Harmonic Analysis

(1)

KOREA NATIONAL OIL CORPORATION

VIETNAM OFFICE

RONG DOI GAS FIELD DEVELOPMENT PROJECT

HARMONIC PENETRATION ANALYSIS

DISCIPLINE ARCH CONST ELECT INSTR MAT’RL MECH PIPING PIPELINE PROCESS SAFETY STRUC

SIGN/DATE - - - -

D1 28-APR-05 APPROVED FOR CONSTRUCTION YSN JUB/MSH BSK

C1 28-APR-05 APPROVED FOR DESIGN YSN JUB/MSH BSK

B1 28-JAN-05 ISSUED FOR APPROVAL HFS BK KCG TM

A1 26-JAN-05 ISSUED FOR DIC / IDR HFS BK - - -

Rev. Date Description By Checked Approved QA Client

This document is the property of KECS – any unauthorized use of the same will be prosecuted.

Total or partial reproduction and/or utilization of this document are forbidden without prior written authorization of the Owner

Category Code Description

Facility 200 Common

Korea

National Oil Corporation Vietnam Office

Phase 30 Detailed Engineering

Discipline E Electrical Engineering

Type CA Calculation

Project Sequence Revision

As per MOM KNOC UL-0004 DEV/S dated 27th April 05, it is concluded that detailed harmonic analysis calculation is not necessary for Electrical Power System of Rong Doi Gas Field Development Project. Accordingly this document is issued without change and shall be treated as final.

(2)

RONG DOI GAS FIELD DEVELOPMENT PROJECT

HARMONIC PENETRATION ANALYSIS

The Rong Doi and Rong Doi Tay Fields (RD and RDT) are located approximately 320km to the south-east of Vung Tau and were discovered in 1995 and 1996 respectively by KNOC, working as the Operator on behalf of a consortium of seven Korean companies. The Rong Doi Tay Field is located approximately 2.5km to the west of Rong Doi.

The current development schedule will achieve a First Gas Date of 30 September 2006. The field and facilities are designed to deliver an average of 130MMscfd of sales gas but will have the capacity to produce up to 175MMscfd of sales gas for short periods.

The objective of the Rong Doi and Rong Doi Tay development is to design, install, produce and deliver pipeline specification gas to the gas purchaser PetroVietnam, as per the terms of the Gas Sales and Purchase Agreement (GSPA).

The facilities shall consist of a Wellhead Platform bridge connected (80m) to a Production Utilities Quarters Compression Platform (PUQC). An FSO will be installed to receive stabilized condensate stripped from the gas via a 2.5 Km long 6" line. The gas will be transported by a 58 Km 18” pipeline to a Wye in Namcon Son gas trunk line operated by BP.

(5)

2.0 OBJECTIVE

Harmonic analysis has been carried out to study the performance of the electrical system with harmonic loads. The purpose of harmonic analysis is to arrive at the total harmonic distortion at various locations due to harmonic producing loads in the network and to determine the corrective measures required to reduce the harmonic distortion to acceptable levels. Normally harmonic analysis is conducted when harmonic producing loads exceed 10% of total load. In Rong Doi Gas Field Development Project, the harmonic producing loads such as UPS, rectifiers, variable speed drives, thyrister control heaters and lighting constitutes more than 10% of total running loads. This has necessitated to conduct detail harmonic analysis for the complete Generation and Distribution System for Rong Doi Project.

This study considered the impact of the harmonic producing equipment installed on Wellhead Platform (WHd) and Production Utilities Quarters Compression Platform (PUQC).

3.0 ACCEPTABLE HARMONIC DISTORTION LIMITS

The total harmonic voltage distortion shall be limited to following values as indicated in Table 3.1 in compliance to IEC 61000.

TABLE 3.1

LOAD DESCRIPTION

TOTAL HARMONIC DISTORTION (VOLTAGE)

THDU Sensitive Loads

(UPS, Computer, PCS, Printers, Monitors) 5% Industrial Loads

(Motors, Heaters, Capacitor Lighting, Actuators)

8%

Note : As per agreed design basis, the THD (V) shall be limited to 5% in Rong Doi Electrical Power Distribution System.

The total harmonic current distortion limits THD (I) is not well defined in IEC for power distribution system. The total current distortion limits are considered as per IEEE 519-1992. The individual harmonic current and total harmonic current distortion limits are defined in IEEE Std 519 Table 10.3 and the same is reproduced below for information. The current distortion limits for distribution system are

(6)

indicated in Table 3.2 below.

TABLE 3.2 - CURRENT DISTORTION LIMITS FOR GENERAL DISTRIBUTION SYSTEM (120V THROUGH 69,000V

MAXIMUM HARMONIC CURRENT DISTORTION IN PERCENTAGE OF IL Individual Harmonic Order (Odd Harmonics)

Isc/IL <I1 <I1<h<I7 <I7<h<I23 <I23<h<I35 35<h TDD

<20* 4.0 2.0 1.5 0.6 0.3 5.0

20<50 7.0 3.5 2.5 1.0 0.5 8.0

50<100 10.0 4.5 4.0 1.5 0.7 12.0

100<1000 12.0 5.5 5.0 2.0 1.0 15.0

>1000 15.0 7.0 6.0 2.5 1.4 20.0

Even harmonics are limited to 25% of the odd harmonic limits above.

Current distortions that result in a dc offset, e.g., half-wave converters are not allowed.

*All power generation equipment is limited to these values of current distortion, regardless of actual Isc/IL Where

Isc = maximum demand shrt-circuit at PCC

IL = maximum demand load current (fundamental frequency component) at PCC

4.0 STUDIES

Following studies have been carried out:

 Harmonic analysis for current harmonics.  Harmonic analysis for voltage harmonics.

4.1 CURRENT TOTAL HARMONIC DISTORTION (THDI)

THDI = 100 x SQRT ( IH2n) / IHL n = 2, 3……

Where: IHn : Rms value of the nth current harmonic. IHL : Rms value of fundamental current.

4.2 VOLTAGE TOTAL HARMONIC DISTORTION (THDU)

THDV = 100 x SQRT ( VH2n) / VHL n = 2, 3……

(7)

VHL : Rms value of fundamental voltage.

5.0 SYSTEM PARAMETERS

The electrical network for Rong Doi Gas Field Development Project has been planned as per Electrical Overall Key Single Line Diagram drawing number VN01-200-30-E-DW-1100. Harmonic Penetration Analysis has been carried out for the entire system network in WHd and PUQC considering all harmonic sources. The basic network parameters for the Electrical Distribution System are as follows:

TABLE 5.1 - GENERATOR PARAMETERS

DESCRIPTION RATING _IMPEDANCE%

MAX. POWER OUTPUT AT

SITE CONDITION

REMARKS

Generator 230-GT-8001A 1500 kVA /

400 V 12.0 % 1000 kW -

Generator 230-GT-8001B 1500 kVA /

400 V 12.0 % 1000 kW -

Generator 230-GT-8001C 1500 kVA /

400 V 12.0 % 1000 kW -

Emergency Generator 230-GD-8002 750 kVA / _{400 V} 9.0 % 600 kW -

TABLE 5.2 - NER PARAMETERS

DESCRIPTION IMPEDANCE REMARKS

230-NER-8001A 4.6 Ω -

230-NER-8001B 4.6 Ω -

230-NER-8001C 4.6 Ω -

230-NER-8002 4.6 Ω -

6.0 HARMONIC PARAMETERS

The electrical network at Rong Doi Gas Field Development Project WHd and PUQC Platform feeds various types of loads. The major harmonic producing loads are as follows:

 Variable speed drives for Generator & Compressor starting motor

 AC UPS

(8)

 Thyrister heater

6.1 VSD FOR STARTING MOTOR

There are three (3) VSD drives for gas turbine generator starting motor and one (1) VSD drive for flash gas compressor starting motor. However, each VSD is assumed to produce the harmonic current content as per IEEE 519 and same is detailed in Table 5.2. This assumption is made in view of VSD shall be procured to meet IEEE 519 requirement.

Under normal operation, one (1) VSD drive for flash gas compressor is considered as continuous harmonic source contributing to the electrical network. While during emergency operation, one (1) VSD drive for gas turbine generator shall be deem as harmonic source. They are connected to “LVS A” switchboard and Table 6.1 shows the VSD rating considered for this study.

TABLE 6.1 – VSD LOAD RATING

VSD TAG VSD RATING (kVA) SWB-8301

A-8001A 98.8

KM-2401 384.3

TABLE 6.2 - HARMONIC CURRENT IN VSD

HARMONIC ORDER COMPONENT CURRENT % OF FUNDAMENTAL 1 100 5 4 7 4 11 2 13 2 17 1.5 19 1.5 23 0.6 25 0.6 29 0.6 31 0.6 35 0.3

(9)

HARMONIC ORDER COMPONENT CURRENT % OF FUNDAMENTAL

37 0.3

Note : The above data used is defined by IEEE Std 519-1992 Table 10.3. This value shall be applied for all VSD. However actual vendor data shall be used once it becomes available.

6.2 UPS AND DC CHARGERS

There are two (2) UPS, each rated at 40kVA output, four (4) Gas Turbine DC Battery Chargers each rated at 12kVA, and one (1) Navigational Aids battery Charger rated at 3kVA (Refer section 7.1 for operational consideration). In this harmonic study, the UPS loads are separately modelled while the Battery Charger loads are lumped at respective switchboard. The harmonic current content at UPS and DC Chargers is also considered as per IEEE 519 and same is given in Table 6.3 below.

TABLE 6.3 - HARMONIC CURRENT IN UPS & BATTERY CHARGER

HARMONIC ORDER COMPONENT CURRENT % OF FUNDAMENTAL 1 100 5 4 7 4 11 2 13 2 17 1.5 19 1.5 23 0.6 25 0.6 29 0.6 31 0.6 35 0.3 37 0.3

Note : The above data used is defined by IEEE Std 519-1992 Table 10.3. This value shall be applied for all UPS and Battery Charger. However actual vendor data shall be used once it becomes available.

(10)

Heater load that utilised thyrister control will contribute harmonic and thus considered as harmonic source. There are three (3) heater loads considered for harmonic study as shown in Table 6.4. The harmonic current content is assumed o be the same for all heaters as detailed in Table 6.5.

TABLE 6.4 – HEATER LOAD RATING

Continuous Load TAG NO. DESCRIPTION

kW kVAR SWB-8301 Switchboard “A”

E-4401 Fuel Gas Superheater 69.0 44.6 SWB-8401 Switchboard “B”

E-4101 HP Flare Drum Heater 31.6 0.0 E-4801 Closed Drains Drum Heater 125.0 142.3

TABLE 6.5 - HARMONIC CURRENT IN THYRISTER HEATER

Note : The above data used is defined by IEEE Std 519-1992 Table 10.3. However actual vendor data shall be used once it becomes available.

(11)

Lighting Loads (Fluorescent fixture, high pressure sodium vapour incandescent lamp) under normal operating conditions does not produce harmonics. However during starting specially the chokes do produce harmonics. The impact of harmonics during starting of chokes operated lighting fixture are ignored due to short duration

The emergency light fitting with inbuilt battery charger do produce harmonics continuously. The light fitting with electronic controls also produces harmonics. The harmonics content of such light fittings shall be limited to IEEE 519.

The impact of harmonic producing lighting loads is evaluated. The harmonic current content is assumed to be same as per IEEE 519. The emergency lighting loads is estimated as follows;

TABLE 6.6 - EMERGENCY LIGHTING LOAD

Continuous Load S/No. DESCRIPTION

kW kVAR

1 Platform 15.0 7.26

2 Living Quarter 12.0 5.81

TABLE 6.7 - HARMONIC CURRENT IN LIGHTING LOAD

(12)

Note : The above data used is defined by IEEE Std 519-1992 Table 10.3. However actual vendor data shall be used once it becomes available.

7.0 SYSTEM CONSIDERATION

7.1 OPERATING CONDITIONS

Harmonic analysis has been carried out using EDSA with the above parameters. Normal electrical power system operation has been considered, while the harmonic sources in the electrical network have been considered under full production condition.

The impact of harmonics on the system is highest where the system has maximum impedance. The harmonic contribution of the VSD drive for starting AC motor has been considered despite the short duration during starting. To check maximum impact, however it may not be necessary to consider for sizing filter etc. Only one (1) such VSD drive shall be connected at any one time depending on the operation. The complete interconnected network has been simulated for harmonic study.

Both 40kVA AC UPS are normally loaded to 50% capacity but during emergency generator operation, only one is considered as 100% loaded. Although DC battery chargers for Gas Turbines shall be operating at full capacity for short duration but to observe maximum impact they have been considered as continuous load.

For the purpose of harmonic analysis, all the major loads have been considered including all supporting process loads in the network. The harmonic source is separately modelled where individual load has been represented in the network. The lump load model that contain harmonic, its contribution is lumped under the respective “LVS A” or “LVS B” switchboard.

Note : Please note that Electrical Power Generation and Distribution System for Rong Doi Gas Field Development project has been designed to feed electrical loads of PUQC platform & WHd platform only. The drilling loads, workover loads or any other external loads are not considered in design and shall not be feed from this power system. The drilling and workover loads usually have high harmonic content and may adversely affect the power system.

7.2 ASSUMPTION

(13)

standards 519 Table 10.3.

b) Cable impedance has been considered as per Kukdong Cable Vendor data available, and Motor parameters where not available are assumed based on IEC / IEEE standards, while generator sub transient reactance used are based on data supplied by KNOC / HHI.

c) Non harmonic loads are simulated as lumped load where not indicated. Harmonic producing loads are combined together with non harmonic producing loads under “LVS A” and “LVS B” switchboard for harmonic analysis.

8.0 METHODOLOGY

Harmonic study has been carried out on the EDSA Technical 2004 (Electrical Design and System Analysis) Software of EDSA Micro Corporation USA.

9.0 CALCULATION

Refer to Appendix A and B for EDSA computer printout report.

10.0 RESULTS

Below is a series of tabulated result for two (2) cases of the Harmonic Analysis conducted under Normal Operation where all loads for production are connected, and Emergency Operation where only essential loads in switchboard “LVS A” are connected.

Although relative harmonic impact will be higher during start up of emergency generator as loads on it will comprise of mainly AC UPS and lighting. But it will persist for small duration i.e. switching transients and step loading till other loads on Living Quarters are activated. This transitional period should be minimised. The emergency transitional period is not analysed due to short duration.

The total harmonic voltage distortion THD(V) and total harmonic current distortion THD(I) are evaluated on each bus / link and same is reported under respective case.

(14)

Case I - Normal Operation TABLE 10.1 LOCATION(BUS) VOLTAGE (VOLTS) THD(V) % THD(I) % PUQC Platform SWB-8301 400 1.02 1.59 SWB-8401 400 1.02 1.17 MCC-8302 400 1.00 5.22 DP-8203 400 0.31 6.79 DP-8204 400 0.31 6.79 WHD Platform MCC-8402 400 1.02 0.49

Case II - Emergency Operation

TABLE 10.2 LOCATION(BUS) VOLTAGE (VOLTS) THD(V) % THD(I) % PUQC Platform SWB-8301 400 0.84 2.68 SWB-8401 - - - MCC-8302 400 0.82 8.15 DP-8203 400 0.62 6.79 DP-8204 - - - WHD Platform MCC-8402 - - - 11.0 RESULT ANALYSIS

The harmonic analysis indicates that voltage distortion on all the switchboards, MCC and distribution buses are within normal industry acceptable level of 5%. The maximum total voltage distortion THD(V) for the two (2) cases is only 1.02% on SWB-8301, SWB-8401 & MCC-8402 switchboard. This is not considered to be significant to the system network and is acceptable for industrial loads. The

(15)

maximum total current distortion THD(I) 8.15% is observed at switchboard MCC-8302 for living quarter loads. This information shall be used when sizing circuit breakers along this path. Further UPS vendor to limit output harmonic current distortion less than 5%, in view of the 6.79% THD(I) at the AC UPS distribution panel.

12.0 RECOMMENDATION

The Electrical distribution network at Rong Doi Gas Field Development Project has been analysed in detail to check the suitability under normal and emergency operating conditions with harmonic producing loads. Since the harmonic distortion is within acceptable limits, there is no need to apply separate harmonic filter in Rong Doi distribution system.

13.0 REFERENCES

VN01-200-25-E-PH-0001 Electrical Systems Philosophy

VN01-200-30-E-DW-1100 Electrical Overall Key Single Line Diagram

VN01-200-30-E-CA-8001 Load Flow Analysis

VN01-200-30-E-ST-8002 Electrical Load List - Normal, Emergency & UPS

VN01-200-30-E-CA-8003 Short Circuit Analysis

VN01-200-30-E-CA-8004 Voltage Drop And Cable Sizing Calculations

VN01-200-30-E-CA-8005 Motor Start-up Analysis On Large Load

VN01-200-30-E-CA-8009 Main & Emergency Generator Capacity Study & Calculations

(16)

APPENDIX A