Friday, June 3, 2011
Sunday, February 27, 2011
Wednesday, February 23, 2011
Monday, February 21, 2011
Sunday, February 20, 2011
Saturday, February 19, 2011
Tuesday, August 31, 2010
Monday, August 30, 2010
Thursday, August 26, 2010
Wednesday, August 25, 2010
Monday, August 23, 2010
Saturday, August 21, 2010
Saturday, July 17, 2010
Monday, May 3, 2010
all the "gangs" gathered~
Thursday, April 29, 2010
I read the Distribution Planning Guideline Handbook. One of the topic is about MV Network Configuration. The MV Distribution Network in TNB operates at voltages of 6.6, 11, 22 and 33 kV
and interlinks the transmission system and the LV distribution system.
TYPE OF NETWORK CONFIGURATION
There are three basic network configurations that are commonly in use are;
(a) the radial circuit,
(b) the mesh circuit, and
(c) the loop circuit.
Performance of some common network configuration with respect to several different sets of characteristics as listed below:-
• Construction characteristic
• Operation characteristic
• Maintenance characteristic
The salient features of the various network configurations under consideration are
• Radial circuit
• Mesh circuit
• Loop circuit from same ppu/pmu
• Loop circuit from different ppu/pmu
• Loop via switching station (n+1 grouping)
• Petal configuration
• Bulk supply interconnector configuration
Today, my focus suggested by my supervisor is the Petal Configuration.
• The “petal configuration” is one method to improve reliability and security of supply.
• The “petal configuration is developed by interconnecting a loop circuit form one PPU/PMU to a loop circuit from another PPU/PMU via a switching station or the bus-section of a normal substation.
• Individual cable loops are operated in a “close loop” arrangement with 50% loading level.
• All circuit breaker substations are installed with unit protection for cable and SCADA supervisory system for remote switching
• An off-point is maintained at the switching station or bus-section.
The main advantages of this network configuration are:-
• No supply interruption due to single cable fault outage
• Full feedback even if one of the PPU/PMU outage
• SCADA system to detect cable fault and perform remote switching
The disadvantage of this network configuration is:-
• the inherent high cost of installing SCADA system and circuit breaker substations.
I studied about Distribution Network Master Plan (DNMP).It is part of a distribution planning cycle and process to assess the future (planning horizon: 1-3 years for 11kV and 1-5 years for 33kV) distribution system conditions and identify system development options for compliance to the distribution system performance objectives or defined performance targets.
The key objectives of this annual planning exercise for distribution system planners are:
1) To provide fact-based assessment of network performance (existing and future years within planning horizon).
2) To review system performance objectives/targets.
3) To review TNB Distribution planning and development strategies, policies if necessary.
4) To develop & test network solutions in meeting system performance objectives.
5) To identify and select best network development options.
6) To identify medium-term system development and reinforcement CAPEX for a supply zone and state.
Overall, the system planning process and preparation of a master plan undertaken in
DNMP would provide a comprehensive analysis and documentation of the current and future system performance status as well as the investment required to meet the targeted system performance objectives.
The DNMP will encompass the following tasks and analyses for a supply zone:
1) Network modeling of all subsystems (33kV)
2) Load scaling based on disaggregated demand forecast.
3) Load flow, security and contingency analyses.
4) Short circuit analysis.
5) Determination of target networks founded on best network solutions.
6) Recommendation of network expansion and reinforcement projects.
7) Preparation of summary report.
The methodology or approach adopted for 33kV DNMP is as outlined in Appendix 1. A brief overview of the methodology and tasks undertaken in this planning exercise is shown in the flow-chart below.
that's all for the day~
Friday, April 23, 2010
Today I revised the next topic after Load Disaggregation which is Sub-Transmission Capacity Planning (STCP)
Represents the finding and recommendations on PMU Plant-up requirements for the supply zone (SZ) up to the planning horizon for certain year.
STCP encompasses the following:
1) Capacity / demand balance analysis of sub-transmission capacity under n-1 firm capacity and group firm operational criteria.
2)Performance analysis of sub-transmission level and distribution network within the supply zone in terms of loading levels under normal and contingency, load transferability and security level.
3)Summary of distribution development option related to sub-transmission capacity utilization within supply area.4)Proposed PMU plant-up for the planning horizon.
Today, I have revised about Load Disaggregation.
The objectives of load disaggregation viewed from the perspective of distribution planners are as follows:
1)The information and data will form the basis for transmission capacity planning and development.
2)The data will equally provide the initial data for medium term distribution system reinforcement planning and system operational study – in terms of constraints, limitations and opportunities.
3)The data will also serve as the basis to determine on distribution main-intake (PPU) planning to transmit transmission intakes’ 22kV capacity to satisfy localized developments needs.
that's all for the day
Today, I have reviewed about TNB Distribution 33kV planning cycle and I put my focus on load forecast. The load forecast is used as a means of predicting future electricity demands or sales growth based on historical data.
The future electricity demand information derived will assist system planners in proposing new equipment and facilities as well as reinforcing and upgrading the existing system to meet the increasing demand.
Accurate, reliable, and defendable forecast will help planners in making prudent investment decision for system expansion, reinforcement and new plant-up.
The forecast horizon has been defined in accordance to the upcoming Malaysian Distribution code:
Short term 1-2 years
Medium term 3-5 years
Long term 6-10 years
Short term forecast is useful for operational planning and capital budgeting as well as for material procurement planning requirements.
PPU plant-up proposal and distribution network planning will use short-to-medium term forecast.
Alternatively, sub-transmission capacity planning or PMU planning will utilizes medium-term forecast.
A long term forecast are strategic in nature and being used to provide inputs and lead time for generation plants ups, substation sites and the associated way leave identification and acquisition.
Since everybody in the department were too busy this week and some of them were sent to ILSAS for a course,especially Kak Ina, then in order to fill the free time with some beneficial stuffs. Soo, I have to go through electricity supply application handbook given by kak ina before she left to ILSAS and I became more understand about TNB’s core activities which are in generation, transmission, and distribution of electricity which are being handled by its subsidiaries which are TNB Generation Sdn Bhd, TNB transmission Network Sdn Bhd, and TNB Distribution Sdn Bhd
As I am doing my internship in TNB Distribution Sdn Bhd, I can tell that TNB Distribution Sdn Bhd divides its core activities into three main areas which are Customer service (CS), Network Service (NS) , Support service (SS).
that's all for the day~
Saturday, April 17, 2010
Today, I went to NERCC (North Eastern Regional Control Centre). I have learnt how to take load reading which is used for load forecast planning. Load reading is a monthly event and it is useful to predict expenses in the future by taking the load reading for each place in the north and eastern. NERCC is placed in the TNB building level 5 in Seberang Prai, Pulau Pinang.
NERCC acts as switching control centre. It controls all the switching of the PPU and PMU (33kV and 11kV). The technician talked about SCADA (Supervisory Control and Data Acquisition) system it to us. They said, “SCADA ni bertujuan memastikan bekalan elektrik ke Wilayah Ekonomi Koridor Utara (NCER) dan Wilayah Ekonomi Pantai Timur (ECER) mencukupi untuk menampung kepesatan aktiviti ekonomi di kawasan berkenaan. Contohnya, system ni dapat mengesan sebarang kerosakan atau masalah berkaitan bekalan elektrik bagi kawasan terbabit dan tindakan memulihkan bekalan akan dilakukan dalam jangkamasa yang cepat. Kalau ada kerosakan kecil, TNB boleh mengambil tindakan awal untuk memulihkan keadaan bagi mengelakkan kerosakan menjadi lebih buruk.”
Pulau Pinang became the second RCC (Regional Control Centre) in Malaysia after Bangsar in Port Klang. Other than that, MSRCC (Metro South Regional Control Centre) in Bangsar distribute the electricity supply to the south and western part of Malaysia.
In the PMU and PPU, there is RTU (Remote Terminal Unit). All the value measured and the data of the load is connected to it and the data will be sent through transducer in the RTU to RCC.
We can get the idea by finding the value from the load reading. the method of reading the value ca become tedious if the value given is not specified whether it is in the morning or night. So, we need to do a comparison at specified time throughout the month.
Then we went back home. We finally reached at the company at 6.10 pm. So from the punch card, it’s looked like we did an overtime work with “no salary”.
that's all for today