Condition Monitoring of Submodule capacitors in Modular Multilevel Converters

Project Title

Condition Monitoring of Submodule capacitors in Modular Multilevel Converters

Project Area of Specialization Electrical/Electronic EngineeringProject Summary

In the emerging industrial era, the use of converters has rapidly increased to control different appliances according to their power requirement conditions. Specifically, for the high voltage direct current (HVDC) transmission, modular multilevel converter (MMC) technology was introduced because of its enormous benefits like high-quality output voltage and lower switching frequency. But, some failure cases in MMC has created its major flaw in the market because of its sub-module (SM) capacitor’s operating conditions issues. To maintain its reliable operation, a suitable condition monitoring (CM) method is required, which is the core objective of our prototype. Such Prototype-based MMC can ensure us to adjust operating condition i-e the loss of capacitance should be less than 20% to make the capacitance under optimal conditions. As our prototype is comprised of two arms, in each arm, 4 sub-modules and an arm inductor are connected for the single-phase to produce the 5-level output voltage. For the condition monitoring technique, the discharging time of the SM capacitor voltage is utilized to trace the degradation trend of the capacitor. During this process, only targeted SM will be considered under the procedure for condition monitoring rather than effecting the main circuit, which is also the main feature of this novel technology. The control mechanisms for the switching of each SM switches will be performed through Industrial Arduino Microcontroller integrated with MATLAB by simulating different algorithms. In this way designed MMC will help us to monitor the continuous health-state of respective SM capacitors through its voltage discharging curve. 

Project Objectives

The aim of the project is to develop a prototype for the condition monitoring of Submodule capacitors of Modular Multilevel Converters (MMC) and their application in HVDC transmission.

Objectives:

1. To develop the required algorithm and to perform its simulation in MATLAB/Simulink.
2. To develop the appropriate hardware-based prototype.
3. To perform the condition monitoring of the SM capacitor by recording it’s voltage discharging curve.
4. To test and characterize the performance of the developed Porotype based MMC Model and its validation for industrial and HVDC transmission.

Project Implementation Method

The development of the project is based on two major parts. The first part is the hardware-based development of the MMC prototype circuit. As our prototype is based on single-phase MMC topology, it is comprised of 2 arms, each arm is comprised of 4 sub-modules (SMs) and one arm inductor Larm. First, each SM will be designed by applying half-bridge (HB) topology, in which two insulated gate bipolar transistors (IGBTs) with their anti-parallel diodes are connected to a parallel combination of SM capacitor (CSM) and a bleeding resistor (Rb). Afterward, all the SMs will be assembled through Industrial Arduino Microcontroller to control the switching of SMs switches and to produce voltage balancing among all SMs. An Energy dissipation model (EDM) will be connected across the selected SM capacitor as mentioned in the diagram, which is used to discharge the respective sub-module capacitor. Finally, the voltage discharging curve of the respective capacitor will be recorded to analyze its health status.

The second part of our prototype is software-based, in which we will integrate MATLAB with the Industrial Arduino microcontroller of the respected MMC model. With the help of Applied Algorithm deferent switching the condition will be provided to control module capacitor parameters and monitor the reordered voltage discharging curve, on the bases of recorded parameters, data will be interpreted by considering different conditions as mentioned in the flow chart.

                                                           

                          

Benefits of the Project

The Modular Multilevel Converter (MMC) technology use is increasing day by day due to its enormous advantages over the conventional converters. The developed prototype can produce the reliable operation with a highly secured system to regulate the quality output voltage. It is convenient to repeat this condition monitoring (CM) regularly to mitigate disturbances and get the degradation trend. With the increase of Sub-modules (SMs) in the system, there will be negligible impacts on the normal operation of MMC. The degradation of capacitor can be monitored with this continuous condition monitoring rather than manual maintenance inspection.

Technical Details of Final Deliverable

The final product of the proposed project is a single-phase five-level modular multilevel converter whose submodule capacitors are being monitored by the discharging voltage curve of the submodule capacitor.

The final deliverable is divided into primary, secondary and tertiary deliverables; whose details are given below:

1) Primary Deliverable: Develop a Simulink model for Singl-Phase MMC

Simulink model will be developed by using MATLAB R2018a software. A set of four Half-bridge topology submodules are connected in series in each arm.

2) Secondary Deliverable: Development of a prototype of MMC and comparison of outcomes with the Simulink model

A prototype will be developed which is based on single-phase MMC topology. it is comprised of 2 arms, each arm is comprised of 4 sub-modules (SMs) and one arm inductor Larm. So first of all, each SM will be designed by applying half-bridge (HB) topology, in which two insulated gate bipolar transistors (IGBTs) with their anti-parallel diodes are connected to a parallel combination of SM capacitor (CSM) and a bleeding resistor (Rb). The switching signal will be applied by using an Industrial Arduino (a microcontroller).

3) Tertiary Deliverable: Build an Algorithm for condition monitoring of submodule capacitor in the MMC

Condition Monitoring ensures reliable and safer operation of the MMC and it warns the operator before the occurrence of fault. The continuous values of the submodule capacitor discharging voltages will be obtained by the developed Algorithm; simultaneously, all submodules are analyzed. 

Final Deliverable of the Project HW/SW integrated systemCore Industry Energy Other Industries Telecommunication Core Technology OthersOther Technologies OthersSustainable Development Goals Decent Work and Economic Growth, Industry, Innovation and InfrastructureRequired Resources

Item Name	Type	No. of Units	Per Unit Cost (in Rs)	Total (in Rs)
			Total in (Rs)	39634
Arduino Industrial 101	Equipment	2	7500	15000
N-Channel IGBT Transistor HGTG30N60C3D	Equipment	16	620	9920
Diode	Equipment	16	7	112
Resistor	Equipment	30	2	60
Electrolytic Capacitor (2200uF)	Equipment	30	25	750
Inductor	Equipment	20	150	3000
Jumper Wires (M to M, F to F, M to F)	Equipment	150	8	1200
Heat sink with screws	Equipment	40	30	1200
Multimeter (UT33A+Digital)	Equipment	1	1650	1650
Vero board	Equipment	5	80	400
Adjustable DC Regulated Power Supply DIY Kit	Equipment	1	4192	4192
LCD Display	Equipment	4	150	600
Bread Board	Equipment	2	150	300
Soldering iron	Miscellaneous	1	350	350
Soldering wire 100gm	Miscellaneous	2	200	400
Wire cutter corved jaw plier	Miscellaneous	1	500	500