Lingwei Zhan - Academia.edu (original) (raw)

Papers by Lingwei Zhan

IEEE Transactions on Power Delivery, 2016

IEEE Transactions on Smart Grid, 2016

International Journal of Energy Research, 2015

IEEE Transactions on Power Delivery, 2015

2015 IEEE Power & Energy Society General Meeting, 2015

This paper analyzes the theoretical accuracy limitation of synchrophasors measurements on phase a... more This paper analyzes the theoretical accuracy limitation of synchrophasors measurements on phase angle and frequency of the power grid. Factors that cause the measurement error are analyzed, including error sources in the instruments and in the power grid signal. Different scenarios of these factors are evaluated according to the normal operation status of power grid measurement. Based on the evaluation and simulation, the errors of phase angle and frequency caused by each factor are calculated and discussed.

2015 IEEE Power & Energy Society General Meeting, 2015

2015 IEEE Power & Energy Society General Meeting, 2015

2010 International Conference on Electrical and Control Engineering, 2010

This paper presents a specific method that uses the transfer matrix [A] to analyze insertion loss... more This paper presents a specific method that uses the transfer matrix [A] to analyze insertion loss of EMI filter. Based on the EMC standard emission limit, the needed insertion loss is calculated. Then proper EMI filter and components with appropriate parameters are selected to design the power supply EMI filter. Finally some experiments are made to verify the validity of the filter.

Diangong Jishu Xuebao/Transactions of China Electrotechnical Society

For high output voltage and high power full bridge converter with wide range of input voltage, th... more For high output voltage and high power full bridge converter with wide range of input voltage, the secondary rectifier diodes in a traditional clamp circuit suffer fr om too high voltage stress. A three windings full bridge converter with a lossless clamp circuit is proposed in this paper. The converter achieves that the upper limit of input voltage is more than twice as high as the lower limit, and the voltage stress of the rectifier diodes is effectively clamped to the output voltage. Firstly, the calculation formula of rectifier diode voltage stress is derived. Secondly, the problems in the present clamp circuit are analyzed. The working principle of the proposed clamp circuit is elaborated in detail. Theoretical analysis is carried out to optimize the secondary windings' turn ratio to achieve the wide range of input voltage. A 300W prototype is developed to verify the validity of the theoretical analysis. Finally, the PSPICE simulation results show the proposed three winding...

2010 International Conference on Electrical and Control Engineering, 2010

This paper deals with the dc magnetic biasing of high frequency transformer of the isolated full ... more This paper deals with the dc magnetic biasing of high frequency transformer of the isolated full bridge converter. Analytical calculations are given detailed based on the modes of the converter considering leakage inductance. Herewith, the impact of the source, load, leakage inductance, magnetizing inductance and line resistance on dc magnetic biasing is considered and analyzed. Finally simulation results are presented to verify the validity of the analytical calculations. Keywords-isolated full birdge converter; high frequency tansformer; dc magnetic biasing 1 3 2 3 s B 之间选择。 表 1 常见高频变压器磁芯材料的磁特性

International Journal of Energy Research, 2015

ABSTRACT Because of zero greenhouse gas emission and decreased manufacture cost, solar photovolta... more ABSTRACT Because of zero greenhouse gas emission and decreased manufacture cost, solar photovoltaic (PV) generation is expected to account for a significant portion of future power grid generation portfolio. Because it is indirectly connected to the power grid via power electronic devices, solar PV generation system is fully decoupled from the power grid, which will influence the interconnected power grid dynamic characteristics as a result. In this paper, the impact of solar PV penetration on large interconnected power system frequency response and inter-area oscillation is evaluated, taking the United States Eastern Interconnection (EI) as an example. Furthermore, based on the constructed solar PV electrical control model with additional active power control loops, the potential contributions of solar PV generation to power system frequency regulation and oscillation damping are examined. The advantages of solar PV frequency support over that of wind generator are also discussed. Simulation results demonstrate that solar PV generations can effectively work as ‘actuators’ in alleviating the negative impacts they bring about. Copyright © 2015 John Wiley & Sons, Ltd.

2014 IEEE PES General Meeting | Conference & Exposition, 2014

This paper proposes an improved method for estimating synchronized angle and frequency under both... more This paper proposes an improved method for estimating synchronized angle and frequency under both steadystate and dynamic conditions based on the weighted least squares Taylor expansion Fourier (WLS-TF) method. The WLS-TF method using classical windows as weighting factors assumes the input signal is a narrowband band-pass signal, and it has efficient performance under most conditions. However, error arises when the signal is not a band-pass signal, which is the case for the waveforms of power system. This paper extends the band-pass signal model to a more general signal model that considers 2 nd order harmonic and proposes a new method to estimate the frequency. Examples of the proposed method are illustrated following different steady-state and dynamic conditions considered in power system.

Synchronized phasor measurements are becoming one of the key measurement elements of wide area me... more Synchronized phasor measurements are becoming one of the key measurement elements of wide area measurement systems in advanced power system monitoring, protection, and control applications. Availability of global positioning system (GPS) provides the possibility of wide-area deployment of Phasor Measurement Unit (PMU) and Frequency Disturbance Recorder (FDR) in power system. GPS is the only timing source for PMU and FDR so far, and they will cease to work when GPS signal is lost or unstable. In addition, phasor data is transferred over the Internet without any encryption, which exposes data to cyber-attacks. The purpose of this paper is to develop an alternative GPS independent timing synchronization method for PMU and FDR, and to implement an encryption system without disrupting real-time data delivery. Primary test results confirm improvement of timing reliability and data transfer security of synchrophasor measurements.

2014 IEEE International Conference on Smart Grid Communications (SmartGridComm), 2014

Information about the frequency deviation is critical to reliable and stable operation of the pow... more Information about the frequency deviation is critical to reliable and stable operation of the power grid. Current widearea power grid monitoring systems consist of Phasor Measurement Units (PMUs) at both high-voltage transmission level and low-voltage distribution level, but are generally unsatisfactory for large-scale deployment over highly distributed microgrids in individual households and local communities due to their high cost and low accessibility. In this paper, we present a practical system design which significantly improves the accessibility and reduces the cost of frequency monitoring by unleashing the capabilities of modern mobile platforms in computation, communication, and storage. In our system, the Network Time Protocol (NTP) is exploited for time synchronization, replacing inflexible GPS receivers that are widely used in current PMUs. A small quantity of peripheral hardware components are used to build up an embedded sensing component for efficient and accurate frequency measurement. The experiment results compared to the traditional Frequency Disturbance Recorders (FDRs) show the effectiveness of the proposed frequency monitoring system.

2013 IEEE Power & Energy Society General Meeting, 2013

Frequency disturbances is one of the most important indicator that reflects the state of an elect... more Frequency disturbances is one of the most important indicator that reflects the state of an electrical power system. Making accurate frequency measurement from low voltage distribution systems through the wide deployment of Frequency Disturbance Recorders (FDRs) has been the major innovation for the Frequency monitoring network (FNET). Currently, the frequency calculation algorithm based on the phasor angles (FPA) of the measured voltage signal in the FDR, has achieved high accuracy. However, this algorithm is very sensitive to noise which is inevitable in the signal sampling process. As a result, the frequency estimation accuracy will be degraded if the measured signal is not clean enough. Therefore, to achieve even more accurate and robust frequency estimation from the measu red voltage signal, a novel algorithm is proposed in this paper consisting of two stages of operations. The first stage applies a band pass filter that eliminates the irrelevant harmonics; while the second stage removes the noise within the pass band and estimates the frequency fluctuation simultaneously based on the least squares nonlinear curve fitting. The experiments based on synthetic data and real data validates the effectiveness of the proposed method for improving the accuracy of frequency estimation.

IEEE Transactions on Smart Grid, 2015

ABSTRACT This paper proposes a method for estimating synchronized phase and frequency at the dist... more ABSTRACT This paper proposes a method for estimating synchronized phase and frequency at the distribution level under both steady-state and dynamic conditions. The discrete Fourier transform-based method is widely used for phasor and frequency estimation, thanks to its low computational burden. However, errors arise when the power system is operating at off-nominal frequency, especially under dynamic conditions such as phase modulation. Additionally, the power grid signal at the distribution level contains more noise and harmonics, which cause phase and frequency estimation errors. In this paper, a synchronized phase and frequency estimation algorithm suitable for measurement at the distribution level is proposed and tested under noise and harmonic conditions, as well as various conditions in the phasor measurement unit Standard (C37.118.1-2011 and C37.118.1a-2014), to verify its measurement accuracy at the distribution level.

IEEE Transactions on Power Delivery, 2016

IEEE Transactions on Smart Grid, 2016

International Journal of Energy Research, 2015

IEEE Transactions on Power Delivery, 2015

2015 IEEE Power & Energy Society General Meeting, 2015

This paper analyzes the theoretical accuracy limitation of synchrophasors measurements on phase a... more This paper analyzes the theoretical accuracy limitation of synchrophasors measurements on phase angle and frequency of the power grid. Factors that cause the measurement error are analyzed, including error sources in the instruments and in the power grid signal. Different scenarios of these factors are evaluated according to the normal operation status of power grid measurement. Based on the evaluation and simulation, the errors of phase angle and frequency caused by each factor are calculated and discussed.

2015 IEEE Power & Energy Society General Meeting, 2015

2015 IEEE Power & Energy Society General Meeting, 2015

2010 International Conference on Electrical and Control Engineering, 2010

This paper presents a specific method that uses the transfer matrix [A] to analyze insertion loss... more This paper presents a specific method that uses the transfer matrix [A] to analyze insertion loss of EMI filter. Based on the EMC standard emission limit, the needed insertion loss is calculated. Then proper EMI filter and components with appropriate parameters are selected to design the power supply EMI filter. Finally some experiments are made to verify the validity of the filter.

Diangong Jishu Xuebao/Transactions of China Electrotechnical Society

For high output voltage and high power full bridge converter with wide range of input voltage, th... more For high output voltage and high power full bridge converter with wide range of input voltage, the secondary rectifier diodes in a traditional clamp circuit suffer fr om too high voltage stress. A three windings full bridge converter with a lossless clamp circuit is proposed in this paper. The converter achieves that the upper limit of input voltage is more than twice as high as the lower limit, and the voltage stress of the rectifier diodes is effectively clamped to the output voltage. Firstly, the calculation formula of rectifier diode voltage stress is derived. Secondly, the problems in the present clamp circuit are analyzed. The working principle of the proposed clamp circuit is elaborated in detail. Theoretical analysis is carried out to optimize the secondary windings' turn ratio to achieve the wide range of input voltage. A 300W prototype is developed to verify the validity of the theoretical analysis. Finally, the PSPICE simulation results show the proposed three winding...

2010 International Conference on Electrical and Control Engineering, 2010

This paper deals with the dc magnetic biasing of high frequency transformer of the isolated full ... more This paper deals with the dc magnetic biasing of high frequency transformer of the isolated full bridge converter. Analytical calculations are given detailed based on the modes of the converter considering leakage inductance. Herewith, the impact of the source, load, leakage inductance, magnetizing inductance and line resistance on dc magnetic biasing is considered and analyzed. Finally simulation results are presented to verify the validity of the analytical calculations. Keywords-isolated full birdge converter; high frequency tansformer; dc magnetic biasing 1 3 2 3 s B 之间选择。 表 1 常见高频变压器磁芯材料的磁特性

International Journal of Energy Research, 2015

ABSTRACT Because of zero greenhouse gas emission and decreased manufacture cost, solar photovolta... more ABSTRACT Because of zero greenhouse gas emission and decreased manufacture cost, solar photovoltaic (PV) generation is expected to account for a significant portion of future power grid generation portfolio. Because it is indirectly connected to the power grid via power electronic devices, solar PV generation system is fully decoupled from the power grid, which will influence the interconnected power grid dynamic characteristics as a result. In this paper, the impact of solar PV penetration on large interconnected power system frequency response and inter-area oscillation is evaluated, taking the United States Eastern Interconnection (EI) as an example. Furthermore, based on the constructed solar PV electrical control model with additional active power control loops, the potential contributions of solar PV generation to power system frequency regulation and oscillation damping are examined. The advantages of solar PV frequency support over that of wind generator are also discussed. Simulation results demonstrate that solar PV generations can effectively work as ‘actuators’ in alleviating the negative impacts they bring about. Copyright © 2015 John Wiley & Sons, Ltd.

2014 IEEE PES General Meeting | Conference & Exposition, 2014

This paper proposes an improved method for estimating synchronized angle and frequency under both... more This paper proposes an improved method for estimating synchronized angle and frequency under both steadystate and dynamic conditions based on the weighted least squares Taylor expansion Fourier (WLS-TF) method. The WLS-TF method using classical windows as weighting factors assumes the input signal is a narrowband band-pass signal, and it has efficient performance under most conditions. However, error arises when the signal is not a band-pass signal, which is the case for the waveforms of power system. This paper extends the band-pass signal model to a more general signal model that considers 2 nd order harmonic and proposes a new method to estimate the frequency. Examples of the proposed method are illustrated following different steady-state and dynamic conditions considered in power system.

Synchronized phasor measurements are becoming one of the key measurement elements of wide area me... more Synchronized phasor measurements are becoming one of the key measurement elements of wide area measurement systems in advanced power system monitoring, protection, and control applications. Availability of global positioning system (GPS) provides the possibility of wide-area deployment of Phasor Measurement Unit (PMU) and Frequency Disturbance Recorder (FDR) in power system. GPS is the only timing source for PMU and FDR so far, and they will cease to work when GPS signal is lost or unstable. In addition, phasor data is transferred over the Internet without any encryption, which exposes data to cyber-attacks. The purpose of this paper is to develop an alternative GPS independent timing synchronization method for PMU and FDR, and to implement an encryption system without disrupting real-time data delivery. Primary test results confirm improvement of timing reliability and data transfer security of synchrophasor measurements.

2014 IEEE International Conference on Smart Grid Communications (SmartGridComm), 2014

Information about the frequency deviation is critical to reliable and stable operation of the pow... more Information about the frequency deviation is critical to reliable and stable operation of the power grid. Current widearea power grid monitoring systems consist of Phasor Measurement Units (PMUs) at both high-voltage transmission level and low-voltage distribution level, but are generally unsatisfactory for large-scale deployment over highly distributed microgrids in individual households and local communities due to their high cost and low accessibility. In this paper, we present a practical system design which significantly improves the accessibility and reduces the cost of frequency monitoring by unleashing the capabilities of modern mobile platforms in computation, communication, and storage. In our system, the Network Time Protocol (NTP) is exploited for time synchronization, replacing inflexible GPS receivers that are widely used in current PMUs. A small quantity of peripheral hardware components are used to build up an embedded sensing component for efficient and accurate frequency measurement. The experiment results compared to the traditional Frequency Disturbance Recorders (FDRs) show the effectiveness of the proposed frequency monitoring system.

2013 IEEE Power & Energy Society General Meeting, 2013

Frequency disturbances is one of the most important indicator that reflects the state of an elect... more Frequency disturbances is one of the most important indicator that reflects the state of an electrical power system. Making accurate frequency measurement from low voltage distribution systems through the wide deployment of Frequency Disturbance Recorders (FDRs) has been the major innovation for the Frequency monitoring network (FNET). Currently, the frequency calculation algorithm based on the phasor angles (FPA) of the measured voltage signal in the FDR, has achieved high accuracy. However, this algorithm is very sensitive to noise which is inevitable in the signal sampling process. As a result, the frequency estimation accuracy will be degraded if the measured signal is not clean enough. Therefore, to achieve even more accurate and robust frequency estimation from the measu red voltage signal, a novel algorithm is proposed in this paper consisting of two stages of operations. The first stage applies a band pass filter that eliminates the irrelevant harmonics; while the second stage removes the noise within the pass band and estimates the frequency fluctuation simultaneously based on the least squares nonlinear curve fitting. The experiments based on synthetic data and real data validates the effectiveness of the proposed method for improving the accuracy of frequency estimation.

IEEE Transactions on Smart Grid, 2015

ABSTRACT This paper proposes a method for estimating synchronized phase and frequency at the dist... more ABSTRACT This paper proposes a method for estimating synchronized phase and frequency at the distribution level under both steady-state and dynamic conditions. The discrete Fourier transform-based method is widely used for phasor and frequency estimation, thanks to its low computational burden. However, errors arise when the power system is operating at off-nominal frequency, especially under dynamic conditions such as phase modulation. Additionally, the power grid signal at the distribution level contains more noise and harmonics, which cause phase and frequency estimation errors. In this paper, a synchronized phase and frequency estimation algorithm suitable for measurement at the distribution level is proposed and tested under noise and harmonic conditions, as well as various conditions in the phasor measurement unit Standard (C37.118.1-2011 and C37.118.1a-2014), to verify its measurement accuracy at the distribution level.