Case Stu Study: dy: EA-254 EA-254
Energy Energy Audit of Railway ailway Traction Distribut ion System System
Ab ou t Th e Ins tal lat io n: Traction Sub-station (TSS) is the substation feeding power to traction lines. The traction substation draws electricity at 132 KV or 220 KV and supplies at 25 KV to the traction lines. Locomotives are the major loads in the traction distribution whereas contribution of other loads (signaling & other single phase loads) is negligibly small (less than 1%). The substations in Indian Railways generally have two transformers of capacity 21.6 MVA or 12.5 MVA. One transformer is kept as standby (hot/cold) in order to have more reliability. There are many auxiliary transformers of 10 KVA each, which are feeding signaling and other point loads etc. Capacitors along with series reactors are installed at 25 KV bus bar to improve the power factor. This Detail Energy Audit has been carried out at one of the TSS of Indian Railways. Contract Demand for this substation is 15.5 MVA. This TSS feeds 4 sections. Annual energy consumption is 57.63 million KWH. Ab ou t t he A ss ig nm ent : Scope of work for this Detail Energy Audit has been: 1. Qualitative and quantitative quantitative study of all components components of energy payable payable i.e. KW, KWh, KVAR, MD, PF and harmonics etc. 2. Study of system network, rating/capacities, operational pattern and energy metering systems 3. Study voltage profiles over 25 KV lines, lines, variations in the system and optimal voltage voltage pressure for utilization with least specific energy consumption, energy flow and identification of wastages 4. Capacitor Banks: 4.1 4.2 4.3
Energy dissipation dissipation in series reactor reactor and capacitor banks banks and measures to minimize losses. Switched capacitor banks Scope of using using series capacitor capacitor banks and/or and/or capacitor capacitor banks at sectioning-cum Paralleling posts (far end)
5. Review of auxiliary auxiliary transformer transformer installed in the traction traction system, rating, utilization utilization and losses. losses. 6. Study of Loco Loco consumption consumption profile for Passenger train, train, Express train train and Goods Goods train etc. 7. Suggestion/measures Suggestion/measures to reduce reduce transmission transmission losses losses for energy energy conservation conservation How did we Approach? Energy Audit for traction is comparatively more recent than Energy Audit in manufacturing sector. The issues are also different: like working with moving load which is also highly unsteady, single phase nature of operation (traction motors), HT load causing limitations for measurements, longer transmission lines & others. The areas identified for energy conservation to be done are as follows: 1. 2. 3. 4. 5. 6.
Transmission line losses in HT lines lines from metering point of SEB SEB to the Traction Substation Main transformers at Traction Substation Series Reactors & Capacitor Bank Traction line Locomotive Auxiliary transformers
Overall focus has been on measurements & quantification of losses in energy transmission and analysis thereupon. The study has finally evolved measures to improve energy efficiency. Observations: Variations in V, I, KWH consumption, PF and harmonics are observed & studied: 7,000,000.00
0.99
6,500,000.00 0.98
6,000,000.00
r 0.97 o t c a F 0.96 r e w o 0.95 P
5,500,000.00 H W5,000,000.00 K
4,500,000.00 4,000,000.00
0.94
3,500,000.00 3,000,000.00 4 4 0 0 - r n p u A J
4 4 4 5 0 - 0 - 0 - 0 g t c b u c e e A O D F
5 5 0 0 - r n p u A J
5 5 5 6 0 - 0 - 0 - 0 g t c b u c e e A O D F
6 6 0 0 - r n p u A J
6 6 6 7 0 - 0 - 0 - 0 g t c b u c e e A O D F
0.93
7 7 0 0 - r n p u A J
4 0 r p A
Monthly KWH for Last 3 Years
4 0 n u J
4 0 g u A
4 0 t c O
4 0 c e D
5 0 b e F
5 0 r p A
5 0 n u J
5 0 g u A
5 0 t c O
5 0 c e D
6 0 b e F
6 0 r p A
6 0 n u J
6 0 g u A
6 0 t c O
6 0 c e D
7 0 b e F
7 0 r p A
7 0 n u J
Power Factor Variation for Last 3 Years
18 ) M16 K e14 n n12 o T / r 10 u o 8 H t t a 6 W (
10.00
8.000
17.05
14.21
% 6.000
9.45
7.16
4
C E 2 S
4.000
0 1
1-Passenger Train
2
2-Goods Train
2.000
Target SE C Observed SEC
Targeted & Observed SEC
27/08/2007 4:30:00.000 PM
23:45:00 (H:M:S) 4 Hours/Div
28/08/2007 4:15:00.000 PM
Harmoni cs i n Voltage & Current
Findings & Recommendations: 1. At present the metering point TSS is 1.2 Km away from Traction Substation causing 2. 3.
4.
5. 6.
7.
additional transmission losses. It is recommended to shift the metering point to the TSS. It has been found that one 21.6 MVA transformer is kept hot standby. It is recommended to keep it cold standby resulting in 33% loss reduction in total losses in the transformer. While studying load profile in locos, it is observed that PF in locos is in the range of 0.7 to 0.85. It is recommended that dynamic capacitors should be provided in loco itself considering that capacitors should always be provided nearest to the load end. This will result in significant reduction in line losses in the 25 KV line. Wherever possible the load on the auxiliary transformers should be shifted only on one transformer & the surplus transformers should be removed considering the cable length criterion. This will also increase loading of the transformers and thereby improve efficiency. Coasting Boards should be provided so that the drivers will be aware of the coasting period. This kind of practices will help to minimize the specific energy consumption of locomotives. Microprocessor based Energy Meters should be provided in the all Electric Locomotives to monitor the energy consumption. Specific energy consumption (SEC) of the locomotive should be calculated & compared with the benchmark values to take corrective measures. Due to the increasing energy tariffs, installing biomass captive Power Plants and investing in Wind Mills are also good measures, which will provide CDM benefits also.
SEE-Tech Solu tio ns Pvt. Lt d. (Consultants & solution providers for Industrial Safety, Energy Conservation, Environment Protection & Application Software) “Lets Conserve”, 11/5, MIDC Infotech Park, Near VRCE Telephone Exchange, South Ambazari Road, Nagpur-440022 (India) Ph. No. +91-712-2222177, Fax No. + 91-712-2225293 E-mail:
[email protected] Web: www.letsconserve.org
