交直流系統(tǒng)次同步振蕩建模與機理分析
發(fā)布時間：2018-10-18 16:42
【摘要】：隨著“西電東送”發(fā)展戰(zhàn)略的逐步實施,大容量遠距離輸電已經成為我國電網的重要特征。為了提高長距離輸電線路的輸送能力,我國電網廣泛采用了串聯(lián)補償和高壓直流輸電技術。然而,由串聯(lián)補償和高壓直流輸電引起的次同步振蕩風險成為電網安全穩(wěn)定運行面臨的重要問題。本論文對交直流互聯(lián)電力系統(tǒng)次同步振蕩的建模與機理進行了深入研究,主要工作包括： (1)提出了一種應用于次同步振蕩分析的汽輪發(fā)電機組軸系扭振機械阻尼系數在線測量解耦計算的方法。揭示了并列運行的同型機組發(fā)生次同步振蕩時存在的同相振蕩模式和反相振蕩模式現象,并闡明了反相振蕩模式的力矩耦合關系。在此基礎上,利用反相振蕩模式下汽輪發(fā)電機組與電網解耦的特性,提出了一種通過主動激發(fā)反相振蕩模式實現軸系扭振機械阻尼系數在線測量與解耦計算的方法。該方法具有嚴格的理論基礎,且易于現場實施,并在實際系統(tǒng)中得到成功應用,有效的解決了軸系扭振機械阻尼系數在線測量的難題。 (2)闡明了直流輸電系統(tǒng)逆變側故障引發(fā)汽輪發(fā)電機組次同步振蕩的原因,突破了原有僅認為整流側故障才引發(fā)機組次同步振蕩的認識。論文分析了由于逆變側交流系統(tǒng)擾動引起直流輸電系統(tǒng)換相失敗,進一步導致整流側汽輪發(fā)電機組次同步振蕩的物理過程,理論分析結果與實際錄波數據一致,驗證了理論分析的正確性。 (3)完成了具有相近扭振頻率的多機系統(tǒng)的次同步振蕩機理和特性分析。揭示了在具有相近扭振頻率的多機系統(tǒng)中,同時存在機網振蕩模式和機組間振蕩模式,并分析對比了兩種不同振蕩模式的阻尼特征。分析了決定機組間振蕩模式幅值大小的因素及其對軸系扭振嚴重程度的影響。據此對在實際系統(tǒng)中發(fā)生的次同步振蕩現象給出了合理、清晰的解釋。 (4)實現了應用于次同步振蕩仿真的軸系變機械阻尼建模方法。該方法將軸系扭振機械阻尼系數作為變量代入轉子運動方程,實現了軸系扭振機械阻尼系數在仿真過程中可以連續(xù)變化的功能,并在實時數字仿真器RTDS上實現。實現了一種發(fā)電機轉速脈沖信號輸出建模方法。該方法可以模擬與實際現場經由發(fā)電機軸系齒盤原理一樣的轉速脈沖輸出,并具有同樣的動態(tài)特性。進一步針對某大型煤電基地經交直流外送的次同步振蕩問題,建立仿真模型,并開展相關次同步振蕩機理與特性分析,分析結論與現場實際情況吻合。
[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.
【學位授予單位】：華北電力大學
【學位級別】：博士
【學位授予年份】：2014
【分類號】：TM721.1
本文編號：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.
【學位授予單位】：華北電力大學
【學位級別】：博士
【學位授予年份】：2014
【分類號】：TM721.1
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