Assessment of Total Harmonics Effects on Grid-Connected Powered

Inverter Using Sine-Referenced and Static-band Hysteresis of Current

Controllers

referenced and static-band hysteresis of current controllers. To realize this art, current transducer, static-band and sine-referenced

hysteresis current controllers, solar energy source, maximum power point tracker, grid supply and voltage source DC-AC

converter are engaged. The system has these features are: (i) Light weight owing to none transformer-less system application (ii)

Received: May 18, 2021. Revised: February 21, 2022. Accepted: March 20, 2022. Published: April 27, 2022.

Harmonics is the increasing frequency waveform, overlaid

wave-shape. Harmonics rises in power electronic systems as a

result of introduction of power electronics drives for

and control, faulty of relays operations, fading in

communication and control signals [2]. There are innumerable

means of mitigating total harmonics distortions (THD) in

power electronic systems. A few of them are: waveform

regulation by transformer connections, pulse-width modulation

schemes, waveform control by multiple commutations in each

cycle, waveform controlled by using delta-star transformer

output, utilization of filters, and high pulsed rectifier

cascading. In PWM, there are various sub-divisions such as

carrier-based modulation schemes, third harmonic-injection

random pulse width modulation scheme, it relies majorly on

randomizing the frequency of the carrier waveform in order to

allocate the intense energy of the harmonic frequency of the

frequency range. The vital advantage of this scheme is to

mitigate the energy of the harmonics, which in turn will

minimize the THD of the DC-AC converter output voltage [3-

basic frequency component by reducing the size of the

amplitude that affects the value of waveform.

MOSFETS on the same leg, the system can handle it without

any device blow due to the presence of inductors La and Lb as

shown in Fig.1 unlike in conventional H-bridge inverter

The major component values used in this paper are listed in

Table 1.The circuit diagram is shown in Fig.1. The ,method

that is adopted in this research is all about analytical and

simulation methods.

3. Principle Operation of the Grid-

connected DC-AC Converter System

Once the peak power is sensed, the signal is communicated

to the analog-to-digital converter, (A/DC) in control section.

The A/DC digitizes signal and delivers it to the controller’s

signal processing section. The control section then triggers

the output voltage of the combined solar panels is raised

appreciably which is delivered to inverter input terminals after

or equal to the edge voltage to open up the channel of the

MOSFET. Therefore, the previously developed voltage

between drain and the source, pumps the greater carriers from

the source to drain terminals through the inversion layers,

which transform the DC power TO AC power. The

complementary triggering pulses (vg23 and vg24) turn on

MOSFETS (MS3, MS4) during the negative half –cycled

operation. The output waveform of the DC-AC converter is a

square form-based waveform. Then an inductor, Lo filters the

ripples and removes most of the harmonics to generate a

soon as the output of the inductor is made, the regulator

section forces it to trail the modulating current in-between the

top and low band bounds respectively in order to be injected to

the utility network at power factor of either the sine-referenced

band or static-band current controller applied

system at unity. Fig.2 illustrated simulated result of the static-

band hysteresis current based regulator used for regulating the

Furthermore, the harmonization of DC-AC current and utility

voltage at unity power factor wave shapes is displayed Fig.4.

But provided the output inductor current is contained within

the band, the regulator continues on its usual switching state.

And once it tracks it well, the current passing through inductor

and the grid voltage concurrently start from the similar origin,

rise at their peak points of various amplitudes at angles of 𝜋/2

limit, lower limit and peak reference voltage are 130V, 50V

and 90V. The current tracker explore between these two bands

to ensure good synchronization (harmonization) between the

Fig.2: Static-band current regulator wave shapes

.

accompanied with the static-band hysteresis based-current

regulator on the course of controlling the passage of current to

Fig.4: Spectral harmonic content of filtered DC-AC converter output current under static –band current controller.

6. Sine-referenced Current Controller for

Harmonization of DC-AC Converter

Current and Utility Voltage at Unity

The algorithm of the sine-referenced current controller is

deduced in eq.7-9 as follow:

more than zero:

For;

If ; switch OFF MS1 and MS2; switch ON MS3 and

MS4;

If ; switch OFF MS3 and MS4 ; SWITCH ON MS1

and MS2;

For negative half part, i.e. when the is below zero.

If ;

If ; switch ON MS1 and MS2; switch OFF MS3 and

MS4;

If ; switch ON S3 and S4 ; switch OFF S1 and S2;

If sine-referenced current more than zero and the output

referenced current. In addition, the DC-AC converter output

voltage is dropped down to be equal –Vmpp. During the

positive half cycle, once the output inductor current is lower

than the minor current band limit, the comparing device issues

out error current signal to switch OFF MS3 and MS4; and turn

ON MS1 and MS2. This instantly pulls up the voltage across

the DC-AC converter to be equivalent to +Vmpp and also

makes the filtered DC-AC converter current to trace and track

the sine-referenced current. On the negative half cycle, i.e.

when the sine-referenced current is smaller than zero, there

suitably tracing sine-referenced current whereas injecting the

output current of the inverter into the grid utility. However,

once the output inductor is more than the lower current band

bound, then the error current signal sets ON MS3 and MS4;

and turns OFF MS1 and MS2. The DC-AC converter voltage

becomes the equivalent as boosted voltage due to decrease in

current gradient. The uninterruptedly transition of voltage

caused by spontaneously switching ON and OFF of the power

switches as a results the error current signal from the

Fig.5 the sine-referenced current controller waveforms

Fig.6 showed a seamless harmonization of filtered DC-AC

converter current and grid voltage on the course of power

injection into the grid utility under the influence of sine-

referenced current controller. This implies that they have the

identical frequency and are in the same phase. Furthermore, it

means that they began at the same zero angles, reach lowest

point at

nevertheless of various peaks, meet at zero axes at

Fig.6: Synchronized inverter current and grid voltage at under sine-referenced hysteresis current controller.

The spectral total harmonic distortion of the sine-reference

current controller is shown in Fig.7

7. Discussion of Computer Simulated

Results

like waveform of coupling inductor current of static-band

current controller is larger than that of sine-referenced current

band. The cleaned DC-AC converter current injected into the

grid utility under static-band approach in Fig.4 is 99.10A while

the current going into the grid utility under the sine-

referenced-band approach of Fig.7 is 75.12A. The spectral

harmonic spectrum display of the static-band current controller

is displayed in Fig.4 of high amplitudes more than that of

Fig.7.

(India) Pvt.Ltd.2006

[9] N.Mohan, T.M undeland and W.P Robbins,Power

Electronics-Converters Applications andDesign, 2nd; John

Wiley & Sons, Inc.1995.

[10] Candidus U. Eya,“Practical implementation of an

improved standby boost uninterruptible power supply,”

Blaabjerg, and B. Lehman. Step-Up DC–DC Converters: A