Index:
DNP3 Security:
Challenges and Solutions
Alan Scott
Abstract: SCADA networks have historically been designed to optimize efficiency and functionality, without consideration of cyber-security issues. Increasing inter-connectedness of networks and regulatory oversight has now elevated cyber-security to be a mandatory consideration for many network operators.
While DNP3 is among the SCADA protocols most widely adopted by energy utilities internationally, cyber-security was not a consideration of its original design. The DNP Users Group has recently adopted security extensions for the protocol that provide low-overhead mechanisms to ensure reliable authentication of DNP3 messages. These security mechanisms are currently being trialed and evaluated. This paper reports on outcomes and recommendations from these trials.
Practical implications for network operators who wish to apply DNP3 security within their network are discussed, as are future proposed security enhancements for DNP3.
APPLICATION
OF ADVANCES IN MAGNETIC ACTUATOR, VACUUM INTERRUPTER AND MICROPROCESSOR
TECHNOLOGY TO IMPROVE NETWORK PERFORMANCE THROUGH AUTOMATION
AND BETTER PROTECTION GRADING OF AUTO RECLOSERS
Neil O'Sullivan and Tony Stacey
Abstract: Today's electricity utilities are challenged with
achieving greater performance and reliability levels than
ever before, generally with fewer resources available to them.
Use of modern auto reclosers with Intelligent Electronic Device
(IED) controllers is one of the most effective tools available
to today's utility engineer to increase overhead network performance.
ESTIMATION
OF DIELECTRIC STRENGTH OF COMMERCIAL VI
Irina N. Poluyanova
Abstract: Combined conditioning and test method suitable for
estimation of dielectric strength of commercial vacuum interrupters
has been offered. Comparison with the conventional “up
and down” method has been provided. Method has been
successfully applied for a range of commercial vacuum interrupters.
FIELD
EMISSION METHOD OF PRESSURE DYNAMICS REGISTRATION IN VACUUM
INTERRUPTERS
Sergey V. Sydorenkov, Andrey S. Baturin,
Eugeny P. Sheshin
Abstract: A new method of pressure dynamics registration in
vacuum circuit breakers (VCBs) is described. It is based on
dependence of field emission parameters on the pressure in
VCB. It was noticed that position of current-voltage characteristic
in the Fawler-Nordheim (F-N) coordinates depends on the pressure
in vacuum chamber. Having made some assumptions we could register
pressure dynamics by registering the change of current-voltage
characteristic’s intercept calculated at constant slope.
This value was named as the A_ -parameter. On measuring dependence
of the A_ -parameter on time during a comparatively short
period, one can forecast the alteration of the pressure in
vacuum interrupter for a long time period.
FUTURE
TRENDS IN DEVELOPMENT OF LOW-VOLTAGE VACUUM SWITCHGEAR
Alexy M. Chaly, John Cunningham
Abstract: A range of new products emerging from recent development
in vacuum switching technology is presented. Their technical
characteristics as well as particular benefits providing for
customers are discussed.
HIGH-CURRENT
VACUUM ARC APPEARANCE IN NON-HOMOGENEOUS AXIAL MAGNETIC FIELD
A.M. Chaly, A.A. Logatchev, K.K. Zabello,
S.M. Shkol'nik.
Abstract: The distribution of the spots over the cathode of
high-current vacuum arc stabilized by axial magnetic field
(AMF) has been investigated. AMF configuration has been varied
from conventional
"bell-shaped" to "magnetic barrier", where
substantial AMF is created in the electrode edge virtually
vanishing in the center. Complex effect of the AMF configuration
on the behavior of cathode spots has been found. This behavior
has been satisfactory explained based on the Steenbeck principle.
It has been shown that "magnetic barrier" represents
optimum AMF configuration providing even current distribution
and minimum arc voltage.
PECULIARITIES
OF NON-SUSTAINED DISRUPTIVE DISCHAGES AT INTERRUPTION OF CABLE/LINE
CHARGING CURRENT
A. M. Chaly, L.V. Denisov, V.N. Poluyanov,
I.N. Poluyanova
Abstract: It has been found out that NSDD probability increases
at cable/line charging current interruption compared with
no-load test. This fact has been explained by formation of
contact welds at closing of the preliminary charged cable/line.
These welds being torn apart at the following contact partition
may serve as a source of macroparticles or surface irregularities
resulting in increased probability of NSDD.
Overvoltages
Measurement and Statistical Simulation
Abstract: Overvoltage is one of the main reasons for damage
of power networks up to 38kV. In overhead lines mainly lightning
overvoltages, caused by phase fault, earth fault and ferroresonance
occur (80, 10 and 5% respectively). Neither lightning overvoltages,
nor ones caused by ferroresonance and earth faults depend
on the type of switching devices applied in the network. Only
transient overvoltages, their levels and probability significantly
depend on the type and turning quality of switching devices.
A
Computer Simulation Of Transformer Magnetizing Current Interruption
By A Vacuum Circuit Breaker
Alexey M.Chaly, Alevtina T.Chalaya
Abstract: A computer program has been elaborated to calculate
switching overvoltages during transformer interruption of
a magnetizing current by a vacuum circuit breaker (VCB). This
program uses the Monte Carlo simulation technique and takes
into account a three-phase switching phenomena in an isolated
neutral electric circuit.
Computer
Aided Reconstruction Of The Cathode Image In High Current
Vacuum Arc From The Results Of High Speed Photography
V.P. Afanas'ev, A.M. Chaly*,
A.A. Logatchev, S.M. Shkol'nik, K.K. Zabello
Abstract: The images of the cathode, obtained by the method
of high speed photography, are of ellipsoidal form as they
are taken at the small (about 10 degrees) angle to the cathode
surface. For this reason it is very difficult, if possible
at all, to make conclusions about the spatial distribution
of cathode spots and current density over the cathode surface.
One can perform inverse parallel projection, but previously
it is necessary to clean the image from the noise occurring
from the plasma radiation and from other noise sources. In
this paper we propose the method of image filtering, based
on contours of equal intensity evaluation and subsequent estimation
of the current density on the cathode.
New
generation of medium voltage circuit breakers
A. Chaly, A. Gusev
Abstract: Today vacuum circuit breakers (VCB) have become
dominant apparatuses for a wide range of electrical networks
with rated voltages of 6-36 kV. It is a matter of fact, that
a portion of this kind of switching devices for these voltage
classes within total amount of produced circuit breakers in
Europe and USA is about 70%, in Japan is 100% and in 1997
in Russia this fraction outreached 50%.
The
Effect of the Stray Cable Parameters on the HF Interrupting
Capacity of VCB
Alexey M. Chaly, Alevtina T. Chalaya,
Victor N. Poluyanov, Irina N. Poluyanova
Abstract: HF interruption behaviour of VCB is very important
for analysis of switching surges induced at interruption of
inductive load by VCB. In an actual network, HF current is
produced when power cable is discharged through VCB separating
contacts. Many researchers dealt with this problem by simulating
actual cable by LC circuit with lumped elements. We have conducted
experimental research concerning HF interruption behaviour
of VCB with CuCr contacts at interruption of the «artificial»
cable and equivalent single-frequency LC circuit. The experimental
results revealed a strong effect of cable stray parameters
on the VCB HF interruption behaviour.
The
Features of 0.4kV Motor Interruption by a Vacuum Contactor
with Different Contact Materials
Alexey M. Chaly, Alevtina T. Chalaya,
Irina N. Poluyanova, Victor N. Poluyanov
Abstract: A computer aided model has been used to simulate
current chopping behaviour at different current levels. This
model is based on the known arc life time of a DC current.
The appropriate experimental research has been carried out
for a batch of 35 industrial VI with CuCr contacts. The obtained
dependencies of the average arc life time VC current shows
a certain technological scatter that has been taken into account
in further chopping current simulations. The developed software
has been used to analyze features of 0.4kV motor interruptions
by low voltage vacuum contactor with CuCr and AgWC contacts
(low-surge contact material). The obtained results have been
generalized in «safe operation regions» that allow us to consider
the necessity of the surge suppression when a low voltage
vacuum contactor is applied for motor control.
The
Influence Of A Vacuum Circuit Breaker And Circuit Parameters
Of Switching Overvoltages Generated During Interruption Of
Starting Motors
Alexey M.Chaly, Alevtina T.Chalaya
Abstract: A computer program has been developed for simulating
voltage escalation (VE) when a vacuum circuit breaker (VCB)
interrupts a starting motor. The influences of the vacuum
circuit breaker's high frequency (HF) interrupting capability,
dielectric strength rise, cable length and also, motor power,
has been traced out to produce a sort of general view of the
overvoltage phenomena in actual networks. It has been discovered
that HF interrupting capability is important for high power
motors connected by short cables to the VCB when B-termination
of VE predominates. In the majority of practical cases, overvoltage
protection is recommended for both conventional and low surge
contact materials.
The
Peculiarities of Interruption of the Medium Voltage Motors
by VCB with CuCr Contacts.
Alexey M. Chaly, Alevtina T. Chalaya,
Victor N. Poluyanov, Irina N. Poluyanova
Abstract: Monte-Carlo simulating technique and appropriate
software has been developed to analyze switching overvoltages
occurring at interruption of 6 and 10 kV motors by VCB with
CuCr contacts. VCB parameters have been determined experimentally.
A comparison has been provided between VCB switching behaviour
at interruption of 6 and 10kV motors. Voltage escalation has
been shown to be the most important process for 6kV motors
with respect to switching overvoltages generation. In contrast
to 6kV motors three phase virtual current chopping predominates
for 10kV motors. It has been deducted that for the majority
of the real field applications VCB with the most popular contact
material (CuCr base) can create dangerous overvoltages. Switching
surge analysis conducted with the aid of Alternative Transients
Program (ATP) proved metal oxide surge arrester connected
in parallel to VCB contacts to be the most effective way to
suppress phase to ground overvoltages. Turn-to-turn overvoltages
induced at interruption of medium voltage motors by VCB with
described protection have also been studied. These overvoltages
have been compared with turn-to-turn overvoltages induced
by «ideal» breaker that does not interrupt high frequency
current at all. Our analysis revealed that maximum turn-to-turn
overvoltages induced by VCB with adequate protection do not
exceed overvoltages induced by the «ideal» circuit breaker
(ICB) for more then 15% and are lower then similar overvoltages
induced by conventional breakers in the same conditions (oil,
air, magnetic).
Novel
Approach To Insulating Medium Voltage Reclosers.
Abstract: Tavrida Electric's novel insulation system developed
for medium voltage reclosers is based on the effect of combined
insulation. It presents an effective alternative to SF6 and
solidly insulated recloser designs. The positive aspects of
both systems are combined to provide the design flexibility
offered by SF6 insulated switchgear with the environmental
advantages of solidly insulated switchgear while eliminating
the shortcomings of these insulation systems. |
