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Proceedings ArticleDOI

Development of Dynamic Equivalents for MicroGrids using System Identification Theory

TL;DR: In this paper, the authors proposed an approach based on system identification theory for developing dynamic equivalents for microgrids, which are able to retain the relevant dynamics with respect to the existing medium voltage (MV) network.
Abstract: Large deployment of microgrids will have a considerable impact on the future operation of the electrical networks and will greatly influence the power system dynamics mainly at the Medium Voltage (MV) level whenever the upstream system has been lost. In dynamic studies the whole power system cannot be represented in a detailed manner because the huge system dimension would require a very large computational effort. Therefore dynamic equivalents for microgrids need to be derived. The proposed approach is based on system identification theory for developing dynamic equivalents for microgrids, which are able to retain the relevant dynamics with respect to the existing MV network.

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      
        
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
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
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(+
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"-+,./01
 , $,%   !# "-   
* '  (   +'+
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(  + ' "&
"' '+"+*$2#% 
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:"++2"(22
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@2=!"++2"(2"+
+':2;:'
+  * 2 2 2' $>4
/? '%
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,$,%"++&*"+
+ "- +  >, 2/ 
56789$8%'(+(&+*'
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B''+,
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("+' 
+&'('+,(&+*'
&   ' + & '
B' * + ' ( "+  
'&(B'
+' '+*(*
,"++#"-(
' ' '  + 
(B'*,B'
* ( B'* +B'  
+ "  0914 $% +( E $%
 + E $%  "-
'E $*%   * D"* 
 " ( +(   
(  (   ,   
+!#"-+'+*
+ (+*('
+&('(
"+*"('
**"+,
*( * "-  + '&
* , B'* * + & 
 '+ B'* *  *( ' +
*(B'*
,'(+(
:@2=! 

A
' ( +B'  (  +( +
&)&(B'*,
  "+ (  ( 
"++&&'+&
 &*   + ( &  
+'&'' +'
+++(
+ ' *  -"  +( +
&' + ( *( ' "+   
''" & -  4<- &)
( &)  0F1 + ) &- &)  
'"-"(''(
&' ( B'*  , 081   + "
(&'"+0F1
+++*&+(-"&'+
,()+''&''
-"+( ""+ +'-"
 +'&+(&)
+   ( -"  +(  
 +  ''   +(
0G1
+B'*+'&"'
,('"+*'&
+ # * '  - # "-   
"      " *'
+'+ ' +' +'(
++'+&,(B'*


,

D
,!#&'("++
'  (   + "+ !#
 :
:  , +'  '    
*
+ ,  (    &( 
,$,%+#H!#
'&  "++  * -( '  +
+++('B'+
  *
&+ '  $%  ! 
$!% +   ++  * 
&+  + ' $%   *4 
(+**"'*
&!+'++
'&(
 ,
2
!
!
>

,

: + ) + ,  )&( +
#*'&++'"+
,'&+(
   "( +  , +'  ,   -
 + &( ' * - '  + '
" (  &(   - 
B'
:",+'( 
,"&-"++#"-
"+ + (+' +  + #
**B'(
 ( B'*(   "+
* " (  ,   * 
  &+ +(   
+ - -'+"
( +'   &' ( B'*  ,
&  +(   +  (  
*  "  +    + ' 
'' ,       
&((+"
 
*    ' '   '& 
"   2# ( +* &  071
D"* +"-():'$:%
+++'&$%'"+
+"  $H*:
 HH *%*"
' " *'
"+ "   $HH * 
("+H*&%
 !"
*&"
4 2I *   # ' *
$#%  061 + 2I * /  +  +
" *&   ' + * " /
  > *' "++  & 
+('(+
,0A13 +(+(&+*'
 ,  *   ( &( + 
' +"+
+#'+&+*'(+'+
**B'(  + ,'
D"*&
 "++#"-+
' B'( 

+ # * " '' 
 &( + B'(  +   
:A

C
:A:B'(
 # '   * '
 ' ' *  * "
:B'(  '' * '  &+
+'+    + +  
"#('&$)
+%&(*&
051
# $#
3 +*+,"
(*+B'(
"&&*'+
 + #  +   ' " ' "
* &( / &&  ' *
"(+,B'(*
+'+    * '  * +*
 (   ( ' +( 
+ + ( B'( +' &  +
*'
%
+#*"'
:+'"(
&"4('2
 + &    ( 
&(+,&+ *'*
"''+(('+'&
&+B'(*01 :
CD"* ++(+(
("
:C!(B'(&
3 +  ,    + ' "
( +(+'++#*
" &&&  '( D"*
"'&+#*-" 
( B'( +  # * "
*++
( B'(  & 
+(B'(+*'+'++
  " * "    + (
(''+,"&'+"+
+ (+' + & * " 
'(
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::
!
J
J
  "+ (  ( 
"++&&'+&
 + &*   + ( <   '&
 '' +   '  + 
++(&0G1
+ '((
)   + & ( 
&(''&''
 /'      +
 ' ( B' &(  
<+("++' 
&'  +  ''  #&' 
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*(    () * + "+ +  +
'& (
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:9+&''+++
(''"&)'+'
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:9<'+'(+(

++&'"+'&
 + ' +" " +   + (
(&+*' "+ ++ "  +
   + + ' + 
&+*+&-
' ( + + +'+ 
+ ++''*
2''(&
  +  +  + &
 * , "++ *  +  
+(''+(
''''(-B''
+*&(B'$% 
( )
=
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+
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A
KE
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θ
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 0F1 +   +B' 
'+ &"  & +B' +
   +B' * '
'+'+*++ "++
   +    +  
& &( +&'+  '+   
&(**+ 
'++*
'*&'

9
+&+
'  + +  &(  **
*'( + $% '  + 
&++B'0F1
2"$2%++&
'  (    "+ 
 2*+(
*&*0A1*'(2
"  $2% & + &  
2  +'+ + ' +  *
*(0C1'
&'
:(   *' "++ +  
'++';+*+
+-++*&'
''+(+*
(&-+'*
+*'
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+  +  , ( B'*
* ) (  +( ( 
+(  +  + '  (
&  + *& +( -"  (
*'(+,(B'*B'
&   ( '   
'+*(,"++#
"-" (,
"    + + -" &'
+ , ( " ' + "+ + 
' &+"
 
:('+"+,"-*
4 +"-"+ '&-
 "+ +  + ( B'*  &
&*  + ) ("+  
 + (    B'  +  
&  &( B'*+'
+)(+,
+"-+,"-
+ +( " + & + , ( "
'+ &" "  ( 
 + *   + ,4 % +  
* "+  #  * (  (
 "+ &% + &  "+  2I *
 ( " (    
+'++
!#  +'+ * "+ 2I   + 
&+'+&
+ '   '& ( B'*  ,
++*#
  
, (  ++  , " ( '
 :F

&



'
"


:F,(B'*
+ , ( B'* "  "+ + 
"- +'+ + (&'(4 + &'( &' 
+"&)&(&+&'(&'*
(B'(*&(*(+/
'+(:F

+ -( '   (  '  +
 ''   +  + +( "+
 ) + , " ( ' + '(
'+(++
* + * "     ' +' +
((&(''
   *  "++   '
.
/
0
/
* +'+ + &- 
:8
1
A
A
+
2
+
2
:8''+,(B'*
+ ''  "+ *' +* &
'+'+
+* 
[
]
221
AA
=
θ
$9%
+ *&
3

 : 8  + * " 
&(+,+#+
+ ' " +( 091 " '  
"+''
44!
+**&($9% 2
 ) + "+ + ' B'  
B'$A%+'+
*'   '& ( ' 
+   &" 2  + (
'   B' 2  + 
*+('+
 '  2 * +  
'*':G
-  ' + '  + + 
*    + *  "++  " &
'  *     &  +


F
Σ
:G2+
#
J
!
2
!:
 '  " * '
./
0/
*'>+(
*' +   '( + , (
B'* + '  " ' +
,    "   
  +  + , (
B'*+'+++:G
(  *   (  : 
,+!#"-+'+
+ *   "      
&     " +'
+#*'(+'+
8+  +"+'*'
$(%*>'&
5$
  0F1 "  ! 
      
B'*  *( +  "-
'&+#!# &(+
)&'
5$

#
!
!

+  +   &'  (
B'*+,+(
:7 "++,+,(
"'(+'$F55-#%
+#"-+"+#!#
 #H!# &'  ; +
, + , " C5-3   C5-3
:  +   * $("+% + '(
("+,'+:7
+    &  +  (
 :" + ,   +
'" (   " 
+ # "- "   ' 
B''&'7
$!%   +  + '   ' * 95
$+  '     LA 
LA5% "++'+(
   ' + *&   * F
"+*5
>8
+,
&&
'%
(
:7(>4$%(E$&%'
(
<!
,
2,

<
:
!,
!$M#% ,'$-3 E-#%
#"- F55N/55 4AF5EA4A55
, F5N/5 LALFN/A
:LFN/AE#L/F
  +    +
+( & &* +  + ,
(B'*&+,&+*'"
+,  '" "*'
: +''+*&'
+&'"++&"++
, + (+,
(B'**" 
&+*'''",
&&&A
<!
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2,<:!,
!$M#% ,'$-3 E-#%
#"- F55N/55 4A55EA4A55
, F5N/5 L5N/AE#L/F
AL:LFN/A
 + "   + "
B'*"'4%#"-
LFE A%   " '   LA5E C%
 + '*'(
L95    &" +  & 
'(:6>
:  +"   &" + * "
/&(+, "(B'*+
:"+,
   B'( *   & +"
: 5 +' + # / * "  
++,*''
 + +  "+ (  B'( 
 + "+ + (+' + 
B'('+
(&&*:6 *(

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TL;DR: A thorough survey on the academic research progress and industry practices is provided, and existing issues and new trends in load modeling are highlighted.
Abstract: Load modeling has significant impact on power system studies. This paper presents a review on load modeling and identification techniques. Load models can be classified into two broad categories: 1) static and 2) dynamic models, while there are two types of approaches to identify model parameters: 1) measurement-based and 2) component-based. Load modeling has received more attention in recent years because of the renewable integration, demand-side management, and smart metering devices. However, the commonly used load models are outdated, and cannot represent emerging loads. There is a need to systematically review existing load modeling techniques and suggest future research directions to meet the increasing interests from industry and academia. In this paper, we provide a thorough survey on the academic research progress and industry practices, and highlight existing issues and new trends in load modeling.

304 citations


Cites methods from "Development of Dynamic Equivalents ..."

  • ...The authors presented an alternative approach in [73] using a grey box modeling approach....

    [...]

  • ...gated models for the entire network using black-box [70]–[72] and grey-box [37], [38], [73] approaches....

    [...]

01 Feb 2014
TL;DR: This paper summarizes major results of the work of the CIGRE working group on load modeling of new types of load including renewables using measurement data and historical data after two years' activities.

123 citations

Journal ArticleDOI
TL;DR: In this paper, the grey-box approach was used for model development as it incorporates prior knowledge about the ADN structure into the model, making the model more physically relevant and intuitive than black-box or white-box models, and potentially improves the accuracy of the model.
Abstract: This paper presents the development of the dynamic equivalent model of an active distributed network (ADN) based on the grey-box approach. The equivalent model of an ADN comprises a converter-connected generator and a composite load model in parallel. The grey-box approach was chosen for model development as it incorporates prior knowledge about the ADN structure into the model, makes the model more physically relevant and intuitive than black-box or white-box models, and potentially improves the accuracy of the model. The dynamic equivalent model is presented in the seventh-order nonlinear state space format. It was initially loosely developed from the algebraic and differential equations describing assumed typical components of an ADN. Various static load models, dynamic load compositions, fault locations and a diverse range of distributed generation types and scenarios are considered in order to establish the generic range of model parameters for an ADN. The model is intended for the use in large power system stability studies.

110 citations


Cites methods from "Development of Dynamic Equivalents ..."

  • ...A dynamic equivalent of the MicroGrid (MG) was developed using the grey-box approach and evolutionary particle swarm optimization (EPSO) for parameter estimation purposes in [10]....

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Proceedings ArticleDOI
01 Dec 2012
TL;DR: In this paper, the authors proposed a combined energy storage using batteries and super capacitors with high energy and power density for the photovoltaic (PV) based micro grid.
Abstract: The energy flow between source and the load of micro grid must be balanced to have a constant dc grid voltage. Due to intermittency in the natural sources and the variations in load, energy balance operation demands storage. The commonly preferred choice of energy storage in micro grid is valve regulated lead acid batteries. When batteries are used as energy storage, due to its low power density, the charge and discharge rate is low. It causes severe stress on the battery under quick load fluctuations and results in increase in the number of charge/discharge cycles. Hence, the lifetime of the battery reduces. The super capacitors have high power density and it can react speedily to quick load fluctuations. However, super capacitors alone cannot be used as energy storage as it cannot supply load for a longer time. Hence, this paper proposes a combined energy storage using batteries and super capacitors with high energy and power density. The photovoltaic (PV) based micro grid with combined energy storage is designed and the control strategy is validated for different atmospheric and load conditions.

101 citations


Cites background from "Development of Dynamic Equivalents ..."

  • ...It has numerous advantages which includes the utilization of natural sources, low carbon emission, decentralized power system network etc [1]....

    [...]

Journal ArticleDOI
TL;DR: The dynamic equivalent model of ADNC is presented in a seventh-order nonlinear quasi state space format, developed from the algebraic and differential equations describing assumed typical components of the ADNC.
Abstract: Paper presents an equivalent model of an active distribution network cell (ADNC) with distributed generation for transmission system stability studies. The equivalent model of ADNC comprises a converter-connected generator and a composite load model in parallel. The gray-box approach was chosen as it enables inclusion of prior knowledge about the ADNC structure into the model development, hence making the model more physically relevant and intuitive than a black-box or white-box model. The dynamic equivalent model is presented in a seventh-order nonlinear quasi state space format, developed from the algebraic and differential equations describing assumed typical components of the ADNC. The developed equivalent model of ADNC was validated through small and large disturbance studies using the modified IEEE nine-bus transmission system model.

85 citations


Cites methods from "Development of Dynamic Equivalents ..."

  • ...In [11], a gray-box approach was combined with an Evolutionary Particle Swarm Optimization (EPSO) algorithm for parameter estimation of a microgrid (MG)....

    [...]

References
More filters
Journal ArticleDOI
TL;DR: The objective of this paper is to present novel control strategies for MicroGrid operation, especially in islanded mode, that involve mainly the coordination of secondary load-frequency control by a MicroGrid Central Controller that heads a hierarchical control system able to assure stable and secure operation when the islanding of the MicroGrid occurs.
Abstract: The objective of this paper is to present novel control strategies for MicroGrid operation, especially in islanded mode. The control strategies involve mainly the coordination of secondary load-frequency control by a MicroGrid Central Controller that heads a hierarchical control system able to assure stable and secure operation when the islanding of the MicroGrid occurs and in load-following situations in islanded mode.

78 citations

Journal ArticleDOI
27 Dec 2004
TL;DR: In this article, an approach to identify generic dynamic equivalents to distribution systems using recurrent artificial neural networks (ANN)s is presented, which depends on variables at the boundary buses, hence no knowledge of the parameters and the topology of the distribution system is needed.
Abstract: An approach to identify generic dynamic equivalents to distribution systems using recurrent artificial neural networks (ANN)s is presented. It is expected that in the near future a large number of active sources will be utilised within distribution systems and thus, neither detailed modelling nor lumped-load representation for distribution areas will be acceptable. Therefore, the paper suggested training a recurrent ANN to represent the dynamic behaviour of the distribution network is. To involve the dynamic characteristics in the ANN, values of the features that are involved are also introduced at the input layer, thereby defining the order of the dynamic equivalent. The approach depends on variables at the boundary buses, hence no knowledge of the parameters and the topology of the distribution system is needed. At the same time, the computational requirements and the accuracy of the proposed technique are independent of the size and complexity of the network. A 16-machine test network with 112 active distributed sources in the low-voltage area is used to verify the suggested method. Comparisons between the response of the original system and the ANN-based dynamic equivalent show the accuracy of the equivalent model and the validity of the proposed method.

69 citations

29 Aug 2004
TL;DR: The integration of the above models in a steady state and dynamic simulation tool, which is developed in the framework of the EU funded MICROGRIDS project, will provide a simulation test platform, which will be necessary to define and evaluate the developed operational and control strategies as discussed by the authors.
Abstract: The interconnection of small, modular generation and storage technologies at the MV and LV distribution level have the potential to significantly impact power system performance. In this paper models of the main micro-generation sources are described. In particular, the models of Microturbines, Fuel Cells, Photovoltaic Systems and Wind Turbines, are described. In addition basic models of their power electronic interfaces are given. The integration of the above models in a steady state and dynamic simulation tool, which is developed in the framework of the EU funded MICROGRIDS project, will provide a simulation test platform, which will be necessary to define and evaluate the developed operational and control strategies.

41 citations

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