The Advantages of Capacitor Bank Usage in Energy Consumtion Optimization & kVArh Cost Saving

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International Journal of Engineering & Industry
Publication Date: February, 2021

Ronaldo David, Windarta Jaka & Saptadi Singgih
Master Energy Program, School of Postgraduate Studies, Diponegoro University
Department of Electrical Engineering, Faculty of Engineering, Diponegoro University
Semarang, Indonesia

Journal Full Text PDF: Journal Full Text PDF: The Advantages of Capacitor Bank Usage in Energy Consumtion Optimization & kVArh Cost Saving (Energy Consumtion Optimization & kVArh Cost Saving for PLN UP3 Pekalongan Customer).

Abstract
Abstract: PT Ronny Aquario Perkasa consumed more reactive power (kVArh) from July 2017 to June 2018, which caused PT Ronny Aquario Perkasa to pay IDR 301,702,151,- of kVArh fine to PT PLN. This penalty resulted in a significant increase in operational cost especially in electrical bills. In order to reduce the electrical bills, it is necessary for PT Ronny Aquario Perkasa to install Capacitor Bank to decrease reactive power consumption. However, the implementation of capacitor bank will introduce a significant provision and installation costs. Thus, it is necessary to perform a feasibility study (FS) analysis using the Net Present Value (NPV), Benefit – Cost Ratio (B-CR), Payback Period (PP), and Life Cycle Cost (Life Cycle Cost) method to calculate the feasibility of the investment made by PT Ronny Aquario Perkasa.

Keywords: Capacitor Bank & Reactive Power.

1. Introduction
Indonesian government sets the selling price of electricity based on the Minister of Energy and Mineral Resources (Energy & Mineral Resources) Regulation no. 28 of 2016 which applies to all electricity user managed by the State Electricity Company (PLN). Large-scale customers such as Industrial, Business, Government, and Social tariff groups are given a limit on reactive power usage. If the reactive power usage exceeds 62% of the active power, or cos Q ≤ 0.85 inductive, then the excess reactive power is charged to the consumer.

The reactive power that is consumed by customers mostly is inductive reactive power. Inductive reactive power cannot be converted into power that can be directly used by customer. Inductive reactive power requires by generators, for electrical transmission to all electrical equipment, which uses coils such as electric motors, lamp ballasts, transformers, and others.

Inductive reactive power which arised from reactance in the PLN grid or inductive loads inhibits electrical current which absorbed by the load. Therefore, it is necessary to compensate it with the capacitive reactive loads.

The inductive reactive power of an electrical equipment cannot be eliminated, but it can be compensated by installing electrical equipment that has a capacitive reactive power which resulted in a less reactive power resultant. This electrical equipment is known as the Capacitor Bank.

To achieve cost savings and even free from the penalty caused by excess reactive power usage, precise calculation is required to determine capacity of the capacitor bank that
is going to be installed. The investment costs calculation that may be occurred from the Capacitor Bank installation also required. One time investment will be required and then monthly cost savings will be obtained throughout the life of the capacitor bank used.

Based on ETAP simulation result and harmonic distortion standards, the installation of capacitor banks in the industry leads to an increment of power factor in the electrical power network and can be operated without conneted to the system grid (Henri Matius Naibaho, 2016). After Capacitor Bank being installed in PT Ronny Aquario Perkasa’s electrical system, the reactive power usage will decrease. If there will be a business expansion or additional plan to increase the load in the future, it is necessary for PT Ronny Aquiario Perkasa to perform further analysis on capacitor banks capacity that has been installed in the factory to reduce reactive power consumption using the ETAP 16.0 application.

The installation of a capacitor bank at the PT Ronny Aquario Perkasa factory may reduce factory electrical bills. However, the implementation of bank capacitors will introduce a significant provision and installation costs. Thus, it is necessary to perform a feasibility study (FS) analysis using the Net Present Value (NPV), Benefit – Cost Ratio (B-CR), Payback Period (PP), and Life Cycle Cost (Life Cycle Cost) method to calculate the feasibility of the investment made by PT Ronny Aquario Perkasa.

2.1 Research Scope
The tools used for data collection in general are stationery, calculation tools, computers, printers, photocopy machines, cameras, transportation and accommodation, and others. The tools used for data analysis is a set of computers which consist of hardware and software.

To perform investment feasibility study analysis calculation, customer will need hardware and softwares. The hardware that is used to perform this calculation is a computer with minimum specification such as Intel Core i5 Processor, RAM Memory, Flash disk, and Printer. There are two softwares that are used, they are the ETAP PowerStation 16.0 application software for simulation and the customized excel based application which is used to calculate investment feasibility study analysis itself.

To present the result of the study analysist, customer will use the following programs:

a. Microsoft Word 2018, this program is used to generate reports to show the results of research data analysis process.

b. Microsoft Excel 2018 is used for processing and data

storage.

This research was conducted by analyzing and processing Load Profile result and Billing PT Ronny Aquario Perkasa as a customer. The Load Flow simulation process was carried out using the ETAP application in order to obtain the required data related to the Capacitor Bank.

2.2 Research Variables
1. Network variable value based on installed system on customer premises: approximate installed underground cable length.

2. Electrical system installation drawing: existing electrical system installation drawing is outdated, so this research uses typical installation drawing which shows the location of the capacitor bank and cable detail (e.g. the type and cable size) of the network to the load point.

3. CAPEX variable value: The former goods and services procurement data is not completely available, this research uses current price.

4. Energy consumption data variable: energy consumption has never been recorded since the first time Capacitor Bank was installed, so this research uses the averaged energy consumption over the past one year.

2.3 Data Collection Techniques

This research was carried out on a 380 Volt , low-voltage installation network, as a load from a consumer-owned distribution transformer which is supplied by the 20 kV medium voltage PLN substation in Batang.

Data collection of all electrical network installations and existing equipment is made by capturing size, quantity, and location / placement. Data load collection for each of the equipment was made at its full operated mode in order to obtain energy consumption, operation voltage, and load factor. After all data being recorded and recapped from each of the equipment, the next step is to measure the energy consumption load in each of the branch and at the main distribution panel.

The next step is to generate a single line diagram of system installation which is completed with cable data (e.g. cable type, size and length), location of electrical equipment such as the transformer, main distribution panel, equipment safeguard, load, and capacitor bank. All data from single line diagram is put together in one drawing using the ETAP PowerStation application and finally the
research data can be displayed as a complete picture. Single line diagrams which correlates with the location can be found in appendix 3a and single line diagram resulted form Etap can be found in appendix 3b. Below are steps to select appropriate capacitor bank:

1. Measure the initial load factor (CosQ1), voltage, and current at its maximum load.
CosQ1 =? V =? I =?
2. Calculate the apparent power (kVA), initial reactive power (kVAR1) from the initial CosQ (CosQ1). kVA1 = V.I.√3
kVAR1 = V.I.SinQ1.√3
3. Using kVA as reference (fixed kVA), calculate the final kVAR (kVAR2) with final CosQ (CosQ2) = 0.85. kVAr2 = V.I.SinQ2.√3
4. The capacity of the capacitor can be obtained from the difference between the initial kVAR minus the final kVAR.
KVAR Capacitor = kVAR1 – kVAR2
5. Determine the capacitor size per unit step. Common capacitor sizes that available on the market are 5kVAR, 10kVAR, 15kVAR, 25kVAR and 50kVAR. For the rest of the value (capacitor size), it can be double / paralleled per step.
6. Determine the number of switching steps. The number of steps is proportional to the number of machines / equipment which CosQ stability is maintained, because there is a possibility where machines do not operate simultaneously. Typically, switch that is available in the market starts from 3 to 12 steps.
7. Plant and equipment development data

To get a smooth curve CosQ value, it is recommended to use a large number of steps, but it will require a larger investment. Data collection carried out in this study was carried out by literature and experimental studies.

2.4 Data Analysis Techniques
The secondary data is obtained from literature studies while The primary data is obtained from measurement result using an application which later on will be processed and analyzed using quantitative methods at certain experimental object condition where some of variables are being set and manipulated.

The first application uses a software tool called ETAP PowerStation 16.0 which is one of the most widely used applications to simulate electric power systems. In general, in the planning simulation and analysis of electric power, there are important steps that must be taken, they are:
a. Draw a load plan
b. Know the data for each load
c. Design singleline diagram
d. Calculate load flow (load flow)
e. Do simulation using several alternatives of load power or the network used.

The analysis data that can be generated as a result is the amount of drop voltage and drop current on each of the conductor and equipment or load point, by knowing the magnitude of the load factor.

The second application uses MS Excel to determine investment feasibility analysis using tools that is designed to process quantitative data that is normally used in solving various business problems. The financial aspect plays important role as a basis in decision making, despite other aspects of the project feasibility study. Excel as a product of Microsoft Corp. equipped with various financial functions, including assessment of investment feasibility with the ARR (average rate of return), PP (payback period), IRR (internal rate of return), NPV (net present value) and PI (Profitability index) methods.

The research process flow on capacitors impact from a technical point of view describes as follows:
1) Inventory of goods and services procurement cost from Capacitor Banks installation.
2) Inventory of operational and maintenance cost from capacitor banks usage.
3) Inventory of electricity consumption costs paid to the electricity supplier (PLN).
a) Using a Capacitor Bank.
b) Without using a Capacitor Bank.
c) Cost savings.

3. Design and Evaluation Result
3.1 Equipment Data and Specifications
PT Ronny Aquario Perkasa is a company works in the stone crusher business which is located on Jl. Circle of Alas Roban Tegalsari Sentul, Grinsing District, Batang Regency. PT Ronny Aquario Perkasa is one of the industrial consumers of PT PLN (Persero) in the Pekalongan area, at PLN Rayon Batang, with a power subscription of 690 kVA. PT Ronny Aquario Perkasa has several production equipment that uses electricity from PT PLN as its main power supply such as Jaw Crusher, Vibrating Feeder, Cone Crusher, Belt Conveyor, and Vibrating Screen which are described in the following sub-chapters

3.1.1 Single Line Diagram PT Ronny Aquario Perkasa

The following is a single line diagram from PT Ronny Aquario Perkasa:

Figure 2 single line diagram of PT Ronny Aquario Perkasa

3.1.2 Total Installed Power

PT Ronny Aquario Perkasa has eight load areas with different installed power. The following is the breakdown of the power at each of area in PT Ronny Aquario Perkasa.

From the eight load areas at PT Ronny Aquario Perkasa, the total installed power of all areas is 809,200 W.

3.2 Measurement Data

Direct measurement data that is performed at the PT Ronny Aquario Perkasa factory is in the following table

Table 2 Measurement results at PT Ronny Aquario Perkasa

From the measurement data, it can be concluded that the active power consumption used by PT Ronny Aquario Perkasa at the time of measurement was 172.30 kW. Compared with the installed power of 809.2 kW, PT Ronny Aquario Perkasa only uses 21.3% of the total active power installed. The reactive power used by PT Ronny Aquario Perkasa is 226.7 kVAr. Meanwhile, the apparent power used by PT Ronny Aquario Perkasa is 283.4 kVA with a power factor of 0.58.

3.3 Power Factor Improvement Calculation

The calculation of power factor improvement is obtained from field data which later on being processed to get the value of the power factor improvement which is needed to support improvement quality of electric power. This study uses the improved power factor> 0.85 which is aligned with the limit of the power factor allowed by PT PLN. , Data that is used for power factor improvement calculation is the load data installed with a power factor of 0.58, corrected to 0.85. The improvement that needs to be done is by installing a reactive power compensator which is using Qc value calculation of the capacitor bank as follows:

Based on power factor improvement calculation result from 0.58 to 0.85, the power required by the capacitor bank is 631.2 kVAr. However, in the capacitor bank design process which is 631.2 kVAr is not available in the market. Therefore, in bank capacitors design process, the selected bank capacitor capacity is 700 kVAr.

3.4 Etap 16.0 Load Flow Simulation

all the observation data is used to generate a single line diagram modeling using Etap 16.0 software. The following is the equipment settings in Etap 16.0.

Figure 3 Load settings on etap 16.0

The above figure is an example of the load setting in Etap 16.0. The load is set using the load data at each load. The power factor that is used in Etap is the power factor measured at the PT Ronny Aquario Perkasa factory. At loading column, the design row is filled by 100% to see if the simulation of load flow is at the maximum load at PT Ronny Aquario Perkasa. While the normal line is filled by 25% to see if the simulation of load flow at normal load based on the load measurement data used at PT Ronny Aquario Perkasa. The load type is assumed at 80% constant kVA and 20% constant Z. This is caused by most the load consist of an electric motor.

Figure 4 Setting bank capacitor on etap 16.0

In the above capacitor setting, the capacitor used is 1 unit of capacitor with 700 kVAr capacity which is used to improve the power factor at PT Ronny Aquario Perkasa’s factory.
After setting all the components in Etap 16.0, a single line diagram is obtained at the following

Figure 5 PT Ronny Aquario Perkasa single line diagram

3.4.1 Existing Conditions

At the existing conditions, load flow simulation is performed at the maximum load conditions with the capacitor bank is not installed. The following is the existing load flow conditions.

Figure 6 Load flow with existing conditions

After simulating the load flow in the existing conditions, a load flow report is obtained from the simulation, see following table

Table 3 load flow report on existing conditions

The existing conditions simulation, the power factor at the PT Ronny Aquario Perkasa factory is still 0.57 as seen in the PLN panel. In real conditions, this condition results in kVAr fines that must be paid by the factory PT Ronny Aquario Perkasa to PT PLN.

3.4.2 Capacitor Bank Simulation Results

In the load flow simulation using a capacitor bank, it is performed by simulating two different load conditions. The first condition is the load is set under normal conditions using 25% load. Whereas in the second simulation, it is set by using the maximum load designed conditions of 100% of the installed load.

1. 25% load

At 25% load condition, the capacitor bank capacity is 35% to get power factor more than 0.85. The following is a simulation of a load flow with 35% load.

Figure 7 25% load flow with 35% capacitor bank

Table 4 load flow report 25% load condition

In the simulation of 25% load conditions, the power factor at PT Ronny Aquario Perkasa’s factory is still 0.98 as seen as on the PLN panel. In real conditions, this let PT Ronny Aquario Perkasa’s factory free from the kVAr penalty to PT PLN.

2. Maximum load

In the maximum load condition, the capacitor bank capacity is 100%, to get a power factor greater than 0.85. The following is a simulation of the maximum load flow.

Figure 8 PT Ronny Aquario Perkasa load flow with

capacitor bank

After the load flow simulation is performed at 100% maximum load condition , see above image, below is a load flow report resulted from the simulation

Table 5 Load flow report maximum load conditions

After simulating the load flow under 25% load and 35% capacitor bank, see above image, below is a load flow report resulted from the simulation

In the maximum load condition simulation, the power factor of the PT Ronny Aquario Perkasa factory is still 0.869 as seen as on the PLN panel. In real conditions, PT Ronny Aquario Perkasa factory is still free from kVAr penalty to PT PLN.

The simulation at maximum load shows that PT Ronny Aquario Perkasa only uses 25% of the total power from the equipment installed. If at any time PT Ronny Aquario Perkasa increases the amount of production to use 100% of the installed equipment power capacity, then PT Ronny Aquario Perkasa must increase its power subscription, which was previously 690 kVA to 1110 kVA. This activity must be done, because at the maximum load, PT Ronny Aquario Perkasa uses an apparent power of 961.3 kVA.

3.5 Capacitor Bank Economic Value

The consideration of bank capacitors installation is considered to be an economic factor. This study compares the costs required to purchase a capacitor bank and the advantages of installing this capacitor bank in economic calculations.

Costs incurred for investing in capacitor banks consist of costs for purchasing and installing bank capacitors as well as costs for maintaining bank capacitors themselves.

Procurement and installation cost of capacitor bank with 700 kVAr capacity is about IDR 240,000,000. The follow is the maintenance costs for 700 kVAr capasitor bank capacity

Table 6 Damaged Materials Replacement Cost

Note: Assuming 5% price increase of goods & services per year

year of 5%, the total cost incurred for replacing the damaged bank capacitor component is IDR 127,559,112 within 10 years.

The bank capacitor that has been installed requires maintenance costs to maintain bank capacitor reliability. The bank capacitors maintenance cost can be found in the following table:

Table 7 Maintenance costs for bank capacitors

Employee salary Damage Costs Amount of capital

Person Rupiah

Note: Assuming 5% price increase of goods & services per year

In the table above, it can be found that with the assumption of the price of goods and services increase per year of 5%, the total costs incurred for maintaining the bank’s capacitor component is IDR 784,860,494 within 10 years. If the cost of replacing damaged capacitor bank components is added into the component, the total maintenance cost is IDR 912,419,607, – within 10 years.

3.5.1 Revenue

In bank capacitors installation investment at PT Ronny Aquario Perkasa’s factory, the revenue is obtained from saving excess usage of kVArh which is compensation from installing the capacitor bank. In 2018 until 2019, the excess use of kVArh was obtained from the power factor of PT Ronny Aquario Perkasa was 0.58 based on power factor measurement data carried out in October 2020. Data from 2020 until 2027, rupiah excess kVArh assumption is as same as average kVArh usage in 2018 to 2020. Below is the table of revenue (Revenue) from the installation of bank capacitors at PT Ronny Aquario Perkasa.

In the table above, it can be found that with the

assumption of prices of goods and services increase per

Table 8 Income from the installation of bank capacitors

From above table, it can be found that the total revenue from the capacitors bank installation investment at the PT Ronny Aquario Perkasa factory for 10 years is IDR 3,118,366,387 with an average monthly income of IDR 311,836,639.

3.5.2 Cash Flow

Cash flow is the flow of cash income and disbursements of an activity / project or company which always changes in each accounting period (month, quarter, semester, or year). Cash inflow from the capacitors bank installation investment at the PT Ronny Aquario Perkasa factory is obtained from the sum of income and depreciation of investment costs. The following is a cash flow table from the capacitors bank installation investment at the PT Ronny Aquario Perkasa factory.

3.5.3 Economic Analysis of Investment Feasibility Technique

The principles of technical economics application is used both in the economic viability analysis of engineering projects and assisting in decision making, based on the following economic parameters

1. Accounting Rate of Return (ARR)
From the data table, total investment costs and income per year can be used to calculate Accounting Rate of Return (ARR) value of at PT Ronny Aquario Perkasa as follows:

From the calculation, the value of the Accounting Rate of Return (ARR) of bank capacitor development at PT Ronny Aquario Perkasa is 27.06%. Refer to the company, the ARR eligibility standard that is feasible to be implemented is greater than 25%. So, based on the ARR data calculation, it can be concluded that the investment in installing bank capacitors is feasible.

2.Payback Period (PP)

Payback period (PP) is the time required to return the investment value. The method of calculating PP is to calculate the time required (years) so that the estimated cumulative net cash flow will as same as the initial investment. From the above cash flow data table, the Payback period (PP) calculation of the capacitor bank development investment at PT Ronny Aquario Perkasa is the following:

From the calculation, the value of the Payback period

(PP) from the expansion of bank capacitors at PT Ronny Aquario Perkasa is 3 years 4 months. Based on the results of these calculations, it can be concluded that the investment in the expansion of bank capacitors at PT Ronny Aquario Perkasa is feasible.

3. Net Present Value (NPV)

From the cash flow data table with assumption of the reference interest rate is above 16.21%, the Net Present Value (NPV) of the capacitor bank development investment at PT Ronny Aquario Perkasa can be calculated as following:

By using calculations using Ms Excel, the NPV calculation results are Rp. 409,499,416, -. Based on the results of these calculations, it can be concluded that the investment in the expansion of bank capacitors at PT Ronny Aquario Perkasa is feasible.

4. Internal Rate of Return (IRR)

Internal Rate of Return, abbreviated as IRR, is an indicator of an investment efficiency level. The IRR value is the value of the interest rate when the NPV is 0. Therefore, the IRR value is calculated based on the interpolation of the NPV value when it is negative and the NPV value when it is positive. In the calculation, the IRR value of 25% and 30% has been calculated using Ms Excel. The following is the calculation of the IRR interpolation value from the bank’s capacitor expansion investment at PT Ronny Aquario Perkasa.

From the calculation, the value of the Internal Rate of Return (IRR) from the investment of bank capacitor development at PT Ronny Aquario Perkasa is 27.08%. The IRR value is greater than the reference interest rate used which is 16.21%. Therefore, based on the results of these calculations, it can be concluded that the investment of bank capacitor development at PT Ronny Aquario Perkasa is feasible.

5. Profitability Index (PI)

The Profitability Index (PI) is a capital budgeting technique for their viability or profitability of investment projects evaluation. The following calculations are used to find the value of the Profitability Index (PI):

From the calculation, the value of the Profitability Index (PI) from the investment of bank capacitor development at PT Ronny Aquario Perkasa is 1.36. The PI value is greater than 1. Therefore based on the results of these calculations it can be concluded that the investment of bank capacitor development at PT Ronny Aquario Perkasa is feasible.

4. Conclusion

From the research that has been performed, it can be concluded as following:

1. The power factor improves from 0.58 to 0.85, the power required by the capacitor bank is 631.2 kVAr. However, in the design process the Capacitor Bank which is 631.2 kVAr is not available in the market. Therefore, in the bank capacitors design process, the selected bank capacitor capacity is 700 kVAr.

2. Based on simulation of the existing conditions, the power factor at the PT Ronny Aquario Perkasa factory is still 0.57 as seen in the PLN panel. In real conditions this will lead kVAr fines that must be paid by PT Ronny Aquario Perkasa to PT PLN.

3. Based on 25% load conditions simulation, the power factor at PT Ronny Aquario Perkasa’s factory is still 0.98 as seen on the PLN panel. In real conditions, this will let PT Ronny Aquario Perkasa’s factory free from the kVAr fine paid to PT PLN.

4. Based on the maximum load condition simulation, the power factor at the PT Ronny Aquario Perkasa factory is still 0.869 as seen in the PLN panel. In real conditions, the PT Ronny Aquario Perkasa factory is still free from kVAr penalty to PT PLN.

5. The total costs incurred for the capacitor bank components maintenance is IDR 784,860,494 for 10 year period. If the damaged capacitor bank components replacement being added, the total maintenance cost is IDR 912,419,607, – within 10 years.

6. Based on the calculation results, the value of the Accounting Rate of Return (ARR) from bank capacitor development at PT Ronny Aquario Perkasa is 27.06%.
7. Based on calculation results, the value of the Payback period (PP) from the expansion of bank capacitors at PT Ronny Aquario Perkasa is 3 years 4 months. Based on the results of these calculations it can be concluded that the investment in the expansion of bank capacitors at PT Ronny Aquario Perkasa is feasible

8. Based on Ms Excel calculation, the NPV calculation results are Rp. 409,499,416, -. Based on the results of these calculations, it can be concluded that the investment in the expansion of bank capacitors at PT Ronny Aquario Perkasa is feasible.

9. Based on the calculation, the Internal Rate of Return (IRR) value of the bank capacitor development investment at PT Ronny Aquario Perkasa is 27.08%. The IRR value is greater than the reference interest rate. Therefore, it can be concluded that the investment of bank capacitor development at PT Ronny Aquario Perkasa is feasible.

10. Based on the calculation results, the value of the Profitability Index (PI) from the investment of bank capacitor development at PT Ronny Aquario Perkasa is 1.36. The PI value is greater than 1. Therefore, it can be concluded that the investment of bank capacitor development at PT Ronny Aquario Perkasa is feasible to be implemented.

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