improved performance of diesel driven permanent magnet synchronous generator using
DESCRIPTION
Improved Performance Of Diesel Driven Permanent Magnet Synchronous Generator Using Battery Energy Storage System. By JANE MARIA S Edited By Sarath S Nair www.technologyfuturae.com. OVERVIEW. Introduction Need of BESS Schematic block of BESS based supply system - PowerPoint PPT PresentationTRANSCRIPT
Improved Performance Of Diesel Driven Permanent Magnet
Synchronous Generator Using Battery Energy Storage System
ByJANE MARIA S
Edited BySarath S Nair
www.technologyfuturae.com
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OVERVIEW
Introduction Need of BESS Schematic block of BESS based supply system Control scheme of BESS-PMSG system Principle of operation & control Modeling of Control Scheme Advantages Summary
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INTRODUCTION
• BESS (Battery Energy storage System) is used for load compensation of PMSG driven by diesel engine to enhance its performance.
• BESS has capabilities of reactive power, harmonics, unbalanced load compensation.
• Control of BESS is achieved by indirect current control scheme.
• The voltage at PCC is controlled using BESS under various loads.
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NEED OF BESS
• Diesel engine based electricity generation unit (DG set) may be loaded with unbalanced & non-linear loads.
• Unbalanced & distorted currents lead to unbalanced & distorted 3 phase voltages at PCC.
• It leads to increased fuel consumption, poor efficiency & reduced life of DG sets.
• It leads to operation of DG sets under derated condition, results into increased cost of the system.
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contd..
• The BESS system may improve the performance of DG set to feed unbalanced load without derating.
• BESS can provide compensation of harmonics & reactive power & load balancing.
• PMSG are most efficient machines & robust due to brushless construction.
• Integration of BESS with such a DG set provides active power conditioning .
• BESS can absorb excessive power when load is less & can replenish at the time of peak load. 5
Schematic Diagram for BESS based Supply system
BESS-PMSG based DG set feeding to variety of loads:
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SYSTEM DESCRIPTION
• Consists of the IGBT based 3-phase 3-leg VSI system.
• BESS regulates the PCC voltage constant. Hence, voltage regulator is avoided.
• The governor block is disabled since the active power drawn from PMSG is kept constant.• This leads to single point of operation & load leveling
with BESS.
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contd..
• PMSG is operated at constant rated power with proper utilization of generated electrical energy.
• The surplus power is absorbed by the BESS and during peak load,it replenishes the increased requirement of load, which offers load leveling.
• Here, active component of source current remains fixed, whereas reactive power component depends upon requirement of AC terminal voltage control.
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Control Scheme of BESS-PMSG system
11 12 13 149
Principle of Operation & Control
• 3 phase ism* have two components:• The in-phase component• The quadrature component -(w. r. to phase voltages)
• The in phase components of ref. source currents (isad*, isbd*, iscd*) is required to charge battery of BESS and (or) to feed active power to the load.
• This active power component may be kept constant.• The magnitudes of ismd* can be assigned to a constant
value.10
MODELING of Control Scheme
• Mainly used to derive ism*,which are used in PWM current controller.
• The two components of ism* are estimated as follows:• The in-phase unit vectors,
ua = va / Vm;
ub = vb / Vm;
uc=vc/Vm
Vm = 2/3 √(va2+vb
2+vc2)
va, vb, and vc are the instantaneous voltages at PCC
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Contd..
• va = vsan - Rs isa - Ls pisa
vb = vsbn - Rs isb - Ls pisb
vc = vscn - Rs isc - Ls pisc vsan, vsbn, and vscn are the three phase instantaneous input
supply voltages at PCC
• vsan=vsm sin(ωt)
vsbn=vsm sin(ωt-2π/3)
vscn=vsm sin(ωt+2π/3)
• The in-quadrature unit vectors can be derived by taking a quadrature transformation of the in-phase unit vectors ua, ub and uc as:
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Contd..
• wa = - ub/ √3 + uc/ √3
wb = √3 ua/ 2 + (ub -uc)/(2 √3)
wa = -√3 ua/ 2 + (ub -uc)/(2 √3)
• The quadrature component of the reference source currents is computed as:
• Ver(n) = Vref(n) – Vm(n)
• I*smq(n) = I*smq(n-1) +K p { Ver(n) - Ver(n-1) }+ KiVer(n)
• i*saq = I*smq wa;
i*sbq = I*smq wb;
I*scq = I*smq wc
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Contd..
• The in-phase component of the reference source currents is computed as:
i*sad = I*smd ua;
i*sbd = I*smd ub;
i*scd = I*smd uc
• Reference source currents are computed as:• i*sa=i*saq+i*sad;
i*sb= i*sbq + i*sbd;
i*sc= i*scq + i*scd 14
Modeling of Permanent Magnet Synchronous Machine
• Vd =Rsid+p φ d-wr φ q
• Vq = Rsiq + p φ q + wr φ d
• V’fd = R’fdi’fd + p φ’fd
• V’kd = R’kdi’kd + p φ’kd
• V’kq1=R’kq1i’kq1+p φ’kq1
• V’kq2 = R’kq2i’kq2 + p φ’kq2
where,
• φ d = Ld id + Lmd ( i’fd + i’kd)
• φ q = Lq iq + Lmq i’kq
• φ’fd = L’fd i’fd + Lmd ( id + i’kd)
• φ’kd = L’kd i’kd + Lmd ( id + i’fd)
• φ’kq2= L’kq2i’kq2+Lmqiq 15
Modeling of System Loads
1. Balanced and Unbalanced Delta Connected Linear Loads The current derivative model equations are given as:
p iLap = (vab - RL iLap )/ LL
p iLbp = (vbc - RL iLbp )/ LL
p iLcp = (vca - RL iLcp )/ LL
In case of unbalanced loads the particular phase of the load is made open.
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Contd..
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2. Non-Linear Load The basic equations in derivative form are as:
p id = (vmax-vd )/ 2 Ls
p vd = (id- io)/ Co
Contd..3. The Motor Load
• The model equations defining transient performance of an induction machine are represented as:
[v] = [R] [i] +[L] p[i] + wr [G] [i]
Te = J(2/poles) p wr + TL
where [ v ] = [vsd vsq vrd vrq ]T
[ i ] = [isd isq ird irq ]T
Te = (3/4) poles Lm (isq ird – isd irq)
• p[i] = [L]-1 {[v] – [R] [i] – wr [G] [i]}
pwr = poles (Te – TL) / (2 J)
For generating mode load torque is made negative.18
Advantages of BESS-PMSG system
• The system can feed unbalanced loads without derating.
• Can provide compensation for harmonics and reactive power and load balancing.
• It provides active power conditioning featuring power quality improvement.
• It avoids the need of voltage regulators.• It offers load leveling.
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SUMMARY
• The BESS can be used to improve the performance of a diesel driven PMSG. It regulates supply currents under unbalanced load currents.
• The control scheme & modeling of BESS-PMSG system is discussed.
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REFERENCES
[1] Jashvir Singh, Rajveer Mittal, D. K. Jain, ”Improved Performance of Diesel Driven Permanent Magnet Synchronous Generator Using Battery Energy Storage System”, IEEE Electrical Power & Energy Conference 2009
[2] M.D. Anderson, D. S. Carr, ”Battery Storage Technologies”,Voltage.81,No.3,pp 475-479, March 1993
[3]www.wikipedia.org
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