Evaluating the effect of frequency regulation modes on the reliability and economic efficiency of thermal power generation units

Abstract

Tests for evaluating the effect of primary and automatic secondary frequency control on the reliability and economic efficiency of thermal condensation power generator units with flow-through boilers are described briefly. The results of these tests serve as initial data for the development of a method of estimating the consequences and additional expenses involved in bringing thermal power generator units into operation in these frequency regulation modes.Keywords: power generator unit, general and standard primary frequency regulation, secondary frequency and power regulation, flow-through boiler, steam turbine.The involvement of the power generator units of thermal power plants in frequency and power regulation of the power system is currently quite widespread in Russia. Here there are basically two ways of operating the equipment: standard primary frequency regulation (NPRCh) and automatic secondary frequency and overcurrent regulation (AVRChM). During operation in the primary mode, a power generator unit must react to deviations in the grid frequency greater than 20 mHz with a proportional change in active power by imposing power changes within the corresponding specifications on the dynamics. During operation with secondary regulation, the active power of a power generator unit must vary at the specified rate (no more than 4% of the nominal unit power N nom in 1 min) within a reserve of ±5% N nom in accordance with specifications from the central automatic frequency and overcurrent regulation system (in addition to power changes according to the system schedule [1]). Combined operation in the primary and secondary modes is possible.These modes apply, first of all, gas-oil fired power generator units with powers of 800, 300, and 200 MW "selected" for this purpose [2]. Most of these were brought into operation more than 30 -40 years ago and have already been run longer than their design lifetimes. The primary and secondary frequency regulation modes are not part of the original design for these units, since they were designed for operation in their base modes. Thus, it is natural that the frequency and power regulation modes should have an effect on the operational reliability and economic efficiency of these units and lead to additional wear on the engineering equipment.Here we examine the results of a study of the effect of the primary and secondary frequency regulation modes on the reliability and economic efficiency of gas-oil power generation units carried out by JSC "VTI" at the request of JSC "SO EÉS." Although many power generation units (more than 50) have already been certified in tests of their suitability for the primary and secondary frequency regulation modes, they are not yet in practical use. Thus, there are no statistics on the operation of the equipment in these modes, so, besides a computational-analytic approach (calculations of lifetime, etc.), in our study we used an experimental-statistical method with expert evaluation of the results. Special tests were done on the 300 MW power generat...

An estimate of the additional operating costs due to the participation of gas-oil power plants in frequency and power regulation

“…Overregulation may be reflected in economy in the operation of the equipment, in particular, in efficiency and the supply of electric power for particular needs. Moreover, as investigations have shown [1,2], when the equipment is operating in ASFPR modes or with the combined action of ASFPR and NPFR modes it is possible for the repair component of the operating costs to increaseprimarily due to the increase in the wear of the regulating units and the heated surfaces of the boiler.The economic component of the additional operating costs C e , due to the participation of the power units of a thermal power plant in the NPFR and ASFPR modes of operation, may be represented as the sum of the costs due to the reduction in the efficiency of the boiler arising from the oversupply of fuel C e f , the increase in the consumption of electric power for particular needs C e pn and the change in the steam pressure in the turbine to satisfy the requirements of the NPFR in the dynamics of the power change C e p , i.e. …”

“…Overregulation may be reflected in economy in the operation of the equipment, in particular, in efficiency and the supply of electric power for particular needs. Moreover, as investigations have shown [1,2], when the equipment is operating in ASFPR modes or with the combined action of ASFPR and NPFR modes it is possible for the repair component of the operating costs to increaseprimarily due to the increase in the wear of the regulating units and the heated surfaces of the boiler.…”

“…The increase in the repair component of the operating costs is due to the increase in the wear (the reduction in the life) in the main regulating units and the hot surfaces of the boiler, and may occur primarily when the equipment is operating in the ASFPR mode [1,2]. On the whole, as estimates show, when the power unit is transferred from the OPFR mode of operation to the ASFPR mode of operation we would expect an increase in the repair component of the operating costs of 3 -6 % per year and an increase in the fuel component of the costs of not more than 0.5 % per year.…”