交直流系统次同步振荡建模与机理分析
发布时间：2018-10-18 16:42
【摘要】：随着“西电东送”发展战略的逐步实施,大容量远距离输电已经成为我国电网的重要特征。为了提高长距离输电线路的输送能力,我国电网广泛采用了串联补偿和高压直流输电技术。然而,由串联补偿和高压直流输电引起的次同步振荡风险成为电网安全稳定运行面临的重要问题。本论文对交直流互联电力系统次同步振荡的建模与机理进行了深入研究,主要工作包括： (1)提出了一种应用于次同步振荡分析的汽轮发电机组轴系扭振机械阻尼系数在线测量解耦计算的方法。揭示了并列运行的同型机组发生次同步振荡时存在的同相振荡模式和反相振荡模式现象,并阐明了反相振荡模式的力矩耦合关系。在此基础上,利用反相振荡模式下汽轮发电机组与电网解耦的特性,提出了一种通过主动激发反相振荡模式实现轴系扭振机械阻尼系数在线测量与解耦计算的方法。该方法具有严格的理论基础,且易于现场实施,并在实际系统中得到成功应用,有效的解决了轴系扭振机械阻尼系数在线测量的难题。 (2)阐明了直流输电系统逆变侧故障引发汽轮发电机组次同步振荡的原因,突破了原有仅认为整流侧故障才引发机组次同步振荡的认识。论文分析了由于逆变侧交流系统扰动引起直流输电系统换相失败,进一步导致整流侧汽轮发电机组次同步振荡的物理过程,理论分析结果与实际录波数据一致,验证了理论分析的正确性。 (3)完成了具有相近扭振频率的多机系统的次同步振荡机理和特性分析。揭示了在具有相近扭振频率的多机系统中,同时存在机网振荡模式和机组间振荡模式,并分析对比了两种不同振荡模式的阻尼特征。分析了决定机组间振荡模式幅值大小的因素及其对轴系扭振严重程度的影响。据此对在实际系统中发生的次同步振荡现象给出了合理、清晰的解释。 (4)实现了应用于次同步振荡仿真的轴系变机械阻尼建模方法。该方法将轴系扭振机械阻尼系数作为变量代入转子运动方程,实现了轴系扭振机械阻尼系数在仿真过程中可以连续变化的功能,并在实时数字仿真器RTDS上实现。实现了一种发电机转速脉冲信号输出建模方法。该方法可以模拟与实际现场经由发电机轴系齿盘原理一样的转速脉冲输出,并具有同样的动态特性。进一步针对某大型煤电基地经交直流外送的次同步振荡问题,建立仿真模型,并开展相关次同步振荡机理与特性分析,分析结论与现场实际情况吻合。
[Abstract]:With the gradual implementation of the development strategy of "power transmission from west to east", large capacity and long distance transmission has become an important feature of power grid in China. In order to improve the transmission capacity of long distance transmission lines, series compensation and high voltage direct current (HVDC) transmission technology are widely used in Chinese power grids. However, the risk of sub-synchronous oscillation caused by series compensation and HVDC transmission has become an important problem in the safe and stable operation of power grid. In this paper, the modeling and mechanism of subsynchronous oscillation in AC / DC interconnected power system are studied. The main works are as follows: (1) A decoupling calculation method for on-line measurement of torsional vibration mechanical damping coefficient of turbogenerator shaft system is proposed. The phenomenon of in-phase oscillation mode and anti-phase oscillation mode when the sub-synchronous oscillation occurs in the parallel operation of the same type unit is revealed and the torque coupling relation of the reverse phase oscillation mode is clarified. On this basis, a method of on-line measurement and decoupling calculation of mechanical damping coefficient of torsional vibration of shafting is proposed by using the decoupling characteristic of turbine-generator set and power grid under inverse oscillation mode. The method has a strict theoretical foundation and is easy to be implemented on the spot, and it has been successfully applied in the practical system. The problem of on-line measurement of mechanical damping coefficient of shaft torsional vibration is effectively solved. (2) the cause of subsynchronous oscillation of turbogenerator set caused by inverter side fault of HVDC transmission system is explained. It breaks through the original understanding that only rectifier side fault causes unit sub-synchronous oscillation. The paper analyzes the physical process of the subsynchronous oscillation of the rectifier turbine-generator set caused by the commutation failure of the DC transmission system caused by the disturbance of the inverter side AC system. The theoretical analysis results are consistent with the actual recorded data. The correctness of the theoretical analysis is verified. (3) the sub-synchronous oscillation mechanism and characteristic analysis of multi-machine systems with similar torsional frequencies are completed. In the multi-machine system with similar torsional vibration frequency, there exists both the grid oscillation mode and the inter-unit oscillation mode, and the damping characteristics of the two different oscillation modes are analyzed and compared. The factors that determine the amplitude of oscillation mode between units and its influence on the severity of torsional vibration of shafting are analyzed. A reasonable and clear explanation is given for the phenomenon of sub-synchronous oscillation occurring in practical system. (4) the method of shafting variable mechanical damping modeling is realized for the simulation of sub-synchronous oscillation. In this method, the mechanical damping coefficient of shafting torsional vibration is substituted into the rotor equation of motion as a variable, and the function of continuous variation of mechanical damping coefficient of shafting torsional vibration is realized in the simulation process, and it is realized on the real-time digital simulator RTDS. A modeling method of generator speed pulse signal output is implemented. This method can simulate the same rotating speed pulse output as the actual field through the generator gear disk, and has the same dynamic characteristics. A simulation model is established to solve the sub-synchronous oscillation problem of a large coal power station through AC / DC transmission. The mechanism and characteristics of the sub-synchronous oscillation are analyzed. The analysis results are in agreement with the actual situation in the field.
【学位授予单位】：华北电力大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TM721.1
本文编号：2279731
[Abstract]:With the gradual implementation of the development strategy of "power transmission from west to east", large capacity and long distance transmission has become an important feature of power grid in China. In order to improve the transmission capacity of long distance transmission lines, series compensation and high voltage direct current (HVDC) transmission technology are widely used in Chinese power grids. However, the risk of sub-synchronous oscillation caused by series compensation and HVDC transmission has become an important problem in the safe and stable operation of power grid. In this paper, the modeling and mechanism of subsynchronous oscillation in AC / DC interconnected power system are studied. The main works are as follows: (1) A decoupling calculation method for on-line measurement of torsional vibration mechanical damping coefficient of turbogenerator shaft system is proposed. The phenomenon of in-phase oscillation mode and anti-phase oscillation mode when the sub-synchronous oscillation occurs in the parallel operation of the same type unit is revealed and the torque coupling relation of the reverse phase oscillation mode is clarified. On this basis, a method of on-line measurement and decoupling calculation of mechanical damping coefficient of torsional vibration of shafting is proposed by using the decoupling characteristic of turbine-generator set and power grid under inverse oscillation mode. The method has a strict theoretical foundation and is easy to be implemented on the spot, and it has been successfully applied in the practical system. The problem of on-line measurement of mechanical damping coefficient of shaft torsional vibration is effectively solved. (2) the cause of subsynchronous oscillation of turbogenerator set caused by inverter side fault of HVDC transmission system is explained. It breaks through the original understanding that only rectifier side fault causes unit sub-synchronous oscillation. The paper analyzes the physical process of the subsynchronous oscillation of the rectifier turbine-generator set caused by the commutation failure of the DC transmission system caused by the disturbance of the inverter side AC system. The theoretical analysis results are consistent with the actual recorded data. The correctness of the theoretical analysis is verified. (3) the sub-synchronous oscillation mechanism and characteristic analysis of multi-machine systems with similar torsional frequencies are completed. In the multi-machine system with similar torsional vibration frequency, there exists both the grid oscillation mode and the inter-unit oscillation mode, and the damping characteristics of the two different oscillation modes are analyzed and compared. The factors that determine the amplitude of oscillation mode between units and its influence on the severity of torsional vibration of shafting are analyzed. A reasonable and clear explanation is given for the phenomenon of sub-synchronous oscillation occurring in practical system. (4) the method of shafting variable mechanical damping modeling is realized for the simulation of sub-synchronous oscillation. In this method, the mechanical damping coefficient of shafting torsional vibration is substituted into the rotor equation of motion as a variable, and the function of continuous variation of mechanical damping coefficient of shafting torsional vibration is realized in the simulation process, and it is realized on the real-time digital simulator RTDS. A modeling method of generator speed pulse signal output is implemented. This method can simulate the same rotating speed pulse output as the actual field through the generator gear disk, and has the same dynamic characteristics. A simulation model is established to solve the sub-synchronous oscillation problem of a large coal power station through AC / DC transmission. The mechanism and characteristics of the sub-synchronous oscillation are analyzed. The analysis results are in agreement with the actual situation in the field.
【学位授予单位】：华北电力大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TM721.1
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