Today, we will continue
explaining other Types of Power Factor Correction Capacitors as in the previous
article “Power Factor Correction Capacitors Sizing Calculations – Part Four”, we showed that the Types
of Power Factor Correction Capacitors according to Location can be categorized
to:
 Individual compensation,
 Group compensation,
 Central compensation,
 Hybrid compensation.
We explained the first
type; Individual compensation in this previous article. So, today we will explain
the following topics:
 Other Types of Power Factor Correction Capacitors according to Location.
2.2.B
Group Compensation

This
type of compensation has many other names like Group,
bank, bulk or bysector compensation.
Electrical
machines that are always switched on at the same time can be combined as a
group and have a joint correction capacitor (see Fig.1). An
appropriately sized unit is therefore installed instead of several smaller
individual capacitors as in individual compensation.
Fig.1
Applications:
Advantages:
Disadvantages:
Choice between individual and group Connection

2.2.C
Central
Compensation

Fig.2
Applications:
Advantages:
Disadvantages:

2.2.D
Hybrid
Compensation

Fig.3
Application:
The advantages and disadvantages

3
General Notes on Different Types of Power Factor
Correction


4 Power Factor Correction Capacitors
Sizing Calculations Steps

Now,
we are going to explain the Power Factor Correction Capacitors Sizing
Calculations Steps for Different Cases of Installations:

4.1 Power Factor Correction Capacitors
Sizing Calculations
For Existing Installations

the
Power Factor Correction Capacitors Sizing Calculations Steps For Existing
Installations include two phases as follows:
Fig.4 shows the phases of
Power Factor Correction Capacitors Sizing Calculations For Existing
Installations.
Fig.4

First: Preliminary Evaluation Phase

The
preliminary evaluation is performed to determine if the application of power
factor correction capacitors is likely to be economical or not. Fig.5 shows
a typical flow chart
for the preliminary evaluation process.
Fig.5
The
preliminary evaluation phase has many steps as follows:
Step#1: Collect monthly billing data; this step is used to
estimate how many capacitors are needed.
Step#2: Make some preliminary measurements for current and voltage;
this step is used to get a rough idea of how heavily loaded the plant cables
and transformers are so that the loss savings can be better estimated.
Step#3: Fill the Economic Screening Worksheet; this step is
used to determine the approximate savings possible through power factor
penalty reduction and loss reduction. The economic screening worksheet is
actually made up of (4) smaller worksheets as follows:
Step#3.A: Fill the Capacitor Costs Worksheet: to Estimate Total
Capacitor Cost,
Step#3.B: Fill the Loss Savings Worksheet: Estimate loss savings,
Step#3.C: Fill the Power Factor Penalty Savings Worksheet: Estimate power factor
penalty savings,
Step#3.D: Fill the Economic Evaluation Worksheet: Evaluate economics
and calculate the payback, present worth and benefit/cost.
Step#4: Make preliminary measurements for harmonics; this step is used to
help identify and report potential harmonic problems,
Step#5: Repeat the Economic Screening Worksheet; this step is used to
include the cost of studies and harmonic mitigation in the cost of the
capacitors' installation,
Step#6: Compare the savings with the probable cost of
capacitors' installation; this step is to determine if the capacitors' installation
process still economical or not? If economical proceed with the design phase,
if not stop or proceed uneconomically.

Second: Design Phase

In
this phase, we will design and select the best economical, efficient and
applicable power factor capacitor scheme for an installation. Fig.6
shows a typical flow chart for the Design process.
Fig.6
The
Design phase has many steps as follows:
Step#1: Performing a Detailed Plant Survey; this step is used to collect
sufficient data about the plant to determine the optimal size of capacitor to
place in each location. It is also for determining if there will be any
detailed studies required to avoid some of the pitfalls associated with
capacitor application.
Step#1.A: Review OneLine Diagram; this step is used to
make judgments about the most appropriate form of power factor correction.
Step#1.B: Take into consideration the loads that produce harmonics or have sophisticated
electronic controls that can interfere with power factor correction efforts.
Step#1.C: collect sufficient data Inventory by using measuring
instruments to understand how the system behaves so that optimal capacitor
configurations may be determined.
Step#2: Select Economical Capacitor Scheme; this step is used to find the lowest cost capacitor scheme that will
adequately correct for the power factor while minimizing the losses.
Step#3: Checking the "No Load" Voltage Rise: this step is used to check that if the Voltage Constraints Met or not.
Step#4: Select Capacitor Switching Options.
Step#5: Check the Harmonic Distortion and make Harmonic
Mitigation Options; this step is used to check if the harmonic
Constraints Met or not.

4.2 Power Factor Correction Capacitors
Sizing Calculations
For New Designs

Power Factor Correction
Capacitors Sizing Calculations Steps For New
Designs will include the following steps:
Step#1: Use the detailed loads schedules; this step is used to calculate
the total KW, total KVAR and total existing PF at each feeder panel so that
optimal capacitor configurations may be determined.
Step#2: Review OneLine Diagram; this step is used to
make judgments about the most appropriate form of power factor correction.
Step#3: check for Potentially Troublesome Loads; in this step, we will
take into consideration the Several different kinds of loads that produce
harmonics or have sophisticated electronic controls can interfere with power
factor correction efforts. These loads
like Adjustable speed drives, Variable frequency drives, DC Drives, Arc
furnaces, large amounts of fluorescent or sodiumvapor lighting and Large UPS
systems.
Step#4: Select Economical Capacitor Scheme; this step is used to find the lowest cost capacitor scheme that will
adequately correct for the power factor while minimizing the losses.
Step#5: Develop a Fixed Capacitor Scheme: this step is used since the lowest cost installations are generally fixed
capacitors with few additional accessories such as automatic switches and
harmonic filters.
Step#6: Checking the "No Load" Voltage Rise: this step is used to check that if the Voltage Constraints Met or
not.
Step#7: Select Capacitor Switching Options.
Step#8: Check the Harmonic Distortion and make Harmonic
Mitigation Options; this step is used to check if the harmonic
Constraints Met or not.
Step#9: Use the Economic Screening Worksheet; this step is used to evaluate the economics of the selected capacitor
scheme, if economical then proceed with installation phase, if not, try to
improve the economics by developing lower cost Capacitor Scheme or abort the
design process.

In the next article, we will continue
explaining the above Power Factor Correction Capacitors Sizing Calculations Steps
in detail. Please, keep following.
The
previous and related articles are listed in below table:
Subject Of
Previous Article

Article









Back To 
Post a Comment
Leave a comment to help all for better understanding