DIgSILENT PowerFactory. Technical Reference Documentation. SVS - Static Var System. ElmSvsThe static var compensator sy...
DIgSILENT PowerFactory Technical Reference Documentation
SVS - Static Var System ElmSvs
DIgSILENT GmbH Heinrich-Hertz-Str. 9 72810 - Gomaringen Germany T: +49 7072 9168 0 F: +49 7072 9168 88 http://www.digsilent.de
[email protected] Version: 2016 Edition: 1
Copyright © 2016, DIgSILENT GmbH. Copyright of this document belongs to DIgSILENT GmbH. No part of this document may be reproduced, copied, or transmitted in any form, by any means electronic or mechanical, without the prior written permission of DIgSILENT GmbH. SVS - Static Var System (ElmSvs)
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Contents
Contents 1 General Description
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1.1 Basic Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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1.2 Load-Flow Analysis
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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1.2.1 Balanced Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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1.2.2 Unbalanced Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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1.3 Short-Circuit Calculations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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1.3.1 VDE 0102 - IEC 60909 - IEC 62363- ANSI . . . . . . . . . . . . . . . . .
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1.3.2 Complete Short Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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1.4 Harmonics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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1.5 RMS Simulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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1.5.1 Balanced RMS Simulation . . . . . . . . . . . . . . . . . . . . . . . . . . .
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1.5.2 Unbalanced RMS Simulation . . . . . . . . . . . . . . . . . . . . . . . . .
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1.5.3 SVS-Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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1.6 EMT Simulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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2 Input/Output Definition of Dynamic Models
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2.1 Stability Model (RMS) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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2.2 EMT-Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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3 Input Parameter Definitions
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3.1
∗
.ElmSvs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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3.2
∗
.ElmSvsctrl . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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4 References
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List of Figures
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List of Tables
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SVS - Static Var System (ElmSvs)
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General Description
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General Description
Figure 1.1: Static VAr System Model
The static var compensator system is a combination of a shunt capacitor bank and a thyristor controlled shunt reactance. The capacitors in the capacitor bank can be switched on and off individually. The capacitors could be switched with thyristors (TSC) or could be permanently (mechanically) connected (MSC) (Figure 1.1) [1]. The static VAr system is important for controlling the voltage at the direct connected busbars or at a remote busbar. The capacitors may be switched on and off, depending on the load situation, in response to changes in reactive power demands. The thyristor controlled reactor fine-tunes the reactive power delivered by the static var system. A SVS can produce a part or all of the reactive power demand of nearby loads. That reduces the line currents necessary to supply the loads; turn in this reduces the voltage drop in the line as the power factor is improved. Because the static var systems lower the reactive requirements from generators, more real power output will become available. The capacitor banks and reactors are connected in delta configuration.
1.1
Basic Data
The SVS element needs no type. On the Basic Data page could be the data for the thyristorcontrolled reactor (TCR), the thyristor-switched capacitors (TSC) and the mechanically-switched capacitors (MSC) entered. Furthermore it is possible to define the kind of control (balanced/unbalanced).
SVS - Static Var System (ElmSvs)
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General Description
Figure 1.2: Basic Data Page of the Static Var System (∗ .ElmSvs)
SVS - Static Var System (ElmSvs)
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General Description
1.2
Load-Flow Analysis
Figure 1.3: Load-Flow Set-Up of the SVS Element
In the following the different control combinations how the internal admittance of the SVS (ysvs ) is calculated are described. For balanced load flow is only one value calculated, for unbalanced load flow are all three admittances calculated. The current for balanced operation is then calculated according to the following equation: i1 = j · ySV S · u1
(1)
With the setting balanced on the basic data page all three admittances are equal. If the control is set to unbalanced control then all admittances are calculated separately according to the selected control mode on the load flow page and the general settings of the load flow command. If the current of the SVS is displayed in per unit values then the values are based on 1 MVar and the voltage of the connected bus. SVS - Static Var System (ElmSvs)
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General Description
1.2.1
Balanced Operation
If a balanced load flow is executed one of the following control options could be used.
No control If this control option is selected on the Basic Data page, the SVS will have a fixed admittance, which is defined by the input parameters qtcr,actual and the number of switched capacitor ntsc . The total admittance of the SVS is calculated as follows: ySV S = qtsc · ntsc + qtcr,actual + qf ixcap · nf ixcap
(2)
Reactive power control Reactive power control can be done locally, i.e. the reactive power output of the SVS is controlled to a constant value. It is also possible to control the reactive power flow on a remote branch to the desired Q setpoint. Note that capacitive reactive power hast to be inserted as a negative value. A warning will be displayed in the output window if the setpoint for Q is out of range (1.2.1 SVS range) and if the option Consider Reactive Power Limits is not used in the load flow command.
Voltage control The SVS can be set to control the local voltage at its terminal or the voltage on a remote busbar to a specified setpoint. When set to voltage control droop control could be activated. The voltage at local or remote busbar is then controlled according equation 3. The droop control is also depicted in Figure 1.4. With droop control the setpoint is not reached in any case because the setpoint is moved as more reactive power is needed to reach the original voltage setpoint of the SVS. The advantage of the droop control is that more than one SVS at one busbar could control the voltage. As well as the participation of the SVS could be configured with the setting of the droop value.
Figure 1.4: Droop control
ubus = usetpoint +
SVS - Static Var System (ElmSvs)
Qmeas Qdroop
(3)
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General Description
where: ubus is the voltage in p.u. at measurement point usetpoint is the reference voltage in p.u. Qmeas is the reactive power flow at Q-Measurement point. If no Q-Measurement point is select then Q is the reactive power output of the SVS Qdroop is an input parameter the unit is Mvar/p.u. Alternatively could also the rated apparent power (Srated ) and the droop (ddroop) in % be entered instead of Qdroop . Qdroop is then calculated as follows:
Qdroop =
Srated · 100% ddroop
(4)
If no Q-Measurement Point is selected the local reactive power flow in Mvar is used. If a QMeasurement Point is selected (cubicle) the reactive power flow in Mvar of the Q-Measurement Point is used. The Q-flow direction of the Q-Measurement Point should be equal to the Q-flow direction of the SVS. This is depicted in Figure 1.5.
Figure 1.5: Q-Measurement Point flow direction
Station controller The SVS can also be part of a station controller. The admittance will then be calculated according to the following equation: ySV S = Kq · qstationctrl
(5)
where:
SVS - Static Var System (ElmSvs)
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General Description
Kq is the distribution factor in p.u. of the station controller and qstationctrl is the reactive power input signal (from station controller)
SVS Range The SVS can only operate in the given limits. The minimum and maximum reactive power output is defining the minimum and maximum admittance of the SVS. The upper limit is defined as pure capacitor: Minimum admittance:ymin = −(qtcr,max + qf ixcap · nf ixcap )
(6)
Maximum admittance:ymax = −(ntsc · ntsc,max + qf ixcap · nf ixcap )
(7)
where qtcr,max = TCR, max. limit in Mvar qtsc = Q per switched capacitor unit (
