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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#% ,'$-3 E-#%
#"- F55N/55 4AF5EA4A55
, F5N/5 LALFN/A
:LFN/AE#L/F
  +    +
+( & &* +  + ,
(B'*&+,&+*'"
+,  '" "*'
: +''+*&'
+&'"++&"++
, + (+,
(B'**" 
&+*'''",
&&&A
<!
A
3
,
2,<:!,
!$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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Journal ArticleDOI
TL;DR: A comprehensive survey of existing MG models is provided as well as discusses the principles behind, and their applicability, along with a method for classification of various modelling techniques under four categories viz. component-wise, single entity or lumped, stochastic modelling and dynamic equivalence.

48 citations

Journal ArticleDOI
TL;DR: In this paper, the authors used gray-box modeling concepts to develop a static equivalent of distribution grids comprising a large number of photovoltaic (PV) systems embedded with voltage support schemes.
Abstract: High penetrations of photovoltaic (PV) systems within load pockets in distribution grids have changed pure consumers to prosumers This can cause technical challenges in distribution and transmission grids, such as overvoltage and reverse power flow Embedding voltage support schemes into PVs, such as standard ${\cos \phi (P)}$ characteristic proposed by the German grid codes, may cause more changes in the steady-state behavior of distribution grids and, in turn, the transmission side Accordingly, it is important to properly model active distribution grids to analyze the system impacts of these changes to plan and operate future smart power grids However, due to the high dimension of distribution grids, considering a detailed distribution grid to study the transmission side or a fraction of the distribution grid is either cumbersome or impractical Therefore, it is required to develop a reasonable equivalent that can fairly capture the dominant behavior of the distribution grids The aim of this paper is to use gray-box modeling concepts to develop a static equivalent of distribution grids comprising a large number of PV systems embedded with voltage support schemes In the proposed model, the PV systems are aggregated as a separate entity, and not as a negative load, which is traditionally done The results demonstrate the superior quality of the proposed model compared with the model with PV systems as the negative load

47 citations


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

  • ...The gray-box load modeling has been addressed in [25]–[28]....

    [...]

Journal ArticleDOI
TL;DR: In this article, the authors present a methodology for the investigation of the dynamic behavior of microgrids based on measurements using Prony analysis and state-space black-box modeling techniques.
Abstract: The dynamic performance of microgrids is of crucial importance, due to the increased complexity introduced by the combined effect of inverter interfaced and rotating distributed generation. This paper presents a methodology for the investigation of the dynamic behavior of microgrids based on measurements using Prony analysis and state-space black-box modeling techniques. Both methods are compared and evaluated using real operating conditions data obtained by a laboratory microgrid system. The recorded responses and the calculated system eigenvalues are used to analyze the system dynamics and interactions among the distributed generation units. The proposed methodology can be applied to any real-world microgrid configuration, taking advantage of the future smart grid technologies and features.

36 citations

Journal ArticleDOI
TL;DR: In this paper, a dynamic equivalent black-box model based on Prony analysis is presented for dynamic studies of microgrids, considering changes in the active and reactive powers, bus voltages, currents and frequency.
Abstract: A dynamic equivalent black-box model, based on Prony analysis is presented. The proposed model is suitable for dynamic studies of microgrids, considering changes in the active and reactive powers, bus voltages, currents and frequency. The developed model is evaluated using simulation results obtained from a medium-voltage microgrid and test measurements recorded in a low-voltage microgrid laboratory test facility. Results from the proposed model are in good agreement with the corresponding responses obtained from both simulations and laboratory tests. The examined microgrid configurations include rotating machines and inverter interfaced units implementing different control strategies, thus verifying the robustness of the proposed model.

34 citations


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

  • ...The proposed model focuses on the representation of the dynamic behaviour of microgrids, where transients involved are generally faster and with larger damping, due to the small inertias of the rotating DG units and the resistive behaviour of the microgrids [5], [6], [14]-[16]....

    [...]

  • ...Dynamic equivalent models using grey- [14]-[16] and black-box [17]-[21] approaches can overcome the lack of detailed information of the DG unit parameters...

    [...]

Journal ArticleDOI
TL;DR: In this article, a grey-box equivalent model of an active distribution network (ADN) consisting of several micro-grids was developed for frequency stability studies. But, the model is not suitable for the case of continuous and discontinuous uncertainties.
Abstract: This study presents an approach for developing the dynamic equivalent model of an active distribution network (ADN), consisting of several micro-grids, for frequency stability studies. The proposed grey-box equivalent model relies on Prony analysis to establish stop time and load damping as the required modelling parameters. Support vector clustering (SVC) and grouping procedure are employed for aggregation and order-reduction of ADN. This significantly decreases the sensitivity of the estimated parameters to operating point changes which, in turn, guarantees the model robustness. This is done through representing the SVC output, that is, clusters, by cluster substitutes. The final ADN dynamic equivalent model is represented by several groups, in which their mutual interactions are taken into account by a new developed mathematical-based criterion. Simulation results reveal that the proposed model is robust which could successfully take into account the continuous and discontinuous uncertainties.

33 citations

References
More filters
Journal ArticleDOI
TL;DR: In this paper, a new instantaneous reactive power compensator comprising switching devices is proposed, which requires practically no energy storage components, and is based on the instantaneous value concept for arbitrary voltage and current waveforms.
Abstract: The conventional reactive power in single-phase or three- phase circuits has been defined on the basis of the average value concept for sinusoidal voltage and current waveforms in steady states. The instantaneous reactive power in three-phase circuits is defined on the basis of the instantaneous value concept for arbitrary voltage and current waveforms, including transient states. A new instantaneous reactive power compensator comprising switching devices is proposed which requires practically no energy storage components.

3,331 citations

Journal ArticleDOI
TL;DR: What are the common features in the different approaches, the choices that have to be made and what considerations are relevant for a successful system-identification application of these techniques are described, from a user's perspective.

2,031 citations

Proceedings ArticleDOI
07 Aug 2002
TL;DR: In this article, the authors present a control technique for distributed generation (DG) plants that use feedback of only locally measurable variables, which allows correct system operation and switching between parallel and isolated modes without needing online communication of control signals between the generators.
Abstract: It is expected that dispersed generation (DG) will play an increasing role in electric power systems in the near future. Among the benefits that DG can give to the power system operators and to the electricity customers, one of the most attractive is the possibility of improving the continuity of power supply. DG plants can be designed to supply portions of the distribution grid in the event of an upstream supply outage. Techniques for controlling DG plants that use feedback of only locally measurable variables are presented. This solution allows correct system operation and switching between parallel and isolated modes without needing online communication of control signals between the generators. The control technique is described with particular reference to inverter-interfaced systems (micro-turbines, fuel cells). Simulations of sample cases including different size and type of generators are presented.

310 citations

Journal ArticleDOI
TL;DR: In this article, a sequence of actions and conditions to be checked during service restoration in the low voltage area are identified and tested through numerical simulation, and the need of storage devices is addressed in order to ensure system stability, achieve robustness of operation, and not jeopardize power quality.
Abstract: Under normal operating conditions, a MicroGrid is interconnected with the medium voltage network; however, in order to deal with black start and islanded operation following a general blackout, an emergency operation mode must be envisaged. A sequence of actions and conditions to be checked during the restoration stage are identified and tested through numerical simulation. Voltage and frequency control approaches, inverter control modes, and the need of storage devices are addressed in this paper in order to ensure system stability, achieve robustness of operation, and not jeopardize power quality during service restoration in the low voltage area

269 citations

Proceedings ArticleDOI
12 May 2002
TL;DR: A new meta-heuristic (EPSO) built putting together the best features of evolution strategies (ES) and particle swarm optimization (PSO), including an application in opto-electronics and another in power systems is presented.
Abstract: This paper presents a new meta-heuristic (EPSO) built putting together the best features of evolution strategies (ES) and particle swarm optimization (PSO). Examples of the superiority of EPSO over classical PSO are reported. The paper also describes the application of EPSO to real world problems, including an application in opto-electronics and another in power systems.

246 citations

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