PROJECT TITLE Determination/Upgrading of Protection Relay Settings on 220KV Transmission Network. (Case Study of the Bujagali to Kawanda line).

DESIGN OF A 400kV TRANSMISSION NETWORK AND ITS PROTECTION RELAY (CASE STUDY OF KARUMA TO TORORO LINE)

BY OWITI COLLINCE MANUKU BELE MUYINZA ISAAC BELE

Project backgroundThe Energy Policy for Uganda (2002) It was put in place by the Government. Its main policy goal is to meet the energy needs of the Ugandan population for social and economic development in an environmentally sustainable manner.One of UETCL Specific strategies to achieve this is by Increasing the transmission voltage from 66kV and 132kV to 220kV and 400kV

Problem statement Uganda is introducing a 400 kV network to its existing grid. This high transmission voltage is going to result into more severe faults and without appropriate design and protection it can be hazardous to both personnel and equipment.

ObjectivesMain Objective:To design 400kV Transmission line from Karuma to Tororo and come up with its Protection Relay system . Specific Objectives: To design a Transmission power system network from Karuma to Tororo.To design a protection relay system for transmission lines, busbars and transformers.

MethodologyStep 1: Literature reviewStudied relays and the different protection schemes. Step 2: Data collectionCollected parameters required to calculate the settings. Step 3: Data analysis (calculation)Calculated the relay settings for 400 kV.Used DigiSilent simulation software. Step 4: ResultsCame up with a design and settings to be used for proposed 400kV transmission network.

Generator specifications

SubstationPower (MVA)Voltage(kV)Active power (MW)ReactivePower (Mvar)Power factorKaruma15017120900.8

Source- Uganda Electricity Transmission Company LimitedSubstationNumber of transformersPower (MVA)Voltage(kV)Power factorKaruma250017/4000.8Lira2320400/330.8Opuyo2320400/330.8Mbale1320400/110.8Tororo2320400/2200.8

Transformer specificationsDesign Stage

Line ratingsTransmissionLineConductor TypeVoltage(kV)Zero phase sequenceImpedance()Positive phase sequence impedance()Line length(KM)Cable cross section(mm2)Karuma To LiraACSR4000.2587 + j1.17400.03293 + j0.318480520Lira to opuyoACSR4000.2587 + j1.17400.03293 + j0.3184116520Opuyo to MbaleACSR4000.2587 + j1.17400.03293 + j0.3184102520Mbale to TororoACSR4000.2587 + j1.17400.03293 + j0.318440520

Source- Uganda Electricity Transmission Company Limited

Power Grid

The grid was divided into two parts . The first part is from Karuma to Opuyo and the second part is from Mbale to Tororo.

Part one of the Grid (Karuma to Opuyo)

Part two of the Grid (Mbale to Tororo.)

Overhead Line ProtectionMain protection -Distance relay protectionBackup Protection Overcurrent relay Protection

Distance relay protection

Tripping Times= Operating time of zone one+ CB operation + Distance relay reset time + Errors of distance relay internal times+ safety margin

Zone reach =(line impedance per km*line length* percentage reach)

Table of resultsZoneImpedance Magnitude ( )Operational time (s)Karuma fowardZone one20.488 < 84.10.02Zone two30.732 < 84.10.14Zone three38.415< 84.10.26Lira forwardZone one29.7 < 84.10.02Zone two53.455 < 84.10.14Zone three76.18 < 84.10.26Lira reverseZone one20.488 < 84.10.02Zone two30.732 < 84.10.14Zone three38.415< 84.10.26

Table of results(cont)Opuyo forwardZone one26.11 < 84.10.02Zone two39.04 < 84.10.14Zone three48 < 84.10.26Opuyo reverseZone one29.696 < 84.10.02Zone two49.92 < 84.10.14Zone three67.84 < 84.10.26Mbale forwardZone one10.24 < 84.10.02Zone two15.36 < 84.10.14Zone three19.2 < 84.10.26Mbale reverseZone one26.112 < 84.10.02Zone two51.2 < 84.10.14Zone three82.56