Robust frequency‐locked loop algorithm for grid synchronisation of single‐phase applications under distorted grid conditions

Bei, Taizhou; Wang, Ping

doi:10.1049/iet-gtd.2015.0914

Cited by 18 publications

(18 citation statements)

References 32 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The positive sequence components rotate in counter-clockwise direction with + ω angular frequency. Applying a power invariant Clarke's transformation to (1) and (2), two other expressions in stationary reference frame (αβ0) can be found, each for voltage and current vectors. Notice that the zero-sequence component is omitted considering a three-phase three-wire system.…”

Section: Positive Sequence Reference Frame Transformationmentioning

confidence: 99%

“…In a low voltage (LV)/medium voltage (MV) distribution network, unbalanced grid faults are more common compared to balanced three-phase faults. In case of a fault, one of the greatest challenges from the inverter's operational point of view is to remain synchronised with the grid [2,3]. In other words, during momentary faults, the inverter overcurrent protection must not trip or disconnect the voltage source inverter (VSI) from the point of common coupling (PCC).…”

Section: Introductionmentioning

confidence: 99%

“…In (1) and (2), n is the number of harmonics, Φ is the corresponding voltage phase angle and δ is the current phase angle. Plus ( + ), minus ( − ) and zero (0) stands for positive, negative and zero sequence components, respectively.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Distributed dynamic grid support using smart PV inverters during unbalanced grid faults

Shuvra

Chowdhury

2019

IET Renewable Power Generation

View full text Add to dashboard Cite

A dynamic voltage support strategy using smart photovoltaic (PV) inverters during unbalanced grid faults events is proposed. It uses Karush-Kuhn-Tucker condition for finding optimal solutions to calculate the inverter's active and reactive current references. The proposed methodology also takes the X/R ratio into consideration which allows the inverter to differentiate weak or strong grid conditions and adjust its reference currents. Existing multiple-complex coefficient-filter based phase locked loop is used to extract the positive and negative sequence components. The proposed strategy deploys existing dual vector current control to ensure optimal current injection and low voltage ride through. A distributed ride-through coordination approach among multiple inverters is also proposed based on different optimisation goals-either fundamental positive or fundamental negative sequence voltage support. The strategy is simulated, and inverter's transient performance is experimentally verified on a modified IEEE-13 bus test feeder using controller hardware-in-the-loop approach. Results show substantial evidence that the proposed method can be successfully applied to support the grid during an unbalanced fault event. Table 1 Voltage ride-through requirement Voltage range, p.u. Clearing time, s

show abstract

Section: Positive Sequence Reference Frame Transformationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Distributed dynamic grid support using smart PV inverters during unbalanced grid faults

Shuvra

Chowdhury

2019

IET Renewable Power Generation

View full text Add to dashboard Cite

show abstract

“…However, for abnormal grid conditions, the performances of these control techniques, are not reported, which is the essential phenomenon of the distribution grid. The other control techniques like, discrete-Fourier transform (DFT), PM (Prony's method), frequency locked loop (FLL) [7], second-order generalized integrator (SOGI) [8] and Kalman filter (KF) [9] have been proposed to handle the abnormal grid condition. However, none of these techniques, is suitable for all types of grid adverse conditions, such as FLL and SOGI based control techniques are unable to handle lower order harmonics and DC offset [10].…”

Section: Introductionmentioning

confidence: 99%

Leaky-Least-Logarithmic-Absolute-Difference-Based Control Algorithm and Learning-Based InC MPPT Technique for Grid-Integrated PV System

Kumar

Singh

Panigrahi

et al. 2019

IEEE Trans. Ind. Electron.

View full text Add to dashboard Cite

This work introduces a novel Leaky Least Logarithmic Absolute Difference (LLLAD) based control algorithm and Learning based Incremental Conductance (LIC) MPPT (Maximum Power Point Tracking) algorithm, for grid-integrated solar PV (Photovoltaic) system. Here, a three-phase topology of grid-integrated PV system is implemented, with the nonlinear/linear loads. Proposed LIC technique is an improved form of an Incremental Conductance (InC) algorithm, where inherent problems of traditional InC technique like steady-state oscillations, slow dynamic responses and fixed step size issues, are successfully mitigated. The prime objective of proposed LLLAD control is to meet the active power requirement of the loads from generated solar PV power, and after satisfying the load demand, the excess power is supplied to the grid. However, when generated solar power is less than the load demand, then LLLAD meets the load by taking extra required power from the grid. During these power management processes, on the grid side, the power quality is maintained. During daytime, the proposed control technique provides load balancing, power factor correction, and harmonics filtering. Moreover, when solar irradiation is zero, then the DC link capacitor and VSC, act as DSTATCOM (Distribution Static Compensator), which enhances the utilization factor of the system. The proposed techniques are modeled, and their performances are verified experimentally on a developed prototype, in solar insolation variation conditions, unbalanced loading, as well as in different grid disturbances such as over and under-voltage, phase imbalance, harmonics distortion in the grid voltage etc. Test results have met the objectives of proposed work and parameters are under the permissible limit, according to the IEEE-519 standard.

show abstract

“…However, the structure is considerably more complicated than the above methods, requiring a phase detector, a low-pass filter (LPF), and a voltage-controlled oscillator in basic, and an extra grid voltage amplitude detection. The frequency-locked loop proposed in [20] can detect the grid frequency for synchronisation under frequency variation, voltage fluctuation, and harmonic distortion but suffers from the same order of complexity as the PLL. Digital computation methods, such as anticonjugate decomposition with cascaded delayed signal cancellation (ACD-CDSC) technique [21], discrete Fourier transform-based second-order generalised-integrator (DFT-SOGI), and SOGI with a differentiation filter (SOGI-DF), have also been proposed [22,23].…”

Section: Introductionmentioning

confidence: 99%

Simple four‐quadrant grid‐tie control scheme with unity power factor rectifier mode for single‐phase DC/AC converters

Chi

Purnama

Hsieh

et al. 2017

IET Renewable Power Generation

View full text Add to dashboard Cite

This study proposes a voltage-oriented control scheme for four-quadrant grid-tie of a single-phase bidirectional direct current/alternating current (AC) voltage-sourced converter (VSC) to operate smartly at modes of unity power factor (PF) rectifier (UPFR), inverter or static var compensator. Given the possible harmonic-distorted AC grid voltage, the proposed scheme follows or filters the grid voltage to generate the appropriate current command template for minimising the harmonic current while synchronising with the grid. The following template is for the UPFR mode, whereas the filtered template is for the other modes. The scheme proposes a unique band-pass filter (BPF) to proceed with direct component generation for the filtered template. The proposed scheme further unifies the grid-tie inductor current-to-voltage conversion for the following emplate and the quadrature component generation for the filtered template into a differentiator. The control laws under the filtered and following templates are derived. The BPF and differentiator designs are introduced. Simulations and experiments are conducted with a one-cycle control full-bridge VSC to verify the proposed grid-tie control scheme and evaluate its performance. Nomenclature v grid AC grid voltage source R grid , L grid AC grid wire resistance, inductance v R grid , v L grid voltages across R grid , L grid i grid , i sgrid , i dgrid AC grid current, its assumed sinusoid, their difference i R , i sR , i dR rectifier mode input current, its assumed sinusoid, their difference i NL , i 1NL , i hNL non-linear load current, its fundamental, harmonic components g emulated conductance of UPFR mode v AC , V AC AC grid voltage vector on point of common coupling, its RMS value v out VSC AC output voltage vector v filter , v R f , v L f voltage across grid-tie filter, resistance, inducatnce of the filter k VSC AC voltage gain v 1 , V^1, V 1 VSC fundamental output voltage vector, its amplitude, RMS value θ 1 phase angle of v 1 * * , I 1 * * AC output voltage command for arm A, B of FB VSC v oA , v oB AC output voltage on arm A, B of FB VSC V oA , V oB average values of v oA , v oB f s , T s , d switching frequency, period, duty cycle over T s V DC DC grid voltage f c , ω c central frequency of the pass band of the BPF, its angular form f cL , ω cL corner frequency of the pass band of the low-pass filter, its angular form f cH , ω cH corner frequency of the pass band of the highpass filter, its angular form ζ L , ζ H damping ratio of low-pass, high-pass filters K L , K H gain in the pass band of low-pass, high-pass filters

show abstract

Robust frequency‐locked loop algorithm for grid synchronisation of single‐phase applications under distorted grid conditions

Cited by 18 publications

References 32 publications

Distributed dynamic grid support using smart PV inverters during unbalanced grid faults

Distributed dynamic grid support using smart PV inverters during unbalanced grid faults

Leaky-Least-Logarithmic-Absolute-Difference-Based Control Algorithm and Learning-Based InC MPPT Technique for Grid-Integrated PV System

Simple four‐quadrant grid‐tie control scheme with unity power factor rectifier mode for single‐phase DC/AC converters

Contact Info

Product

Resources

About