Chongqing KK QIANWEI Wind Power Equipment Co.

Yubei District, China

Chongqing KK QIANWEI Wind Power Equipment Co.

Yubei District, China

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Li H.,Chongqing University | Hu Y.,Chongqing University | Li Y.,Chongqing University | Yang D.,Chongqing University | And 3 more authors.
Dianli Zidonghua Shebei/Electric Power Automation Equipment | Year: 2015

A method of gradual deterioration probability analysis based on the temperature characteristic parameters is proposed for the critical components of WTGS (Wind Turbine Generator System) to grasp their deterioration level and tendency. Since the fixed threshold may not be used to accurately determine the degradation degree, the concept of data fitting and turbine grouping based on the temperature characteristic parameters and rotation speeds of the critical components is proposed to set the dynamic thresholds for the upper and lower limits of degradation degree. In order to include the effects of operating condition and duration on the degradation degree, the nonparametric kernel density estimation method is applied to build the probability density function of degradation degree for the critical components and a method of gradual deterioration probability analysis is presented for different monitoring cycles. With the rear bearing of a wind-turbine generator in an actual wind farm as an example, the proposed dynamic threshold method and probability analysis method are verified based on the historical monitoring data of its gradual deterioration. Compared with the fixed threshold method, the proposed dynamic threshold method can more accurately determine the degradation degree of components and more effectively analyze the deterioration tendency of critical components. © 2015, Electric Power Automation Equipment Press. All right reserved.


Hu Y.,Chongqing University | Li H.,Chongqing University | Liao X.,Chongqing University | Song E.,Chongqing University | And 2 more authors.
Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering | Year: 2016

In order to know about the remaining life of wind turbine bearings, the performance degradation model and real-time remaining life prediction method of wind turbine bearings were proposed based on temperature characteristic parameters. Firstly, because the uncertainty of wind speed and wind direction results in the temperature of wind turbine bearings in a wide range, by using the method of the moving average method, the relative temperature data of wind turbine bearings were smoothed, and the temperature trend data of wind turbine bearings were obtained. Secondly, considering the degradation speed of bearings change with the operational time and external uncertain factors, the performance degradation model was established based on the Wiener process, and the parameters of performance degradation model were obtained by using the method of maximum likelihood estimation. Thirdly, according to the failure principle of the first temperature monitoring value beyond the warning threshold, the remaining life prediction model of wind turbine bearings was established based on the inverse Gaussian distribution. Finally, taken as an example of the remaining life prediction of a practical generator rear bearing, the process of performance degradation and real-time remaining life prediction were demonstrated. By comparison with the practical remaining life, results show that the proposed model and prediction method is correct and effective. © 2016 Chin. Soc. for Elec. Eng.


Li H.,Chongqing University | Fu B.,Chongqing University | Yang C.,Chongqing University | Zhao B.,Chongqing University | Tang X.,Chongqing KK QIANWEI Wind Power Equipment Co.
Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering | Year: 2013

In order to make better use of energy storage system to reduce the fluctuation of active power for large-scale wind farm, this paper proposes the optimization power distribution control strategies of the multistage vanadium redox flow battery (VRB) storage. Firstly, based on the equivalent circuit of a VRB and by using the interface of the DC/AC converter cascade multiple bi-directional DC/DC converter, a vector control strategy of DC/AC converter is presented to keep the stable DC bus voltage, and a double closed loop control strategy of DC/DC converter is established to switch charge-discharge style as a constraint of state of charge (SOC) on a single VRB. Secondly, by taking SOC value of each battery as priority target selection of output power, and by using the limit of external terminal voltage as the constraint conditions for battery safety charging and discharging, an optimization power distribution strategy of the multistage VRB energy storage is proposed. Finally, as an example of two-stage VRB energy storage system with different SOC values, the smoothing results of wind power fluctuation and the operation performances of charge-discharge on every VRB unit are simulated under the wind speed variation, and the simulation results are compared by using the average distribution strategy of active power. the comparative results have shown that the proposed power optimization distribution control strategies for VRB storage system could better smooth wind power fluctuation, but also could further reduce the charging and discharging times of single VRB, and ensure the battery work in the more safe operation region.


Li H.,Chongqing University | Chen H.,Chongqing University | Yang C.,Chongqing University | Zhao B.,Chongqing University | Tang X.,Chongqing KK QIANWEI Wind Power Equipment Co.
Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering | Year: 2013

The grid integration of large scale wind power may increase the risks of inter-area low frequency, local power oscillations and the shaft torsion oscillation of the wind turbine. The paper studied the influence of the integration of doubly fed induction generator (DFIG)-based wind farms integration on the low frequency oscillation characteristics of the power system. In order to do small signal stability analysis, a detailed mathematical model was established by considering the effects of wind turbine drive drain, variable pitch control, dynamic models and control strategy of DFIG. By using modal analysis method low-frequency oscillation modes in an IEEE two-area four-machine power system with DFIG-based wind farm were investigated, and the results of the time-domain simulation demonstrated the validity and effectiveness of the model and the corresponding analysis. In the two cases of the constant and variable power flow, the characteristics of local oscillation modes, inter-area oscillation modes, and shaft torsional vibration modes were respectively analyzed under variable operational conditions, including different operation points, different integrated capacity of wind power and whether wind farm participates in reactive power dispatching. The results show that low-frequency oscillation characteristics are closely related to the variation of the power flow, the control strategy and the capacity of wind farm. A suitable coordinated control scheme of synchronous generators could improve the oscillation damping in the condition of constant power flow.


Li H.,Chongqing University | Chen H.,Chongqing University | Yang C.,Chongqing University | Zhao B.,Chongqing University | Tang X.,Chongqing KK QIANWEI Wind Power Equipment Co.
Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering | Year: 2013

Based on the theory analysis of the transient energy function, this paper proposed a fuzzy additional damping control strategy for a doubly-fed induction generator (DFIG) based wind farms. Firstly, by adjusting the active/reactive output power of the wind farm, a theoretically analysis was carried out to find that, the transient oscillation energy can be continuously reduced to suppress the inter-area low frequency oscillation. Secondly, on the basis of describing a conventional PSS additional damping control of DFIG wind farm, by judging the oscillation stage of the transient energy with the active power variation signal of transmission lines, an additional damping strategy with fuzzy control was proposed. Finally, to compare the three different control straties of fuzzy additional control, traditional PSS control and without any damping controller, the two-area four-machine IEEE power system integrated with a DFIG wind farm is taken as example, and the system dynamic performances were simulated under the operational conditions of 3-phase short-circuit of transmission lines and the small disturbance of active power on the traditional synchronous generator. The simulation results verify the effectiveness of the proposed fuzzy additional damping control strategies on the active/reactive power loop. Furthermore, besides the damping ability of the inter-area low frequency oscillation, the results also show that as with the reactive power loop with fuzzy additional damping control, it can also reduce the shaft torsional torque oscillation of the wind turbine drive train. © 2013 Chin. Soc. for Elec. Eng.


Li H.,Chongqing University | Fu B.,Chongqing University | Yang C.,Chongqing University | Zhao B.,Chongqing University | Tang X.,Chongqing KK QIANWEI Wind Power Equipment Co.
Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering | Year: 2012

In order to satisfy the testing requirements of the low voltage ride through (LVRT) of wind turbine generation system and the need for the electrical model conformance evaluation, a LVRT control strategy of doubly fed induction wind turbine generation system was proposed by considering the reactive current injected into the grid. Based on the description of the LVRT testing requirements and the control principle, the maximum limited reactive current expressions of the stator side of doubly fed induction generator (DFIG) and the grid side converter were derived, respectively. Then the effects of the voltage sag levels, the total output active power of DFIG on the limited reactive current were also investigated. Furthermore, the corresponding reactive current allocation algorithm, the improved control strategies of the active power and the reactive power for the LVRT operation were proposed. Finally, as an example of the factual 2 MW DFIG wind turbine generation system, the simulated comparison and the prototype testing for LVRT operational performances were investigated under the conditions of 5 m/s and 12 m/s wind speed, the grid voltage balancing drop to 20% and 50%, respectively. Compared with the traditional LVRT control method, the results have shown that DFIG can better meet the LVRT testing requirements by using the improved control strategy, the validity of this control strategy and the simulation models is further testified by the prototype testing results. © 2012 Chin. Soc. for Elec. Eng.


Li H.,Chongqing University | Chen H.,Chongqing University | Yang C.,Chongqing University | Zhao B.,Chongqing University | Tang X.,Chongqing KK Qianwei Wind Power Equipment Co.
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2012

From the viewpoint of damping the inter-area low frequency oscillation and decreasing the shaft torsion oscillation of the wind turbine drive train, an ancillary damping control strategy is proposed for wind farms with doubly-fed induction generators (DFIG). Firstly, the transient state models of DFIG considering the drive train shaft tensional flexibility and control strategies are presented. Secondly, ancillary damping control strategies considering the power signals in transmission lines are developed on the reactive power control loop. Finally, an example of two-area four-machine power system of IEEE integrated with wind farms with DFIG is presented, with three-phase short-circuit fault on the transmission lines and the small disturbance of active power on the synchronous generator, dynamic performances of additional damping control are simulated by using different gains on the active power loop and reactive power loop respectively. The simulation results show that the power oscillation in the transmission lines is reduced by using the ancillary damping control strategy on the active power loop and reactive power loop, and that the shaft torsion torque oscillation of the wind turbine drive train cannot be increased by the reactive power loop with this strategy. © 2012 State Grid Electric Power Research Institute Press.


Li H.,Chongqing University | Yang C.,Chongqing University | Zhao B.,Chongqing University | Tang X.-H.,Chongqing KK QIAN WEI Wind Power Equipment Co. | Zheng W.-Q.,Chongqing University
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2011

In order to better reflect the dynamic and transient characteristics of a gird-connected wind turbine generator system(WTGS), studies on the operational performances of a WTGS considering the pitch control system are proposed. Firstly, based on the principle of variable pitch control, the mathematical model of the pitch control system is established by taking a variable-frequency three-phase induction motor as the drive motor, and its control performance of the pitch angle is simulated. Secondly, combining with the variable pitch control system models considering the features of pitch drive motor, the dynamic mathematical models of a grid-connected wind turbine with a squirrel cage induction generator (SCIG) are presented. Finally, the dynamic performance of the grid-connected wind turbine with SCIG is simulated when the wind speed is below and over the rated wind speed, respectively. The results are also compared with that of without considering the characteristics of the pitch drive motor. The compared results have shown that the presented pitch control system can achieve accurate control of pitch angle. Compared with a model without consideration of the pitch-drive motor, the grid-connected WTGS model considering the pitch-drive motor characteristics can more actually reflect the dynamic operating characteristics of a wind turbine system, especially in the condition of above the rated wind speed.


Li H.,Chongqing University | Yang C.,Chongqing University | Zhao B.,Chongqing University | Tang X.,Chongqing KK QIANWEI Wind Power Equipment Co. | Liu X.,Chongqing KK QIANWEI Wind Power Equipment Co.
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2013

To better understand the dynamic characteristics of electric pitch system in a wind turbine generator system (WTGS), it is necessary to study its dynamic model with consideration of drive motor characteristics. By introducing the basic principle of the electric pitch system, its detailed models are presented. The model includes the subsystem models of three-phase induction motor and its vector-control strategy, driver train, back-up battery. A simplified first-order inertia model for the electric pitch system is also introduced. In order to validate the detailed model, a test platform for the electric pitch system is constructed. And additionally, the dynamic performances of the detailed model, including the pitch angle tracking performances, the load disturbance performances, and the low voltage fault performances, are simulated. The simulation results are also compared with those of the simplified first-order inertia model and those of the test platform for the electric pitch system. The comparison shows that the proposed model can better reflect the transients of a real electric pitch system, and can also be used to evaluate the operation characteristics of a real electric pitch system under low voltage faults. © 2013 State Grid Electric Power Research Institute Press.


Li H.,Chongqing University | Zhang Z.-K.,Chongqing University | Yang C.,Chongqing University | Zhao B.,Chongqing University | Tang X.-H.,Chongqing KK QIANWEI Wind Power Equipment Co.
Dianji yu Kongzhi Xuebao/Electric Machines and Control | Year: 2013

In order to improve the stability of large-scale wind power integrated to the power grid and the adaptivity of wind turbine generation system, it is necessary to analyze the impact of wind turbine generation system parameters and operating states on the small-signal stability. The small-signal analysis model of doubly-fed wind turbine generation system considering the operating characteristics was established, including wind turbine drive train, pitch control system and the generator. Based on modal analysis method, the corresponding modals were obtained by calculating the eigenvalues and participation factors, and the influences of drive train mechanical parameters, generator electrical parameters and the operating states on egienvalues were studied. Parameter eigenvalues sensitivity in different operating conditions was also analyzed by introducing the concept of eigenvalue sensitivity. The results show that the oscillation frequency of shaft modal is obviously influenced by mechanical parameters, while the damping of all modals are influenced mainly by electrical parameters. With operating states changing, the system dominant modal is different, and the eigenvalues sensitivity to the same parameters is also quite different.

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