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Volume 47,Issue 3,2020 Table of Contents
2020, 47(3):1-7.
DOI: 10.12177/emca.2019.146
Abstract:
Conventional model predictive torque control (MPTC) of permanent magnet synchronous motor (PMSM) does not concern decreasing switching number, which causes high average switching frequency. The decrease of switching number is considered in the MPTC of surface permanent magnet synchronous motor (SPMSM) as one of the control objects of cost function, and weight coefficient of switching number is designed. The MPTC strategy with dynamic weight coefficient based on fuzzy control is proposed. The effect of different motor torque on switching number weight coefficient is analyzed. Fuzzy control is introduced to adjust the weight coefficient of switching number in real time according to motor system states. Simulation results show that compared with constant weight coefficient of switching number, dynamic weight coefficient based on fuzzy control can reduce the average switching frequency and suppress the torque ripple and flux linkage ripple of system.
Conventional model predictive torque control (MPTC) of permanent magnet synchronous motor (PMSM) does not concern decreasing switching number, which causes high average switching frequency. The decrease of switching number is considered in the MPTC of surface permanent magnet synchronous motor (SPMSM) as one of the control objects of cost function, and weight coefficient of switching number is designed. The MPTC strategy with dynamic weight coefficient based on fuzzy control is proposed. The effect of different motor torque on switching number weight coefficient is analyzed. Fuzzy control is introduced to adjust the weight coefficient of switching number in real time according to motor system states. Simulation results show that compared with constant weight coefficient of switching number, dynamic weight coefficient based on fuzzy control can reduce the average switching frequency and suppress the torque ripple and flux linkage ripple of system.
2020, 47(3):8-11.
DOI: 10.12177/emca.2019.156
Abstract:
Aiming at the speed control of permanent magnet synchronous motor (PMSM), a nonlinear predictive control (NPC) strategy based on reduced order load torque observer is proposed. In the speed loop control law, the load torque is considered as the disturbance value. The reduced order load torque observer is combined with the generalized predictive control strategy. The estimated torque value is used to replace the actual value. Simulation and experimental results show that the control strategy proposed can effectively achieve speed tracking. Compared with the traditional PI control, the overshoot is smaller, the speed approaching to stability is faster, the anti-interference ability is stronger, and the robustness of the speed loop is higher.
Aiming at the speed control of permanent magnet synchronous motor (PMSM), a nonlinear predictive control (NPC) strategy based on reduced order load torque observer is proposed. In the speed loop control law, the load torque is considered as the disturbance value. The reduced order load torque observer is combined with the generalized predictive control strategy. The estimated torque value is used to replace the actual value. Simulation and experimental results show that the control strategy proposed can effectively achieve speed tracking. Compared with the traditional PI control, the overshoot is smaller, the speed approaching to stability is faster, the anti-interference ability is stronger, and the robustness of the speed loop is higher.
2020, 47(3):12-16.
DOI: 10.12177/emca.2019.174
Abstract:
In the speed control system of permanent magnet synchronous motor (PMSM), it is proposed to adopt the active disturbance rejection control (ADRC) to design the speed loop. According to the control performance of the speed control system and the characteristics of the ADRC strategy, the extended state observer in the ADRC is improved. At the same time, the nonlinear extended state observer (NESO) is used for both the observation of the system load torque and the feedforward compensation, so as to reduce the influence of load torque disturbance. Based on the above two measures, an improved ADRC (IADRC) controller of speed loop is designed. The effectiveness of the IADRC controller in the speed control system of PMSM is verified by simulation and experiments.
In the speed control system of permanent magnet synchronous motor (PMSM), it is proposed to adopt the active disturbance rejection control (ADRC) to design the speed loop. According to the control performance of the speed control system and the characteristics of the ADRC strategy, the extended state observer in the ADRC is improved. At the same time, the nonlinear extended state observer (NESO) is used for both the observation of the system load torque and the feedforward compensation, so as to reduce the influence of load torque disturbance. Based on the above two measures, an improved ADRC (IADRC) controller of speed loop is designed. The effectiveness of the IADRC controller in the speed control system of PMSM is verified by simulation and experiments.
2020, 47(3):17-22.
DOI: 10.12177/emca.2019.172
Abstract:
In the permanent magnet synchronous motor (PMSM) drive system, the system current inner loop controller based on the finite control set model predictive current control (FCS-MPCC) algorithm is affected by the variation of motor parameters. The prediction model of PMSM is derived. The cost function is reconstructed with the voltage vector as the constraint, and the current ripple problem caused by the digital delay is compensated. A robust FCS-MPCC algorithm is proposed, which reduces the sensitivity of the algorithm to the parameters by introducing weight coefficients and quantitative adjustments in the prediction model. The simulation results show that the proposed algorithm is effective and can make the system have good dynamic performance and steady state accuracy.
In the permanent magnet synchronous motor (PMSM) drive system, the system current inner loop controller based on the finite control set model predictive current control (FCS-MPCC) algorithm is affected by the variation of motor parameters. The prediction model of PMSM is derived. The cost function is reconstructed with the voltage vector as the constraint, and the current ripple problem caused by the digital delay is compensated. A robust FCS-MPCC algorithm is proposed, which reduces the sensitivity of the algorithm to the parameters by introducing weight coefficients and quantitative adjustments in the prediction model. The simulation results show that the proposed algorithm is effective and can make the system have good dynamic performance and steady state accuracy.
2020, 47(3):23-27.
DOI: 10.12177/emca.2019.164
Abstract:
In order to improve the robustness and control accuracy of permanent magnet synchronous motor (PMSM) and reduce the influence of external disturbance on the control, a sliding mode control method is proposed based on a new reaching law. The new reaching law solves the contradiction between sliding mode surface reaching time and the system chattering in the regular reaching law. Based on the traditional power approaching law, a piecewise power approaching law is proposed. A linear term is added after the second power term to better reduce chattering. A sliding mode disturbance observer is designed with the load torque and rotational speed as the observation objects. The observation results are fed back to the speed control loop to further improve the robustness. The simulation results verify the feasibility and effectiveness of the method.
In order to improve the robustness and control accuracy of permanent magnet synchronous motor (PMSM) and reduce the influence of external disturbance on the control, a sliding mode control method is proposed based on a new reaching law. The new reaching law solves the contradiction between sliding mode surface reaching time and the system chattering in the regular reaching law. Based on the traditional power approaching law, a piecewise power approaching law is proposed. A linear term is added after the second power term to better reduce chattering. A sliding mode disturbance observer is designed with the load torque and rotational speed as the observation objects. The observation results are fed back to the speed control loop to further improve the robustness. The simulation results verify the feasibility and effectiveness of the method.
2020, 47(3):28-33.
DOI: 10.12177/emca.2019.162
Abstract:
In order to reduce the high frequency chattering of sliding mode observer (SMO) of sensorless permanent magnet synchronous motor (PMSM) and improve the observer characteristics, on the basis of conventional SMO, Sigmoid function is used as the switching function to decrease system chattering. Meanwhile, the combination of the low-pass variable cutoff frequency filter and Kalman filter is used to filter high frequency signals and decrease measurement noise and errors. At last, the speed and position of PMSM are acquired by using phase locked loop (PLL) technique. The effectiveness and feasibility of SMO are verified by MATLAB/Simulink simulation. The results show that the improved SMO has higher quality observation signals than conventional SMO, and the dynamic and static characteristics of the control system are also better.
In order to reduce the high frequency chattering of sliding mode observer (SMO) of sensorless permanent magnet synchronous motor (PMSM) and improve the observer characteristics, on the basis of conventional SMO, Sigmoid function is used as the switching function to decrease system chattering. Meanwhile, the combination of the low-pass variable cutoff frequency filter and Kalman filter is used to filter high frequency signals and decrease measurement noise and errors. At last, the speed and position of PMSM are acquired by using phase locked loop (PLL) technique. The effectiveness and feasibility of SMO are verified by MATLAB/Simulink simulation. The results show that the improved SMO has higher quality observation signals than conventional SMO, and the dynamic and static characteristics of the control system are also better.
2020, 47(3):34-37.
DOI: 10.12177/emca.2019.177
Abstract:
The development pace of therobot technology has been further accelerated with the help of model simulation. Based on the application scene and motor control model provided by LabVIEW, an algorithm model for robot trajectory deduction is designed. For a wheeled robot, according to the speeds of the left and right wheels, the model calculates the velocity of the robot in the application scene. Then the model reflects the position change of the robot in the application scene through the track coordinates in the world coordinate system. This model can assess the motor motion control effect and test the control system of wheeled robot by detecting the trajectory change in the world coordinate system.
The development pace of therobot technology has been further accelerated with the help of model simulation. Based on the application scene and motor control model provided by LabVIEW, an algorithm model for robot trajectory deduction is designed. For a wheeled robot, according to the speeds of the left and right wheels, the model calculates the velocity of the robot in the application scene. Then the model reflects the position change of the robot in the application scene through the track coordinates in the world coordinate system. This model can assess the motor motion control effect and test the control system of wheeled robot by detecting the trajectory change in the world coordinate system.
2020, 47(3):38-44.
DOI: 10.12177/emca.2019.165
Abstract:
Winding interturn short circuit fault is one of the most common faults of permanent magnet synchronous generator (PMSG), which usually causes irreversible demagnetization of permanent magnet. In order to solve the problem, a special PMSG with the ability to suppress irreversible demagnetization of the interturn short circuit is established. The special structure of the generator is introduced, and then the theory of suppressing demagnetization is explained through mathematic deduction. The model of the generator is established by Flux software and sudden interturn short circuit fault of the generator during the operation is simulated. The minimum magnetic flux density value at each point of the permanent magnet in the short circuit process is compared with the inflexion magnetic flux density of the demagnetization curve at the corresponding temperature. According to this, the demagnetization of permanent magnet under different short circuit faults is analyzed and the feasibility of suppressing demagnetization is verified.
Winding interturn short circuit fault is one of the most common faults of permanent magnet synchronous generator (PMSG), which usually causes irreversible demagnetization of permanent magnet. In order to solve the problem, a special PMSG with the ability to suppress irreversible demagnetization of the interturn short circuit is established. The special structure of the generator is introduced, and then the theory of suppressing demagnetization is explained through mathematic deduction. The model of the generator is established by Flux software and sudden interturn short circuit fault of the generator during the operation is simulated. The minimum magnetic flux density value at each point of the permanent magnet in the short circuit process is compared with the inflexion magnetic flux density of the demagnetization curve at the corresponding temperature. According to this, the demagnetization of permanent magnet under different short circuit faults is analyzed and the feasibility of suppressing demagnetization is verified.
2020, 47(3):45-50.
DOI: 10.12177/emca.2019.170
Abstract:
In the servo control system, the controller has a great influence on the performance of the interior permanent magnet synchronous motor (IPMSM). The time-stepping finite-element method is used to analyze the IPMSM. Both 3D and 2D transient electromagnetic field finite element models are built in Maxwell software. A model of motor control algorithm is built in Simulink software. The finite element models and motor control algorithm model are combined by Simplorer interface technology. The field-circuit coupling simulation model for IPMSM is built. The data of torque, current, loss and flux weakening speed range of the IPMSM under different control strategies and different working conditions are analyzed. It provides a reasonable method for the calculation and optimal design of the IPMSM servo speed control system.
In the servo control system, the controller has a great influence on the performance of the interior permanent magnet synchronous motor (IPMSM). The time-stepping finite-element method is used to analyze the IPMSM. Both 3D and 2D transient electromagnetic field finite element models are built in Maxwell software. A model of motor control algorithm is built in Simulink software. The finite element models and motor control algorithm model are combined by Simplorer interface technology. The field-circuit coupling simulation model for IPMSM is built. The data of torque, current, loss and flux weakening speed range of the IPMSM under different control strategies and different working conditions are analyzed. It provides a reasonable method for the calculation and optimal design of the IPMSM servo speed control system.
2020, 47(3):51-56.
DOI: 10.12177/emca.2019.169
Abstract:
In practice, it is very significant to monitor the rotor temperature of induction motor quickly and accurately for state evaluation, fault prediction and safety production of electrical equipment. However, due to the limitation of the real operating conditions, it is difficult to directly monitor or indirectly evaluate the rotor temperature. To solve this problem, a rapid parameter identification method for rotor temperature evaluation is proposed. The rotor speed is obtained by using the harmonic identification of rotor slot, and then the rotor resistance is obtained by measuring the electrical parameters at the initial stage of starting which can simulate the locked rotor operation of the motor. The rotor speed and resistance obtained by the above solution are regarded as the extended Kalman filter (EKF) initial value for real-time identification of rotor resistance. The proposed EKF method avoids the problem of long iterative time of initial value, and realizes the rapid on-line identification of rotor resistance. Based on the relationship between the resistance value of metal material and the temperature, the real-time temperature data of rotor can be obtained. Taking a 22 kW induction motor as an example, the rotor temperature under different load conditions is identified, and the validity and feasibility of the proposed method are verified.
In practice, it is very significant to monitor the rotor temperature of induction motor quickly and accurately for state evaluation, fault prediction and safety production of electrical equipment. However, due to the limitation of the real operating conditions, it is difficult to directly monitor or indirectly evaluate the rotor temperature. To solve this problem, a rapid parameter identification method for rotor temperature evaluation is proposed. The rotor speed is obtained by using the harmonic identification of rotor slot, and then the rotor resistance is obtained by measuring the electrical parameters at the initial stage of starting which can simulate the locked rotor operation of the motor. The rotor speed and resistance obtained by the above solution are regarded as the extended Kalman filter (EKF) initial value for real-time identification of rotor resistance. The proposed EKF method avoids the problem of long iterative time of initial value, and realizes the rapid on-line identification of rotor resistance. Based on the relationship between the resistance value of metal material and the temperature, the real-time temperature data of rotor can be obtained. Taking a 22 kW induction motor as an example, the rotor temperature under different load conditions is identified, and the validity and feasibility of the proposed method are verified.
2020, 47(3):57-62.
DOI: 10.12177/emca.2019.175
Abstract:
The core problem of switched reluctance motor (SRM) is the detection and suppression of vibration torque. The linear mathematical model of SRM is established, and the torque change of SRM is closely related to the phase winding current. In order to observe the current change and vibration torque of SRM, a simulation system of SRM is built and the vibration torque and current of SRM in three modes of angular position control (APC), current chopping control (CCC) and chopping voltage control (CVC) are simulated. The results show that the vibration torque with commutation frequency as the main frequency is very obvious. Meanwhile, an experimental platform for testing the vibration torque of SRM is set up, and the actual vibration torque of the motor is detected by angular acceleration sensor. The experimental results are analyzed and discussed.
The core problem of switched reluctance motor (SRM) is the detection and suppression of vibration torque. The linear mathematical model of SRM is established, and the torque change of SRM is closely related to the phase winding current. In order to observe the current change and vibration torque of SRM, a simulation system of SRM is built and the vibration torque and current of SRM in three modes of angular position control (APC), current chopping control (CCC) and chopping voltage control (CVC) are simulated. The results show that the vibration torque with commutation frequency as the main frequency is very obvious. Meanwhile, an experimental platform for testing the vibration torque of SRM is set up, and the actual vibration torque of the motor is detected by angular acceleration sensor. The experimental results are analyzed and discussed.
2020, 47(3):63-68.
DOI: 10.12177/emca.2019.178
Abstract:
For the mining of thin coal seams, prolonging the service life of mines, and improving the utilization rate of coal resources, screw-drilling shearers provide a good and effective choice. The 1 600 kW/3.3 kV inverter is designed for the screw-drilling shearers system and the protection level is IP56. The inverter uses a phase-shifting transformer with 18-pulse phase-shifting rectification technology to achieve no harmonic interference on the grid side. The multi-level power unit series technology is used for the topology, leading to the 13-level output with good sine degree and small du/dt value, which will not damage the cable and motor insulation. The inverter phase-shifting transformer and power unit both use water cooling heat dissipation, which has high efficiency and reliability. The performance of the inverter meets the special working conditions such as three times the starting torque, rapid acceleration, and rapid deceleration of the screw-drilling shearer. Furthermore, a remote communication interface is reserved to facilitate user’s signal control and data acquisition.
For the mining of thin coal seams, prolonging the service life of mines, and improving the utilization rate of coal resources, screw-drilling shearers provide a good and effective choice. The 1 600 kW/3.3 kV inverter is designed for the screw-drilling shearers system and the protection level is IP56. The inverter uses a phase-shifting transformer with 18-pulse phase-shifting rectification technology to achieve no harmonic interference on the grid side. The multi-level power unit series technology is used for the topology, leading to the 13-level output with good sine degree and small du/dt value, which will not damage the cable and motor insulation. The inverter phase-shifting transformer and power unit both use water cooling heat dissipation, which has high efficiency and reliability. The performance of the inverter meets the special working conditions such as three times the starting torque, rapid acceleration, and rapid deceleration of the screw-drilling shearer. Furthermore, a remote communication interface is reserved to facilitate user’s signal control and data acquisition.
2020, 47(3):69-74.
DOI: 10.12177/emca.2019.166
Abstract:
When the aircraft generator controller detects effective voltage value, calculation error is often caused by frequency fluctuation. Three kinds of effective value algorithms are introduced, which are constant frequency sampling algorithm, zero crossing algorithm and quasi-synchronous sampling algorithm. Simulation in MATLAB shows that among the three algorithms, the quasi-synchronous sampling algorithm leads to the minimum error. For the problem of the quasi-synchronous sampling algorithm response time is too long, the semi-periodic integral optimization method is adopted, and the number of iterations is appropriately reduced. The results of simulation and experiment show that when the frequency fluctuates between 380 Hz and 420 Hz, the error of the improved quasi-synchronous sampling algorithm is optimized from 2.63% to 0.14% compared with the traditional constant frequency sampling algorithm. The response time is reduced from 7.42 ms to 2.46 ms compared with the quasi-synchronous sampling algorithm without optimization.
When the aircraft generator controller detects effective voltage value, calculation error is often caused by frequency fluctuation. Three kinds of effective value algorithms are introduced, which are constant frequency sampling algorithm, zero crossing algorithm and quasi-synchronous sampling algorithm. Simulation in MATLAB shows that among the three algorithms, the quasi-synchronous sampling algorithm leads to the minimum error. For the problem of the quasi-synchronous sampling algorithm response time is too long, the semi-periodic integral optimization method is adopted, and the number of iterations is appropriately reduced. The results of simulation and experiment show that when the frequency fluctuates between 380 Hz and 420 Hz, the error of the improved quasi-synchronous sampling algorithm is optimized from 2.63% to 0.14% compared with the traditional constant frequency sampling algorithm. The response time is reduced from 7.42 ms to 2.46 ms compared with the quasi-synchronous sampling algorithm without optimization.
2020, 47(3):75-80.
DOI: 10.12177/emca.2019.158
Abstract:
With the development of wind power generation, the impact of wind power fluctuations on the grid is becoming more and more obvious, and smoothing wind power output is very important. Aiming at the fluctuation characteristics of wind power, a wavelet packet decomposition method is proposed to obtain the wind power connected to grid, the reference power of the hybrid energy storage system, and the state of charge and discharge. Based on the state of charge of the battery and super-capacitor, the coordination control strategy realizes the internal power correction of the energy storage system. The results of the calculation examples show that the coordination control strategy can complete the optimization correction of the internal power of the hybrid energy storage system and effectively smooth the wind power output. Based on actual wind power data, by establishing a mathematical simulation model in MATLAB, the effectiveness of the coordination control strategy is proved.
With the development of wind power generation, the impact of wind power fluctuations on the grid is becoming more and more obvious, and smoothing wind power output is very important. Aiming at the fluctuation characteristics of wind power, a wavelet packet decomposition method is proposed to obtain the wind power connected to grid, the reference power of the hybrid energy storage system, and the state of charge and discharge. Based on the state of charge of the battery and super-capacitor, the coordination control strategy realizes the internal power correction of the energy storage system. The results of the calculation examples show that the coordination control strategy can complete the optimization correction of the internal power of the hybrid energy storage system and effectively smooth the wind power output. Based on actual wind power data, by establishing a mathematical simulation model in MATLAB, the effectiveness of the coordination control strategy is proved.
15 Synchronizing Signal Detection of Grid Voltage in Wind Power Generation Systems Under Grid Faults
2020, 47(3):81-86.
DOI: 10.12177/emca.2019.173
Abstract:
The grid-connected performance of grid-side converters in wind power generation system depends on high-performance synchronous detection system, the quick and accurate extraction of synchronizing signal under power grid fault in especial. A novel phase locked loop based on second-order generalized integrator （SOGI） is proposed, which eliminates the influence of the unbalanced and distorted grid voltage in the dq transform, as well as that of the second-order and higher order harmonic components, realizing the detection of synchronizing signal of the fundamental voltage. MATLAB simulation and experimental results show that the frequency, phase angle and positive and negative sequence components can be obtained quickly and efficiently.
The grid-connected performance of grid-side converters in wind power generation system depends on high-performance synchronous detection system, the quick and accurate extraction of synchronizing signal under power grid fault in especial. A novel phase locked loop based on second-order generalized integrator （SOGI） is proposed, which eliminates the influence of the unbalanced and distorted grid voltage in the dq transform, as well as that of the second-order and higher order harmonic components, realizing the detection of synchronizing signal of the fundamental voltage. MATLAB simulation and experimental results show that the frequency, phase angle and positive and negative sequence components can be obtained quickly and efficiently.
2020, 47(3):87-94.
DOI: 10.12177/emca.2019.161
Abstract:
Interior permanent magnet synchronous motor (IPMSM) is widely used in the electric vehicle field due to its high torque-to-current ratio, wider speed regulation range, high power density, and high efficiency. IPMSM for electric vehicles has a complicated magnetic circuit structure and a high degree of saturation, causing the cross coupling between the magnetic circuits of quadrature- and direct-axis. Therefore, mutual inductance is generated between quadrature and direct axis. Magnetic circuits analysis is carried out for the cross-coupling phenomenon, and the influences of cross coupling on the magnetic flux linkage and inductance parameters are elaborated. The frozen permeability method (FPM) and the finite element method (FEM) are used to calculate the quadrature- and direct-axis inductances, and the changes of inductance parameters with current are quantitatively analyzed. The two calculation methods are compared, and it is found that the calculation results agree well with each other. The advantages and disadvantages of the two methods for calculating the quadrature- and direct-axis inductance are analyzed. The analysis shows that using FEM as the main means and FPM as the auxiliary to calculate the quadrature- and direct-axis inductance parameters, the accuracy of the inductance parameters can be ensured and the calculation time can be shortened.
Interior permanent magnet synchronous motor (IPMSM) is widely used in the electric vehicle field due to its high torque-to-current ratio, wider speed regulation range, high power density, and high efficiency. IPMSM for electric vehicles has a complicated magnetic circuit structure and a high degree of saturation, causing the cross coupling between the magnetic circuits of quadrature- and direct-axis. Therefore, mutual inductance is generated between quadrature and direct axis. Magnetic circuits analysis is carried out for the cross-coupling phenomenon, and the influences of cross coupling on the magnetic flux linkage and inductance parameters are elaborated. The frozen permeability method (FPM) and the finite element method (FEM) are used to calculate the quadrature- and direct-axis inductances, and the changes of inductance parameters with current are quantitatively analyzed. The two calculation methods are compared, and it is found that the calculation results agree well with each other. The advantages and disadvantages of the two methods for calculating the quadrature- and direct-axis inductance are analyzed. The analysis shows that using FEM as the main means and FPM as the auxiliary to calculate the quadrature- and direct-axis inductance parameters, the accuracy of the inductance parameters can be ensured and the calculation time can be shortened.
2020, 47(3):95-99.
DOI: 10.12177/emca.2019.154
Abstract:
Power system stabilizer (PSS) is an important equipment to increase damping and suppress low frequency oscillations of power system. According to the grid operation code (GB/T 31464—2015), the excitation system of thermal-, nuclear- and gas-power generating units (100 MW and above) must have PSS ability. The time constant of lead-lag compensator needs to be configured during PSS test. At present, configuration methods for parameters are inefficient and need to be optimized. In order to solve this problem, automatic configuration method for PSS parameters based on MATLAB simulation is proposed. By setting the expected phase value at each frequency and constructing the objective function with the sum of squares of phase differences, the automatic calculation of PSS parameters under specific phase requirements at each frequency can be realized. The steps of this method are given in detail, and the method is verified on an 1 000 MW thermal-power generating unit during the PSS test.
Power system stabilizer (PSS) is an important equipment to increase damping and suppress low frequency oscillations of power system. According to the grid operation code (GB/T 31464—2015), the excitation system of thermal-, nuclear- and gas-power generating units (100 MW and above) must have PSS ability. The time constant of lead-lag compensator needs to be configured during PSS test. At present, configuration methods for parameters are inefficient and need to be optimized. In order to solve this problem, automatic configuration method for PSS parameters based on MATLAB simulation is proposed. By setting the expected phase value at each frequency and constructing the objective function with the sum of squares of phase differences, the automatic calculation of PSS parameters under specific phase requirements at each frequency can be realized. The steps of this method are given in detail, and the method is verified on an 1 000 MW thermal-power generating unit during the PSS test.
2020, 47(3):100-102.
DOI: 10.12177/emca.2020.001
Abstract:
To study and continuously meet the technical management requirements related to product certification in export target countries is a task that domestic enterprises must face and deal with. One of the main aspects of product certification is the factory’s quality assurance ability. Through analyzing the differences in the "Factory Inspection Procedures Harmonised Requirements" (CIG 021) revised by the European Testing, Inspection and Certification System (ETICS) in comparison with its previous version, the new factory inspection requirements are sorted, the key technical difficulties of the quality management system of factory inspection are put forward, and the corresponding analysis and solving measures are given. Export enterprises should learn and digest the new documents requirements during the transitional period, and improve the quality management system accordingly, so as to adapt to requirements of export product certification.
To study and continuously meet the technical management requirements related to product certification in export target countries is a task that domestic enterprises must face and deal with. One of the main aspects of product certification is the factory’s quality assurance ability. Through analyzing the differences in the "Factory Inspection Procedures Harmonised Requirements" (CIG 021) revised by the European Testing, Inspection and Certification System (ETICS) in comparison with its previous version, the new factory inspection requirements are sorted, the key technical difficulties of the quality management system of factory inspection are put forward, and the corresponding analysis and solving measures are given. Export enterprises should learn and digest the new documents requirements during the transitional period, and improve the quality management system accordingly, so as to adapt to requirements of export product certification.
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Electric Machines & Control Application ® 2025
Supported by:Beijing E-Tiller Technology Development Co., Ltd.
沪ICP备16038578号-3
Electric Machines & Control Application ® 2025
Supported by:Beijing E-Tiller Technology Development Co., Ltd.
