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

Citations
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Proceedings ArticleDOI
19 Jun 2011
TL;DR: In this article, a critical review of existing literature on aggregated models of wind-based generation, active distribution network cells and micro-grids for power system studies is presented.
Abstract: The paper describes some of the initial results of the CIGRE Working Group C4.605 “Modeling and aggregation of loads in flexible power networks”. One of the tasks of the working group is to provide recommendations on developing equivalent static and dynamic models for clusters of diverse loads/generators, i.e., models of distribution network cells and microgrids and recommendations on procedures for data/response gathering and processing. This paper focuses on critical review of existing literature on aggregated models of wind-based generation, active distribution network cells and microgrids for power system studies.

11 citations


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

  • ...The physical laws that approximate the MG slow dynamics under the study are similar to those that govern the active power control in a diesel group [ 33 ], being the parameterized model structure represented in Figure 6....

    [...]

  • ...Therefore, suitable dynamic equivalents for MG comprise the detailed model of the main storage device VSI control and the MG slow dynamics equivalent model corresponding to the aggregated model of the remain MG components, as it can be observed from Figure 4. Therefore, the aim of the system identification procedure is to identify the equivalent model of the MG slow dynamic behavior [ 33 ], [48]....

    [...]

  • ...The detailed model of the whole MG network is divided into two parts: The internal subsystem that has to be retained for detailed analysis and the external subsystem that will be replaced by the equivalent model [ 33 ], [48], as depicted in Figure 2. The dynamic system to be identified consists of a set of differential and algebraic equations corresponding to the dynamic models of the several microgeneration systems describing the state ......

    [...]

  • ...System identification techniques in combination with some general knowledge of network structure, if applied adequately, are suitable for DNC model development as they rely on actual measured system responses and can be easily validated [31]-[ 33 ], [38]-[40]....

    [...]

  • ...Therefore, appropriate dynamic equivalents for MG are required in order to speed up numerical simulations [ 33 ], [48] and to represent the MG’s dynamic behavior with respect to the MV network....

    [...]

Book
29 Apr 2013

10 citations


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

  • ...As a result of the droop control implemented in the VSI, the main storage unit will support all power deviations by injecting or absorbing some amount of active power proportionally to the MG frequency deviation [6, 17]....

    [...]

  • ...More recently EPSO was successfully applied in training a FIS model under an entropy criterion for wind power prediction [214], denoting that EPSO performs well under different criteria, and its robustness has effectively been exploited as a nonlinear global parameter estimation tool to build dynamic equivalents for MG using MSE criterion [17]....

    [...]

  • ...86 with respect to the MV networks, it is necessary to speed up numerical simulations with limited technical resources and therefore the development of dynamic equivalents for MG is required [16, 17]....

    [...]

  • ...In this case the physical laws that approximate the MG slow dynamics under the study are similar to those that govern the active power control in a diesel group [17]....

    [...]

  • ...The mathematical models adopted to represent the dynamic behaviour of each MG generation system were adapted in order to be linked together with the algebraic equations describing the LV network forming thus the whole model of a MG as a multi-machine power system model [16, 17] in chapter 5....

    [...]

Journal ArticleDOI
24 Nov 2017-Energies
TL;DR: In this paper, the authors proposed an equivalent modeling method for the microgrid under grid-tied mode based on a characteristic model, which can simplify the micro-grid model in the numerical simulation of the distribution network.
Abstract: Microgrids can significantly improve the utilization of distributed generation (DG) and the reliability of the power supply. However, in the grid-tied operational mode, the interaction between the microgrid and the distribution network cannot be ignored. The paper proposes an equivalent modeling method for the microgrid under grid-tied mode based on a characteristic model. It can simplify the microgrid model in the numerical simulation of the distribution network. The proposed equivalent model can present the dynamic response of a microgrid but not miss any of its primary characteristics. The characteristic model is represented by a low-order time-varying differential equation with the same characteristics of the original microgrid system. During the modeling process, the voltage and the power exchanged between the microgrid and distribution network are collected as the training data for the identification of model parameters. A recursive damped least squares algorithm (RDLS) is used for the parameter identification. A microgrid system containing different DGs is built to test the proposed modeling method in DIgSILENT, and the results show that the proposed dynamic equivalent modeling method is effective and the characteristic model can present the dynamic behaviors of the detailed model of a microgrid.

10 citations


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

  • ...In [19] an equivalent model of a microgrid is studied for the dynamic analysis based on an optimization method....

    [...]

Journal ArticleDOI
TL;DR: In this paper, a non-mechanism model is proposed to restore the dynamic characteristics of MG better, and the parameters identification of the model is solved by improved immune algorithm.
Abstract: Microgrid (MG) contains large scales of flexible components, so the traditional distribution network equivalent method is not applicable in MG equivalent research. In this study, a novel MG model structure considering the influence of control strategy on the external characteristics of MG is presented, in order to make measurement-based modelling approach more suitable for equivalent research of MG. The proposed model is a non-mechanism model which can restore the dynamic characteristics of MG better, and the parameters identification of the model is solved by improved immune algorithm. Finally, through the fault validation way the effectiveness of the model is demonstrated.

9 citations

Journal ArticleDOI
TL;DR: In this article, a non-linear parameter identification method for evaluating the external equivalent model of a distributed network is presented, which involves an artificial dynamic system, whose dynamics are explicitly designed to be stable by adopting the Lyapunov theory.

8 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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