A Novel Real-time Voltage and Frequency Compensation Strategy for Photovoltaic-based Microgrid
67
Citation
39
Reference
10
Related Paper
Citation Trend
Abstract:
Weather-dependent photovoltaic (PV) system power variation may become frequent and rapid, which could be regarded as perturbation for the microgrid (MG). This perturbation would lead to voltage and frequency fluctuations and dramatically degrade the MG performances. Conventional secondary control strategy could restore the voltage and frequency after a certain time delay, but it cannot satisfy the speed demands when frequent and rapid perturbations appear. To overcome the limitation, this paper proposes a novel real-time voltage and frequency compensation strategy to suppress the fluctuations. The proposed strategy realizes voltage regulation by an adaptive virtual impedance loop and realizes frequency regulation by a virtual frequency-impedance loop. The novel real-time strategy is simple to be implemented and needless of communication; therefore, it is much more suitable for the PV-based MG. Finally, a PV-based MG is established as laboratory prototype, and experimental results validate the effectiveness of the proposed method.Keywords:
Microgrid
Abstract Synchronized Current Phasor Control (SCPC) is a new control method proposed recently for islanded microgrids. This paper firstly investigates the reactive power compensation characteristics of the SCPC islanded microgrid with I-V droop control, then analyzes the influence of the droop coefficient on it. Through this study, we find that the traditional reactive power compensation strategies are no longer adapted to SCPC islanded microgrids, since their characteristics of reactive power compensation are different from the traditional grid or other islanded microgrids controlled by the typical methods.
Microgrid
Power grid
Cite
Citations (0)
Small-disturbance voltage stability is of great significance for microgrid. To improve the small-disturbance voltage stability of microgrid including doubly fed induction generator (DFIG), DFIG reactive power control uses Q/V droop control and the integral logic loop. The reactive power limit corresponding to the DFIG active power in the case of variable wind speed is calculated, so that the integral logic loop and the Q/V droop control are limited. This paper finds the typical eigenvalues reflecting the voltage response characteristic of the microgrid via the small-signal analysis method. The influence on the locus of typical eigenvalues with DFIG different reactive power droop coefficient is analyzed. Through the parameter improvement, the adjustable range of DFIG reactive power droop coefficient is enlarged and the small-disturbance voltage stability of microgrid gets better. Finally, this paper establishes the microgrid model using the software DIgSILENT/PowerFactory. Simulation results verify validity and effectiveness of the proposed control strategy.
Microgrid
Cite
Citations (2)
In this paper, a control technique is developed for parallel inverters with no control interconnections in microgrid. The proposed control technique, based on droop control method and virtual impedance method, uses only locally measurable feedback signals to make some of the parallel inverters supply only reactive power equally for loads while the others share only active power. Simulation results are provided to prove the validity of this approach.
Microgrid
Cite
Citations (16)
This paper describes the operation of a microgrid that contains a custom power park (CPP). The park may contain an unbalanced and/or nonlinear load and the microgrid may contain many distributed generators (DGs). One of the DGs in the microgrid is used as a compensator to achieve load compensation. A new method is proposed for current reference generation for load compensation, which takes into account the real and reactive power to be supplied by the DG connected to the compensator. The real and reactive power from the DGs and the utility source is tightly regulated assuming that dedicated communication channels are available. Therefore this scheme is most suitable in cases where the loads in CPP and DGs are physically located close to each other. The proposal is validated through extensive simulation studies using EMTDC/PSCAD software package (version 4.2).
Microgrid
Cite
Citations (6)
The power-sharing accuracy is highly sensitive to the output impedances of distributed generator (DG) inverters with parallel-connection capability at droop control method. The control strategy of autonomous microgrid based on coordinate rotational virtual impedance is proposed to handle those problem. The coordinate rotational virtual impedance loop is adopted to improve the impedance characteristic, to compensate the active and reactive power unbalance and eliminate the circulating current between each DG unit. Moreover, secondary control is to compensate the voltage deviation and frequency offset. As opposed to centralized control, the use of distributed cooperative control method greatly reduces the burden of system communications, improve system reliability and stability. Simulation results are presented to validate those methods.
Microgrid
Impedance Control
Frequency deviation
Output impedance
Cite
Citations (2)
Line impedance mismatch and unregulated harmonic currents cause serious problems for an islanded microgrid, such as inaccurate reactive power sharing and voltage distortion at the point of common coupling (PCC). To overcome these issues, a coordinated virtual resistance and capacitance are introduced together with its control scheme for parallel distributed generation (DG) in an islanded microgrid. The proposed coordinated virtual impedance control scheme directly modifies the DG output impedance at the fundamental frequency to realise accurate current sharing among DG units. In addition, a variable harmonic impedance control loop is proposed for each DG to absorb the non-linear load harmonic current. Thanks to the proposed control scheme, the PCC harmonic voltage distortion is successfully compensated and power-sharing among DG units is accurately achieved. The stability of the microgrid system was analysed in detail to verify the feasibility of the coordinated virtual impedance control scheme. Experiments on a laboratory prototype microgrid are performed to validate the performance of the proposed control scheme.
Microgrid
Harmonic
Output impedance
Cite
Citations (6)
This paper focus on the characteristics of photovoltaic power changing along with light intensity, and compare the reactive power exchange between system and microgrid according to the different photovoltaic permeability in a microgrid. A method of dynamic reactive compensation capacity in a micro grid considering the different photovoltaic permeability is proposed. The simulation demonstrate the efficiency of this method.
Microgrid
Cite
Citations (2)
Microgrid
Robustness
Cite
Citations (26)
A control technique is developed for parallel operating inverters with no control interconnections in microgrid. This technique uses only locally measurable feedback signals to allow some independent inverters to share the active power for loads, while the others to provide reactive power compensation for loads, both in proportional to their capacities. Simulation results prove the validity of this approach.
Microgrid
Volt-ampere reactive
Cite
Citations (5)
Due to the unbalance condition, the voltage of microgrid would be deteriorated. In this paper, a unify unbalance compensation strategy is proposed to suppress the unbalanced voltage and the voltage variation for islanded microgrid with unbalanced condition. Comparing to the traditional compensation strategy, where only negative sequence components of voltage are suppressed, in the proposed scheme, the voltage and frequency variations resulted from the unbalanced condition are also eliminated. A simulation model of microgrid is developed in PSIM and the simulation and experimental results verify the effectiveness of the proposed method.
Microgrid
Voltage compensation
Cite
Citations (5)