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.
- Local distribution grid
- Interval type 2 fuzzy logic controller
- Power quality and recursive least square filter
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.
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.
 A. Ghosh and G. Ledwich, Power Quality Enhancement Using Custom Power Devices. Norwell, MA, USA: Kluwer, 2002.
 B. Singh, A. Chandra, and K. Al-Haddad, Power Quality: Problems and Mitigation Techniques. London, U.K.: Wiley, 2015.
 R. Bert, “Power quality issues and the effects on medical equipment,” J. Clin. Eng., vol. 22, no. 1, pp. 35_40, Jan. 1997.
 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.
 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.