Voltage Sag Mitigation Matlab

Design of a Sag and Surge Detector For Residential Voltage

Abstract

An inexpensive protection device capable of disconnecting a load upon detecting a voltage sag or surge is presented. Said device is aimed towards the residential voltage of Venezuela’s electrical system. The device is based on the Arduino platform, and uses an ATmega 328P. It detects the presence of a voltage sag or surge by sampling the residential voltage used to feed

1

2 voltage. It disconnects the load after 3 semi-cycles where the residential voltage is outside the boundaries established by Venezuela’s national electrical code, and therefore there’s the presence of a voltage sag or surge. The device is capable of transmitting the data of the sampled signal, for making further analysis.

Figure: System Model & Simulation Flow for Voltage Sag Mitigation Matlab

Introduction

In present day Venezuela various power disturbances such as voltage sags and surges are very prominent. Even though there isn’t any official data disclosed on the topic, it is agreed among many Venezuelans that one of the main sources of damage of electric appliances are volt- age sags and surges. These disturbances arise because Venezuela’s electrical system is in a bad state, which is due to mismanagement. The only permanent solution to this issue would be to make the necessary improvements to the electrical system in order to restore its proper functioning.

Figure: System Model & Simulation Flow for Voltage Sag Mitigation Matlab

For this reason it can be asserted that any permanent solution to the main power quality issues of Venezuela is mid-term, at least. For as long as the improvements aren’t done or even started to do, the voltage sags and surges are going to keep reappearing. This problem gene- rates the necessity of creating a short-term solution, one that doesn’t have to be permanent but that definitely has to have swift means of implementation. The solution has to be very low cost as well, due to the precarious si- tuation of the Venezuelan economy.

The design of a voltage sag and surge detector based on the Arduino platform is presented as a possible so- lution. Said device disconnects any load attached to it,

2 Value Of The Residential Voltage Sig-

nal is outside the boundaries established by Venezuela’s national electrical code (NEC) , for a period of time equal or higher than 3 semi-cycles. The boundaries set (Daniel P´erez).

by Venezuela’s NEC coincide with the ones established residential systems can either use 110 or 120 VRMS, it was decided to use 110 VRMS to set the lower boundary and 120 VRMS to set the upper boundary.

To do the detection, the device samples the residential voltage signal at a rate of 3600 Hz, using the code of a power quality monitor developed to address Venezuela’s power quality issues as well . After establishing the presence of either a sag or surge, the device disconnects the load attached to it by triggering a relay connected in series with the load. The device doesn’t reconnect the load until the residential voltage signal is in compliance with the set boundaries. The device is capable of trans- mitting the sampled data it retrieves, which can be used for either a deep analysis after the fact, or real-time mo- nitoring.

The device distinguishes itself from other protection de- vices using the term “detector”, because usually protec- tors that are marketed as voltage sag or surge protectors offer some sort of relief upon the disturbance, such as peak suppression, instead of just disconnecting the load.

Hardware

The hardware used for this device is comprised by a small and simple circuit used for sampling the residential volt- age signal, a circuit for managing the load attached to the device and the ATmega328P that controls the entire system.

In figure 1 can be seen the PCB design of the entire system. It is shown directly instead of presenting the

Arxiv:2006.02974V2 [Eess.Sp] 7 Aug 2020

schematic first to maintain simplicity in the presenta- tion, and because it lets showcase the positioning of the elements of the system.

Figure 1. Preview of PCB design that encompasses entire

Design. Doesn’T Include Dc Sources

For this design it was assumed that separate modules are going to be used to provide the DC voltages required by the system. Being that this design doesn’t include a model for the case, this gives total freedom in terms of making a design for it. Also, it is worth noting that each pin used for the serial port interface (SPI) is connected to a pad, in such way that is easy to solder any mod- ule that can be used for transmitting the sampled data, which opens up the possibility of assembling an Internet of Things infrastructure with this design. If a compo- nent to send the data isn’t to be added, then the pads of the pins of the SPI should be shorted to ground to avoid leaving them floating.

To lower the amount of noise in the system as much as possible, a series of measures taken in the power qua- lity monitor were employed here as well. Those mea- sures were taken because floating pins generate noise

Dt Transients In The System , And

are based on various concepts of transmission lines,

Grounding, Power Electronics And Electromagnetic

compatibility,. It should be pointed out that in or- der to reduce the overall inductance of the system tracks were kept as short as possible, and to increase the over- all capacitance the gap between power lines was kept as short as possible.

The circuit utilized for sampling is the same used for a power quality monitor targeted for Venezuela’s residen- tial voltage . Said circuit transforms a 120 VRMS at 60 Hz sine wave into one of 0.6 VRMS at 60 Hz with an offset of 3.3 V. This measure was taken to stay in com- pliance with the limits of the analog to digital converter

(Adc) Of The Atmega 328P . This Design Was Pre-

ferred because using a transformer would unnecessarily add noise to the system, and it would incorporate losses as well. The use of resistors in this scenario is valid be- cause the measurement of an analog signal is done with a shunt connection, and the value of the internal resis- tance of the ADC of the ATmega 328P is 100MΩ, which is 20000 times higher than the value of the resistor that perceives the input analog signal.

To manage the load, a relay with a normally open switch is connected in series with it. The ATmega 328P only closes the switch when the code determines that proper conditions for powering the load are met, according to the set boundaries. As can be seen in figure 1, there’s a diode connected to the coil of the relay, and it has the function to prevent that a negative voltage is seen by the pins of the ATmega 328p, scenario that can happen

Due To A Di

dt transient. A couple of LEDs are used to indicate if the residen- tial voltage signal is currently meeting the requirements.

The red LED indicates that the voltage is beyond the

10% Above The 120 Vrms Or 10% Under 110 Vrms,

while the green LED points that the system is providing adequate energy. Adding a small display to indicate the current stats of the residential voltage signal is planned to be added in the future. An alternative design using

An Arduino Nano V3 Is Shown In Figure 2:

Figure 2. Preview of an alternative PCB design that uses an

Arduino Nano V3 Board

This alternative version works exactly the same as the original one. The main difference lies in the fact that up- dating the software is a simple and straightforward pro- cess in this alternative design, because it only requires using a PC with the Arduino IDE and a mini USB ca- ble. Also, it is capable of transmitting data only using the mini USB cable if desired.

Deployment In Out-Of-Position Situations

D. Bendjaballah1, A. Bouchoucha1, M. L. Sahli1,2* and J-C. Gelin2

Abstract

Side-impact collisions represent the second greatest cause of fatality in motor vehicle accidents. Side-impact airbags have been installed in recent model year vehicle due to its effectiveness in reducing passengers’ injuries and fatality rates. In meeting these requirements, simulations of folding and deploying airbags are very useful and are widely used. The paper presents a simulation method for the deploying airbags using three materials in different working conditions. Finite element analysis is primarily used to evaluate this concept. In these simulations, the gas flow is described by the conservation laws of mass, momentum, and energy. The numerical results indicate that the FE method in this paper is capable of capturing airbag deploying process accurately.

Figure: System Model & Simulation Flow for Ansys Airbag Injury Simulation

Keywords: Airbag simulations, Out-of-position, Crash, Modeling, Out-of-position

Background

The passive safety of cars has become a very high prior- ity issue for the automotive industry. Today, there are not only one or two airbags in a car; certain models have ten times more than that. With the increasing usage of airbags, the number of accidents where the airbag itself can cause an injury to the occupant also increases

(Augenstein Et Al. 2003; Gabauer And Gabler 2010;

Audrey et al. 2011). As is well known, safety belts are also now devices designed to provide protection to the users of vehicles during crash events, minimizing the loads necessary to adapt their movement to the move- ment of the car (Freesmeier and Butler 1999; Schmitt et al. 1997). In general, the seat belt is designed to restrain the occupant in the vehicle and prevent the

Occupant From Having Harsh Contacts With Interior

surfaces of the vehicles. The airbag acts to cushion any impact with vehicle structure and has positive internal pressure, which can exert distributed restraining forces over the head and face. As a safety component of auto- mobile, an airbag decreases occupants’ injury likelihood effectively in case of an accident (Ruff et al. 2007). These safety elements can reduce the death rates on the roads, and its protection effects have been widely approved (Crandall et al. 2001; Teru and Ishikawa 2003). With computational tools such as finite element methods designed for dynamic contact problems, crashworthiness simulations can now be used with reliable accuracy to evaluate occupant protection in various collision condi- tions with safety metric/parameters such as acceleration, head injury criteria, intrusion distance, intrusion vel- ocity, and neck forces (neck injury risk or whiplash).

Figure: System Model & Simulation Flow for Ansys Airbag Injury Simulation

Thus, new types of airbag products are being developed to handle different collision scenarios.

Become Standard Equipment On Most New Passenger

vehicles (Braver and Kyrychenko 2004; Teng et al. 2007; Yoganandan et al. 2007). The airbag cushion is com- posed of a woven fabric which is rapidly inflated during a car crash. The airbag dissipates the passenger’s kinetic energy thereby reducing injury through biaxial stretching of the fabric bag and escaping gas through vents. There- fore, the performance of the airbag is greatly influenced by the mechanical properties of the fabric. Generally, air bags are designed to deploy in a crash that is equivalent to a vehicle crashing into a solid wall at 8 to 14 mph.

Figure: System Model & Simulation Flow for Ansys Airbag Injury Simulation

Air bags most often deploy when a vehicle collides with another vehicle or with a solid object like a tree. There are various types of airbags: frontal, side-impact, and curtain airbags. In general, the passenger side airbags are usually larger than the driver airbags (see Fig. 1).

Figure: System Model & Simulation Flow for Ansys Airbag Injury Simulation

Besançon, France

© The Author(s). 2017 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.

Figure: System Model & Simulation Flow for Ansys Airbag Injury Simulation

Bendjaballah et al. International Journal of Mechanical

Doi 10.1186/S40712-016-0070-2

Extensive studies have shown that the airbag deploy- ment in load cases consists of two occupant loading phases: a punch-out effect where the airbag bursts out of its container with the airbag and airbag module cover accelerating towards the occupant and a second loading phase during which the airbag is taking on its deployed shape and volume (membrane-loading effect). Bankdak et al. (2002) developed an experimental airbag test system to study airbag-occupant interactions during close proximity deployment. The results provided insight for simulating the effect of inflation energy and mass flow on target response. Bedard et al. (2002) found that while left-side (driver-side) impacts accounted for only 13.5% of all crashes, the fatality rate among these

Crashes Was 68.3% In Comparison To Front Impact

(48.3%), right-side impact (31.3%), and rear impact (38.4%). These studies underscore the importance of oc- cupant safety during side-impact collisions. In the last years, the current market requested to reduce the time and cost airbag development. In order to achieve this result, virtual simulations play an important role since they allow to minimize the number of experimental tests (Pei et al. 2013; Cao et al. 2014). Several simulation models of airbag were established (Wang et al. 2007). It is feasible to optimize the parameters of airbag deploy- ment using simulation technology. Experimental and numerical studies have quantified injury risks to close- proximity occupants from deploying side airbags. These studies have focused on the prevention of the most ad- verse effects of airbag deployment (Duma et al. 2003).

Other studies have proposed airbag characteristics to minimize particular biomechanical responses (Haland and Pipkorn 1996). In a more recent study, Marklund and Nilsson (2003) compared deformation patterns with experimental data as well as the computational costs associated with three different airbag deployment simu- lation methods; they concluded that the SPH method is relatively inexpensive and produces incremental deform- ation patterns that compare most closely to the experi- mental results. The process of inflation of an airbag is one of the determining factors in saving lives. The duration from the initial impact of the crash to the full inflation of an airbag is about 40 ms, and during this time, the airbag goes from being in a folded state to a fully inflated state, with a high internal pressure. After achieving this state, the airbag begins to deflate, thus providing a nice cushion for the body impacting it.

Ideally, the person in the crash should come into contact with the airbag at this time. In the present study, a large volume passenger side airbag model is developed to handle different collision scenarios. The main aim is evaluate the performance of deploying of passenger side airbag using finite element methods (FEM).

Materials

The tensile specimens were made in different airbags (P: Peugeot, R: Renault, and VW: Volkswagen) with a length of 200 mm long and a width of 40 mm. Table 1 shows the mechanical properties of the airbag.

Tensile Tests

To determine the mechanical properties of the material of airbag used in the test pieces, tensile tests were performed on Lloyd EZ20 universal testing machine in Constantine. These tests were conducted using rect- angular samples. The axial force and axial displacement acquired during a test are converted into stress and the strain in order to be used for the fabric material model.

The continuous recording of the stress-strain data was performed during both the load and unload phases. A minimum of five samples were made in order to check the repeatability of the measurements. All the data was collected by using a PC-based data acquisition system and analyzed by commercial software. The picture frame test device that is made for this study is shown in Fig. 2.

Fig. 1 a Frontal and side airbags. b Oblique view of facet occupant model in sitting posture following airbag deployment (Lim et al. 2014)

0.150

Bendjaballah et al. International Journal of Mechanical and Materials Engineering (2017) 12:12

Page 2 Of 9

Figure 3 shows the stress-strain relationship of the airbag sample under axial tensile loads. The results are showing a linear increase in extension with the increas- ing stresses. This is an expected output and it confirms with the theoretical behavior of a sample subjected to tensile stress. The rupture strain values for different airbags (R/P/VW) were 0.322, 0.441, and 0.472, respect- ively. The measured elastic parameters (i.e., Young’s modulus E and initial yield strength) and Poisson’s ratio are summarized in Table 2. The tensile tests of the woven fabrics can show differences on mechanical prop- erties because woven fabrics can resist in-plane shear loads once the yarn lock-up angle has been reached. The differences of material property on material direction can affect the shape of fully deployed bag (see Fig. 3b).

Theoretical Background

Numerical simulations of airbags use very complex and techniques such as an orthotropic model to identify the mechanical behaviors during the airbag inflation and the fluid mechanics (gas flow) to describe the inflator gas flow (pressure gradient) and improve the representation of the pressures within the airbag. To model the airbag as an orthotropic model, three material constants have to be provided. Assuming a plane stress condition, the

Ð1Þ

where σ is the normal stress and τ is the shear stress, the subscript refers to the principal material directions, i.e., the fill and warp directions. Also, ε and γ are the strain components. The material elastic constants Qij are

Ð2Þ

where E1 and E2 are the Young’s modulus in the fill and wrap directions and G12 is the shear modulus of the fabric material. νij is the Poisson ratio of the material.

The gas exerts a pressure load on the airbag causing it to expand. This expansion puts the airbag under tensile stress lowering the expansion rate. In this study, heat conduction and heat transfer is not taken into account.

Fig. 2 A photograph of Lloyd EZ20 universal testing Fig. 3 Stress versus strain using Lloyd EZ20 machine for a three different airbags at 0° and 90° and b VW airbag test specimens at

Different Angles

Table 2 Physical and mechanical properties of the airbag

Page 3 Of 9

In the deployment of an airbag, an inflator supplies high velocity gas into an airbag causing it to expand rapidly. The gas inside the airbag is assumed to be ideal, to be of constant entropy, and to satisfy the equation of state:

Ð3Þ

Here p, ρ, and e are respectively the pressure, density, and specific internal energy, and γ is the ratio of the heat capacities of the gas. The gas flow is described by the conservation laws for mass, momentum, and energy that

Ð4Þ

here, V is a volume, A is the boundary of this volume,

N Is The Normal Vector Along The Surface A, And U

denotes the velocity vector in the volume. Applying Bernoulli’s equation in the case of an ideal gas with

Ð5Þ

Here, the subscript ex denotes quantities at the throat of the tube. Furthermore u, p, and ρ denote the quan- tities inside that part of the tube that is supplying mass.

Materials And Boundary Conditions

The airbag system mainly consists of three parts: the airbag itself, the inflator unit, and the crash sensor or diagnostic unit. Thus, to study the behavior of the airbag using FE simulations, we need to have an FE model of the airbag in the folded position. A FE model of the airbag was used to simulate the test condition as shown in Fig. 5. LS-DYNA® material model FABRIC (MAT_34) is used to simulate the airbag material. It is a variation of the layered orthotropic material model. Additionally, in the LS-DYNA® material model, fabric leakage can be accounted for. However, for this CAB material, the leak- age is almost negligible and therefore no leakage is specified. The mechanical properties can be determined from the physical test. Typical material properties for airbag fabrics are taken as given in Chawla et al. (2004a) (Table 3). These properties are used to simulate inflation process of airbag (see Table 1). The car dashboard is modeled as the rectangular thin plate using a MAT_RI-

Gid Material, And The Degrees Of Freedom Are Con-

strained in all the directions. The similar properties of thermoplastic polymer are assigned for contact purposes. The porosity of the fabric is assumed zero. The nitro- gen gas is taken for inflating the airbag. Properties of nitrogen gas and initial bag conditions are shown in Table 4. The example on which we perform the study is a typical passenger side airbag. The geometric de- tails have been measured from a commercially avail- able airbag. The initial state of the airbag is a closed rectangular whose sides are to be finished to 482 × 635 mm2 and is shown in Fig. 4.

Table 3 Material properties of airbag and rigid plate used in FE

–

Table 4 Initial values used for FE simulation of the swelling of

3.33 × 10−4

Fig. 4 The initial airbag geometry in the form of a rectangular Bendjaballah et al. International Journal of Mechanical and Materials Engineering (2017) 12:12

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