Shadowing Practice: Back to Back HVDC Modular Multilevel Converter for Transient Voltage Part 1 - Learn English Speaking with Video
Elige un modo de práctica
Cada modo abre una sala de práctica a pantalla completa.
230 oraciones
Si las oraciones son demasiado cortas o largas, haz clic en Editar para ajustarlas.
1
This is Jaan Girbadah Sumrur, Assistant Professor at Electrical Engineering Department, Sakhar IBE University.
2
In our today's video we will discuss one of the research paper which is titled
3
Back -to -Back HVDC Modular Multi -Level Convertor for Transient Voltage Dib Mitigation in Passive Networks.
4
In my previous video I explained this research paper, Design and Control of Modular Multi -Level Convertor for Voltage Dib Mitigation.
5
Now this work is done in 2022 and this work is totally inspired
6
and this work totally follows basically this work which was done in 2018.
7
2018. Alright.
8
This was a thesis performed by a student of Bachelors.
9
And he worked in CERN, European Organization for Nuclear Research for one year.
10
Okay.
11
For nuclear research laboratory like CERN, where the exceptionally high power quality conditioners are required,
12
So there is a dynamic load, high power quality conditioners are used in CERN.
13
The immunity against transient voltage dip is a vital importance.
14
So if there comes the problem of voltage dip on the grid side, this is very important to mitigate that voltage dip.
15
So the problem statement was to overcome the issue of voltage dip coming on the grid side that was affecting their load.
16
By using the traditional HVDC MMC back -to -back configuration with properly dimensioned submodule capacitor, voltage diffs can be mitigated instantaneously.
17
So they performed the steady on MMC back -to -back configuration to mitigate that issue of voltage dip,
18
improving power quality of the network.
19
The diminishing of the capacitor is shown as one of the key elements of this paper, yes,
20
because the fault right through technique applied in this paper is
21
by using inherent energy storage capacity of the capacitors in the MMV.
22
That energy in capacitors is basically utilized to compensate for the missing energy of the voltage dip on the grid side.
23
Firstly, the actual voltage dip statistics recorded at Sun are presented
24
and described than the traditional capacitor submodule dimension method present compared to proposed energy design rule.
25
To validate the energy dimension mitigation perform a detailed Simulink model of 220 MVHVDC modulo multilabular consider is described
26
and the main results are presented.
27
So here they use MATLAB Simulink.
28
For this study, the paper concludes with the main conclusion of this study and the future works.
29
Today's introduction, today several stable solutions.
30
There are several solutions available for voltage mitigation.
31
If for smaller load, UPS can be a good solution to get uninterrupted supply.
32
In case of dip, UPS can work better.
33
But the limitation here is the size of energy storage, which is preferable for battery storage system, and for small systems this can work.
34
But for higher rating, the solution of UPS is not interesting, then researchers move towards DVR.
35
But again, DVR is not the optimum solution.
36
This paper suggests that the optimum solution is to, if you can afford, then the back -to -back HPDC -MMC can be a good
37
solution for mitigating voltage -up issues to deliver constant load power supply to dynamic loads.
38
The idea of using HVDC system completely based on VAC converters to supply a high power demand
39
with high quality was analyzed in SEVEN where certain operation margin allowed to take over one converter from Nether and Kesa fault.
40
If no operation margin is kept, all converters are running at one per unit, then another strategy is to implement the mitigate,
41
has to be implemented to mitigate transient voltage dip.
42
So if all the converters running at their full capacity one per unit,
43
then there need to be some fault right through strategy applied to mitigate the voltage dip,
44
voltage sake issue occurring at the gate side.
45
One of the solutions used by researchers in previous days was
46
by allowing higher currents to flow during the time of transient voltage dip.
47
a compensation effect could be attained.
48
So if there was a voltage dip, so to compensate that missing energy of the voltage dip or voltage sake,
49
higher current, probably two times more than normal current, was taken from the grid to mitigate that, to compensate that missing energy.
50
But this is not a good solution, not recommended.
51
This solution was investigated in research paper 8, concluding that by allowing two times the nominal current,
52
the HVDCVAC solution can protect our network from voltage dip.
53
So they observed that if you, during the voltage dip, if you take two times more current than the normal current,
54
the voltage dip issue was being solved out.
55
Regarding the specific voltage dip mitigation for HVDC links, MMC topology results the most interesting.
56
For these convertors, the electric energy is stored in the capacitor
57
which they need in any case for the normal operation can be partially used to support the voltage during transient voltage dips.
58
So as you know that in MMC, in case of half -built cell or full -built cell,
59
both topologies or every topology has a cell, a capacitor cell.
60
And one of the key characteristics of MMC is inherent energy storage capability.
61
So that energy can be utilized to compensate for the missing energy, caused missing energy due to the voltage dip or voltage.
62
So this capacitor energy can be potentially utilized in this application.
63
In principle, it could be expected that they provide the fast response thanks to the fast release of energy in the capacitor.
64
The energy in the capacitor can be released fast.
65
And fast enough that your DC link does not go to the undervoltage.
66
And the load should not experience even slight disturbance.
67
So you should release the capacitor energy very quickly, and this is possible to release it,
68
so that load may not get disturbance.
69
This voltage -dependent grid side should not affect the load.
70
This is the objective.
71
To explore the potential application of HVDC MMC for voltage -dependent mitigation purpose,
72
an essential question is how much of capacitor energy is needed for good performance.
73
This is the question.
74
So now the question is you need to know how much is missing energy due to the voltage dip
75
and how much extra energy you need to store in the capacitor to mitigate
76
that dip issue or to compensate the missing energy.
77
How much extra energy do you need to store it?
78
In this sense the first decision to be made is to choice between the transient voltage voltage dip mitigation strategies,
79
and increasing line current strategy and energy storage based solution.
80
So there are two approaches.
81
One approach to mitigate that voltage dip strategy is increasing line current strategy, which is not good, because if you are using increasing line current strategy,
82
then the higher currents two times more than normal current will flow.
83
In that case, the converter size will be overrated, converter station will be more costly, more having more footprint weight.
84
So this is not recommended.
85
The recommended approach here in this paper, the energy storage -based solution.
86
But now researchers are working that even the best choices,
87
the controller design should be such effective that neither we should prefer this line current strategy or energy -based storage system.
88
But there should be automatic switching.
89
The controller should be fast enough and robust enough to mitigate this issue.
90
So researchers are also working in this area.
91
Anyhow, in this paper the technique suggested is energy storage based solution.
92
We will discuss energy storage based solution.
93
The first storage strategy is allowing the rectifier to draw increased current during the voltage dips such
94
that the DC bus transfers nominal power at all times.
95
With the inverter synthesizing AC voltage for the load, applying this solution with MMC means
96
that semi -calorie switching devices in sub -module capacitor must be
97
highly overrated compared to record rating for normal operating condition in the rectifier, making the solution less elegant and interesting.
98
Therefore, increasing line current is not good enough because it will increase the overall converter station size cost.
99
The second study which is one of the one
100
which is the one proposed in this paper is to design the MMC sub -module
101
capacitors according to dedicated energy calculation presented in the energy calculation chapter.
102
The rectifier shall be designed to draw nominal current from the gate during a transient voltage dip,
103
extracting the maximum allowed power to optimize the needed storage for dip mitigation.
104
The advantage is that both rectifier inverter will be dimensioned for normal operation condition
105
and by using proposed design method for the overall system design optimum with it.
106
So this is a better approach to use that capacitor energy storage property to mitigate this dip Thank you.
107
In general, the MMC shows very high efficiency and provides several power quality conditioning features to passive networks, such as voltage dip mitigation, reactive power compensation.
108
So reactive power compensation is also possible with MMC -based HVDC system.
109
A passive network in this synopsis in the paper is defined as a network with a short circuit ratio of zero,
110
which means no generation of energy.
111
Okay.
112
Behind acting as a dip mitigation,
113
the inverter can provide reactive power support for the passive load network in two coordinates and even supporting pulsating dynamic loads.
114
So this is an additional advantage
115
that reactive power support of the load is also possible with reactive power controller on the inverter side.
116
In the case of particle excise, this could be a very beneficial feature for it could replace a static VR compensator,
117
so no need of a static VR compensator in this case.
118
If you have back -to -back HVDC MMC system, the rectifier has the ability to support the grid with reactive power injection during phase
119
and can allow power oscillation dipping and grid destabilization.
120
Lastly, the system features steady state control allowing high precision of voltage and frequency regulation for the passive network.
121
So even during this voltage dip, there will be no effect on the load.
122
The load will be getting the constant power supply.
123
There will be no disturbance on the load side.
124
This paper is in general analysis of the potential of transient voltage mitigation of an MMC -based HVDs back -to -back link.
125
An important part is the dimensioning of the capacitors.
126
This is very important.
127
Analyze an energy dimensioning chapter, which highlights also the correlation between storage size and dip mitigation performance.
128
So certainly the storage size capacitor dimensioning will depend upon what is the dip severity, how much dip is happening,
129
for how many seconds, how much amplitude of dip is there, depending upon the dip severity, amplitude of the dip, time of the dip,
130
capacitor dimensioning will be performed, energy storage size will be performed.
131
And this is performed in detail in the thesis work of this same author.
132
You can also refer to that thesis of this author.
133
After the main simulation model is present, including also the control circuit, the conclusion shows the main result concerning dip mitigation performance.
134
OK, the energy dimensioning, which is very important because it uses capacitor energy storage property.
135
So energy dimensioning of capacitor becomes important.
136
The target of this paper is to show the potential of MMC -based HPD -link system for transient voltage dip mitigation
137
and give insight in energy storage calculation for the modules.
138
This will mean a new proposed design rule for MMC converter when transient voltage dip mitigation is required.
139
The traditional way for storage design in the module
140
which is done in the industry is to design the energy storage of MMC converter around 30 to 40 kilojoule per mva.
141
So converter registration, traditional way of storage design is that range is 30 to 40 kilojoule per mva per converter registration.
142
For a break to break system this results in total system energy because one is a rectifier other is inverter,
143
so total system energy is of 60 to 80 kJ per mVA.
144
But with the object or dip mitigation,
145
a new design for the value of stored energy per mVA has to be derived because this is for the normal case.
146
But if you want to mitigate the voltage dip without taking increased line current strategies then this need to be recalculated.
147
The first step is to analyze the discharge capabilities of submodule capacitors.
148
If the modular multilevel converter is assumed to operate with a DC voltage of 1 per unit,
149
so the requirement is that you need to maintain DC voltage 1 per unit, means whatever the desired reference voltage is, that should be tracked.
150
In per unit it should be 1 per unit.
151
At modulation index of 0 .8 in a steady state.
152
So in a steady state, modulation index value uses, you prefer 0 .8.
153
The inverter is limited to minimum DC voltage input of 0 .8 per unit.
154
That means DC link should not fall below 0 .8 per unit.
155
If it falls below the 0 .8, if it becomes 0 .4, 0 .5 per unit, then the inverter has to operate in our modulation,
156
which is not required, which is a big problem.
157
Our modulation is an issue, and if there comes opposite problem, not the undervoltage, but our voltage in the DC link,
158
that is also an issue that will burn the DC cable, our MMC converter station and HVDC can collapse.
159
So both under -voltage and over -voltage in the DC link are not desired.
160
The total energy stored for both inverter and rectifier depends on DC voltage of the bus.
161
The following is the fundamental equation for energy in the capacitor.
162
This is a well -known equation of energy stored in the capacitor 1 over 2 Cv square.
163
With this in mind, the total energy store must be high
164
that after mitigating a dip the DC voltage should not be below 0 .8 per unit based on the previous equation. So, we...
165
We have to make sure that capacitor discharges the energy fast enough so that DC voltage should not fall below 0 .8.
166
This means that capacitor only allowed to discharge up to 36 % of their initial steady -state charge.
167
This result concludes the total energy of the capacitor should be damaged 2 .77 times
168
the missing energy for the inverter operating with modulation index of 0 .8 means if the missing energy,
169
whatever the missing energy is divided by 0 .36
170
this means the missing energy stored in the capacitor should be 2 .77 times more than the missing energy.
171
Calculate the missing energy due to the voltage dip
172
and then you should store 2 .77 times more as compared to E missing, multiplied by E missing.
173
So let's say if E missing is 0 .3 then E stored should be 2 .77 into 0 .3.
174
Second step is to find the missing energy of the system caused by the dip.
175
So a statistical analyzer of all mile voltage dip in a highly sensitive distribution present in figure 1.
176
This shows that this picture shows voltage dip magnitude percentage and for the time,
177
how much time the dip remains.
178
And accordingly, depending upon this curve,
179
we will come to know that how much energy need to be stored in a back -to -back HVDC MMC system.
180
Okay.
181
In a function called dip severity is introduced, dip severity, this function is a dip magnitude multiplied by dip duration.
182
If the dip duration, let us say if it is for 75 millisecond
183
and the dip magnitude is 50 50 % multiplied by 0 .75 ms will be the dip severity. So
184
if you multiply both dip duration with the dip magnitude
185
you will get dip severity where dips are assumed by 3 phase dips.
186
The calculation operates in per unit system with 1 second days per unit in time.
187
This makes power and energy base equal.
188
Figure 2a shows histogram of dip severity for all required dips and log logistic distribution function is fitted to data.
189
As it can be observed the majority of registered voltage dips are included in a window of 50 % at 150 milliseconds.
190
So figure 2a, the data was collected, it was observed
191
that the most repeated pattern of the dip severity was 50 % dip for 150 milliseconds in the CERN network.
192
Figure 2b shows distribution density function rate and the cumulative function
193
essentially shows how to dimension the stored energy of the converter as a function of confidence.
194
With 99 % being the chosen value for the study,
195
more trivially explained that 99 % confidence translates to 99 % of all the voltage diff will be mitigated.
196
So in this research paper,
197
Here the capacitor dimensioning or energy dimensioning is made not 60 to 80 kJ per mEV
198
because this is for the normal case but for voltage dip this needs to be recalculated.
199
So it is designed for such a value so that 99 % of dips are successfully mitigated.
200
The fact that rectifier will always draw a nominal current from the grid means
201
that dip severity in the faked missing energy caused by the dip.
202
So E missing is current dip, change in current dip multiplied by change in V dip multiplied by time in T dip,
203
how much time dip lasts.
204
By graphical solution of our 99 % confidence figure to be the missing energy is seen as 0 .0375 per unit.
205
So if you see here,
206
the missing energy due to the dip in the sun network with
207
that particular load was missing energy in most of the time, 99 % of the time was 0 .0375 per unit.
208
This was the missing energy due to the dip.
209
So if this is a missing energy now, how much energy should be stored in the capacitors?
210
it should be e stored should be 2 .77 times this missing energy
211
so multiply 2 .77 with this value you will get
212
that total stored energy should be 0 .104 per unit of the system for the system
213
Assuming a system of 1 mV rating this means that the reactive inverter together must have an energy of
214
104 .0 .104 means it should have energy of 104 kJ per mVa.
215
Normally it is 60 to 80 kJ per mVa but for the mitigation of voltage dip and for
216
compensating the missing energy
217
and to make sure the 99 percent of the voltage dip
218
severities are successfully mitigated the system should be now having energy storage of 104 kJ per mVA.
219
Now this is the disadvantage
220
that overall energy diminishing is changing overall capacitor sizing will be different
221
so this will make this converter station little bit cost a little bit expensive as compared to normal.
222
So this approach has the disadvantage in terms of cost.
223
Comparing this result with the commonly used 60 to 80 kJ per meter shows by only a slight increase of stored energy.
224
So there is a slight increase, normally it is 80 kJ per mva
225
but to mitigate the voltage it should be the system should be 104 kJ per mva.
226
99 % all volt dips will be mitigated if the system is off, 104 kilojoule per MVA.
227
Energy storage is this one.
228
OK.
229
So in the next part, we will discuss simulation model and the results.
230
Thank you.
Descargar app
Todo lo que necesitas para hablar con fluidez
Pronunciación con IAEvalúa cada oración
Práctica de IPADomina cada sonido
VocabularioConstruye tu banco de palabras
Juego de vocabularioAprende mientras juegas
FOR YOU
Recomendar Video
C22
119 oraciones
17E058 - Back to Back Stations
Daily ConversationUniversity Students
C11
15 oraciones
How does modular construction impact costs?
Daily ConversationUniversity Students
C12
78 oraciones
Vanishing & Exploding Gradient explained | A problem resulting from backpropagation
Daily ConversationUniversity Students
C12
40 oraciones
Inside the Relay Controlled SF6 Circuit Breaker: Preventing Arcs and Ensuring Safety
Daily ConversationUniversity StudentsWorking Adults
C14
50 oraciones
Decompression alone versus decompression with instrumented fusion in the t | Kaiser | EUROSPINE 2025
Daily ConversationUniversity Students
C167 oraciones
The Ultimate IoT Roadmap in 2026? | Embedded Systems & IoT Career Roadmap
Daily ConversationUniversity StudentsWorking Adults
C12
520 oraciones
An Animated Introduction to Vibration Analysis by Mobius Institute
Daily ConversationUniversity Students
C11
7 oraciones
Diodes Explained - The basics how diodes work working principle pn junction
Daily ConversationUniversity StudentsWorking Adults
C11
130 oraciones
Climate Change Debate | Kriti Joshi | Opposition
Daily ConversationUniversity Students
C11
19 oraciones
I Made an EMP Device... It Actually Works
Daily ConversationUniversity StudentsWorking Adults
C11
95 oraciones
26 - How does harmonic phase shifting work including a detailed mathematical explanation to reduce s
Daily ConversationUniversity Students
C12
82 oraciones
CAP Theorem Simplified
Daily ConversationUniversity StudentsWorking Adults
Vocabulario y notas de pronunciación para esta lección
Esta lección de conversación se basa en el vídeo “Back to Back HVDC Modular Multilevel Converter for Transient Voltage Part 1”. Las palabras que más se repiten: dip, energy, voltage, capacitor, missing. Este vídeo tiene 230 frases y 3097 palabras para practicar shadowing. La parte hablada dura 21:27. El hablante mantiene un ritmo constante de unas 144 palabras por minuto, cómodo para el shadowing. Solo el 77 % de las palabras está entre las 3.000 más comunes del inglés, por lo que el vocabulario es exigente.
Vocabulario clave de este vídeo
15 palabras del vídeo que vale la pena aprender, con su pronunciación y significado:
| Palabra | Pronunciación | Significado |
|---|---|---|
| voltage sustantivo | /ˈvəʊltɪd͡ʒ/ | voltaje, tensión |
| mitigate verbo | /ˈmɪt.ɪ.ɡeɪt/ | mitigar |
| dimension sustantivo | /daɪˈmɛn.ʃən/ | dimensión |
| severity sustantivo | /səˈvɛɹ.ə.ti/ | severidad |
| dip verbo | /dɪp/ | mojar, pringar |
| grid sustantivo | /ɡɹɪd/ | cuadrícula, matriz |
| reactive adjetivo | /ɹiːˈæktɪv/ | reactivo |
| compensate verbo | /ˈkɑm.pənˌseɪt/ | compensar |
| passive adjetivo | /ˈpæs.ɪv/ | pasivo |
| magnitude sustantivo | /ˈmæɡnɪtjuːd/ | magnitud |
| researcher sustantivo | /ˈɹiˌsɝ.t͡ʃɚ/ | investigador, investigadora |
| module sustantivo | /ˈmɑd͡ʒul/ | módulo |
| calculation sustantivo | /ˌkælkjuˈleɪʃn̩/ | cálculo, calculación |
| nominal adjetivo | /ˈnɒm.ɪ.nl̩/ | nominal |
| compensation sustantivo | /ˌkɑm.pənˈseɪ.ʃən/ | contrapartida |
Phrasal verbs que vas a escuchar
| Palabra | Significado |
|---|---|
| take over verbo | apoderarse, enseñorearse |
Gramática en este vídeo
Las estructuras que más usa el hablante, con las palabras exactas del vídeo:
| Estructura | En el vídeo |
|---|---|
| Voz pasiva be + participio pasado — importa lo que ocurre, no quién lo hace | is titled · are required · can be mitigated |
| Oraciones de relativo who / which + oración — información extra sobre una persona o cosa | paper which is · work which was · storage, which is |
Pronunciación a tener en cuenta
- Los sonidos de “th”: thesis /ˈθisɪs/, synthesize /ˈsɪnθəsaɪz/
- Los sonidos de “sh” y “zh”: dimension /daɪˈmɛn.ʃən/, calculation /ˌkælkjuˈleɪʃn̩/, compensation /ˌkɑm.pənˈseɪ.ʃən/, duration /dʒʊˈɹeɪ.ʃən/, equation /ɪˈkweɪ.ʒən/
- Palabras largas — cuida el acento: severity /səˈvɛɹ.ə.ti/, compensation /ˌkɑm.pənˈseɪ.ʃən/, successfully /səkˈsɛs.fə.li/, registration /ˌɹɛd͡ʒ.ɪˈstɹeɪ.ʃən/, capability /ˌkeɪ.pəˈbɪl.ɪ.ti/
Sonidos difíciles para hispanohablantes:
- s + consonante al inicio — sin añadir una “e” delante: steady /ˈstɪdi/, slight /slaɪt/, static /ˈstæt.ɪk/, stable /ˈsteɪ.bəl/, statistical /stəˈtɪs.tɪ.kəl/
- /v/ — no es /b/: los dientes tocan el labio inferior: voltage /ˈvəʊltɪd͡ʒ/, severity /səˈvɛɹ.ə.ti/, reactive /ɹiːˈæktɪv/, passive /ˈpæs.ɪv/, observe /əbˈzɜːv/
- /z/ — sonora, no /s/: observe /əbˈzɜːv/, analyze /ˈæn.əˌlaɪz/, translate /tɹænzˈleɪt/, analyzer /ˈæn.əˌlaɪ.zɚ/, excise /əkˈsaɪz/
Cómo practicar con este vídeo
- Escucha el vídeo entero una vez sin hablar y anota las palabras que no conoces.
- Haz shadowing frase por frase a velocidad normal, repitiendo cada una hasta que tu ritmo coincida con el del hablante.
- Grábate y compara con el original, prestando atención a palabras como voltage, mitigate, dimension.
¿Qué es la Técnica de Shadowing?
Shadowing es una técnica de aprendizaje de idiomas respaldada por la ciencia, desarrollada originalmente para la formación de intérpretes profesionales y popularizada por el políglota Dr. Alexander Arguelles. El método es simple pero poderoso: escuchas audio en inglés nativo y lo repites en voz alta de inmediato, como una sombra que sigue al hablante con solo 1-2 segundos de retraso. A diferencia de la escucha pasiva o los ejercicios de gramática, el shadowing obliga a tu cerebro y músculos de la boca a procesar y reproducir simultáneamente patrones de habla reales. Las investigaciones muestran que mejora significativamente la precisión de la pronunciación, la entonación, el ritmo, el habla conectada, la comprensión auditiva y la fluidez al hablar, convirtiéndola en una de las metodologías más efectivas para la preparación del IELTS Speaking y la comunicación en inglés en el mundo real.