Power Quality Issues and Need of Intelligent PQ

Monitoring in the Smart Grid Environment

Mohibullah Shahedul Haque Laskar
Dept of Electrical Engg, Zakir Hussain Electrical Engineering Department,
College of Engg & Tech., AMU, Aligarh, National Institute of Technology, Silchar, India.
Email: muhib50zhcet@gmail.com E-mail:shlaskar@rediffmail.com

Abstract - PQ issues are very much important for utilities, flying close to power lines and getting electrocuted, and
customers and end users and it is essential to be known by the accidental acts such as trees or equipment contacting power
concerned authorities or users for reduction of economic losses lines[1],[2].
due to the poor PQ. The cost of poor PQ is high and rising. The A large number of disturbances generated by customer-
paper gives insights on global economical losses due to poor
PQ. The business risk posed by PQ problems is a real one with owned equipments and plant operations are beyond the
even ‘low tech’ industries exposed to serious financial losses. utility’s control. In industrial and commercial facilities,
The global economic meltdown is not the only factor that is disturbances may be caused by the operation of arc welders
pulling down the revenues of Asian countries. A study released and the switching of power factor capacitors and inductive
said Indian industries lost more than $ 9.6 billion in 2008-
09 due to power outages. According to 2008 reports, poor loads such as motors, transformers, and lighting ballast
power quality costs European business more than 150 billion solenoids. Moreover, fluorescent lamps, CFLs, and other
dollars a year. In this paper, a comprehensive survey on devices that use power electronics such as switch-mode
different power quality related problems as experienced by
power supplies, television sets, light dimmers, and
customers in different countries are highlighted. Summary of
PQ costs are given. As the consequence of poor PQ might have adjustable-speed drives can also inject harmonics into the
large financial impacts on a country’s economy, more power system [3]. Hence reliable power is essential for both
initiatives are expected from the concerned parties and utilities and customers.
regulating bodies to take corrective measures for maintaining
better power quality from utility and at end users. Smart grid Although power production continues to keep up with
requires intelligent PQ monitoring to solve different PQ related demand, investments in transmission assets have been in a
problems. Authors proposed an intelligent power quality steady decline for many years, steadily undermining the
monitoring system that will help to detect different PQ
grids reliability. Consequently, any drop in supply reliability
disturbances and consequently assist in employing or
implementing appropriate mitigation techniques. is surely going to impact power quality. The aging power
Index Terms-- Deregulation, harmonics, interruptions, grid infrastructure and the incompatibility between present
Power quality, voltage sag, smart grid, power quality load characteristics and the electric power supply
monitoring.
environment frequently give rise to poor power quality. This
I. INTRODUCTION results in significant economic losses in a wide range of
Electric power quality (PQ) has become the concern of industries, including financial, services, health care, high
utilities, end users, manufacturers, and all other customers. tech, and process manufacturing. A decrease in supply
Power quality is the set of parameters defining the properties voltage for a fraction of a second can trip a microprocessor-
of power supply delivered to the users in normal operating
based controller offline, disrupting an entire manufacturing
conditions in terms of continuity of supply and characteristics
of voltage (magnitude, frequency, symmetry, waveform etc.). process. A glass factory in France lost $ 8820000 and 3 days
Modern electronic equipments and devices, such as micropro- of production due to consecutive failure of two transformers.
cessors, microcontrollers, telecommunications equipment and The cost of a kWh not supplied because of an outage is
sensitive computerized equipments etc. are susceptible to PQ much higher than the cost of a kWh that is supplied when
problems. Poor PQ has become a more important concern of needed [4]. The global bill for poor power quality is more
both power suppliers and customers. Application of than 500 billion Euros per year which is 50% of the turnover
deregulation policy in power systems results in growing
of the global electricity sector. For many business uses, the
attention regarding power quality issues. Although much
efforts and investments are done by utilities to prevent power cost of poor PQ is higher than the electricity bill and the cost
interruptions, it is not possible to completely control is rising. Also it has been observed in [5,6] that utility
disturbances on the supply system. Many disturbances are due deregulation effects on power quality requiring industry-
to normal operations such as switching loads and capacitors wide action to maintain sufficient standards
or faults and opening of circuit breakers to clear faults. Faults One of the most critical issues in ensuring reliability is
are usually caused by events outside the utility’s control. monitoring power system performance [5]. Monitoring can
These events include acts of nature such as lightning, birds
 provide information about power flow and demand and help currents associated with the starting of large motor loads is
identify the cause of power system disturbances. It can even the most common. These events maybe originated at the
help identify problem conditions on a power system before utility side or at the customer site.
they cause interruptions or disturbances. Many systems are In a deregulated environment, a suitable counter measure
affected due to absence of an effective PQM programme. is required to be taken to prevent system from deterioration,
A solution for this problem is to design a system basing on otherwise probability of increase in the number of the
IEEE recommended practice [3, 10], suitable for exact power voltage sag events is more.
quality measurement and monitoring, so that necessary steps
B. INTERRUPTION
may be taken as precautions/and for proper controlling.
A very short but complete loss of supply is called an
Although much works are done on Real-Time Power Quality
interruption. An interruption occurs when the supply voltage
Monitoring, still much improvement is required for present
decrease less than 10% from its original value up to a period
day problems. We are in need of an intelligent system with
of time not exceeding one minute. The number of
up-to-date and appropriate software that works smoothly with
interruptions of the supply also tends to increase in
appropriate hardware to form a compact single station/system
deregulated environment like voltage sags and a suitable
for power quality monitoring and controlling without the use
mitigation is essential.
of different devices from different vendors. PQM method
should replace earlier methods of one way communication.
C. HARMONICS
This should be compatible with smart grid sensors for smart
A sinusoidal component of a periodic waveform having a
metering with advanced metering infrastructure (AMI) in
frequency that is an integral multiple of the fundamental
distribution system (two-way communication).
system frequency [1], [3]. The Nonlinear characteristics of
devices and loads on the power system give rise to harmonic
II. POWER QUALITY ISSUES AND DISTURBANCES
distortion. Harmonic distortion levels are described by the
Defining power quality and its disturbances is one of the complete harmonic spectrum with magnitudes and phase
PQ issues [1],[2],[5]. An overview of PQ definitions will be angle of each harmonic component. Despite its deficiency as
helpful in understanding different PQ events or parameters. in [1], [2] the Total Harmonic Distortion THD is frequently
In a broad sense power quality may be defined as “any used as a measure of the degree of harmonic distortion of
power problem manifested in voltage, current, or frequency the system. In a deregulated environment harmonic
deviations that result in failure or misoperation of customer problems will continue to increase because of the fact that
equipment” [3]. the independent power producers IPP, which are using wind
“High Power Quality” has become one of the aims of and solar energy to generate power, will depend mainly on
industrial systems design due to the widespread use of inverters to interface with the utility grid leading to the
electronic based equipments in nearly every aspect of our increase of the harmonic distortion [3],[6].
modern life. The most significant power quality problems Besides this, the extensive use of FACT controllers to
that are responsible for poor power quality and are having control the flow of power in transmission line has the ability
detrimental effect on industrial load operation are voltage of boosting the harmonic distortion levels due to the
sags, interruptions, harmonics and voltage flickers [3],[ 6]. inherent non-linearity associated with these devices and the
Electric power quality has become an important issue in normal proliferation of using non-linear and electronically
the deregulated power systems. Deregulation is resulting in switched loads at customer side will continue to increase
important structure changes in the utility industry and affect of harmonics. [2], [3].
presents the possibility of improving the system operation D. VOLTAGE FLUCTUATION AND FLICKER
efficiency. However, there are some significant impacts of Voltage fluctuations are changes or swings of the voltage
deregulation on power quality which need improved envelope in a systematic manner or a series of random
mitigation [6]. voltage variations and are always referred to as voltage
A. VOLTAGE SAG flicker. In addition to its effect on light, it is responsible for
Dips or sags are short-term reductions in the RMS value reduced life of electronic, incandescent, fluorescent and
of supply voltage lasting from a fraction of a second up to cathode ray tubes, malfunction of phase locked–loops PLLs,
several seconds. A sudden reduction (between 10% and misoperation of electronic controllers and protection
90%) of the voltage magnitude at a point in the electric devices. Even under deregulation, voltage fluctuations and
system and lasting from 0.5 cycles to few seconds is termed flicker will increase due to use of nonlinear and vulnerable
as Voltage sag. A voltage dip can be caused either by devices, and in such environment, the control of the voltage
switching operations or any type of faults as well as fault fluctuation should be the responsibility of the Transmission
clearing process. Switching like those associated with a utilities (Transco.) and Distribution Companies (Disco.)
temporary disconnection of the supply or flow of heavy
such as switch-mode power supplies, television sets, light losses suffered due to power disruption, the real figure
dimmers, and adjustable-speed drives can also inject could be much higher if indirect impacts are considered.
provided that industrial customers, especially those Economic Cost of Outages of Bangladesh amounted to
utilizing large arc furnaces, control the amount of
1.72% (US $778millions) of the Country GDP in 2001
fluctuation of their load current. [6].
[9]. Industrial losses due to poor PQ has been estimated
III. IMPACT ON ECONOMY as $150-$200 billion dollars (USD) for European
Union (2001). A recent study by IBM showed that power
A. COST OF POOR POWER QUALITY quality problems costs U.S. businesses more than $15
The impacts of poor power quality on organization’s billion a year. That’s an average of $79,000 for each
operational efficiency are significant and disruptive. It is company [9].
also being evermore clearly understood that financial To get an idea of significance of monitoring and
impacts, where relevant, are far greater than had mitigation of electricity supply needed to solve the
previously been recognized. The economic impacts of staggering economic losses, it is essential to have the
power quality are usually divided into three broad information of electricity consumption in a region. Fig 2
categories [3]: shows a plot of Indian energy consumption projections
i) Direct economic impacts: Production loss, for the period 2001-2025[10].
unrecoverable downtime and resources (e.g. raw
material, labour, capital), process restart costs, spoilage
of (semi-)finished production, equipment damage, direct
costs associated with the human
health and safety, financial penalties incurred through
non-fulfilment of contract, environmental financial
penalties, utility costs associated with the interruption.
ii) Indirect economic impacts: The cost to an
organization of revenue/income being postponed, the
financial cost of loss of market share, the cost of
restoring brand equity.
iii) Social economic impacts: Uncomfortable building
temperatures as related to reduction in efficient
working/health and safety, Personal injury or fear, also as
related to reduction in efficiency and health and safety,
Evacuating neighbouring residential buildings as an
indirect social impact in the event of failure of industrial
safety, as it relates to the additional costs incurred by an
organization that has to carry out these measures.
PQ costs are usually reported in the categories of
.Fig.1 Indian Energy Consumption Projections in Billion KWHr.
Voltage dips and swells, Short interruptions, Long
interruptions, Harmonics, Surges and transients, and It has been observed that there will be steep rise in the
lastly in the category of Flicker, unbalance, earthing and
consumption of energy in India. India has got the third
electromagnetic compatibility (EMC) problems.
highest average annual percentage change (3.3%) in
B. IMPACTS OF POOR POWER QUALITY ON energy consumption in the world [10].
GLOBAL ENVIRONMENT:
C. DOWNTIME IMPACT
It is very difficult to assess the impact of poor PQ
globally, due to non availability of up-to-date global data Downtime causes millions of dollars in damage
and also due to non performance of such assessment or annually to computer networks around the Globe. Power-
study in most of the countries or regions. However the related issues are frequently the cause of time outs,
impacts are experienced by all. unexplained downtime, and other commonplace system
A joint study by the manufacturers association of or networking glitches. Two major studies of power
information technology (MAIT), USA and emersion quality have been completed in recent years by Bell Labs
and IBM [11]. Both found the areas mentioned in the
network power (India) has thrown up the finding that
table 3 to be accounted for most power-related issues:
network power downtime costs Indian economy more Both studies strikingly show similar results. The
than $9.60 billion annually [8]. The findings of the blackouts and large surges only makeup a small
study have turned out to be a real eye-opener for Indian percentage of power quality problems. On the other hand,
industries. While the study has taken account only direct 80-90 percentages are caused by low voltage surges that
 causes networking problems. Thus around 80 to 90
TABLE II
percent of the time, electronic equipment is being COST OF VOLTAGE DIPS (INDUSTRY)/FINANCIAL LOSS
affected by tiny surges as opposed to lightening flashes Cost of voltage dips
or blackouts. To make matters worse, these little spikes
wreak havoc in terms of logic confusion, system errors, Industry/sector Typical financial
and frozen screens. loss per event ($000)
The term “sustained interruption” or “outage” describes Semiconductor production 5579
a situation in a commercial utility system where Financial trading 8820 per hour
automatic protective devices, because of the nature of the
fault, cannot bring power back online, and manual Computer center 1103
Telecommunications 45 per minute
intervention is required. (IEEE Standard 100-1992) [7].
Steel works 515
Notable outages/blackouts give an idea of disruptive i Glass manufacture 368
mpacts and huge economic losses which were discussed Offshore platforms 375-1100 per day
in [9],[12]. Dredging/and reclamation 75-400 per day
The global downtime impact of poor PQ and its
disruptions are shown in the following table I and II. It
has been observed that 60% of firms face power The average cost of long interruptions is $133,800 and
disruption is more homogenous across whole survey sample. The
generic cost per event for surges and transients for this
TABLE I survey ranges from $176,400 to $264,600.[3,10]
COST OF VOLTAGE DIPS (COUNTRY)
In addition to economical loss due to production stops,
Cost of voltage dips
there exists an extra KWH losses due to harmonic
pollution in typical network components such as
Industry Duration Cost/sag
transformers, cables and motors. As this loss has to be
supplied by the utility power plants, a financial loss and
U.K. steelworks 30% for $457447
3.5 cycles CO2 emissions can be assigned to it. Amount of loss due to
US glass plant Less than 1s $200 this attains figures like few thousand dollars per year
US petrochemicals 2s $600 easily. This corresponds to a few tens of CO2
US Annual $10m emissions/year. Hence running cost of such installations
exposure can be significant. European PQ survey is an eye opener
South Africa Annual $3bn
exposure for the whole world and authorities felt the need of regular
PQ survey for their own system and to reconsider their
power contingency.
more than once a month [9],[13]. Table I shows cost of European PQ survey is an eye opener for the whole
voltage dips (country-wise) and Table II shows cost of world and authorities felt the need of regular PQ survey for
voltage dips (industry-wise). their own system and to reconsider their power
One study[12],[14] carried out by a major generator, contingency measures and adopt proper mitigation.
measured voltage disturbances at 12 sites with demand Blackouts in New York and Europe have prompted the
between 5 and 30 MVA. In a 10 month period 858 authorities to reconsider their power contingency
disturbances were logged with a financial loss totalling measures.
$1.10m. The table 6 gives some typical values. It is
D. IMPACTS IN INDIA
evident that industries or plants making high value added
Power scenario in India seems to be worsening. A
products and those requiring multistage manufacturing
study by IT industry body, the Manufacturers Association
processes, such as semiconductors, would face much
of Information Technology(MAIT) and US-based power
higher losses.
distribution solution provider Emerson Network Power,
In relation to public services like hotels and retail India showed that India Inc lost $4.80 billion in 2003, and
sectors, the PQ impact is measured in terms of slowing $9.60 billion in 2008-09, in direct losses, due to poor
down their business activities, in terms of revenues that power quality and operating environment related
are irrevocably lost. downtime.[7], [8], [15]. The revenue loss due to power
In addition to economical loss due to production stops, failure grew at an average of 11.9% in the past five years.
there exists an extra KWH losses due to harmonic Major reasons for downtime are power cuts (scheduled and
pollution in typical network components such as unscheduled) due to stress on infrastructure and poor
transformers, cables and motors. quality of power and the major impact of downtime is loss
From the surveys, it was observed that the cost per of work in progress and employee productivity. According
voltage dip event iswas very high and single short to the study, power disruption frequency was highest in
interruptions on average are 3.3 times more costly for Delhi followed by Pune and Bangalore, while the average
industry and just over 9 times more costly for services; downtime cost was $1210 per/hr.
 This trend will continue due to the lessons from global network , low metering efficiency and bill collection and
power failures encountered in western countries. Firms power theft- smart grid is essentially required.
will need to pay more attention to maximising uptime to The power quality issues are very important and plays
remain competitive in a globally networked economy. the most significant role for the development of smart
For electricity consumers in India, supply interruptions grids. The “smart” properties of future grids would be a
and low voltage levels are a constant source of concern challenge for new approaches in an efficient management
and utilities are making major investments to improve of power quality. Especially the advanced communication
power quality. Government and regulatory commissions technologies can establish new ways for selective power
in India use IEEE developed reliable indices such as quality management.
CAIDI, SAIDI, and SAIFI. However their use is still in Smart grid is a vision. A more reliable, secure,
an initial phase in India. For the first time in India [8], economical, efficient, environmentally friendly, and more
ESMI captured supply interruptions data as well as safer grid is the vision in the name of the smart grid.[3]. In
voltage levels at the ordinary consumer location at Pune. such vision, monitoring of power quality is the real
A weekly supply interruptions recorded in Pune in challenge. The present methods or systems of monitoring
2007 is shown in the pie diagram (fig. 2). The Pie-chart are not capable to cope with the intelligent smart grid
shows the weekly voltage profile, i.e. % of time the system. An intelligent power quality monitoring system is
voltage (V) was in a particular range. The results might an essential requirement of the smart grid. The PQM
look startling for PQ experts who are working in should be capable to detect most (and almost all) of the
European or North American Standards for monitoring. power quality events and disturbances smartly. Intelligent
The rated voltage was supplied only 23% of the time. PQM is the need for smart grid due to principal
The voltage was low 69% of the time. The voltage was functionality characteristics of Smart Grids, which
very low 7% of the time and there was no supply at all includes: i) active participation by consumers,
1% of the time, which means that there were outages for ii) accommodation of all generation and storage options,
one hour and forty minutes during that week. According iii) enabling new products, services, and markets,
to the annual report of the Ministry of Power, India, iv) providing power quality (PQ) for the digital economy,
losses of State Electricity Boards were $4.3billion (in v) optimizing asset utilization and to operate efficiently,
2000) and $ 6 billion (in 2005). Losses in the supply of vi) to anticipate and respond to system disturbances (self-
electricity are 40% of production. heal), and
vii) to operate resiliently against attack and natural disaster
(cyber security). [3],[16],[17],[18].
The smart grid of the future should include:
i) Network monitoring to improve reliability,
ii) Equipment monitoring to improve maintenance,
iii) Product (power) monitoring to improve PQ.
In order to achieve these goals, the actual distribution
system infrastructure (especially meters and remotely
controlled IEDs) should be used to gather as much
information as possible related to network, equipment and
product (i.e. power quality and reliability) to improve the
distribution system overall performance.
In all these aspects, a smart power quality monitoring is
an essential requirement. This will be an instrumental to
Fig.2. Weekly Voltage Profile, Prayas, (India) make the smart grid perform efficiently, reliably with
proper real-time monitoring and corresponding automatic
Losses for the economy due to poor electricity and mitigation and other required follow-up actions. Then only
transport are 2% of the GDP per year [15],[16]. this smart grid vision will become a reality leading to the
fulfilling of the power demand of the present and future
IV. SMART GRID ENVIORNMENT AND PQ world.

An adequate power quality guarantees the necessary V. CONCLUSIONS

compatibility between all equipments connected to the
grid. It is therefore an important issue for the successful The cost of poor PQ is high and rising. Utility
and efficient operation of existing as well as future grids. deregulation effects on power quality requiring industry-
Due to large gap between generation and load, inefficient wide action to maintain sufficient standards. The paper
generating stations, overloading of system components, gives insights on global economical losses due to poor PQ.
higher losses in the system, lack of reactive power support The business risk posed by PQ problems is a real one with
and regulation services, poorly planned distribution even ‘low tech’ industries exposed to serious financial
losses.
 Smart grid is the most important vision for future power [6] W.L. Tse and 1W.L. Chan,“A Low Cost Web-based Supply
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with smart grid sensors for smart metering with advanced Following Deregulation”, Proc. IEEE, vol.88, pp.246-251,
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[8] IEEE Recommended Practice for Monitoring Electric Power
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Quality, 1159-2009
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provide the information needed to validate compliance, India. (2009). http://www.prayaspune.org/peg
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Technical report, Euroelectric, 200
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[11] Projections of Energy Information Administration (EIA), System
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Survey- A study of the impact of power quality on electrical energy
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