Solar Powered Unmanned Aerial Vehicle With Active Output Filter Under Non-Linear Load Conditions

ABSTRACT:

This paper presents a new electric power train for solar powered unmanned aerial vehicle (UAV). The proposed system structure is based on the development of the power supply system for both the So long and Zyphyr aircraft models. The proposed UAV model incorporates the Zyphry UAV use of an AC line feeder instead of DC power lines to power the propellers. The proposed power train includes solar panels, an energy management system based on lithium sulfide battery, inverter, AC bus-line and active output filter (AOF). AOF topology is composed of a high switching frequency H-bridge inverter with a reduced size LC filter. The utilization of AOF system reduces the size and weight of the power transmission system and significantly improves its conversion efficiency by introducing an emulated series resistance with the H-bridge stage to ensure high quality pure sinusoidal waveform of the line voltage. This emulated series resistance produces an injected voltage across it to diminish unwanted harmonics created from the non-linear load. A simulation model and experimental setup are created to simulate the proposed system and the system is tested under non-linear load condition with closed-loop feed-back control strategy. The obtained simulation and experimental results demonstrate that high-quality sinusoidal line voltage waveforms can be obtained using the active resistance compensation technique with total harmonic distortion factor less than 3%. Moreover, power losses analysis and conversion efficiency calculation of the proposed system are performed and compared with that of the conventional three-phase PWM inverter, which proved that the power losses are reduced by 31%.

KEYWORDS:

1.      Active output filter

2.      Active resistance compensation

3.      Loss analysis

4.       Non-linear load

5.       Solar powered

6.      Unmanned aerial vehicle

 SOFTWARE: MATLAB/SIMULINK

CIRCUIT DIAGRAM:

Figure 1. Proposed Solar Powered Uav And Aof, (A) Single-Phase Square Wave Inverter With Ac-Bus Line And (B) Three-Phase Six-Step Inverter With Ac-Bus Line.

 EXPECTED SIMULATION RESULTS:

Figure 2. Tested Insolation Conditions For Uav Pv Power System.

 

Figure 3. Pv Harvested Power.

 

Figure 4. Pv Voltage (Upper Trace) And Current (Low Trace).

 

Figure 5. Battery Power.

 

Figure 6. Non-Linear Load Output Dc Power.

Figure 7. Pv Harvested Power During Different Operating Modes.

 

CONCLUSION:

A new electric power generation system for solar powered unmanned aerial vehicle (UAV) using active output filter has been proposed and investigated in this paper. The proposed power generation system is a potential progress of both the Solong and Zyphyr UAV models using the AC-bus line instead of the DC-bus line to power the propellers. It includes solar PV system, lithium-sulfur based power management system, inverter, AC bus-line. Balanced DC-link voltages of AOF have been accomplished using closed loop control of active resistance compensation, which produces an injected voltage across it to diminish unwanted harmonics created from the non-linear load. The obtained simulation and experimental results and the voltage and current waveforms demonstrated the viability and the correctness of the proposed power generation system. The proposed active resistance compensation ensures a high-quality sinusoidal line voltage with total harmonic distortion less than 3%. Moreover, power loss analysis and conversion efficiency of the proposed system are performed and compared with that of the conventional three-phase PWM inverter. The obtained results proved that the power loss is reduced by 31%. More investigation of the proposed AOF for large-scale PV plants application with Battery energy management system integration using different wide band gab devices to optimize the system efficiency are required with applying different PWM techniques to utilize the passive elements sizing design which are the subject of future work.

REFERENCES:

[1] U. Burup, P. N. Enjeti, and F. Blaabjerg, ``Anewspace-vector-based control method for UPS systems powering nonlinear and unbalanced loads,'' IEEE Trans. Ind. Appl., vol. 37, no. 6, pp. 1864_1870, Nov./Dec. 2001, doi: 10.1109/28.968202.

[2] D. Zhang, J. He, and D. Pan, ``A megawatt-scale medium-voltage high efficiency high power density `SiCCSi' hybrid three-level ANPC inverter for aircraft hybrid-electric propulsion systems,'' IEEE Trans. Ind. Appl., vol. 55, no. 6, pp. 5971_5980, Nov. 2019, doi: 10.1109/TIA.2019.2933513.

[3] M. N. Boukoberine, Z. Zhou, and M. Benbouzid, ``A critical review on unmanned aerial vehicles power supply and energy management: Solutions, strategies, and prospects,'' Appl. Energy, vol. 255, no. 1, pp. 1_22, Dec. 2019, doi: 10.1016/j.apenergy.2019.113823.

[4] X. Zhao, J. M. Guerrero, and X. Wu, ``Review of aircraft electric power systems and architectures,'' in Proc. IEEE Int. Energy Conf. (ENERGY- CON), Cavtat, Croatia, May 2014, pp. 949_953, doi: 10.1109/ENERGYCON. 2014.6850540.

[5] O. D. Dantsker, S. Imtiaz, and M. Caccamo, ``Electric propulsion system optimization for long-endurance and solar-powered unmanned aircraft,'' in Proc. AIAA Propuls. Energy Forum (EATS), Indianapolis, IN, USA, Aug. 2019, pp. 1_24, doi: 10.2514/6.2019-4486.

 

Small Signal Stability Analysis Oriented Design of Hybrid Anti-Islanding Protection Technique Based on Active Disturbance Injection

ABSTRACT:

 The conventional over/under voltage, over/under frequency based anti-islanding protection scheme presents significant nondetection zone (NDZ) under critical loading conditions of distribution networks. To overcome this challenge, a unique hybrid technique has been proposed in this article for the anti-islanding protection of distributed generators (DGs). The algorithm requires the injection of an active oscillatory disturbance signal of very small magnitude through the current control loop along the direct axis of the synchronously rotating reference frame of the converter. Small signal stability analysis of the system is carried out to analyze the effect of such active signal injection having different frequencies. The anti-islanding protection algorithm first involves the superimposition of d-axis voltage. Thereafter, two novel indexes are proposed based on which the trip signal logic is developed for the protection scheme. The methodology has been found to detect an unintentional islanding scenario within 90 ms from the initiation instant. The efficacy of the proposed hybrid anti-islanding protection scheme is tested under various abnormal operating conditions by performing simulations on the CIGRE LVtest system. Experimental validation of the proposed methodology has also been carried out in Controller Hardware-in-the-Loop (CHIL) platform using Typhoon HIL 602+ and Speedgoat baseline real-time target machine.

KEYWORDS:

1.      Active disturbance injection

2.      Anti-islanding protection

3.      Distributed generators (DGs)

4.       Small signal stability

5.      Superimposition

SOFTWARE: MATLAB/SIMULINK

CONTROL DIAGRAM:

Fig. 1. Control strategy adopted for the DGs with signal injection through direct axis current control loop.

 EXPECTED SIMULATION RESULTS:

Fig. 2. Performance of the proposed scheme under zero power mismatch condition.

Fig. 3. Performance of the proposed scheme under different types of load Switching

Fig. 4. Performance of the proposed scheme under unbalanced loading condition

 

CONCLUSION:

Small signal stability analysis-oriented design of a hybrid real-time anti-islanding protection scheme has been proposed and successfully demonstrated in this article. The prominent features of the proposed method can be listed as follows.

1) Faster detection time of an unintentional islanding event compared to most of the proposed methods in literature even under the worst case scenario.

2) The selection of amplitude of the disturbance signal has been done considering the negative impact on power quality. On the other hand, the frequency of the active disturbance signal has been selected in such a way that it avoids any kind of excitation of the modes of the system thereby causing instability.

3) Due to the superimposition of the d-axis voltage, the effects due to transients are nullified and the methodology preserves both security and dependability attribute.

4) Although the theoretical analysis has been carried out in the standard IEEE 1547 test system, the protection technique proposed in this article is generalized and can be applied for DGs in any distribution networks.

The efficacy of the proposed algorithm is evaluated under various operating conditions by conducting simulations on the CIGRE LV distribution network. Further, the real-time performance evaluation of the proposed algorithm has been carried out in the CHIL platform using Typhoon HIL 602+ and Speed goat baseline real-time target machine on standard IEEE 1547 test system under various operating conditions. It has been observed that the algorithm is robust under different operating scenarios and is able to preserve its desired functionality in most of the cases.

REFERENCES:

[1] F. Blaabjerg, Y. Yang, D. Yang, and X. Wang, “Distributed power generation systems and protection,” Proc. IEEE, vol. 105, no. 7, pp. 1311–1331, Jul. 2017.

[2] UL Standard for Safety for Inverters, Converters, Controllers, and Interconnection System Equipment for Use with Distributed Energy Resources, UL 1741, 2010.

[3] “Standard for interconnecting distributed resources with electric power systems,” in Proc. IEEE Std. 1547, 2003, pp. 1–28.

[4] F. Noor, R. Arumugam, and M. Y. Vaziri, “Unintentional islanding and comparison of prevention techniques,” in Proc. 37th Annu. North Amer. Power Symp., 2005, pp. 90–96.

[5] S. Dutta et al., “Shifting of research trends in islanding detection method— A comprehensive survey,” Protection Control Modern Power Syst., vol. 3, pp. 1–20, 2018.

Robust Control for Islanded and Seamless Mode Switching of Wind-PV-Grid Tied Generation System

  ABSTRACT:

 This paper deals with robust control strategy for a distributed generation system (DGS), which operates in both islanded and grid-connected modes. Generally, in the low-voltage islanded mode of DGS, the PCC (Point of Common Coupling) voltages are unbalanced due to the unbalanced load connection. Therefore, in an islanded mode of DGS, the LSC is controlled using the IPR (Improved Proportional Resonant) controller to maintain the PCC voltages quality within the IEEE-1547 standard. Moreover, the DGS is capable to synchronize to the grid without any transient current. During the change of modes of DGS, large transients occur in the battery current due to the switching of battery control. This problem is resolved by the presented bidirectional DC-DC converter control strategy and robust ILQSOGI (Inner Loop Quadrature Second Order Generalized Integrator) based PLL. The effectiveness of this DGS control strategy is verified by the corresponding MATLAB/Simulink platform under load unbalance, solar irradiance changes and during mode of switching. Moreover, the simulation results are validated using the test results and show the robustness of the control strategy during abnormal grid voltage condition.

KEYWORDS:

1.      Solar Photovoltaic Array

2.      Power Quality

3.      Bidirectional DC-DC Converter

4.      Load Side Converter (LSC) and Machine Side Converter (MSC)

SOFTWARE: MATLAB/SIMULINK

SCHEMATIC DIAGRAM:

Fig.1 Proposed DGS configuration

EXPECTED SIMULATION RESULTS:

Fig. 2 Performance of DGS during mode of switching from IMS to GCM

 

Fig. 3 Power quality indices of DGS in GCM (a) harmonic spectrum of ig (b) harmonic spectrum of iL

Fig. 4 Performance of BDC control under mode of transition (a) without and with BDC control under grid connection (b) without and with BDC control under grid disconnection.

 

Fig. 5 Comparison of load voltage waveforms (a) with proposed islanded control technique (b) conventional islanded PI control techniq

Fig. 6 Comparison of load voltage THD (a) with proposed islanded control technique (b) conventional islanded PI control technique

 

Fig. 7 Performance of DGS (a) solar and wind power variation in IMS (b) at unbalanced load condition in IS mode

CONCLUSION:

The proposed islanded control technique has used the positive sequence load current components with PR control, which has improved the load voltage quality under unbalanced nonlinear load condition and the results have proven the robustness of control technique in islanded mode of DGS. Simulated results have shown the significant difference in PCC load voltage quality using conventional and proposed islanded control technique. Moreover, simulated results have proven the good load voltage quality under unbalanced nonlinear load condition and the range of load voltage quality lies under the IEEE-1547.4 standard. Experimental results show the robustness of the control strategy, which is capable to operate the DGS in different modes such as in grid connected mode and islanded mode. Moreover, the transient free mode change is also presented through test results. The qualities of PCC voltages and currents are also maintained under the IEEE-1547 standard, in the grid connected mode, an islanded mode and during mode transitions. Test results have presented the performance of DGS under different dynamic conditions and validated the robustness and effectiveness of control schemes. Test results have also shown the effectiveness of feed-forward term in grid connected mode and the smooth operation of grid connected mode under battery disconnection.

REFERENCES:

[1] B. Zeng, J. Zhang, X. Yang, J. Wang, J. Dong and Y. Zhang, “Integrated Planning for Transition to Low-Carbon Distribution System with Renewable Energy Generation and Demand Response,” IEEE Trans. Power Systems, vol. 29, no. 3, pp. 1153-1165, 2014.

[2] M. Savaghebi, A. Jalilian, J. C. Vasquez and J. M. Guerrero, “Secondary Control Scheme for Voltage Unbalance Compensation in an Islanded Droop-Controlled Microgrid,” IEEE Trans. Smart Grid, vol. 3, no. 2, pp. 797-807, June 2012.

[3] IEEE Guide for Design, Operation, and Integration of Distributed Resource Island Systems with Electric Power Systems, IEEE Standard

[4] Bhutto, Ghullam and Bak, C.L. and Ali, Ehsan, “Controlled Operation of the Islanded Portion of the International Council on Large Electric Systems (CIGRE) Low Voltage Dist. Network”, Energies, 20.17.

[5] M. E. Baran and F. F. Wu, “Network reconfiguration in distribution systems for loss reduction and load balancing,” IEEE Trans. Power Delivery, vol. 4, no. 2, pp. 1401-1407, April 1989.

 

Power Quality Enhancement in Sensitive Local Distribution Grid Using Interval Type-II Fuzzy Logic Controlled DSTATCOM

ABSTRACT:

In the current scenario, integration of renewables, growth of non-linear industrial and commercial loads results in various power quality issues. Among commercial utilities connected to the grid, hospital-operated loads include sensitive, linear, non-linear, and unbalanced loads. These loads are diverse as well as prioritized, which also causes major power quality issues in the local distribution system. Due to its widespread divergence, it leads to harmonic injection and reactive power imbalance. Distribution Static Compensator (DSTATCOM) is proposed as a solution for harmonic mitigation, load balancing, reactive power imbalances, and neutral current compensation. The present work utilizes Interval Type-2 Fuzzy Logic Controller (IT2FLC) with Recursive Least Square (RLS) filter for generating switching pulses for IGBT switches in the DSTATCOM to improve power quality in the Local Distribution Grid. The proposed approach also shows superior performance over Type 1 fuzzy logic controller and Conventional PI controller in mitigating harmonics. For effective realization, the proposed system is simulated using MATLAB software.

KEYWORDS:

1.      Local distribution grid

2.      DSTATCOM

3.      Interval type 2 fuzzy logic controller

4.      Power quality and recursive least square filter

SOFTWARE: MATLAB/SIMULINK

SCHEMATIC DIAGRAM:

Figure 1. Proposed Dstatcom Configuration With Interval Type-2 Fuzzy Logic Controller.

 

EXPECTED SIMULATION RESULTS:

Figure 2. Source And Load Current Waveforms Of The Hospital Loads Connected To Ldg Without Dstatcom.

Figure 3. Phase B Harmonic Spectrum.

Figure 4. Source Current Waveforms Of The Hospital Loads Connected To Ldg With Dstatcom.

Figure 5. Load Current Waveforms Of The Hospital Loads Connected To Ldg With Dstatcom.

CONCLUSION:

The performance of IT2FLC based DSTATCOM has been validated in this work and satisfactory results corroborate its effectiveness when sensitive loads are connected to the grid. With proficient behavior of control along with its fast response, it has been proved effective in mitigating harmonics. The simulated results and tabulation highlight the efficacy of the proposed controller over conventional ones. This paper paid close attention to the effective operation of the local distribution grid with sensitive loads which are the source of disturbances from the generation viewpoint. Integration of IT2FLC based DSTATCOM in the system significantly reduces the total harmonic distortion in the system and the RLS filter helps in _ne-tuning it to the acute levels. Also, substantial improvement in the total harmonic distortion is aided by reducing the harmonic value of currents at the source side and provides a much better profile of voltage and current waveforms. Neutral current flow due to unbalanced loads is mitigated with the help of the fourth leg of VSC. Summarized results show that THD levels are less when compared with PI controller and T1FLC at various time instant.

REFERENCES:

[1] A. Ghosh and G. Ledwich, Power Quality Enhancement Using Custom Power Devices. Norwell, MA, USA: Kluwer, 2002.

[2] B. Singh, A. Chandra, and K. Al-Haddad, Power Quality: Problems and Mitigation Techniques. London, U.K.: Wiley, 2015.

[3] R. Bert, ``Power quality issues and the effects on medical equipment,'' J. Clin. Eng., vol. 22, no. 1, pp. 35_40, Jan. 1997.

[4] U. Rao, S. N. Singh, and C. K. Thakur, ``Power quality issues with medical electronics equipment in hospitals,'' in Proc. Int. Conf. Ind. Electron., Control Robot., 2010, pp. 18_34.

[5] L.-G. Angantyr, E. Häggeström, and P. Kulling, ``KAMEDO report no. 93_The power failure at Karolinska university hospital, Huddinge, 07 April 2007,'' Prehospital Disaster Med., vol. 24, no. 5, p. 468, 2009.

Power and Current Limiting Control of Wind Turbines Based on PMSG Under Unbalanced Grid Voltage

 ABSTRACT:

Unbalanced grid voltage sags are the severe challenge for wind power generation system which connected to the grid successfully. The dc bus voltage and output power will fluctuate under unbalanced grid voltage. Moreover, the voltage sags will lead to the increase of peak current, which will bring potential safety hazards to the operation of wind power system. This paper proposes a simple current limiting control scheme without auxiliary equipment, which based on the detailed analysis of the excessive peak current. In this scheme, the machine side converter (MSC) controller adjusts the electromagnetic power according to the power transmitted to the grid by the grid side converter (GSC). Meanwhile, it converts the unbalanced power on the dc-link into the rotor kinetic energy, avoiding the dc-link overvoltage. The GSC controller can not only ensure that the three-phase inverter currents are in the maximum safe range that the converters can bear, but also provide reactive power support for the grid. Furthermore, the fluctuations on dc bus voltage and output power can be eliminated effectively by using the GSC controller. The feasibility of the proposed scheme and the superiority over the traditional control schemes have been verified by simulations under different types of unbalanced voltage.

KEYWORDS:

1.      Unbalanced grid voltage

2.       Peak current

3.      Current limiting control

4.      Rotor kinetic energy

        Reactive power support

 SOFTWARE: MATLAB/SIMULINK

SCHEMATIC DIAGRAM:

Figure 1. The Simplified System Structure.

EXPECTED SIMULATION RESULTS:

Figure 2. (A)The Three-Phase Unbalanced Voltages With 3956 90_, 5636 􀀀30_, 5636 􀀀150_Under Case 1, (B) The

Three-Phase Unbalanced Voltages With 3956 86_, 5406 􀀀28_, 5886 􀀀148_ Under Case 2, (C) Wind Speed.

 

Figure 3. Control Performance Of Different Control Schemes Under Case 1 (A) Control Strategy I, (B) Control Strategy Ii, (C) Proposed Control Strategy.

 

Figure 4. Control Performance Of Different Control Schemes Under Case 2 (A) Control Strategy I, (B) Control Strategy Ii, (C) Proposed Control Strategy.

CONCLUSION:

This paper presents a new power and current limiting control of wind turbine based on PMSG for enhanced operation performance under unbalanced grid voltage. The contributions of this work mainly includes the following parts: 1) Based on the detailed analysis of the output current, a peak current limiting scheme is proposed to ensure the three-phase currents are within the safe range; 2) The unbalanced power in the system is converted into rotor kinetic energy, which solves the problem of dc bus overvoltage; 3) The fluctuations on dc bus voltage and output power are eliminated effectively. The advantages of the proposed scheme for this work are as follows: 1) No additional auxiliary equipment is needed, avoiding high costs; 2) There is no need to exchange the control functions of MSC controller and GSC controller, which avoids the problem of resetting the control parameters; 3) The control of three-phase inverter currents is realized in αβ coordinate system, without the separation of positive and negative sequence of current and complex rotating coordinate transformation, the structure is simple. The effectiveness and superiority of the proposed control strategy have been verified by comparing the simulation results with the other two control strategies under the two different grid faults.

REFERENCES:

[1] M. Qais, H. M. Hasanien, and S. Alghuwainem, ``Salp swarm algorithmbased TS-FLCs for MPPT and fault ride-through capability enhancement of wind generators,'' ISA Trans., vol. 101, pp. 211_224, Jun. 2020.

[2] M. A. Soliman, H. M. Hasanien, S. Alghuwainem, and A. Al-Durra, ``Symbiotic organisms search algorithm-based optimal control strategy for efficient operation of variable-speed wind generators,'' IET Renew. Power Gener., vol. 13, no. 14, pp. 2684_2692, Oct. 2019.

[3] H. M. Qais, M. H. Hasanien, and S. Alghuwainem, ``Enhanced whale optimization algorithm for maximum power point tracking of variable speed wind generators,'' Appl. Soft Comput. J., vol. 86, Jan. 2020, Art. no. 105937.

[4] S. M. Tripathi, A. N. Tiwari, and D. Singh, ``Grid-integrated permanent magnet synchronous generator based wind energy conversion systems: A technology review,'' Renew. Sustain. Energy Rev., vol. 51, pp. 1288_1305, Nov. 2015.

[5] H. Geng, L. Liu, and R. Li, ``Synchronization and reactive current support of PMSG-based wind farm during severe grid fault,'' IEEE Trans. Sustain. Energy, vol. 9, no. 4, pp. 1596_1604, Oct. 2018.