commutated converter based high voltage direct current,LCCHVDC)直流输电的拓扑结构和控制策略,实现了对电网侧电压的补偿,当交流母线电压降低时,无需调节变压器分接开关而维持阀侧电压在额定值水平,大大降低了分接开关的动作次数,提高了工程运行的可靠性。以CIGRE直流输电标准模型为算例,分析了提电压补偿在传统LCC-HVDC直流输电系统中应用的机理,验证了该控制策略的正确性和有效性。展开更多
模块化多电平电压源换流器高压直流输电(modular multilevel converter high voltage direct current,MMC-HVDC)技术是一种新型的电压源换流器直流输电技术。计及交流系统与换流站交换功率的数学关系,应用图解法分析了交流电网强度对MMC...模块化多电平电压源换流器高压直流输电(modular multilevel converter high voltage direct current,MMC-HVDC)技术是一种新型的电压源换流器直流输电技术。计及交流系统与换流站交换功率的数学关系,应用图解法分析了交流电网强度对MMC-HVDC系统稳态特性的影响,同时分析了接入强、弱交流电网的直流系统在不同控制方式下设定值改变时的暂态特性。结果表明功率圆的大小及其相对位置可以直观地反映交流电网的强弱,以及控制方式对MMC-HVDC系统运行特性的影响。最后PSCAD电磁暂态仿真验证了上述结论的正确性。展开更多
换相失败在高压直流输电系统(high voltage direct current power transmission,HVDC)中时有发生。针对现有自校正控制器依赖参考模型的局限性和模糊自适应PI控制器运算复杂且需先判断出故障类型再选择最优控制方式的局限性,采用一种基...换相失败在高压直流输电系统(high voltage direct current power transmission,HVDC)中时有发生。针对现有自校正控制器依赖参考模型的局限性和模糊自适应PI控制器运算复杂且需先判断出故障类型再选择最优控制方式的局限性,采用一种基于比例积分运算式离散化推导的自适应PI控制器,提出抑制HVDC系统换相失败的自适应PI控制方法。通过对原始CIGRE HVDC标准模型和含直流电流预测控制和换相失败预防控制(commutation failure prevention,CFPREV)模块的CIGRE HVDC系统的仿真,结果表明:在40组测试中,有37组的临界换相失败电抗得到降低。相比现有系统中参数固定的PI控制器,该自适应PI控制方法能够有效抑制HVDC系统的换相失败。展开更多
为提高风电场交直流混合输电并网的系统性能,提出一种更加灵活的电压源换流器高压直流(voltage source converter based high voltage direct current,VSC-HVDC)控制策略。对于风电场侧电压源换流器,设计了一种新的交流电压–功角控制...为提高风电场交直流混合输电并网的系统性能,提出一种更加灵活的电压源换流器高压直流(voltage source converter based high voltage direct current,VSC-HVDC)控制策略。对于风电场侧电压源换流器,设计了一种新的交流电压–功角控制方法。对于交直流混合输电模式,该方法通过调节风电场交流母线电压与电压源换流器输出电压间的功角来实现定有功功率控制。对于纯柔性直流输电模式,风电场交流母线电压自动被调节为具有恒幅恒频的交流电压,实现了对波动风电的同步输送。该方法中输电模式的变化无需切换控制;另外,通过附加电流高通滤波器增强了对系统谐振的阻尼作用。对电网侧电压源换流器,采用一种新的直接电流矢量控制,使直流电压稳定在参考值上。运用PSCAD/EMTDC仿真软件对分别接入笼型感应发电机(squirrel cage induction generator,SCIG)风电场和双馈感应发电机(doubly fed induction generator,DFIG)风电场的交直流混合输电系统建模仿真。一系列运行条件下的仿真结果验证了控制方法的有效性与可行性。展开更多
文摘Reliability level of HVDC power transmission systems becomes an important factor impacting the entire power grid.The author analyzes the reliability of HVDC power transmission systems owned by SGCC since 2003 in respect of forced outage times,forced energy unavailability,scheduled energy unavailability and energy utilization eff iciency.The results show that the reliability level of HVDC power transmission systems owned by SGCC is improving.By analyzing different reliability indices of HVDC power transmission system,the maximum asset benef its of power grid can be achieved through building a scientif ic and reasonable reliability evaluation system.
文摘Recently, introduction of renewable energy sources like wind power generation and photovoltaic power generation has been increasing from the viewpoint of environmental problems. However, renewable energy power supplies have unstable output due to the influence of weather conditions such as wind speed variations, which may cause fluctuations of voltage and frequency in the power system. This paper proposes fuzzy PD based virtual inertia control system to decrease frequency fluctuations in power system caused by fluctuating output of renewable energy sources. The proposed new method is based on the coordinated control of HVDC interconnection line and battery, and energy balancing control is also incorporated in it. Finally, it is concluded that the proposed system is very effective for suppressing the frequency fluctuations of the power system due to the large-scale wind power generation and solar power generation and also for keeping the energy balancing in the HVDC transmission line.
文摘Power sharing among multiterminal high voltage direct current terminals(MT-HVDC)is mainly developed based on a priority or sequential manners,which uses to prevent the problem of overloading due to a predefined controller coefficient.Furthermore,fixed power sharing control also suffers from an inability to identify power availability at a rectification station.There is a need for a controller that ensures an efficient power sharing among the MT-HVDC terminals,prevents the possibility of overloading,and utilizes the available power sharing.A new adaptive wireless control for active power sharing among multiterminal(MT-HVDC)systems,including power availability and power management policy,is proposed in this paper.The proposed control strategy solves these issues and,this proposed controller strategy is a generic method that can be applied for unlimited number of converter stations.The rational of this proposed controller is to increase the system reliability by avoiding the necessity of fast communication links.The test system in this paper consists of four converter stations based on three phase-two AC voltage levels.The proposed control strategy for a multiterminal HVDC system is conducted in the power systems computer aided design/electromagnetic transient design and control(PSCAD/EMTDC)simulation environment.The simulation results significantly show the flexibility and usefulness of the proposed power sharing control provided by the new adaptive wireless method.
基金This work is funded by National Key Research and Development Program of China(2021 YFB2400500).The authors would like to thank Guoqing He,Haijiao Wang,Yuntao Xiao,and Yuqi Duan for their contributions in research review,field test verification,and data analysis.
文摘Renewable energy transmission by high-voltage direct current(HVDC)has attracted increasing attention for the development and utilization of large-scale renewable energy under the Carbon Peak and Carbon Neutrality Strategy in China.High-penetration power electronic systems(HPPESs)have gradually formed at the sending end of HVDC transmission.The operation of such systems has undergone profound changes compared with traditional power systems dominated by synchronous generators.New stability issues,such as broadband oscillation and transient over-voltage,have emerged,causing tripping accidents in large-scale renewable energy plants.The analysis methods and design principles of traditional power systems are no longer suitable for HPPESs.In this paper,the mechanisms of broadband oscillation and transient over-voltage are revealed,and analytical methods are proposed for HPPESs,including small-signal impedance analysis and electromagnetic transient simulation.Validation of the theoretical research has been accomplished through its application in several practical projects in north,northwest,and northeast region of China.Finally,suggestions for the construction and operation of the future renewable-energy-dominated power system are put forward.
文摘随着近年来高压直流输电的快速发展,换流变压器有载分接开关频繁动作导致故障数量明显增加,直接影响了直流工程的可靠性与电网的安全运行。运用(modular multilevel converter,MMC)模块化多电平可控电压源技术和基本原理,提出了一种新型具备有载调压功能的(line commutated converter based high voltage direct current,LCCHVDC)直流输电的拓扑结构和控制策略,实现了对电网侧电压的补偿,当交流母线电压降低时,无需调节变压器分接开关而维持阀侧电压在额定值水平,大大降低了分接开关的动作次数,提高了工程运行的可靠性。以CIGRE直流输电标准模型为算例,分析了提电压补偿在传统LCC-HVDC直流输电系统中应用的机理,验证了该控制策略的正确性和有效性。
文摘模块化多电平电压源换流器高压直流输电(modular multilevel converter high voltage direct current,MMC-HVDC)技术是一种新型的电压源换流器直流输电技术。计及交流系统与换流站交换功率的数学关系,应用图解法分析了交流电网强度对MMC-HVDC系统稳态特性的影响,同时分析了接入强、弱交流电网的直流系统在不同控制方式下设定值改变时的暂态特性。结果表明功率圆的大小及其相对位置可以直观地反映交流电网的强弱,以及控制方式对MMC-HVDC系统运行特性的影响。最后PSCAD电磁暂态仿真验证了上述结论的正确性。
文摘换相失败在高压直流输电系统(high voltage direct current power transmission,HVDC)中时有发生。针对现有自校正控制器依赖参考模型的局限性和模糊自适应PI控制器运算复杂且需先判断出故障类型再选择最优控制方式的局限性,采用一种基于比例积分运算式离散化推导的自适应PI控制器,提出抑制HVDC系统换相失败的自适应PI控制方法。通过对原始CIGRE HVDC标准模型和含直流电流预测控制和换相失败预防控制(commutation failure prevention,CFPREV)模块的CIGRE HVDC系统的仿真,结果表明:在40组测试中,有37组的临界换相失败电抗得到降低。相比现有系统中参数固定的PI控制器,该自适应PI控制方法能够有效抑制HVDC系统的换相失败。
文摘为提高风电场交直流混合输电并网的系统性能,提出一种更加灵活的电压源换流器高压直流(voltage source converter based high voltage direct current,VSC-HVDC)控制策略。对于风电场侧电压源换流器,设计了一种新的交流电压–功角控制方法。对于交直流混合输电模式,该方法通过调节风电场交流母线电压与电压源换流器输出电压间的功角来实现定有功功率控制。对于纯柔性直流输电模式,风电场交流母线电压自动被调节为具有恒幅恒频的交流电压,实现了对波动风电的同步输送。该方法中输电模式的变化无需切换控制;另外,通过附加电流高通滤波器增强了对系统谐振的阻尼作用。对电网侧电压源换流器,采用一种新的直接电流矢量控制,使直流电压稳定在参考值上。运用PSCAD/EMTDC仿真软件对分别接入笼型感应发电机(squirrel cage induction generator,SCIG)风电场和双馈感应发电机(doubly fed induction generator,DFIG)风电场的交直流混合输电系统建模仿真。一系列运行条件下的仿真结果验证了控制方法的有效性与可行性。
