Quotation method for maximization of benefits of coal-fired unit in electricity spot market

Abstract

The present invention relates to a quotation method for maximizing the benefit of a coal-fired unit on an electricity spot market. The technical solution is as follows: obtaining, by means of calculation, a fuel cost C1 of a unit, a start cost (comprising a fuel consumption fee C2 for starting and a maintenance fee C3 related to the starting of the unit), an opportunity cost C4 caused by an increase in an equivalent forced outage rate, and a fixed cost C5; and on the basis of the cost components of the unit, using a cost-plus pricing method to perform on-grid quotation. A variable cost and the fixed cost of the unit are comprehensively taken into consideration, such that the cost analysis is more comprehensive; and in view of routine thermal performance test results of the unit, by taking factors such as normal aging of the unit, a thermodynamic device defect and an operation parameter deviation into consideration, and on the basis of D+1 load scheduling, fuel costs of the unit under different loads can be known in advance.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the field of operating cost accounting of electricity spot markets and coal-fired units, and in particular, to a method for determining an on-grid price quotation for maximization of benefits of a coal-fired unit in an electricity spot market. BACKGROUND

[0002] Spot trading, as a key link of an electricity market, is an important means for determining values of various electricity commodities by unit bidding, network constraints, and market requirements, and can fully reflect the values of electricity as commodities in time, space, and category. As a market subject, a generator unit is involved in a plurality of links such as electricity bidding, unit clearing, and ancillary service market. Therefore, a power generation cost must be known fully to give a reasonable on-grid price quotation.

[0003] At present, most power generation enterprises still adopt a production cost accounting manner in a “planned” environment, i.e., “ex-post accounting”, to measure and calculate their total power production costs and respective kilowatt-hour average costs with a month, a quarter, and a year as an accounting cycle. However, in a spot market, prices of electricity commodities are influenced by a plurality of factors. A traditional rough cost calculation manner is not adaptable to the market environment which dynamically varies in real time. SUMMARY

[0004] In view of the above, in order to overcome the shortcomings of the prior art, an objective of the present disclosure is to provide quotation method for maximization of benefits of a coal-fired unit in an electricity spot market. Based on a designed value of a unit, with reference to routine thermal test results and in comprehensive consideration of factors such as normal aging of the unit, thermal equipment defects, and operating parameter deviations, the fuel costs of the unit under different loads can be known in advance according to a predicted load plan of D+l days, so as to guide the unit to participate in a spot price quotation.

[0005] The present disclosure adopts the following technical solutions.

[0006] A quotation method for maximization of benefits of a coal-fired unit in an electricity spot market includes the following step:

[0007] step 1, calculating a fuel cost (a coal consumption cost) Cx of a unit;

[0008] = b^generation x Pcw x IO’3 (1)

[0009] where:

[0010] bpc0^ generation represents an actual coal consumption for power generation under different loads, in units of g / kWh;

[0011] Pcw represents the standard coal price, in units of Yuan / t; and

[0012] C) represents a fuel cost during operation of the unit, in units of Yuan / MWh;

[0013] A, for a straight condensing unit, the actual coal consumption for power generation under different loads is calculated according to the following formula:

[0014] bpower generation (h0 + Abi) X C:iac^ pressure X Caging + ^b2 (2)

[0015] where:

[0016] h0 represents a designed coal consumption for power generation under different loads, in units of g / kWh;

[0017] △hi represents an increase in coal consumption caused by performance deterioration of a unit device, in units of g / kWh;

[0018] △b2 represents an increase in coal consumption caused by system leakage, auxiliary steam, soot blowing, and pollution discharge during actual operation of the unit (estimated from historical statistical values), in units of g / kWh;

[0019] Cback pressure represents an effect of a vacuum change of condenser on coal consumption in different seasons and different time periods; and

[0020] Paging represents an effect of aging of the unit device with increasing operating time after overhaul of the unit;

[0021] step A involves the following parameters:

[0022] (1) the designed coal consumption b0 for power generation under different loads:

[0023] b0 = Ko + x N1 + K2 x N2 + K3 X N3 + K4 x A4 (3)

[0024] where:

[0025] Ko, Klt K2, K3, and K4 are coefficients related to initial / fmal parameters of the unit, relative internal efficiency of a steam engine, and a thermal system structure;

[0026] N represents a day-ahead generated power, in units of MW;

[0027] (2) the increase in coal consumption &b4 caused by performance deterioration of the unit device:

[0028] the parameter is determined from an actual experimental testing value; a deep load changing condition is determined from actual positive balance data; and the method uses linear interpolation in calculation according to the following formula: |0029| = K5 . + X (W, - WKn-i))1 (4) ( {Nl(n)~"l(n-1)) J

[0030] where:

[0031] and Ab-^ represent increases in coal consumption at known load points Ni(n-i) and N^, in units of g / kWh; and

[0032] Ks represents an adjustment coefficient for the increase in coal consumption at different load rates;

[0033] (3) a back pressure correction coefficient Cbackpressure:

[0034] a correction curve provided by a manufacturer is directly used for correction according to the following computational formula:

[0035] Cfoack pressure 4” X Poperation^ 4” X Poperation^ + ^9 X Poperation^ (5)

[0036] where:

[0037] K6, K7, Kq, and K9 are coefficients;

[0038] Poperation represents an operating back pressure at load N of a generator, in units of kPa;

[0039] (4) an aging correction coefficient Caging:

[0040] unit aging correction is calculated according to the following formula:

[0042] where:

[0043] BF represents a basic coefficient;

[0044] N represents a unit power;

[0045] Po represents a unit initial pressure, in units of MPa; and

[0046] A represents a unit form, a thermal power generating unit being 1.0;

[0047] B, for a heat supply unit, the actual coal consumption for power generation under different loads is calculated from a converted generated power according to formula (1), where a computational formula for the converted generated power is as follows: r xH

[0048] N = Ngr + AN = Ngr + X pjd (7)

[0049] where:

[0050] Ngr represents a day-ahead designed power generation load of the heat supply unit, in units of MW;

[0051] Fgr represents a heat supply flow rate of a steam extraction opening j, in units of t / h;

[0052] Hj represents a working capability of extracted steam of unit mass at the steam extraction opening j, in units of kJ / kg;

[0053] Pjd represents an electromechanical efficiency; and

[0054] AN represents a generated power converted from the heat supply flow rate, in units of MW;

[0055] the working capability Hj of extracted steam of unit mass at the steam extraction opening j is calculated according to different methods depending on different positions of the steam extraction opening, and specific methods are as follows:

[0056] (1) when the steam extraction opening is located in front of a reheating hot section, the following computational formula is used:

[0057] H,= ^,.) (8)

[0058] where:

[0059] hn represents an exhaust enthalpy of a steam turbine, in units of kJ / kg;

[0060] hj represents an exhaust enthalpy of heat supply, in units of kJ / kg;

[0061] Ar represents a water draining heat release or a water feeding heat release of a heater r, depending on a heater form, in units of kJ / kg; and

[0062] T]r represents an extraction steam efficiency at any energy level;

[0063] (2) when the steam extraction opening is located behind the reheating hot section, the following computational formula is used:

[0064] Hj = hj + a-hn- (Ar X (9)

[0065] where:

[0066] a represents an amount of heat absorption by 1 kg of steam in a reheater, a = hxr — hz(. in units of kJ / kg;

[0067] hzr represents an exhaust enthalpy of the reheating hot section, in units of kJ / kg; and

[0068] hzi represents an exhaust enthalpy of a reheating cold section, in units of kJ / kg;

[0069] step 2, calculating a unit start-up fuel consumption expense C2;

[0070] where the following computational formula is used:

[0071] C2 = Fs x P„ = [F„ + F, x (1 - er'. / '")] x P„ (10)

[0072] where:

[0073] Fo represents a start-up consumption of the steam engine, in units of t / h;

[0074] F1 represents a start-up consumption when a boiler is started from a fully cooled state, in units of t / h;

[0075] ts represents a downtime, in units of h;

[0076] t0 represents a boiler cooling time constant;

[0077] Fs represents a start-up consumption required to restart the unit after the boiler is shut down, in units of t / h;

[0078] Pcw represents the standard coal price, in units of Yuan / t; and

[0079] C2 represents the unit start-up fuel consumption expense, in units of Yuan;

[0080] step 3, calculating a maintenance expense C3 related to a unit start-up;

[0081] where proportions of a maintenance expense of single unit start-up and a base-load operation maintenance expense are calculated to share a total maintenance expense, thereby determining the maintenance expense related to the start-up;

[0082] assuming that a maintenance expense in a unit effective utilization hour is fixed, the step is split as follows:

[0083] Heu = Hu+%.TsixEsi (11)

[0084] cmph = cm + Heu(ny

[0085] Cmps.i = Esi X Cmph (13)

[0086] C3 = Cmph (14)

[0087] where:

[0088] Heu represents a number of converted effective utilization hours, in units of h;

[0089] Hu represents the annual average of effective utilization hours in the previous overhaul period, in units of h;

[0090] Tsi represents an annular average number of certain start-ups in the previous overhaul period (i being a cold state, warm state, or hot state start-up);

[0091] Esi represents a number of converted effective utilization hours for a single certain start-up (i), namely converting damage caused by a single start-up to damage caused by a number of specific effective utilization hours;

[0092] Cm represents an annular average maintenance expense in the previous overhaul period, in units of Yuan;

[0093] Cmpsi represents the maintenance expense in the unit effective utilization hour, in units of Yuan / h;

[0094] Cmph represents a maintenance expense for a single certain start-up, in units of Yuan; and

[0095] C3 represents a no-load maintenance expense in a unit hour, in units of Yuan;

[0096] step 4, calculating an opportunity cost C4 caused by an increase in equivalent forced outage rate (EROR);

[0097] ^=C^ + ^ = ^ + ^ + ^ = C^ + C^ + C^ + C^ (15)

[0098] Cfv = (Fmax-Fmin) / (Gmax-Gmln) X Pcw (16)

[0099] C^f = Fnl x Pcw x Hr / (H xj. th )()

[0100] = C3 x Hr / (HuxGmax')(18)

[0101] C4 = (Pele -~QxHux Gmax x XEF0R (19)

[0102] where:

[0103] Cv represents an average variable cost, in units of Yuan / MWh;

[0104] Cmar represents a kilowatt-hour average marginal cost, in units of Yuan / MWh;

[0105] Cnl represents a kilowatt-hour no-load cost, in units of Yuan / MWh;

[0106] Cfv represents an average fuel consumption expense, in units of Yuan / MWh;

[0107] CTM represents an average material consumption expense (including water, limestone, and sprayed ammonia), in units of Yuan / MWh;

[0108] Cnif represents a kilowatt-hour no-load fuel consumption expense, in units of Yuan / MWh;

[0109] Cnim represents a kilowatt-hour maintenance expense, in units of Yuan / MWh;

[0110] C3 represents the no-load maintenance expense in the unit hour, in units of Yuan;

[0111] Fmax represents a power supply fuel consumption with a rated output of the unit, in units of t / h;

[0112] Fmin represents a power supply fuel consumption with a minimum technical output of the unit, in units of t / h;

[0113] Gmax represents a rated capacity of the unit, in units of MW;

[0114] Gmln represents the minimum technical output of the unit, in units of MW;

[0115] Hu represents the annual average of effective utilization hours in the previous overhaul period, in units of h;

[0116] Hr represents an annual average number of operating hours in the previous overhaul period, in units of h;

[0117] Fnt represents a no-load fuel consumption, in units of t / h;

[0118] Pcw represents the standard coal price, in units of Yuan / t; and

[0119] XEF0R represents a promotion amount of a single start-up to the EROR;

[0120] step 5, calculating a fixed cost Cs of the unit;

[0121] C5 = Cjz X (20)

[0122] where:

[0123] C5 represents a depreciation expense of a fixed asset, in units of Yuan;

[0124] Cjz represents a base cost of a fixed investment of a unit capacity, in units of Yuan / MW;

[0125] n represents a service life of the unit, in units of year; and

[0126] r / czi represents an expected ratio of remaining value of the fixed asset, in units of %, listed according to 5%; and

[0127] step 6, determining an on-grid price quotation according to a power generation cost;

[0128] where the power generation cost C of the unit is obtained by step 1 to step 5, which includes the fuel cost of the unit, the start-up cost (including the start-up fuel consumption expense C2 and the maintenance expense C3 related to the unit start-up), the opportunity cost C4 caused by the increase in EROR, and the fixed cost C-, and the on-grid price quotation is provided using a cost plus method according to the costs:

[0129] 0 = C + A = C, + △ = (1.13 + f) X C (21)

[0130] where:

[0131] 0 represents a price quotation, in Yuan / kWh;

[0132] C represents the power generation cost, in Yuan / kWh;

[0133] △ represents a target profit, in Yuan / kWh;

[0134] 1.13 is a rate of value-added tax; and

[0135] f represents a profit rate.

[0136] Compared with the prior art, the method of the present disclosure has the following advantages:

[0137] 1) At present, a power generation enterprise usually acquires coal consumption levels of different units using a day-after statistical method to obtain the fuel cost of the unit. The method is hysteretic and has a large error. By the method of the present disclosure, in combination with routine thermal test results of the unit and in consideration of factors such as normal aging of the unit, thermal equipment defects, and operating parameter deviations, the fuel costs of the unit under different loads can be known in advance according to a predicted load plan of D+l days.

[0138] 2) The fuel cost calculation method used in the method of the present disclosure is relatively simple. Historical operation data is used, and the thermal test does not need to be performed again. The acquisition cost is greatly reduced.

[0139] 3) The method of the present disclosure takes the variable costs and the fixed costs of the unit into comprehensive cost, and the cost analysis is more comprehensive. BRIEF DESCRIPTION OF THE DRAWINGS

[0140] FIG. 1 is a market price quotation curve of a power plant contract in an application example of the present disclosure. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0141] The specific implementation of the present disclosure will be described in further detail below in conjunction with the examples.

[0142] The present disclosure provides a quotation method for maximization of benefits of a coal-fired unit in an electricity spot market, including the following steps.

[0143] In step 1, a fuel cost (a coal consumption cost) C4 of a unit is calculated:

[0144] Ci = b^generation x Pcw x IO"3 (22)

[0145] where:

[0146] bpC0^ generation represents an actual coal consumption for power generation under different loads, in units of g / kWh;

[0147] Pcw represents the standard coal price, in units of Yuan / t; and

[0148] C1 represents a fuel cost during operation of the unit, in units of Yuan / MWh.

[0149] A, for a straight condensing unit, the actual coal consumption for power generation under different loads is calculated according to the following formula:

[0150] bpower generation (bo + Abi) x Cbackpressure x Caging + Af>2 (23)

[0151] where:

[0152] b0 represents a designed coal consumption for power generation under different loads, in units of g / kWh;

[0153] Ahi represents an increase in coal consumption caused by performance deterioration of a unit device, in units of g / kWh;

[0154] Ab2 represents an increase in coal consumption caused by system leakage, auxiliary steam, soot blowing, and pollution discharge during actual operation of the unit (estimated from historical statistical values), in units of g / kWh;

[0155] Cback pressure represents an effect of a vacuum change of condenser on coal consumption in different seasons and different time periods; and

[0156] Paging represents an effect of aging of the unit device with increasing operating time after overhaul of the unit.

[0157] Step A involves the following parameters:

[0158] (1) the designed coal consumption b0 for power generation under different loads:

[0159] b0 = Ko + K± X N1 + K2 X N2 + K3 X N3 + K4 X A4 (24)

[0160] where:

[0161] Ko, Klt K2, K3, and K4 are coefficients related to initial / final parameters of the unit, relative internal efficiency of a steam engine, and a thermal system structure; and

[0162] A represents a day-ahead generated power, in units of MW;

[0163] (2) the increase in coal consumption &b4 caused by performance deterioration of the unit device :

[0164] the parameter is determined from an actual experimental testing value; a deep load changing condition is determined from actual positive balance data; and the method uses linear interpolation in calculation according to the following formula: |0165| &b, = Ks + (25)

[0166] where:

[0167] Abxand Ab^) represent increases in coal consumption at known load points ^i(n^i) and ^i(n), in units °f g / kWh; and

[0168] K5 represents an adjustment coefficient for the increase in coal consumption at different load rates, with specific values shown in Table 1;

[0169] Table 1 Adjustment Coefficients for Increase in Coal Consumption of Unit under Working conditions below 50% turbine heat acceptance (THA) Grade Load Rate Adjustment Coefficient Normal working condition Load rate>50% 1 First grade 40%<load rate<50% 1.1 Second grade 35%<load rate<40% 1.5 Third grade 30%<load rate<35% 3.0 Fourth grade Load rate<30% Determined by positive balance

[0170] (3) a back pressure correction coefficient Cback pressure:

[0171] a correction curve provided by a manufacturer is directly used for correction according to the following computational formula:

[0172] f back pressure Poperation^ + Poperation^ + Poperation^ (26)

[0173] where:

[0174] K6, K7, Ke, and K9 are coefficients;

[0175] Poperation represents an operating back pressure at load N of a generator, in units of kPa;

[0176] (4) an aging correction coefficient Caging:

[0177] unit aging correction is calculated according to the following formula (recommended by ASME PTC96 procedures): [°1781 C^=^X^XA <27>

[0179] where:

[0180] BF represents a basic coefficient;

[0181] N represents a unit power;

[0182] Po represents a unit initial pressure, in units of MPa; and

[0183] A represents a unit form, a thermal power generating unit being 1.0.

[0184] B, for a heat supply unit, the actual coal consumption for power generation under different loads is calculated from a converted generated power according to formula (1), where a computational formula for the converted generated power is as follows: F x W •

[0185] N = Ngr + AN = Ngr+^Xt]jd (28)

[0186] where:

[0187] Ngr represents a day-ahead designed power generation load of the heat supply unit, in units of MW;

[0188] F gr represents a heat supply flow rate of a steam extraction opening], in units of t / h;

[0189] Hj represents a working capability of extracted steam of unit mass at the steam extraction opening], in units of kJ / kg;

[0190] T / jd represents an electromechanical efficiency; and

[0191] AN represents a generated power converted from the heat supply flow rate, in units of MW.

[0192] The working capability Hj of extracted steam of unit mass at the steam extraction opening j is calculated according to different methods depending on different positions of the steam extraction opening, and specific methods are as follows:

[0193] (1) when the steam extraction opening is located in front of a reheating hot section, the following computational formula is used:

[0194] Hj = hJ-hn-^-=11(ArXT]r) (29)

[0195] where:

[0196] hn represents an exhaust enthalpy of a steam turbine, in units of kJ / kg;

[0197] hj represents an exhaust enthalpy of heat supply, in units of kJ / kg;

[0198] Ar represents a water draining heat release or a water feeding heat release of a heater r, depending on a heater form, in units of kJ / kg; and

[0199] T]r represents an extraction steam efficiency at any energy level;

[0200] (2) when the steam extraction opening is located behind the reheating hot section, the following computational formula is used:

[0201] + (30)

[0202] where:

[0203] a represents an amount of heat absorption by 1 kg of steam in a reheater, a = hzr — hzb in units of kJ / kg;

[0204] hzr represents an exhaust enthalpy of the reheating hot section, in units of kJ / kg; and

[0205] hzi represents an exhaust enthalpy of a reheating cold section, in units of kJ / kg;

[0206] In step 2, a unit start-up fuel consumption expense C2 is calculated.

[0207] The following computational formula is used:

[0208] C2 = Fs x Pcw = [Fo + x (1 - e’^Ao)] x Pcw (31)

[0209] where:

[0210] Fo represents a start-up consumption of the steam engine, in units of t / h;

[0211] F± represents a start-up consumption when a boiler is started from a fully cooled state, in units of t / h;

[0220]

[0221]

[0222]

[0223]

[0224]

[0225]

[0212] ts represents a downtime, in units of h;

[0213] t0 represents a boiler cooling time constant;

[0214] Fs represents a start-up consumption required to restart the unit after the boiler is shut down, in units of t / h;

[0215] Pcw represents the standard coal price, in units of Yuan / t; and

[0216] C2 represents the unit start-up fuel consumption expense, in units of Yuan;

[0217] In step 3, a maintenance expense C3 related to a unit start-up is calculated.

[0218] Proportions of a maintenance expense of single unit start-up and a base-load operation maintenance expense are calculated to share a total maintenance expense, thereby determining the maintenance expense related to the start-up.

[0219] Assuming that a maintenance expense in a unit effective utilization hour is fixed, the step is split as follows: Heu = + Tsi x Esi (32) Cmph Cm ~ Heu (33) Cmps,i Esi X Cmph (34) c3 = Cmph (35) where: Heu represents a number of converted effective utilization hours, in units of h; Hu represents the annual average of effective utilization hours in the previous overhaul period, in units of h;

[0227] Tsi represents an annular average number of certain start-ups in the previous overhaul period (i being a cold state, warm state, or hot state start-up);

[0228] Esi represents a number of converted effective utilization hours for a single certain start-up (i), namely converting damage caused by a single start-up to damage caused by a number of specific effective utilization hours, with specific values shown in Table 2;

[0229] Cm represents an annular average maintenance expense in the previous overhaul period, in units of Yuan;

[0230] Cmpsi represents the maintenance expense in the unit effective utilization hour, in units of Yuan / h;

[0231] Cmph represents a maintenance expense for a single certain start-up, in units of Yuan; and

[0232] C3 represents a no-load maintenance expense in a unit hour, in units of Yuan.

[0233] Table 2 Number Esl of Converted Effective Utilization Hours at Single Start-Up Start-Up Supercritical Unit Large Subcritical Unit Small Subcritical Unit Type (500-1300 MW) (300-900 MW) (<300 MW) Cold state 35.1 39.2 44.0 Warm state 21.6 24.2 47.0 Hot state 18.2 22.0 28.1

[0234] In step 4, an opportunity cost C4 caused by an increase in equivalent forced outage rate (EROR) is calculated:

[0235] Cv = Cmar + Cnt = Cfv + CTM + Cni = Cfv + CTM + Cnif + Cnim (36)

[0236] C^v (Fmax Fmin) / (Gmax Gmin") X Pcw (37)

[0237] C^f = Fnl X Pcw X Hr / (Hu*GmaJ (38)

[0238] = C3 x Hr / (HuxGmax)(39)

[0239] Hu X Gmax x Xefor (40)

[0240] where:

[0241] Cv represents an average variable cost, in units of Yuan / MWh;

[0242] Gmar represents a kilowatt-hour average marginal cost, in units of Yuan / MWh;

[0243] Cni represents a kilowatt-hour no-load cost, in units of Yuan / MWh;

[0244] Cfv represents an average fuel consumption expense, in units of Yuan / MWh;

[0245] CTM represents an average material consumption expense (including water, limestone, and sprayed ammonia), in units of Yuan / MWh;

[0246] Cnif represents a kilowatt-hour no-load fuel consumption expense, in units of Yuan / MWh;

[0247] Cnim represents a kilowatt-hour maintenance expense, in units of Yuan / MWh;

[0248] C3 represents the no-load maintenance expense in the unit hour, in units of Yuan;

[0249] Fmax represents a power supply fuel consumption with a rated output of the unit, in units of t / h;

[0250] Fmin represents a power supply fuel consumption with a minimum technical output of the unit, in units of t / h;

[0251] Gmax represents a rated capacity of the unit, in units of MW;

[0252] Gmin represents the minimum technical output of the unit, in units of MW;

[0253] Hu represents the annual average of effective utilization hours in the previous overhaul period, in units of h;

[0254] Hr represents an annual average number of operating hours in the previous overhaul period, in units of h;

[0255] Fni represents a no-load fuel consumption, in units of t / h;

[0256] Pcw represents the standard coal price, in units of Yuan / t, and

[0257] XEF0R represents a promotion amount of a single start-up to the EROR, with specific data shown in Table 2.

[0258] Table 3 Promotion Amount XEFOR / %o of Single Start-Up to EROR of Unit Start-Up Type Supercritical Unit (500-1300 MW) Large Subcritical Unit (300-900 MW) Small Subcritical Unit (<300 MW) Cold state 0.088 0.088 0.106 Warm state 0.054 0.07 0.123 Hot state 0.037 0.057 0.086

[0259] In step 5, a fixed cost C5 of the unit is calculated:

[0260] C5=CJzx^^ (41)

[0261] where:

[0262] C5 represents a depreciation expense of a fixed asset, in units of Yuan;

[0263] Cjz represents a base cost of a fixed investment of a unit capacity, in units of Yuan / MW;

[0264] n represents a service life of the unit, in units of year; and

[0265] r]czi represents an expected ratio of remaining value of the fixed asset, in units of %, listed according to 5%; and

[0266] In step 6, an on-grid price quotation is determined according to a power generation cost.

[0267] The power generation cost C of the unit can be obtained by step 1 to step 5, which includes the fuel cost of the unit Ct, the start-up cost (the fuel expense C2 and the maintenance expense C3), the opportunity cost C4 caused by the increase in EROR, and the fixed cost C5, and the on-grid price quotation is provided using a cost plus method according to the costs:

[0268] O = C + A = Xj G + △ = (1-13 + / ) x C (42)

[0269] where:

[0270] O represents a price quotation, in Yuan / kWh;

[0271] C represents the power generation cost, in Yuan / kWh;

[0272] A represents a target profit, in Yuan / kWh;

[0273] 1.13 is a rate of value-added tax; and

[0274] f represents a profit rate.

[0275] The method of the present disclosure is shown to achieve good technical effects in practical application. The application example is as follows:

[0276] Taking a power plant A as an example, its rated capacity is 4x600 MW; its monthly contract volume is 2.2 billion kWh; its load rate is 70%; its standard coal price of long-term contracted coal is 726.18 Yuan / ton; its contracted quantity is 0.6 million ton; and its standard coal price of market coal is 620.11 Yuan / ton. The supply can be guaranteed. According to the document of performance responsibility contracted by the power generation enterprise, the lowest profit rate can be inferred. The profit rate is set to 10%. A quotation function is finally obtained according to the method of the present disclosure.

[0277] 0 = (1.13 + 0.1) x C = 1.23C

[0278] The market price quotation curve of the power plant contract is as shown in FIG. 1. The curve in FIG. 1 is fitted, and the price quotation curve of the plant can be obtained.

[0279] O = 0.1338 x p2 - 18.635 x p + 899.91 (22)

[0280] With this model, the power generation earnings of the power plant in each month over the full year is as shown in Table 4, increased year on year by 6740.8 thousand and grown year on year by 13.83%.

[0281] Table 4 Statistical Table of Earning Increases by a Strategy of a year Month Original Earnings (ten thousand Yuan) Adjusted Earnings (ten thousand Yuan) Profit and Loss (ten thousand Yuan) Proportion (%) January 714.62 744.10 29.49 4.13 February 219.34 230.68 11.34 5.17 March 559.77 661.55 101.78 18.18 April 297.10 325.49 28.39 9.56 May 223.63 247.99 24.36 10.89 June 264.61 291.37 26.77 10.12 July 276.74 313.05 36.31 13.12 August 461.10 505.13 44.03 9.55 September 523.23 623.18 99.95 19.10 October 553.37 689.87 136.50 24.67 November 453.12 562.12 109.00 24.06 December 328.13 354.29 26.16 7.97 Total 4874.74 5548.83 674.08 13.83

Claims

1. A quotation method for maximization of benefits of a coal-fired unit in an electricity spot market, comprising the following steps:step 1, calculating a fuel cost Q of a unit;r _ tactual x p y -10^3 / nupower generation ' civwherein:bpower generation represents an actual coal consumption for power generation under different loads, in units of g / kWh;Pcw represents a standard coal price, in units of Yuan / t; andC1 represents a fuel cost during operation of the unit, in units of Yuan / MWh;A, for a straight condensing unit, the actual coal consumption for power generation under different loads is calculated according to the following formula:Upower generation (^0 + X Cback pre-.cure X Caging + (2)wherein:b0 represents a designed coal consumption for power generation under different loads, in units of g / kWh;△bi represents an increase in coal consumption caused by performance deterioration of a unit device, in units of g / kWh;&b2 represents an increase in coal consumption caused by system leakage, auxiliary steam, soot blowing, and pollution discharge during actual operation of the unit (estimated from historical statistical values), in units of g / kWh;Cback pressure represents an effect of a vacuum change of condenser on coal consumption in different seasons and different time periods; andCaging represents an effect of aging of the unit device with increasing operating time after overhaul of the unit;step A involves the following parameters:(1) the designed coal consumption b0 for power generation under different loads:b0 = Ko + Ki x N1 + K2 x N2 + K3 x N3 + K4 X A4 (3)wherein:Ko, K±, K2, K3, and K4 are coefficients related to initial / final parameters of the unit, relative internal efficiency of a steam engine, and a thermal system structure (whether the coefficients are undoubtedly determinable from the above contents by those skilled in the art? the coefficients are determinable from a heat balance diagram of the unit, and the diagram is basicdata of the unit); andTV represents a day-ahead generated power, in units of MW;(2) the increase in coal consumption Abr caused by performance deterioration of the unit device:the parameter is determined from an actual experimental testing value; a deep load changing condition is determined from actual positive balance data; and the method uses linear interpolation in calculation according to the following formula:=Ks. (4)wherein:and Ab^) represent increases in coal consumption at known load points and Ni(n), in units of g / kWh; andK5 represents an adjustment coefficient for the increase in coal consumption at different load rates;(3) a back pressure correction coefficient Cbackpressure:a correction curve provided by a manufacturer is directly used for correction according to the following computational formula:Cback pressure + K7 X Poperation^ + Poperation^ + Poperation^ (5)wherein:Ke . K7 , Kq , and Kg are coefficients (whether the coefficients are undoubtedly determinable by those skilled in the art? the coefficients are determinable from a back pressure correction curve of the unit, and the curve is also basic data of the unit); andPoperation represents an operating back pressure at load N of a generator, in units of kPa;(4) an aging correction coefficient Caging:the unit aging correction coefficient is calculated according to the following formula:C — BF x I P° x 4 (61Gaglng |og(M) ^ / 16.55 Wwherein:BF represents a basic coefficient;N represents a unit power;Po represents a unit initial pressure, in units of MPa; andA represents a unit form, a thermal power generating unit being 1.0;B, for a heat supply unit, the actual coal consumption for power generation under different loads is calculated from a converted generated power according to formula (1), wherein a computational formula for the converted generated power is as follows:F„rXH,N = Ngr+AN = Ngr+^Xt]jd (7)wherein:Ngr represents a day-ahead designed power generation load of the heat supply unit, in units of MW;Fgr represents a heat supply flow rate of a steam extraction opening j, in units of t / h;Hj represents a working capability of extracted steam of unit mass at the steam extraction opening j, in units of kJ / kg;T]jd represents an electromechanical efficiency; and△IV represents a generated power converted from the heat supply flow rate, in units of MW;the working capability Hj of extracted steam of unit mass at the steam extraction opening j is calculated according to different methods depending on different positions of the steam extraction opening, and specific methods are as follows:(1) when the steam extraction opening is located in front of a reheating hot section, the following computational formula is used:Hj = hj -hn- (Ar x rjr) (8)wherein:hn represents an exhaust enthalpy of a steam turbine, in units of kJ / kg;hj represents an exhaust enthalpy of heat supply, in units of kJ / kg;Ar represents a water draining heat release or a water feeding heat release of a heater r, depending on a heater form, in units of kJ / kg; andT]r represents an extraction steam efficiency at any energy level;(2) when the steam extraction opening is located behind the reheating hot section, the following computational formula is used:Hj = hj + a-hn- (Ar X 7 / r) (9)wherein:a represents an amount of heat absorption by 1 kg of steam in a reheater, o = hzr - hzb in units of kJ / kg;hzr represents an exhaust enthalpy of the reheating hot section, in units of kJ / kg; andhzi represents an exhaust enthalpy of a reheating cold section, in units of kJ / kg;step 2, calculating a unit start-up fuel consumption expense C2;wherein the following computational formula is used:C2 = F, x Pcw = [F„ + F, X (1 - £->= / '•)] x P„„ (10)wherein:Fo represents a start-up consumption of the steam engine, in units of t / h;represents a start-up consumption when a boiler is started from a fully cooled state, in units of t / h;ts represents a downtime, in units of h;t0 represents a boiler cooling time constant;Fs represents a start-up consumption required to restart the unit after the boiler is shut down, in units of t / h;Pcw represents the standard coal price, in units of Yuan / t; andC2 represents the unit start-up fuel consumption expense, in units of Yuan;step 3, calculating a maintenance expense C3 related to a unit start-up;wherein proportions of a maintenance expense of single unit start-up and a base-load operation maintenance expense are calculated to share a total maintenance expense, thereby determining the maintenance expense related to the start-up;assuming that a maintenance expense in a unit effective utilization hour is fixed, the step is split as follows:Heu = Hu+YtTsiKEsi (11)Emph — Em ~ Heu (12)Emps,i Esi X Cmp / [ (13)c3 = Cmph (14)wherein:Heu represents a number of converted effective utilization hours, in units of h;Hu represents an annual average of effective utilization hours in a previous overhaul period, in units of h;Tsi represents an annular average number of certain start-ups in the previous overhaul period (i being a cold state, warm state, or hot state start-up);Esi represents a number of converted effective utilization hours for a single certain start-up (i), namely converting damage caused by a single start-up to damage caused by a number of specific effective utilization hours;Cm represents an annular average maintenance expense in the previous overhaul period, in units of Yuan;Emps,i represents the maintenance expense in the unit effective utilization hour, in units of Yuan / h;Cmph represents a maintenance expense for a single certain start-up, in units of Yuan; andC3 represents a no-load maintenance expense in a unit hour, in units of Yuan;step 4, calculating an opportunity cost C4 caused by an increase in equivalent forcedoutage rate (EROR);v Gmar + ^nl C fv + ^TM + Gni Gfv + ^TM + ^nlf + ^nlm (1$)Gfv (fmax ^min) / (fimax^min) * Pew (16)Cnlf Pnl * Pew X Hr / CHu^Gmax) (17)Ct = (Pele~) x Hu x Gmax X XEF0R (19)wherein:Cv represents an average variable cost, in units of Yuan / MWh;Gmar represents a kilowatt-hour average marginal cost, in units of Yuan / MWh;Cnl represents a kilowatt-hour no-load cost, in units of Yuan / MWh;Cfv represents an average fuel consumption expense, in units of Yuan / MWh;CTM represents an average material consumption expense (comprising water, limestone, and sprayed ammonia), in units of Yuan / MWh;Cnif represents a kilowatt-hour no-load fuel consumption expense, in units of Yuan / MWh;Cnim represents a kilowatt-hour maintenance expense, in units of Yuan / MWh;C3 represents the no-load maintenance expense in the unit hour, in units of Yuan;Fmax represents a power supply fuel consumption with a rated output of the unit, in units of t / h;Fmin represents a power supply fuel consumption with a minimum technical output of the unit, in units of t / h;Gmax represents a rated capacity of the unit, in units of MW;Gmin represents the minimum technical output of the unit, in units of MW;Hu represents the annual average of effective utilization hours in the previous overhaul period, in units of h;Hr represents an annual average number of operating hours in the previous overhaul period, in units of h;Fnt represents a no-load fuel consumption, in units of t / h;Pcw represents the standard coal price, in units of Yuan / t; andXEfor represents a promotion amount of a single start-up to the EROR;step 5, calculating a fixed cost C3 of the unit;(20)wherein:C5 represents a depreciation expense of a fixed asset, in units of Yuan;represents a base cost of a fixed investment of a unit capacity, in units of Yuan / MW;n represents a service life of the unit, in units of year; andr]czi represents an expected ratio of remaining value of the fixed asset, in units of %, listed according to 5%; andstep 6, determining an on-grid price quotation according to a power generation cost;wherein the power generation cost C of the unit is obtained by step 1 to step 5, which comprises the fuel cost of the unit C1? the start-up cost, the opportunity cost C4 caused by the increase in EROR, and the fixed cost C5, and the on-grid price quotation is provided using a cost plus method according to the costs:O = C + A = ^Q + A = (1.13 + f) x C(21)wherein:0 represents a price quotation, in Yuan / kWh;C represents the power generation cost, in Yuan / kWh;△ represents a target profit, in Yuan / kWh;1.13 is a rate of value-added tax; and / represents a profit rate; andthe start-up cost comprises the start-up fuel consumption expense C2 and the maintenance expense C3 related to the unit start-up.

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