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Journals
5. Ankit Yadav, S. N. Singh & S. P. Das, "Symmetrical Multi-pole MMC-HVDC with DC Fault Ride Through Capability Using HBSM," Electric Power Components and Systems, Vol. 51, issue 10, pp 991-1008, 2023 DOI: 10.1080/15325008.2023.2188315
Abstract
The modular multilevel converter (MMC) has proven to be the most advanced voltage source converter (VSC). For long-distance power transfer, high-voltage DC (HVDC) is the best choice. Across the globe, electric power networks are witnessing rapid growth in MMC-HVDC installation to meet the ever-growing power demand. The existing AC transmission lines can be converted to DC lines by adding converters. The MMC-based multi-pole HVDC presents an adequate solution for upgradation. However, more study is required to make it a reality. The present paper attempts to bridge this gap. The proposed study can be divided into two parts. Initially, the concept of symmetrical multi-pole MMC-HVDC is proposed, and its mathematical relations have been derived. The multi-pole has been subdivided into an even and an odd configuration. The half-bridge submodule (HBSM)-based MMC lacks DC fault handling capability. The second part of the study includes controller and fault analysis of the HBSM-based tri-pole MMC HVDC. The study shows the severity of the pole-to-pole faults, leading to a complete shutdown of the transmission line. A controller and an algorithm for the DC fault-ride-through (FRT) have been proposed. The proposed controller has digital switches to temporarily bypass the real-time measurement values with measurements taken under healthy conditions. An impact analysis of the parameters of one MMC on the equilibrium of the entire multi-pole configuration is performed. The performance of the proposed controller has been carried out on a real-time digital simulator (RTDS). The proposed controller and FRT algorithm ensure that the tri-pole HVDC maintains the power supply during all DC faults. In the worst-case scenario, the shutdown is averted with a 50% reduction in power transfer capability. The transients in active and reactive power are minimized and eliminated within a cycle. Further, using the most economical and simplest submodule ensures the configuration without any additional cost.
4. Ankit Yadav, SN Singh, and SP Das, “Suppression of Third-Order Harmonic Current in Transformerless MMC,” in IET Energy Conversion and Economics, Vol. 3, issue 4, pp. 244-257, August 2022
Abstract
The modular multilevel converter (MMC) based high voltage DC (HVDC) system can be effectively used for bulk power transmission. The MMC topology for the voltage source converter (VSC) has several advantages. In this work, the transformerless operation of MMC is explored. The internal dynamic of MMC can induce a third-order zero-sequence harmonic current. Its effect on the system is analysed, including the adverse impacts on energy requirement per arm and power transfer capability. The internal dynamic equations of the transformerless MMC configuration are derived, and two different controllers: the proportional-resonant (PR) controller and proportional-integral (PI) controller, were applied to suppress the unwanted third-order current. The performance analysis of these controllers is presented and the results indicate that the controllers efficiently suppress the third-order harmonic current. Moreover, the electromagnetic transient (EMT) models of MMC under different configurations have been developed on the real-time digital simulator (RTDS) platform. An analysis of internal variables of the MMC is also included to ensure that the controller does not adversely affect the system. Lastly, the state-space model is developed, and the stability is analysed.
3. Ankit Yadav, SN Singh and SP Das, “Design of internal dynamics based MMC controller for HVDC transmission,” in IET Energy Conversion and Economics, Vol. 1, Issue 2, pp. 93-103, November 2020.
Abstract
Currently, the modular multilevel converter (MMC) is the most advanced voltage source converter topology. Because the MMC is a converter topology, the most common approach for controller design is considering the conventional converter model to design the controller accordingly. Though this approach ignores the internal dynamics of the MMC, the modular structure enables distribution of the capacitors in six arms of the MMC. However, this distribution leads to a complex internal dynamic that affects the controller operation and cannot be disregarded. In this study, a detailed fundamental and circulating current model of the MMC is developed while considering its internal dynamics. The detailed modelling reveals cross‐ and inter‐couplings. On the basis of the detailed model and analysis of the couplings, three controllers have been proposed. Moreover, the performances of the proposed and conventional controllers have been analysed and compared under steady‐state and active and reactive power changes. The proposed controllers are observed to achieve improved decoupling compared to that achieved by the conventional controller.
2. Ramakrishna Kappagantu, S. Arul Daniel and Ankit Yadav, “Power Quality Analysis of Smart Grid Pilot Project, Puducherry” in Procedia Technology, Science Direct, Elsevier, Vol. 21, pp. 560-568, November 2015.
Abstract:
The concept of smart grid lies in the integration of information and communication technologies into the existing power system infrastructure to get maximum benefit to the end-user. The objective of implementing smartness in the grid is to increase the reliability, efficiency, customer satisfaction and power quality of the vast electrical distribution network. This paper presents the power quality analysis of a smart grid pilot project of utility in Puducherry implemented under collaboration of Power Grid Corporation of India Limited. The analysis has been done by data collected via power analyser at several locations in the smart grid pilot project. Analysis includes harmonics, sub-harmonics, total harmonic distortion and other various components of power quality. Instead of using only voltage parameters, current parameters are also considered for analysis.
1. Ankit Yadav and M. M. Tripathi, “Novel switching scheme for single phase VS Inverter using value of output current as modulating signal,” in International Journal of Science & Technology. ISSN (online): 2250-141X, Vol. 3 Issue 3, December 2013.
Abstract
Power electronic devices and especially inverters have emerged as one of the most important devices of power electronics based system. With the time inverters (both 1–phase 3–phase) are gaining more attention due to their application in renewable energy system and smart grid system. These inverters and other power electronics devices are basically combination of power electronic switches, which are operated and controlled by some switching scheme. This paper is presenting a new switching scheme for single phase H-bridge VS (voltage Source) DC–AC inverter. The new Switching Scheme for Single Phase VS Inverter using value of output current as modulating signal has been designed and presented in this paper. The simulation has been carried out under different loading conditions and results have been compared with the results of PWM under same loading conditions. The new switching scheme shows several advantages over the PWM scheme.
Conference
7. P. K. Mallaiah, A. Yadav and G. Ravikumar, "Data Integrity and Cyberattack Detection using Dynamic Watermarking for Resilient Microgrids," 2024 IEEE Power & Energy Society Innovative Smart Grid Technologies Conference (ISGT), Washington, DC, USA, 2024, pp. 1-5, doi: 10.1109/ISGT59692.2024.10454158.
Abstract
Cyber-attacks on microgrid systems, especially data manipulation attacks such as replay attack and Denial-of-Service (DoS), causes communication delay and unstable responses. Even though control strategies such as Consensus Control (CC) are able to coordinate electric current and voltage flow, they are at risk of malicious attacks. Communication delay leads to undetected changes in line current, and voltage leads to incorrect responses from the consensus controller, which overloads the microgrid in milliseconds. To address these challenges, this paper presents an Observer System (OS) based Dynamic Watermark (DW) detection model that detects delay-induced cyber-attacks during steady states and load fluctuations. We have developed a Grid-Specific Dynamic Watermarking (GSDW) signal that enhances real-time detection capabilities, resulting in a real-time non-zero residual showing cyber attack dynamics in the proposed observer system. Our detailed case study demonstrates real-time attack detection and prevention, ensuring the stability and integrity of Microgrid (MG) systems under challenging cyber threat conditions. Comprehensive simulations and validation demonstrate the practicality and efficacy of our approach in mitigating risks posed by delay-induced cyber attacks in MG systems.
6. Ankit Yadav, S N Singh and S P Das, “Design and Analysis of Multi-pole MMC-HVDC”, IEEE PES General Meeting 2021, 26-29 July 2021
Abstract:
Modular multilevel converter (MMC) is replacing all existing voltage source converters (VSCs) in various applications. Muti-pole high voltage DC (HVDC) is one among the few applications, still unexplored significantly. The present paper tries to bridge that gap. Three-wire symmetrical and asymmetrical MMC-HVDC configurations using two MMCs are proposed. Performance analysis has been carried out with both MMCs operating under identical as well as different settings. An analysis to ascertain the impact on one MMC following the changes in operating conditions of other MMC has been carried out. The present work focuses on the three-wire structure as a three-wire structure can be used to upgrade existing AC transmission lines into an HVDC transmission line. The proposed study has been carried out using the electromagnetic transient (EMT) model of MMC on the real-time digital simulator (RTDS).
5. Ankit Yadav, SN Singh and SP Das, “Analysis of Transformerless MMC and Suppression of Third Order Harmonic Current”, in 9th National Power Electronics Conference, NPEC2019, NIT Tiruchirappalli (T.N.), India, December 13-19, 2019.
Abstract
In the rapidly expanding electrical power network the modular multilevel converter (MMC) based high voltage DC (HVDC) presents the most effective mean for bulk power transmission. This recently developed MMC topology for the voltage source converter (VSC) has many advantages. The one unexplored advantage of MMC is transformerless operation. This paper analyses the transformerless operation of the MMC. The internal dynamic of the MMC generates third order voltage ripple, which has the potential to induce the third order harmonic current. With star-delta transformers as an interface between MMC and AC network, this harmonic current is blocked. However, with the transformerless MMC and physically grounded DC terminal, this third order harmonic current poses severe harm to the MMC as well as to the AC source. This paper also proposes a Proportional Resonant (PR) controller to suppress the third order harmonic current. To perform the analysis, electromagnetic transient (EMT) model of MMC under different connection has been developed on the real-time digital simulator (RTDS). The developed controller successfully suppresses the third order harmonic current.
4. Ankit Yadav, SN Singh and SP Das, “Development of EMT Model for Circulating Current Control”, in 5th IEEE International Conference on Electrical, Computer and Electronics, UPCON 2018, MMMUT Gorakhpur (U.P.), India, November 2-4, 2018. (Best Paper Award)
Abstract:
The structure of the modular multilevel converter (MMC) gives it an edge with respect to other converter topologies. Being in its early phase, MMC is still evolving in term of architecture, modelling and the control philosophy. Contributing to same, this paper presents the electromagnetic-transient (EMT) model on real-time digital simulator (RTDS) platform and the detailed small-signal model of MMC along with control structure. Results of both models have been compared. Further, along with the stability analysis, necessity and impact of the circulating current controller have also been investigated.
3. Ankit Yadav, SN Singh and SP Das, “Modular Multi-level Converter Topologies: Present Status and Key Challenges”, in 4th IEEE UPCON international Conference, GLA University Mathura, 26-28 October 2017. (Best Paper Award)
Abstract
Modular multilevel converter (MMC) is an emerging technology for various applications including high voltage dc transmission and wind energy conversion systems. Submodule based MMC architecture dominates over other converters topologies, due to various technological as well as economic advantages. This paper presents a comprehensive review of MMC topology and its submodules. Different types of submodule architectures are discussed to provide an overview of evolving technology. Different submodules are grouped in accordance to their output terminal voltage levels. The key issues and challenges are also highlighted.
2. Ankit Yadav and M. M. Tripathi, “A Novel Wavelet Modulation Scheme for Single Phase Inverter,” in IEEE Power India International Conference (PIICON), December 2014.
Abstract:
DC-AC Inverters are key components in various industrial applications that include power supplies, motor drive systems and power systems. Now-a-days dc-ac inverters (both 1-phase & 3-phase) are finding more attention in renewable energy systems also. In this paper a new kind of switching scheme is discussed where gate pulses for switching of Single Phase 4 pulse voltage source (VS) DC-AC inverters are generated using wavelet modulation. Simulation for different loading conditions is performed and results are compared with results of PWM and Square pulse switching under same loading conditions. The wavelet modulation technique has shown tremendous advantages over PWM technique.
1. Ankit Yadav and M. M. Tripathi, “Modified hysteresis switching scheme for 3-phase voltage source inverter,” in IEEE Power India International Conference (PIICON), December 2014.
Abstract
This paper presents a new switching scheme for 3-phase Voltage source inverter to tackle the harmonics problem in off-grid power system. The proposed strategy is modification over the existing strategy of hysteresis band current control method. The proposed switching strategy for 3-phase inverter system is an upgrade of the scheme that has been tested already with 1- phase system. Simulation with linear as well as nonlinear loads has been performed using new scheme as well as PWM scheme. The results obtained have been compared with results of PWM scheme and the proposed scheme has shown much improved outcomes compared to the PWM scheme. The comparatively higher output voltage and current also ascertain the usefulness of new proposed switching methodology.