Upload
others
View
16
Download
9
Embed Size (px)
Citation preview
REVIEW OF CONTROL STRATEGIES OF DSTATCOM
Avinash Purandare, Dr. N. Gopalakrishnan, Dr. Y. P. Nerkar and Hrishikesh Mehta Department of Electrical Engineering,
PVG‟s College of Engineering and Technology, Pune, India
Abstract— DSTATCOM is used to mitigate many voltage quality problems like sag, swells, impulses, voltage unbalances, fluctuations and
current quality problems like harmonics elimination, power factor correction, load balancing and noise cancellation. Effectiveness of
DSTATCOM greatly depends upon the control technique that is adopted. Many research papers have been critically studied and an overview of
different control techniques and controllers is reviewed in this paper.
Keywords— DSTATCOM, PFC, Load Balancing, Harmonics, Power Quality, Voltage Sag – Swell
I. INTRODUCTION
In distribution systems, major power consumption has been in reactive loads, such as motive load. These loads draw lagging
power-factor currents and therefore give rise to reactive power burden in the distribution system. This eventually decreases power
factor, due to which line current increases, line voltage-drop increases and hence bus voltage decreases. Moreover, situation
worsens in the presence of unbalanced loads. The operation of transformers and generators is greatly affected by unbalanced loads.
A Distribution STATic COMpensator (DSTATCOM) can be used for compensation of reactive power and unbalance loading in
the distribution system [1]. The performance of DSTATCOM depends on the control algorithm used for extraction of reference
current components. For this purpose, many control schemes are widely used in practice and are reported in the literature, and
some of these are instantaneous reactive power (IRP) theory, instantaneous synchronous reference frame (SRF) theory and
symmetrical component theory. Various types of controllers such as PI controller, adaptive PI controller, sliding mode controller,
sinusoidal PWM controller, space vector PWM (SVPWM) modulation, hysteresis current controller and neural network based
controller are widely used in DSTATCOM. Many research papers have been referred and critical review of different control
techniques is done in this paper.
II. PRINCIPLE OF OPERATION OF DSTATCOM
Distribution Static Compensator (DSTATCOM) is connected in parallel like a STATCOM but at distribution level. Its main
function is to inject harmonically distorted current in phase opposition to the load current thereby supressing harmonics in the
supply current. In addition to this it also supplies required reactive power to the load. A typical block diagram of a DSTATCOM
with unbalanced and non-linear load is depicted in Fig.1 and its equivalent circuit is given in Fig. 2, where Vsabc is phase voltage
of supply, VSHabc is fundamental component of phase output voltage of DSTATCOM and ISHabc is fundamental component of
DSTATCOM current.
Fig. 1 Block diagram of DSTATCOM
JASC: Journal of Applied Science and Computations
Volume V, Issue XII, December/2018
ISSN NO: 1076-5131
Page No:2150
Fig. 2 Equivalent circuit of DSTATCOM
The operation of DSTATCOM is explained in the following modes [2]:
Mode 1: If VSHabc is in-phase and equal to VSabc then DSTATCOM does not inject and absorb any reactive power.
Mode 2: If VSHabc is greater than VSabc and ISHabc leads VSabc by some angle, then DSTATCOM will supply the reactive power of
the system. This mode can also be called as capacitive mode and its phasor representation is given in Fig. 3(a). Here DSTATCOM
supply all required load reactive power thereby making supply currents free from reactive currents.
Mode 3: If ISHabc lags VSabc then DSTATCOM will take reactive power from the system. This mode can also be called as inductive
mode and its phasor representation is shown in Fig. 3(b).
(a) (b)
Fig. 3 Phasor representation of DSTATCOM
From the phasor diagrams it is clear that, DSTATCOM either generates or absorbs the reactive power by controlling the phase
angle (α) between VSHabc and VSabc thereby regulating the magnitude of the VSHabc and thus DC Link capacitor voltage.
III. CONTROL TECHNIQUES OF DSTATCOM
A. INSTANTANEOUS REACTIVE POWER THEORY (IRP Theory)
IRP theory was first proposed by Akagi [3] and is also known in the literature as p-q theory. The detailed mathematical
formulation of IRP theory is reported in [4]. In a three phase three wire system, zero sequence component is zero. Therefore,
instead of α-β-0, frame is denoted as α-β frame. In this method, the three phase voltages and currents are transformed into two
phase quantities in α-β frame using Clarke’s transformation. From two phase quantities of voltages and currents, instantaneous
active and reactive powers are calculated which are passed through LPF to filter oscillating components. The average components
obtained from LPF are used to calculate two phase quantities iα and iβ. Using inverse Clarke’s transformation iα and iβ are
converted into reference source currents isa*, isb*, isc*. Actual instantaneous source currents are compared with reference source
currents in hysteresis based PWM current controller and the error signals so generated are given to gates of switching devices of
3-phase VSI [4].
JASC: Journal of Applied Science and Computations
Volume V, Issue XII, December/2018
ISSN NO: 1076-5131
Page No:2151
Fig. 4. Block diagram of IRP Theory [4]
The system voltages va, vb,vc and load currents iLa, iLb, iLc are transformed into α-β quantities using Clarke’s transformations as
= (1)
= (2)
The instantaneous active and reactive powers p,q are given as
= (3)
Instantaneous active and reactive power p and q can be divided into an average component and an oscillatory component .
Reference source currents are calculated to compensate the average and oscillatory components of reactive powers and oscillatory
component of active power. In this case the source transmits only the non-oscillating component of the active power. Therefore
the reference source currents and in α-β co-ordinate are expressed as
= (4)
where + .
Reference source currents in α-β frames are transformed into reference source currents in a-b-c frame using inverse Clarke’s
transformation as
= (5)
JASC: Journal of Applied Science and Computations
Volume V, Issue XII, December/2018
ISSN NO: 1076-5131
Page No:2152
where is the zero sequence component, which is zero in three phase three wire system. IRP theory is used widely for reactive
power compensation. There is a delay in compensation which is due to LPF employed for filtering of power signals. Moreover,
IRP theory uses voltage signals to compute instantaneous active and reactive powers; any distortion and unbalance in voltages
lead to inaccuracy in the estimation of reference source currents.
B. SYNCHRONOUS REFERENCE FRAME (SRF) Theory
SRF theory is based on the transformation of currents in synchronously rotating d–q frame [18, 19]. Fig. 5 shows the basic
building blocks of this theory. Sensed inputs va, vb, and vc and iLa, iLb , and iLc are fed to the controller. Voltage signals are
processed by a phase-locked loop (PLL) to generate unit voltage templates (sine and cosine signals). Current signals are
transformed to d–q frame, where these signals are filtered and transformed back to abc frame to obtain These are
fed to hysteresis-based PWM current controller where they are compared actual source currents to generate final switching
signals fed to the 3- phase VSI.
Fig. 5. Block diagram of SRF theory [4]
The detailed mathematical transformation equations are described in [20]. Zero sequence current is absent in a balanced three
phase three wire system. Hence it is not shown in above equation. The currents generated in α-β co-ordinates can be transformed
to d-q frame with Park’s transformation [4]
= (6)
where is the angle between phase ‘a’ axis and d-axis of d-q frame where q-axis leads d-axis by 90 deg.
Since 3-phase a. c. currents contain harmonics, are not ripple free. are passed through LPF to smoothen out ripples.
These extracted dc components iddc and iqdc are transformed back into α–β frame using inverse Park’s transformation [4].
= (7)
These currents are transformed to obtain three phase source currents in abc co-ordinates as.
= (8)
JASC: Journal of Applied Science and Computations
Volume V, Issue XII, December/2018
ISSN NO: 1076-5131
Page No:2153
In SRF theory, there is a delay in compensation which is due to employment of LPF to filter power signals. Sine and cosine
signals are generated by PLL. This slows down the process and introduces some delay in compensation. Further in harmonically
polluted system, there are tracking errors.
C. ADALINE BASED CONTROL ALGORITHM
ADALINE means Adaptive Linear Element. The basic theory of the proposed Adaline based control is based on Least Mean
Square (LMS) algorithm and its training through Adaline, which tracks the unit vector templates to maintain minimum error [4].
A block diagram of Adaline-based control scheme is shown in Fig. 6.
The control algorithm is based on the extraction of current component in phase with the unit voltage template. To estimate the
fundamental frequency positive sequence real component of load current, the unit voltage template should be in phase with the
system voltage and should have unit amplitude, and it must be undistorted. For the calculation of templates, voltage at the point of
common coupling is sensed. Sensed voltages are filtered through a bandpass filter, and their amplitude is computed. Sensed three-
phase voltages are divided by this amplitude to get three-phase voltage templates ua, ub, and uc shown in Fig. 6.
Fig. 6. Block diagram of Adaline theory [4]
The fundamental active and reactive power components of load currents are obtained by estimating the respective weights
corresponding to the fundamental active ( , , ) and reactive ( , , ) components of load currents. The
weights are updated using LMS algorithm. The average weight corresponding to the active and reactive components of load given
as
= (9)
= (10)
The active and reactive components of reference source currents are obtained [21] as follows,
(11)
(12)
(13)
The reference source currents are used for the control of VSC. The sensed and reference currents are compared and error is used
to generate the gating signals for the electronic switches such as IGBTs [22, 23].
The reference source currents are given as
(14)
(15)
(16)
JASC: Journal of Applied Science and Computations
Volume V, Issue XII, December/2018
ISSN NO: 1076-5131
Page No:2154
Above reference source currents are compared with actual source currents in a hysteresis current controller to generate requisite
gate signals to turn on the switching devices.
D. SYMMETRICAL COMPONENT THEORY
In this theory, positive sequence voltage and currents are considered to obtain balanced source currents [26]. Therefore, the
reference source currents can be considered
=0 (17)
Control technique is illustrated in block diagram shown in Fig.7.
Fig. 7. Block diagram of implementation of symmetrical component theory [24]
The power generated from the source is constant and equal to the dc value of the load power. The average load power is computed
by using filters. From the average load power, sensed voltages and sensed currents the reference source currents are computed.
These reference source currents are compared with actual source currents which generates error signals which are used as gate
signals to fire switching devices in the inverter of DSTATCOM.
E. PI CONTROLLER and ADAPTIVE PI CONTROLLER
PI controller is simplest in design and most widely used in industry. Design of PI controller for D.C. link voltage of D-STATCOM
is widely considered. The D.C. bus voltage is filtered and then compared with the reference value [4]. The resulting error signal
is obtained as difference between reference dc quantity and actual dc voltage.
(18)
(19)
The output voltage is obtained as
+ (20)
where and are proportional and integral gain constants for the PI controller.
The output is taken as amplitude of after limiting it to a safe value. A traditional PI controller used for D.C. link
voltage control suffers from high overshoot and undershoot during the supply voltage fluctuations.
As electric load on a power system varies continuously, fixed values of Kp and Ki will not lead to the desired voltage response
[25]. Therefore, need of a controller which adjusts values of Kp and Ki dynamically to achieve the desired voltage response is
necessary. It requires additional logic to monitor the PCC voltage with respect to desired response. It is achieved by comparing the
RMS value of the measured PCC voltage Vt and desired voltage reference Vt' to determine the error which is fed to a PI controller.
In this approach, the actual voltage deviation and desired voltage deviation are monitored at every instant. Ratio of actual voltage
deviation and ideal voltage deviation gives scaling factor.
JASC: Journal of Applied Science and Computations
Volume V, Issue XII, December/2018
ISSN NO: 1076-5131
Page No:2155
F. Sliding Mode Controller
The sliding mode controller (SMC) maintains the system on sliding surface(s) so that actual compensating currents move
closer to reference compensating currents [28]. Three steps are required to design a SMC 1) proposal of sliding surface, 2)
verification of existence of SMC and 3) establishment of stability. Sliding surface is chosen in such a way that the controller is
able maintain system within surface. Let z be the sliding surface and z’ be the first derivative of z. In order to guarantee the sliding
mode existence, the condition zz’ < 0, must be fulfilled and this fact guarantees the attraction of the system to surface. This
controller has been widely applied to power converter due to its fastness, robustness and stability and takes into account the
switching nature of the power converters. Sliding mode controller is designed by choosing state variables x1, x2 which are
defined as [16]
= = - (21)
And its derivative
= - (22)
Where is sampling interval
Let denote the switching hyper plane function defined as
(23)
The switching functions are defined as
(24)
(25)
(26)
(27)
Now, the reference supply current is given by
(28)
Three phase reference currents are obtained using and unit vectors and thereafter appropriate current controller schemes are
employed for fast control of actual and reference supply currents. The gain constants are suitably tuned to obtain
faster system response [27].
G. Sinusoidal PWM Controller
In pulse width modulation control, a fixed D.C input voltage is given to the inverter and a controlled a. c. output voltage is
obtained by adjusting the ON and OFF periods of IGBT switches [28].
Fig. 9. Sinusoidal PWM technique [28]
This method is very popular method and is widely used in different industrial applications. PWM technique is characterized by
constant amplitude pulses. The width of these pulses is, however, modulated to control output voltage of inverter and to reduce
harmonic content in output voltage [28]. Referring to Fig.5,in sinusoidal pulse width modulation, a high frequency triangular
carrier wave is compared with a sinusoidal reference wave of the desired frequency (frequency of output voltage). The
intersection of and waves determines the switching instant and commutation of the modulated pulse. Let and be the
peaks of carrier and reference waves respectively.
JASC: Journal of Applied Science and Computations
Volume V, Issue XII, December/2018
ISSN NO: 1076-5131
Page No:2156
The ratio is called modulation index (MI). It lies between 0 to 1 for linear modulation. MI controls the magnitude and
harmonic content of output voltage. Magnitude of output voltage is directly proportional to MI. The carrier and reference waves
are mixed in a comparator. When sinusoidal wave has a magnitude higher than the triangular wave, the comparator output is high,
otherwise it is low. When comparator output is high, a gate pulse is generated.
If N denotes the number of pulses per half cycle, then (2N 1) is the order of dominant harmonic number [28]. Thus, by
increasing number of pulses per half cycle (N), the order of dominant harmonic frequency can be raised, which can then be
filtered out easily. But higher value of N also results in higher switching frequency. This leads to higher switching losses and
consequently inverter efficiency decreases. Therefore, a compromise between the filtering requirements and inverter efficiency
needs to be made.
The difference of reference and actual D-STATCOM currents gives error signals which is then converted to modulated voltage
signals for the three-phases. This conversion may be achieved by using three PI controllers one for each phase. The intersection of
modulated voltage signal with carrier signals defines the switching logic for phase ‘a’ and for other two legs for the VSI based D-
STATCOM.
H. Space vector modulation (SVM)
SVM is an advanced and possibly the best among all the PWM techniques for variable frequency drive applications. With a
machine load, the load neutral is normally isolated, which causes interaction among the phases [29-31]. The SVM method
considers this interaction of the phases and optimizes the harmonic content of the three phase isolated neutral load. SVM theory is
based on the concept of rotating space vector. If the three phase sinusoidal and balanced voltages given by equations
va = Vm cos wt (29)
vb = Vm cos(wt- ) (30)
vc = Vm cos(wt+ ) (31)
are applied to a three phase induction motor, it can be shown that the space vector V with magnitude Vm rotates in a circular orbit
at angular velocity w where the direction of rotation depends on the phase sequence of the voltages. With sinusoidal three phase
command voltages, the composite PWM fabrication at the inverter output should be such that the average voltages follow these
command voltages with a minimum amount of harmonic distortion.
Fig. 10. Circuit configuration of a basic three phase inverter
Fig. 10 shows a three-phase inverter which converts DC supply into 3- phase A.C. voltages which could be connected to a three-
phase motor. The switches must be controlled so that at no time both the switches in the same leg are turned on or else the DC
supply would be shorted. This requirement may be met by the complementary operation of the switches within a leg. i.e. if A+ is
on, then A− is off and vice versa. This leads to eight possible switching vectors for the inverter, V0 through V7 with six active
switching vectors and two zero vectors [31-33].
JASC: Journal of Applied Science and Computations
Volume V, Issue XII, December/2018
ISSN NO: 1076-5131
Page No:2157
Table I. Switching Vector Table
Vector A+ B+ C+ A− B− C− VAB VBC VCA
V0 = {000} OFF OFF OFF ON ON ON 0 0 0 zero vector
V1 = {100} ON OFF OFF OFF ON ON +Vdc 0 −Vdc active vector
V2 = {110} ON ON OFF OFF OFF ON 0 +Vdc −Vdc active vector
V3 = {010} OFF ON OFF ON OFF ON −Vdc +Vdc 0 active vector
V4 = {011} OFF ON ON ON OFF OFF −Vdc 0 +Vdc active vector
V5 = {001} OFF OFF ON ON ON OFF 0 −Vdc +Vdc active vector
V6 = {101} ON OFF ON OFF ON OFF +Vdc −Vdc 0 active vector
V7 = {111} ON ON ON OFF OFF OFF 0 0 0 zero vector
Note that looking down the columns for the active switching vectors V1-6, the output voltages vary as a pulsed sinusoid, with each
leg offset by 120 degrees. To implement space vector modulation, a reference signal Vref is sampled with a frequency fs (Ts = 1/fs).
The reference signal may be generated from three separate phase references using the α β γ transform. The reference vector is
then synthesized using a combination of the two adjacent active switching vectors and one or both of the zero vectors. Various
strategies of selecting the order of the vectors and which zero vector(s) to use exist. Strategy selection will affect the harmonic
content and the switching losses.
Fig. 11. Representation of Space vector modulation
I. HYSTERESIS CONTROLLER
In this type of controller, the error signals of the reference and the actual (instantaneous) source currents are determined and
compared within a small hysteresis band generally ± 1% to ± 5% of reference sine wave. Let denote instantaneous value of
actual source current and denote instantaneous value of reference source current and let denote hysteresis band. The control
logic for hysteresis control is as follows.
If then upper switch of the VSI on arm’ a’ is OFF and lower switch is ON.The upper and lower switching
devices (IGBT in the model) are switched in a complementary fashion. The hysteresis band can be varied. A narrow hysteresis
band results in a very good and fast tracking of currents but in that case switching frequency may become quite high[Ref.]. A wide
hysteresis band may not provide effective tracking and the system may tend to become unstable. Principle of hysteresis controller
is explained with respect to Fig. 12.
JASC: Journal of Applied Science and Computations
Volume V, Issue XII, December/2018
ISSN NO: 1076-5131
Page No:2158
Fig. 12. Principle of hysteresis current controller
J. Neural network based control of DSTATCOM
The load current can be resolved into active component (ip), reactive component (iq) for positive sequence and negative sequence
current(i-) [22].
iL(t) = ip*(t) + iq*(t) + i-(t) (32)
The control algorithm estimates based on the proposed theory requires unit vector template corresponding to fundamental positive
sequence component of current in phase with phase voltage waveform. For proper estimation of components of load current unit
voltages templates must be undistorted and can be represented as:
vp(t) = Usinwt (33)
In case of voltage being distorted, the zero crossing of phase voltage is detected to generate sinusoid (sinωt) vector template,
synchronized with ac mains. The signal is generated from look-up table by adjustment of delay to track the change in frequency of
the ac mains. The initial estimates of active and reactive part of current on single-phase basis can be chosen as:
ip(t) = Wpvp(t) (34)
where weight (Wp) is estimated using Adaline. The weight can be represented in terms of voltage and current given as:
Wp – I1cosø1/U (35)
For proper estimation of reference signals, the weights are averaged to compute the equivalent weight for positive sequence and
negative sequence current component in the decomposed form. The averaging of weights helps in removing the unbalance from
the current components. These estimated reference source currents are compared with actual source currents and error signals are
used to switch on devices in the VSI of DSTATCOM through a hysteresis current controller by forcing the source currents to
follow these reference three-phase currents. Fig. 13 (a) shows the basic control scheme for unity power factor mode of operation.
The output signal given by PI controller to maintain the constant dc bus voltage is added to the average weight. Fig. 13 (b) shows
the basic control scheme for ac voltage regulation mode of operation. The output signal given by PI controller is multiplied by the
unit templates quadrature with phase voltage and added to the real reference current component calculated using neural network.
The reduction in rating of DSTATCOM is an important feature as it not only reduces the cost of the system but also gives freedom
to operate with power electronic devices like IGBT for high power application at higher PWM switching frequency. As the
calculation of weights has been performed on line, this scheme envisages nearly zero phase shift to extract the reference current
with simplicity. Besides the indirect current control along with Neural Network based extraction does not need any feed forward
compensation for the delay caused by LC ripple filter.
JASC: Journal of Applied Science and Computations
Volume V, Issue XII, December/2018
ISSN NO: 1076-5131
Page No:2159
Fig. 13. Control scheme (a) for unity power factor mode of operation (b) for voltage regulation mode of operation [22]
IV. CONCLUSIONS
Various control techniques and controllers are reviewed in this paper. PI based hysteresis current controller is the simplest to
implement as the number of control parameters are fewer. The performance results of this controller is affected by bandwidth. The
major disadvantage of controller is high switching losses with increase of frequency. High acoustic noise may make the controller
unsuitable for commercial applications. Moreover, the hysteresis controller maintains instantaneous currents for all the three
phases exactly within the tolerance band. It has provided simple, very effective control with almost zero tracking errors and good
response to dynamics of load changes. The design of PWM based controller for a DSTATCOM aims at unity power factor at the
source. The PWM current controller has a distinct advantage over the hysteresis current controller in terms of fixed switching
frequency. However, there are inherent tracking errors which can be reduced by proper tuning of PI controllers. The performance
results with SMC controller are found to be different from those obtained from PI controller. The DC link voltage does not return
to its reference value after each load disturbance. Moreover, tuning of SMC controller requires optimum values of all control
parameters simultaneously which is a tedious task. The performance of PI and SMC controller is similar under steady state
conditions but is different under dynamic conditions. SMC controller needs tuning of parameters but its parameters are less
sensitive to variation in system parameters. It can be concluded that effectiveness of DSTATCOM is greatly affected by the
control technique being implemented. The review of various control techniques will be useful to researchers.
REFERENCES [1] L.Xu, V.G.Agelidis and E.Acha, “Development considerations of DSP controlled PWM VSC-based STATCOM”, IEE Proc. Electr. Power Appl., Vol. 148,
No. 5, September 2001.
[2] Venkata Reddy Kota, Sudheer Vinnakoti, “Synchronous Reference Frame Based Control of MLI-STATCOM in Power Distribution Network”, IEEE, 2016.
[3] H. Akagi, E. H. Watanabe, and M. Aredes, “Instantaneous Power Theory and Applications to Power Conditioning”, Hoboken, NJ: Wiley, 2007.
[4] Bhim Singh, Alka Adya and A.P. Mittal, “A comparison of control algorithms for D-STATCOM”, IEEE Trans. Industrial Electronics, vol.56, No.7,
July2009.
[5] A. Moreno-Munoz, “Power Quality: Mitigation Technologies in a Distributed Environment”, London, U.K.: Springer-Verlag, 2007.
[6] B.-S. Chen and Y.-Y. Hsu, “A minimal harmonic controller for a STATCOM,” IEEE Trans. Ind. Electron., vol. 55, no. 2, pp. 655–664, Feb. 2008.
[7] H. Akagi, E. H. Watanabe, and M. Aredes, “Instantaneous Power Theory and Applications to Power Conditioning”, Hoboken, NJ: Wiley, 2007.
JASC: Journal of Applied Science and Computations
Volume V, Issue XII, December/2018
ISSN NO: 1076-5131
Page No:2160
[8] R. S. Herrera, P. Salmeron, and H. Kim, “Instantaneous reactive power theory applied to active power filter compensation: Different approaches,
assessment, and experimental results,” IEEE Trans. Ind. Electron., vol. 55, no. 1, pp. 184–196, Jan. 2008.
[9] D. M. Divan, S. Bhattacharya, and B. Banerjee, “Synchronous frame harmonic isolator using active series filter,” in Proc. Eur. Power Electron. Conf., pp.
3030–3035, 1991.
[10] B. Singh and V. Verma, “Selective compensation of power-quality problems through active power filter by current decomposition,” IEEE Trans. Power
Del., vol. 23, no. 2, pp. 792–799, Apr. 2008.
[11] C. Lascu, L. Asiminoaei, I. Boldea, and F. Blaabjerg, “Frequency response analysis of current controllers for selective harmonic compensation in active
power filters,” IEEE Trans. Ind. Electron., vol. 56, no. 2, pp. 337– 347, Feb. 2009.
[12] A. Luo, Z. Shuai, W. Zhu, and Z. J. Shen, “Combined system for harmonic suppression and reactive power compensation,” IEEE Trans. Ind. Electron., vol.
56, no. 2, pp. 418–428, Feb. 2009.
[13] K.-K. Shyu, M.-J. Yang, Y.-M. Chen, and Y.-F. Lin, “Model reference adaptive control design for a shunt active-power-filter system,” IEEE Trans. Ind.
Electron., vol. 55, no. 1, pp. 97–106, Jan. 2008.
[14] S. Mohagheghi, Y. Valle, G. K. Venayagamoorthy, and R. G. Harley, “A proportional-integrator type adaptive critic design-based neurocontroller for a
static compensator in a multi-machine power system,” IEEE Trans. Ind. Electron., vol. 54, no. 1, pp. 86–96, Feb. 2007.
[15] Z. Shu, Y. Guo, and J. Lian, “Steady-state and dynamic study of active power filter with efficient FPGA-based control algorithm,” IEEE Trans. Ind.
Electron., vol. 55, no. 4, pp. 1527–1536, Apr. 2008.
[16] B. Singh, V. Verma, and J. Solanki, “Neural network-based selective compensation current quality problems in distribution system,” IEEE Trans. Ind.
Electron., vol. 54, no. 1, pp. 53–60, Feb. 2007.
[17] B. Widrow, J. M. McCool, and M. Ball, “The complex LMS algorithm,” Proc. IEEE, vol. 63, no. 4, pp. 719–720, Apr. 1975.
[18] D. M. Divan, S. Bhattacharya, and B. Banerjee, “Synchronous frame harmonic isolator using active series filter,” in Proc. Eur. Power Electron. Conf., pp.
3030–3035, 1991.
[19] B Singh and V. Verma, “Selective compensation of power-quality problems through active power filter by current decomposition”, IEEE Trans. Power
Del., vol. 23, no. 2, pp. 792–799, Apr. 2008.
[20] Singh B., Jayaprakash P., Kothari D., “New control approach for capacitor supported DSTATCOM in three phase four wire distribution system under non-
ideal supply voltage conditions based on synchronous reference frame theory”, Int. Journal Electrical power energy systems, 2011.
[21] Singh B. et al, “Implementation of DSTATCOM using neural network based radial basis function”, Industry applications society annual meeting., 2013.
[22] Singh B. et al, “Neural network based DSTATCOM controller for three phase three wire system”, International conference on power electronics, drives
and energy systems (PEDES), 2006.
[23] Kumar S. et al, “Control of 4-leg VSC based DSTATCOM using modified instantaneous symmetrical component theory”, International conference on
power systems (ICPS), 2009.
[24] Zavery T. et al, “Control techniques for power quality improvement in delta connected load using DSTATCOM”, IEEE International Electric Machines
Drives Conference (IEMDC), 2011.
[25] Vishal Hande et al., “Voltage regulation with adaptive control algorithm for D-STATCOM”, IEEE Power and energy systems: Towards Sustainable
Energy, 2015.
[26] Gokulnanda Sahu and Kamalakanta Mahapatra, “Model predictive control off DSTATCOM for power quality improvement: Modelling, simulation and
analysis-Part1”, 2015.
[27] Bhim Singh, Alka Adya and A.P. Mittal, “Modelling, design and analysis of different controllers for D-STATCOM”, IEEE Trans. Industrial Electronics
2008.
[28] Dr. P. S. Bimbhra, “Power Elecronics”, Khanna Publishers, 2016.
[29] M.P. Kazmierkowski; R. Krishnan & F. Blaabjerg, “Control in Power Electronics: Selected Problems”, San Diego: Academic Press. ISBN 978-0-12-
402772-5.
[30] R. Zhang, V. Himamshu Prasad, D. Boroyevich and F.C. Lee, “Three-Dimensional Space Vector Modulation for Four-Leg Voltage-Source Converters,”
IEEE Power Electronics Letters, vol. 17, no. 3, May 2002.
[31] M.A. Perales, M.M. Prats, R.Portillo, J.L. Mora, J.I. León, and L.G. Franquelo, “Three-Dimensional Space Vector Modulation in abc Coordinates for
Four-Leg Voltage Source Converters,” IEEE Power Electronics Letters, vol. 1, no. 4, December 2003.
JASC: Journal of Applied Science and Computations
Volume V, Issue XII, December/2018
ISSN NO: 1076-5131
Page No:2161