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 Authors : Izilein Fred, Onyegbadue Ikenna A. , Ugada Chukwuemeka Martin, Belgore A. Talatu
 Paper ID : IJERTV4IS070014
 Volume & Issue : Volume 04, Issue 07 (July 2015)
 Published (First Online): 09072015
 ISSN (Online) : 22780181
 Publisher Name : IJERT
 License: This work is licensed under a Creative Commons Attribution 4.0 International License
Simulation of Statcom for Voltage Improvement in an Electric Power Network
Izilein Fred1, Onyegbadue Ikenna.A.2, Ugada Chukwuemeka Martin3 and Belgore. A. Talatu4
Department of Electrical/Electronic Engineering, Igbinedion University Okada,
Edo State, Nigeria.1, 2, 3, 4
Abstract – This research work illustrates the importance of STATCOM for Voltage improvement and stability in a power transmission network. A three bus network was first tested to observe the response of a transmission line when STATCOM was introduced to the network.
The Nigerian 330kV line network was used as a case study to show the importance of STATCOM for voltage improvement. Firstly, two techniques (Newton Raphsons and Fast decoupled) were used to carry out a load flow study of the network .This was done to obtain the buses with low voltage magnitude. STATCOM installation was then simulated on the buses with low voltage magnitude.
It was observed after keen analysis that installation of STATCOM on bus 16 produced an optimal result. The other buses in which STATCOM was installed also showed some level of improvement in the voltage magnitude of some buses. STATCOM is a shunt FACTS device used to inject VAr into the network.
Keywords: STATCOM (Static Synchronous Compensator), Power System Network (PSN), Newton Raphson (NR), Fast Decoupled (FD), Real and Reactive Power.
INTRODUCTION
The function of a power system network (PSN) is to generate and transmit power to load centers at specified voltage and frequency levels and statutory limits exist for the variation about base levels. The nominal frequency shall be 50Hz Â± 0.5%. Under system stress the frequency on the power system could experience variations within the limits of 50Hz Â± 2.5% (i.e. 48.75 51.25 Hz and the nominal voltage shall be 330, 132kV Â± 0.5% while Under system stress or following system faults, voltages can be expected to deviate outside the limits by a further Â± 5% (excluding transient and subtransient disturbances). As the system load changes, the resulting change in real and reactive power demands causes variation in the system voltage and frequency levels. The power system is
stations. This has caused most PSNs to be weak, heavily loaded and prone to voltage instability [3].
Voltage stability can be defined as the ability of a power system to maintain steady and acceptable voltage at all buses in the system at normal operating conditions, after being subjected to a disturbance. It is desired that the power system remains in the equilibrium state under normal conditions, and reacts to restore the status of the system to acceptable conditions after a disturbance, i.e. the voltage after a disturbance is restored to a value close to the predisturbance situation [4].
MATHEMATICALMODELLING OF STATCOM FOR LOAD FLOW ANALYSIS
The equivalent circuit diagram for STATCOM is shown in fig 1
Figure 1: Equivalent circuit for STATCOM
Vstc Vk Zsc I stc 1
equipped with controllers that reduce these variations to acceptable levels well within the statutory limits. In the operation and control of a power system network (PSN),
I stc I N
Where
YstcVk 2
voltage stability is a major concern to the power system engineer as the PSN nowadays operates very close to its
stability limits [1][2].
I N YstcVstc
In these expressions, Vk
represents bus k voltage and V
stc
This is due to increasing load demand, industrialization, environmental and economic factor which hampers the construction of new transmission lines and generating
represents voltage source inverter
IN is the Norton current while Istc is the current in the inverter.
Zsc and Ysc are the transformer impedance and short circuit admittance respectively.
The STATCOM voltage injection Vstc bound constraint is
The current expression in 1.2 is transformed into power expression by the VSC and the power is injected into bus k as shown in equation 1.7 and 1.9.
as follows
S V
I * 4
Vstc min VstcVstc max.3
Where Vstc min and Vstcmax are the STATCOMs minimum and maximum voltage.
stc
stc
stc
S V
(I *
Y *V * ) 5
is simulated on the line for voltage compensation. A
stc
stc N
sc k
twentyseven bus system was later analyzed for load flow
S V
(Y *V *
Y *V * ) 6
stc
stc
sc stc
sc k
using Newton Raphson and fast decouple techniques. The
S V Y V Y V 7
2 * * *
stc stc sc stc sc k
S V I 8
*
k k stc
S V Y *V * V 2Y * 9
voltages whose magnitude was less than or more than 5% of its magnitude was considered for the simulation of STATCOM. The improvement on the line is observed. MATLAB 7.5 was used for the simulation for 0.4sec.
k stc sc k k sc
METHODOLOGY
A three bus system with 330kV line network was first considered in order to properly visualize the effect of STATCOM model on the network. The STATCOM model
CASE STUDY
791 MW
495 MVR
Birnin K Kainji G
Kaduna Kano
89 MW
55 MVR
146 MW
90 MVR
Shiroro
260 MW
161 MVR
114 MW
90 MVR
226 MW
140 MVR
130 MW
80 MVR
Jebba Gs Jebba TS
339 MW
7 MW
4 MVR
413 MW
823 MVR
236 MW
146 MVR
Jos
182 MW
Gombe 0 MW
19 MVR
49 MVR
194 MW
120 MVR
Abuja
112 MVR
Calabar
Aiyede
Oshogbo
72 MW
45 MVR
N Haven
210 MW
130 MVR
Ajaokuta
146 MW
77 MVR
Onitsha
Alaoji
248 MW
153 MVR
484 MW
300 MVR
Ikj West Benin
437 MW
68 MVR
Okpai
Akangba
174 MW
107 MVR
136 MW
84 MVR
120 MW
75 MVR
389 MW
241 MVR
Egbin
967 MW
AES
SAP P/S 0 MW
Delta PS
Afam PS 316 MW
542 MVR
Aja
253 MW
2 MVR
16 MVR
Aladja
498 MW
13 MVR
105 MW
65 MVR
148 MVR
200 MW
Figure 2: 330kV Line of Nigeria Power Network
The system may be divided into three major sections: – North, SouthEast and the SouthWest sections. The North is connected to the South through one triple circuit lines between Jebba and Oshogbo while the West is linked to the East through one transmission line from Oshogbo to Benin and one double circuit line from Ikeja to Benin. The data of the Nigerian transmissio n system were sourced from the National Control Centre of Power Holding Company of Nigeria, Oshogbo, Nigeria. According to
[5] and [6], the datas for the oneline diagram in figure 2 were obtained.SIMULATION RESULT AND ANALYSIS
0.8
0.6
0.4
0.2
0
0.2
0.4
0.6
0.8
PQ
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4
Figure 3: The Real and Reactive Power Response Curve in Bus 1
The real and reactive power in fig 3 is in per unit (pu) value. The reactive power curve is of importance because it gives a picture of the variation in voltage at bus 1.From Figure 3, after a simulation time of 0.108 second, the reactive power demand on line 1 increases and hence, the STATCOM begins to inject reactive power into the network. This continues till the simulation time approaches approximately 0.218 second. At this point, the reactive power increases sharply to approximately 0.76pu, then, the STATCOM begins to demand reactive power from line 1 linking bus 1.The injection and demand of reactive power by the STATCOM, regulates the voltage magnitude of the BUS 1.
0.8
0.6
0.4
0.2
0
0.2
0.4
0.6
0.8
IqIqref
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4
Figure 4: Simulation graph for the quadrature current and quadrature current reference
The quadrature current through bus1 is inversely proportional to the bus1 voltage. From figure 4, it can be seen that the quadrature current began to increase at 0.1 second. It continued till it approached approximately 0.7pu and then it remained constant for about 0.06second .It reduced considerably and then achieved a steady state at 0.35second.At this point, the reactive power demand and generation is approximately equal.it should also be noted that as the current increased, the voltage decreased at almost similar rate.
1.03
1.02
1.01
1
0.99
0.98
0.97
0.96
Vmes_Vref
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4
Figure 5:Simulation Graph of the Measured and Reference Voltage
From Figure 5, it can be seen that at approximately 0.1 second, the voltage magnitude at bus1 began to reduce. This was as a result of the reduction in the reactive power generated by the transmission line linking bus1.At about 0.2second of the simulation, the voltage began to increase. This was as a result of the reactive power injected by the STATCOM into bus1.The voltage approaches steady state at 0.35second of the simulation time.
1.5
1
0.5
0
0.5
1
1.5
Vabc_B2
0.1 0.15 0.2 0.25
Figure 6 Simulation Graph of the Three Phase Voltage in Bus 2
From Fig 6, it can be seen that the three phase voltage in bus2 is balanced and out of phase by 1200.
Vabc_B3
1.5
1
0.5
0
0.5
1
1.5
0.295 0.3 0.305 0.31 0.315 0.32
Figure 7: Simulation Graph of the Three Phase Voltage in Bus 3
From Fig 7, it can be seen that the three phase voltage in bus2 is balanced and out of phase by 1200.
Result from Load Flow Study using Fast decouple Technique
Bus No. 
Voltage Magnitude 
Generation 
Load 

P(MW) 
Q(MVAR) 
P(MW) 
Q(MVAR) 

1 
1.000 
1066.88 
214.72 
—— 
——— 
2 
1.000 
413.00 
923.83 
—— 
——— 
3 
1.000 
339.00 
151.20 
—— 
——— 
4 
0.966 
—— 
—— 
—— 
——— 
5 
1.000 
967.00 
871.54 
—— 
——— 
6 
1.000 
316.00 
276.56 
—— 
——— 
7 
1.000 
498.00 
173.05 
—— 
——— 
8 
1.000 
235.00 
42.57 
—— 
——— 
9 
0.979 
——– 
——– 
— 
——– 
10 
0.974 
——– 
——– 
89.00 
55.00 
11 
0.825 
——– 
——– 
226.00 
14.00 
12 
0.815 
——– 
——– 
114.00 
9.00 
13 
0.769 
——– 
——– 
130.00 
80.00 
14 
0.881 
——– 
——– 
260.00 
161.00 
15 
0.973 
——– 
——– 
7.40 
3.79 
16 
0.922 
——– 
——– 
236.00 
146.00 
17 
0.902 
——– 
——– 
194.00 
120.00 
18 
0.921 
——– 
——– 
72.00 
45.00 
19 
0.878 
——– 
——– 
182.00 
112.00 
20 
0.802 
——– 
——– 
210.00 
130.00 
21 
0.854 
——– 
——– 
484.00 
300.00 
22 
0.946 
——– 
——– 
136.00 
84.00 
23 
0.918 
——– 
——– 
146.00 
77.00 
24 
0.978 
——– 
——– 
248.00 
153.00 
25 
0.700 
——– 
——– 
389.00 
241.00 
26 
0.955 
——– 
——– 
200.00 
124.00 
27 
0.989 
——– 
——– 
4.80 
2.46 
Total 
3834.88 
2138.89 
3328.20 
1857.25 
Fastdecoupled power flow converged in 28 Piterations and 28 Qiterations after 0.12 second.
From the load flow analysis, the following buses have voltage magnitude less than the 5% of the reference voltage magnitude (330kV).
Installation of STATCOM on Bus 11 (Kano)
STATCOM is installed on the Kano bus and the effect on the voltage of the remaining buses is shown in figure 8.
1
0.95
0.9
0.85
Voltage magnitude Before installation Voltage magnitude After installation
0.8
0.75
0.7
Voltage Magnitude (PU)
Figure 8: Chart of Bus Voltage before and after the Installation of STATCOM at Bus 11
Installation of STATCOM on Bus 11(Kano) shows increase in voltage magnitude on buses 11(Kano), 12(Jos), 14(Kaduna), 17(Oshogbo), 18(Ajaokuta), 19(New haven), 20(Aiyede), 21(Ikejawest), 22(Benin), 23(Onitsha), &25(Akangba) except bus 16(katampe) which no increase in voltage was recorded.
Installation of STATCOM on Bus 12 (Jos)
Voltage magnitude (pu)
STATCOM is installed on the Jos bus and the effect on the voltage of the remaining buses is shown in figure 9.
1
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
Voltage magnitude Before
installation
Voltage magnitude After installation
Buses
Figure 9: Chart of Bus Voltage before and after the Installation of STATCOM at Bus 12
Installation of STATCOM on Bus12 (Jos) shows that bus 16(katampe) had no increase in voltage magnitude, but all others i.e. bus11 (Kano), 12(Jos), 14(Kaduna), 17(Oshogbo), 18(Ajaokuta), 19(New haven), 20(Aiyede), 21(Ikejawest), 22(Benin), 23(Onitsha) and 25(Akangba) showed reasonable increase in voltage magnitude.
Installation of STATCOM on Bus 14 (Kaduna)
STATCOM is installed on the Kaduna bus and the effect on the voltage of the remaining buses is shown in figure 10
1.2
0.2
0
buses
0.4
0.6
0.8
Voltage magnitude
Before installation Voltage magnitude After installation
1
voltage magnitude (pu)
Figure 10: Chart of Bus Voltage before and after the Installation of STATCOM at Bus 14
Installation of STATCOM on Bus14 (Kaduna) shows increase in voltage magnitude on buses11 (Kano), 12(Jos), 14(Kaduna), 17(Oshogbo), 18(Ajaokuta), 19(New haven), 20(Aiyede), 21(Ikejawest), 22(Benin), 23(Onitsha) &25(Akangba), but bus 16(katampe) had no increase in voltage.
Installation of STATCOM on Bus 16 (Katampe)
STATCOM is installed on the Katampe bus and the effect on the voltage of the remaining buses is shown in figure 11.
1.2
Voltage magnitude
Voltage magnitude (pu)
1 Before installation
0.8
0.6
0.4
0.2
0
Buses
Figure 11: Chart of Bus Voltage before and the Installation of STATCOM at Bus 16
Installation of STATCOM on Bus16 (katampe) shows increase in voltage magnitude on all the buses.
Installation of STATCOM on Bus 17 (Oshogbo)
STATCOM is installed on the Oshogbo bus and the effect on the voltage of the remaining buses is shown in figure 12.
1.2
1
0.8
0.6
0.4
0.2
0
Voltage magnitude
Before installation
Buses
Voltage magnitude pu
11(Kano)
12(Jos)
14(Kaduna) 16(Katampe) 17(Oshogbo) 18((Ajaokuta) 19(New haven) 20(Aiyede) 21(Ikejawest)
22(Benin) 23(Onitsha)
25(Akangba)
Figure 12: Chart of Bus Voltage before and after the Installation of STATCOM at Bus 17
Installation of STATCOM on Bus17 (Oshogbo) shows increase in voltage magnitude only on buses 17(Oshogbo), 18(Ajaokuta), 19(New haven), 20(Aiyede), 21(Ikejawest), 22(Benin), 23(Onitsha) &25(Akangba).
Installation of STATCOM on Bus 18 (Ajaokuta)
STATCOM is installed on the Ajaokuta bus and the effect on the voltage of the remaining buses is shown in figure 13.
1.2
Voltage magnitude (pu)
1
0.8
Voltage magnitude Before installation
Voltage magnitude After installation
0.6
0.4
0.2
0
Buses
Figure 13: Chart of Bus Voltage before and after the Installation of STATCOM at Bus 18
Installation of STATCOM on Bus18 (Ajaokuta) shows increase in voltage magnitude only on buses 17(Oshogbo), 18(Ajaokuta), 19(New haven), 20(Aiyede), 21(Ikejawest), 22(Benin), 23(Onitsha) &25(Akangba).
Installation of STATCOM on Bus 19 (New heaven)
Voltage magnitude Before
installation
Voltage magnitude After installation
0.4
0.2
0.6
0.8
Voltage magnitude (pu)
STATCOM is installed on the New heaven bus and the effect on the voltage of the remaining buses is shown in figure 14
1.2
1
0
Buses
Figure 14: Chart of Bus Voltage before and after the Installation of STATCOM at Bus 19
Installation of STATCOM on Bus19 (New haven) shows increase in voltage magnitude only on buses 17(Oshogbo), 18(Ajaokuta), 19(New haven), 20(Aiyede), 21(Ikejawest), 22(Benin), 23(Onitsha) &25(Akangba).
Installation of STATCOM on Bus 20 (Aiyede)
STATCOM is installed on the Aiyede bus and the effect on the voltage of the remaining buses is shown in figure 15.
1.2
1
0.8
0.6
0.4
0.2
Voltage magnitude Before
installation
Voltage magnitude After installation
0
Buses
Voltage magnitude (pu)
Figure 15: Chart of Bus Voltage before and after the Installation of STATCOM at Bus 20
Installation of STATCOM on Bus20 (Aiyede) shows increase in voltage magnitude only on buses 17(Oshogbo), 18(Ajaokuta), 19(New haven), 20(Aiyede), 21(Ikejawest), 22(Benin), 23(Onitsha) &25(Akangba).
Installation of STATCOM on Bus 21 (IkejaWest)
Voltage magnitude (pu)
STATCOM is installed on the Ikejawest bus and the effect on the voltage of the remaining buses is shown in figure 16.
1.2
1
0.8
0.6
0.4
0.2
Voltage magnitude Before
installation
Voltage magnitude After installation
0
Buses
Figure 16: Chart of Bus Voltage before and after the Installation of STATCOM at Bus 21
Installation of STATCOM on Bus21 (Ikejawest) shows increase in voltage magnitude only on buses 17(Oshogbo), 18(Ajaokuta), 19(New haven), 20(Aiyede), 21(Ikejawest), 22(Benin), 23(Onitsha) &25(Akangba).
Installation of STATCOM on Bus 22 (Benin)
STATCOM is installed on the Benin bus and the effect on the voltage of the remaining buses is shown in figure 17.
1.2
1
Voltage magnitude (pu)
0.8
0.6
0.4
0.2
Voltage magnitude Before installation
Voltage magnitude After installation
0
Buses
Figure 17: Chart of Bus Voltage before and after the Installation of STATCOM at Bus 22
Installation of STATCOM on Bus22 (Benin) shows increase in voltage magnitude only on buses 11(Kano), 17(Oshogbo), 18(Ajaokuta), 19(New haven), 20(Aiyede), 21(Ikejawest), 22(Benin), 23(Onitsha)&25(Akangba).
Installation of STATCOM on Bus 23 (Onitsha)
STATCOM is installed on the Onitsha bus and the effect on the voltage of the remaining buses is shown in figure 18.
1.2
1
0.8
0.6
0.4
0.2
Voltage magnitude Before
installation
Voltage magnitude After installation
0
Buses
Voltage magnitude (pu)
Figure 18: Chart of Bus Voltage before and after the Installation of STATCOM at Bus 23
Installation of STATCOM on Bus23 (Onitsha) shows increase in voltage magnitude only on buses 17(Oshogbo), 18(Ajaokuta), 19(New haven), 20(Aiyede), 21(Ikejawest), 22(Benin), 23(Onitsha) &25(Akangba).
Installation of STATCOM on Bus 25 (Akangba)
STATCOM is installed on the Akangba bus and the effect on the voltage of the remaining buses is shown in figure 19.
Voltage magnitude (pu)
1.2
1
0.8
0.6
0.4
0.2
0
Voltage magnitude Before installation
11(Kano)
12(Jos)
14(Kaduna) 16(Katampe) 17(Oshogbo) 18((Ajaokuta) 19(New haven) 20(Aiyede) 21(Ikejawest)
22(Benin) 23(Onitsha)
25(Akangba)
Voltage magnitude After installation
Buses
Figure 19: Chart of Bus Voltage before and after the Installation of STATCOM at Bus 25
Installation of STATCOM on Bus25 (Akangba) shows increase in voltage magnitude only on buses 17(Oshogbo), 18(Ajaokuta), 19(New haven), 20(Aiyede), 21(Ikejawest), 22(Benin), 23(Onitsha) &25(Akangba).
CONCLUSION
This research work illustrates the importance of STATCOM for Voltage improvement and stability in a
power transmission network. A three bus network was first tested to observe the response of a transmission line when STATCOM was introduced to the network.
The Nigerian 330kV line network was used as a case study to show the importance of STATCOM for voltage improvement. Firstly, two techniques (NR and FDLF) were used to carry out a load flow study of the network .This was done to obtain the buses with low voltage magnitude. STATCOM installation was then simulated on the buses with low voltage magnitude.
It was observed after keen analysis that installation of STATCOM on bus 16 produced an optimal result.
It is not economically viable to install STATCOM on all the buses with low voltage magnitude hence, it becomes necessary to obtain an optimal location for the installation of STATCOM. For optimal installation of STATCOM, Bus16 becomes an ideal bus because every other bus showed a noticeable increment in voltage magnitude when STATCOM was installed at Bus16.
RECOMMENDATIONS
Based on the findings of this research work, the following recommendations have been suggested.

STATCOM should be installed at bus 16 (Katampe) for optimal improvement of voltage in the network.

In order to successfully install and operate the FACTS device, adequate training should be given to the power system operators.

As the power network increases, load flow analysis should be regularly conducted in order to monitor the changes in voltage magnitude along buses.

For further research purposes, the benefit of other FACTS devices in voltage, power factor and transmission losses improvement should be studied.
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