discussion paper on parallel operation charge - Infraline

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(4) Captive power plants will have higher fault level support when they are connected in parallel with the grid supply (Table-VI). Because of the higher fault level, the voltage drop will be less in the system. (5) Additional revenues can be generated by the CPPs by sale of surplus power to utility grid (fig.11) which could attract new investments in CPP. In addition to above, CPPs enjoy the following advantages also: (1) In case of fault in CPP generating units or other equipment, bulk consumers can draw the required power from the grid and can save their production loss. (2) The shock and disturbances in the generating units and also of industries are absorbed by the grid system which is very large (infinite bus). (3) The grid provides stability to the plant to start heavy loads like HT motors. (4) The variation in the voltage and frequency at the time of starting large motors and heavy loads is minimized in the industry, as the grid supply acts as an infinite bus. (5) The impact created by sudden load throw off and consequent tripping of CPP generator on over speeding is avoided with the grid taking care of the impact. (6) The transient surges reduce the life of equipment of CPP. In some cases the equipment fails if transient is beyond limit. If the system is connected to the grid, however, the grid absorbs the transient. Hence grid enhances the life of CPP equipments. In short, for smooth operation of industry and generator, CPPs gain is manifold in case there is grid support from the utility. 5.6 ADVANTAGE OF PARALLEL OPERATION TO UTILITY (1) Power generated by captive power plants (bulk consumers) partially bridges the gap between demand and supply because there is a gap between generation and demand in most of the States in the country. (2) Fault level of both the grid and CPP improves due to parallel operation of captive power plant connected with the grid. However, the fault level contribution by CPP units is less as compared to the contribution of grid. (3) CPP takes power from the grid at very low load factor with respect to its contract demand, which results in high diversity. The demand charge is recovered from the consumers irrespective of diversity and also results in lower per MVA investment cost. 20
Also due to higher diversity, in addition to recovery of full demand charges from CPPs, the utility will have surplus stand by power which can be used as spinning reserve. (4) Addition of generation capacity at centralized station may not be the most economical solution to the power sector utilities, but to manage generation capacities belonging to other generators like CPPs at different location may be an optimum solution (lesser T & D loss). (5) The service lines are lightly loaded due less power flow to the CPPs. The capacity of service line is very much higher than the contract demand. Hence, it reduces the line losses to a small extent. Utility gets over compensated by such lightly loaded lines. 5.7 DISADVANTAGE OF PARALLEL OPERATION TO CPP (1) CPP holder is required to pay for minimum contract demand even if connection is floating to take care of emergency. (2) CPP holder is required to install higher rating switchgear depending on grid fault level. 5.8 DISADVANTAGE OF PARALLEL OPERATION TO UTILITY (1) Load fluctuations of consumers are passed on to utility’s system thereby the efficiency of utility’s system may be affected, which will have impact on utility’s other consumers. (2) In case of an ungrounded (or grounded through resistance) system supply, fault on interconnecting line (consumer’s side) results into interruption of system. For single phase to ground fault which are 80 to 85% of the short circuit fault level, the grounding of the system is achieved through the neutral or step down transformer of the utility, when the generator runs in parallel with the utility’s grid. This supply is likely to cause damage to the terminal equipments at utility’s sub-stations and line insulators, as voltage on the other two healthy phases rise beyond the limit, under such conditions. (3) Utility has to sustain the impact of highly fluctuating peak loads like Arc Furnace, Rolling Mill etc. for which utility does not get any return on the capital investment to create system reserve. (4) The variation in reactive power requirement increases the system losses and lowering of the voltage profile. Utility is incurring the cost of such effects. (5) The lower voltage profile and fluctuations affect the service to the neighboring consumers due to deteriorations in quality of supply thus resulting in revenue loss to the utility. 21
Page 1 and 2: CHHATTISGARH STATE ELECTRICITY REGU
Page 3 and 4: By the time this judgement was rece
Page 5 and 6: commissioning two new units of 250
Page 7 and 8: Sl.No. Name of Consumers (CPPs) Loc
Page 9 and 10: Thus the provisions of the Electric
Page 11 and 12: (b) The studies mentioned below to
Page 13 and 14: 5.3 HIGHLIGHTS OF MEASURED POWER QU
Page 15 and 16: 5.3.3 POWER FACTOR Fig.5 Power Fact
Page 17 and 18: 5.3.5 REACTIVE POWER Fig.9 Reactive
Page 19: Table-VI Sr. No. Name of CPP Fault
Page 23 and 24: For example, Capacity of captive po
Page 25 and 26: (4) As per the tariff order passed
Page 27 and 28: sample CPPs can be considered. Due
Page 29 and 30: and quantity. Power quality paramet

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