A power dispatching method applied to a regional combined heat and power unit

Abstract

The application discloses a power scheduling method applied to a regional combined heat and power unit, and is based on a three-part framework of a combined heat and power system, a regional energy system and a heat and power separation system. After a relational expression of the three parts is established, the regional energy system heat load is introduced, the minimum power generation of the unit when the heat load demand is met is obtained, and the reasonable operation space of the total power generation of the combined heat and power unit is established based on the total cost of the combined heat and power unit being less than the total cost of the heat and power separation system. Through the analysis on the heat supply characteristics of the combined heat and power unit and the comparative analysis with the heat and power separation system, the best operation interval and the maximum benefit operation mode of the combined heat and power unit are obtained, so that the operation practice can be correctly guided.

Description

Technical Field

[0001] This invention belongs to the field of energy conservation and consumption reduction technology for coal-fired power units, and specifically relates to a power dispatching method applied to regional cogeneration units. Background Technology

[0002] Combined heat and power (CHP) units can simultaneously produce electricity and heat, representing a highly efficient form of energy utilization. The energy savings of CHP units stem from the fact that, compared to separate heat and power generation, CHP is more economical in producing the same amount of electricity and heat. Therefore, based on regional energy prices and the characteristics of CHP units, there exists an optimal power dispatching method for CHP units.

[0003] To meet winter heating demands, regional energy systems typically operate combined heat and power (CHP) units. In this system, the heat load is met by the CHP units to address residential heating needs, while the electricity load is met by both the CHP units and the regional power grid to meet residential electricity needs. While CHP units generally possess some capacity to regulate electricity load, the current challenge lies in how to adapt and adjust the electricity load according to residential heating requirements and the actual conditions of the CHP units. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a power dispatching method for regional cogeneration units, so as to solve the problem that the electrical load is difficult to regulate fully and effectively in the prior art.

[0005] To achieve the above objectives, the present invention employs the following technical solution:

[0006] A power dispatching method for regional combined heat and power units includes the following steps:

[0007] Step 1: Collect the total heat supply of the cogeneration unit and establish the first relationship between the total heat supply of the cogeneration unit, the total heat consumption of the cogeneration unit, and the total power generation of the cogeneration unit.

[0008] Step 2: Introduce the regional energy system heat load into the first relationship, and after simplification, obtain the second relationship between the total power generation of the cogeneration unit and the heat load of the regional energy system. The minimum power generation of the unit when the heat load demand is met is obtained through the second relationship.

[0009] Step 3: Based on the premise that the total cost of combined heat and power (CHP) is less than the total cost of separate heat and power generation, and considering the ratio of regional energy system heat load to heating boiler efficiency, obtain the reasonable operating range for the total power generation of the CHP unit. Specifically, establish a comparison formula between the ratio and a set coefficient, where the ratio is the ratio of local electricity price to heat price. When the ratio is greater than the set coefficient, the total power generation of CHP is greater than or equal to the maximum value of N' and N'', and less than or equal to N''. b When the ratio is less than the set coefficient, the total power generation of the combined heat and power is greater than or equal to N', and less than or equal to N” and N. b The minimum value in the range; where N' is the minimum power generation of the unit while meeting the heat load demand; N” is the value that the unit's power generation load must meet to make cogeneration power generation less energy-efficient than separate generation power generation; N b This is the electricity demand for the region.

[0010] A further improvement of the present invention is that:

[0011] Preferably, in step 1, the first relation is:

[0012] Q t =η QNET (F t -N t (1)

[0013] Where, η QNET Net thermal efficiency, %;

[0014] F t The total heat consumption of the combined heat and power unit is expressed in MW.

[0015] Q t Total heat supply for cogeneration units, MW;

[0016] N t This represents the total power generation of the combined heat and power (CHP) unit, in MW.

[0017] Preferably, the formula for calculating the net thermal efficiency is:

[0018] η QNET =η t ξ (2)

[0019] Where, η t Let be the gross thermal efficiency, %; ξ be the heat loss coefficient, %; the formula for calculating the gross thermal efficiency is:

[0020] η t =f(N) t (3)

[0021] Preferably, the formula for calculating the total heat consumption of a combined heat and power unit is:

[0022] F t=aN t +b (4)

[0023] In the formula: a and b are both coefficients, which are obtained by calculation through the heat balance diagram of the unit's heating supply.

[0024] Preferably, in step 2, the formula for calculating the minimum power generation of the unit is:

[0025] N'=a'Q h +b' (7)

[0026] Where a' and b' are both coefficients.

[0027] Preferably, among which,

[0028]

[0029]

[0030] In the formula, η hc The heat loss coefficient of the first station of the heating network, %;

[0031] η QNET Net thermal efficiency, %.

[0032] Preferably, the formula for calculating that the total cost of combined heat and power (CHP) is less than the total cost of separate heat and power (SHP) is as follows:

[0033] (N b ×10 3 Cost e +(F h ×3.6) Cost c ≥[(N b -N t )×10 3 Cost e +(F t ×3.6) Cost c (12)

[0034] In the formula:

[0035] Cost F Total cost of thermal power generation, in yuan;

[0036] Cost L Total cost of cogeneration, in yuan;

[0037] F h Heat consumption for heat generation and supply from combined heat and power plants, in MW;

[0038] F t Combined heat and power (CHP) heat consumption, in MW;

[0039] N bRegional electricity demand, in MW;

[0040] N t Combined heat and power (CHP) power generation, in MW;

[0041] Cost c : Price of heat, yuan / GJ;

[0042] Cost e Electricity price, yuan / kWh.

[0043] Preferably, to ensure that equation (12) holds true, the conditions to be met during the design of a combined heat and power plant are as follows:

[0044]

[0045] Among them, R cost F is the ratio of electricity price to heat price. h It is the ratio of the regional energy system's heat load to the efficiency of the heating boiler.

[0046] Preferably, in step 3, the method for obtaining the maximum benefit of the cogeneration unit is as follows: when the ratio is greater than a set coefficient, the total power generation of the cogeneration unit is the regional demand for electricity; when the ratio is less than the set coefficient, the total power generation of the cogeneration unit is the minimum power generation of the unit while meeting the heat load demand.

[0047] Preferably, the condition that the combined heat and power unit meets to maximize its benefits is:

[0048]

[0049] Compared with the prior art, the present invention has the following beneficial effects:

[0050] This invention discloses a power dispatching method for regional combined heat and power (CHP) units. Based on a three-part framework of a CHP system, a regional energy system, and a separate heat and power generation system, after establishing the relationship between these three components, the regional energy system's heat load is introduced to obtain the minimum power generation of the unit when the heat load demand is met. A reasonable operating range for the total power generation of the CHP unit is established, with the total cost of CHP being less than the total cost of separate heat and power generation. Through analysis of the heating characteristics of the CHP unit and comparative analysis with the separate heat and power generation system, this invention obtains the optimal operating range and the most profitable operating mode for the CHP unit, providing accurate guidance for operational practice. This method also addresses the issue of regional winter heating demand by activating the CHP unit. The CHP unit can simultaneously produce electricity and heat, representing a highly efficient energy utilization method. Based on the analysis of the characteristics of the CHP unit and through comparison with the separate heat and power generation system, this invention determines the optimal dispatching method for the CHP unit while meeting regional heating demand, thereby maximizing the economic benefits of the CHP unit. Attached Figure Description

[0051] Figure 1 This is a circulation diagram of the cogeneration unit of the present invention. Detailed Implementation

[0052] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0053] See Figure 1 This invention discloses a power dispatching method for regional combined heat and power units, the method comprising the following steps:

[0054] Step 1: Analysis of the heating characteristics of the combined heat and power unit

[0055] Under a certain heat load, the total heat supply Q of a combined heat and power unit t Total heat consumption F of cogeneration unit t Total power generation N of combined heat and power units t The following relationship exists, which is the first relation:

[0056] Q t =η QNET (F t -N t (1)

[0057] Where, η QNET Net thermal efficiency, %;

[0058] F t Total heat consumption of the combined heat and power unit, in MW;

[0059] Q t Total heat output of the combined heat and power unit, in MW;

[0060] N t Total power generation of the combined heat and power unit, in MW.

[0061] The formula for calculating net thermal efficiency is:

[0062] η QNET =η t ξ (2)

[0063] Where, η t Let be the gross thermal efficiency, %; ξ be the heat loss coefficient, %; the formula for calculating the gross thermal efficiency is:

[0064] η t =f(N) t (3)

[0065] Total heat consumption F of cogeneration unit t The calculation formula is:

[0066] Ft =aN t +b (4)

[0067] In the formula: a and b are both coefficients, which are obtained by calculation through the heat balance diagram of the unit's heating supply.

[0068] Total heat supply Q of cogeneration unit t It can also be calculated using the following formula:

[0069]

[0070] In the formula:

[0071] Q h Regional energy system heat load, MW;

[0072] η hc Heat loss coefficient at the first station of the heating network, %;

[0073] To meet the regional energy system's heat load Q h Simplifying formulas (1), (4), and (5), the electrical load should meet the following requirements:

[0074]

[0075] To simplify formula (6), that is, to simplify the relationship between the total power generation of the cogeneration unit and the heat load of the regional energy system, a second relationship (6) is obtained.

[0076] definition:

[0077] N'=a'Q h +b' (7)

[0078] N' represents the minimum power generation of the unit while meeting the heat load demand. In the above calculation formula...

[0079]

[0080]

[0081] Step 2, Comparative analysis with the thermal power generation system

[0082] Energy saving in combined heat and power (CHP) units is reflected in the fact that the total cost of CHP should be less than the total cost of separate heat and power generation, as shown in the following formula:

[0083] Cost F ≥Cost L (10)

[0084] N b Cost e +F h Cost c ≥(Nb -N t Cost e +F t Cost c (11)

[0085] (N b ×10 3 Cost e +(F h ×3.6)Cost c ≥[(N b -N t )×10 3 Cost e +(F t ×3.6)Cost c (12)

[0086] In the formula:

[0087] Cost F Total cost of thermal power generation, in yuan;

[0088] Cost L Total cost of cogeneration, in yuan;

[0089] F h Heat consumption for heat generation and supply from combined heat and power plants, in MW;

[0090] F t Combined heat and power (CHP) heat consumption, in MW;

[0091] N b Regional electricity demand, in MW;

[0092] N t Combined heat and power (CHP) power generation, in MW;

[0093] Cost c : Price of heat, yuan / GJ;

[0094] Cost e Electricity price, yuan / kWh;

[0095] The coefficients in formula (11) are derived from the demand given by the power grid and heating network dispatching, specifically as follows: Figure 1 The parameters within.

[0096] Simplifying equation (11), we define R cost F is defined as the ratio of electricity price to heat price. h The ratio of the regional energy system heat load to the heating boiler efficiency is shown below:

[0097]

[0098]

[0099] η h Heating boiler efficiency;

[0100] Combining equation (12), it can be seen that when designing the overall power supply demand for cogeneration, the following conditions must be met:

[0101] tidy:

[0102]

[0103] Combining equations (4) and (14) with equation (15), we can see that:

[0104]

[0105] When Rcost > a:

[0106]

[0107] When Rcost < a:

[0108]

[0109] Combining equations (17) and (18), it can be seen that when the ratio of electricity price to heat price is greater than the set value 'a', the combined heat and power (CHP) power generation is greater than the ratio on the right side of equation (17), making the total cost of CHP less than the total cost of separate heat and power generation; when the ratio of electricity price to heat price is less than the set value 'a', the CHP power generation is less than the ratio on the right side of equation (18), making the total cost of CHP less than the total cost of separate heat and power generation.

[0110] In order for combined heat and power generation to be more energy-efficient than separate heat and power generation, the unit's power generation load must meet the value of N".

[0111]

[0112] Theoretical analysis shows that the combined heat and power (CHP) power generation N... t It should not exceed N of the electricity purchased from outside the power grid. b Therefore, combining equations (6), (7), (16), (17), and (18), the reasonable operating range of the cogeneration unit is shown in Table 1 below. When the ratio of electricity price to heat price is greater than the set coefficient a, the cogeneration power generation is less than or equal to the regional demand power, and greater than N' and N”; when the ratio of electricity price to heat price is less than the set value a, the cogeneration power generation is greater than or equal to N', and less than or equal to the regional demand power. The corresponding Table 1 is established, that is, the reasonable operating space of the entire cogeneration unit is determined. When operating within this range, cogeneration power generation is profitable, but the profit varies. When R cost When = a, the operating interval can be any of the following conditions.

[0113] Table 1. Determining the Reasonable Operating Range Through Cogeneration

[0114] Constraints Reasonable operating range <![CDATA[R cost >a]]> <![CDATA[N b ≥N t ≥max(N',N”)]]> <![CDATA[R cost <a]]> <![CDATA[min(N”,N b )≥N t ≥N']]>

[0115] Step 3: Based on Table 2, the maximum benefit analysis of the cogeneration unit is obtained as shown in the following formula.

[0116] Savings = Cost F -Cost L (20)

[0117] Savings = N b Cost e +F h Cost c -[(N b -N t Cost e +F t Cost c ] (twenty one)

[0118] Cost F Cost of completing a thermal power generation system L The total cost of completing a combined heat and power system. Combining equations (3) and (14) and rearranging equation (21), we can see that:

[0119]

[0120] Combining Table 1 and Equation (22), the operating mode with the maximum benefit for a combined heat and power unit is shown in Table 2 below. When R cost When =a, the running interval can be any of the following cases, N in the table below. opt(a) The electrical load at which the combined heat and power unit achieves maximum benefit.

[0121] Table 2:

[0122] Constraints Maximum power <![CDATA[R cost >a]]> <![CDATA[N opt(a) =N b ]]> <![CDATA[R cost <a]]> <![CDATA[N opt(b) =N']]>

[0123] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A power dispatching method applied to regional combined heat and power units, characterized in that, Includes the following steps: Step 1: Collect the total heat supply of the cogeneration unit and establish the first relationship between the total heat supply of the cogeneration unit, the total heat consumption of the cogeneration unit, and the total power generation of the cogeneration unit. The first relation is: （1） in, η QNET Net thermal efficiency, % F t The total heat consumption of the combined heat and power unit is expressed in MW. Q t Total heat supply for cogeneration units, MW; N t The total power generation of the combined heat and power unit is expressed in MW. Step 2: Introduce the regional energy system heat load into the first relationship, and after simplification, obtain the second relationship between the total power generation of the cogeneration unit and the heat load of the regional energy system. The minimum power generation of the unit when the heat load demand is met is obtained through the second relationship. The second relation is: （6） in, and b All are coefficients. η QNET Net thermal efficiency, %. η hc The heat loss coefficient of the first station of the heating network, %. Q h For the regional energy system heat load, MW; Step 3: Based on the premise that the total cost of combined heat and power (CHP) is less than the total cost of separate heat and power generation, and considering the ratio of regional energy system heat load to heating boiler efficiency, obtain the reasonable operating range for the total power generation of the CHP unit. Specifically, establish a comparison formula between the ratio and a set coefficient, where the ratio is the ratio of local electricity price to heat price. When the ratio is greater than the set coefficient, the total power generation of CHP is greater than or equal to... and The maximum value in, and less than or equal to When the ratio is less than the set coefficient, the total power generation from combined heat and power is greater than or equal to... less than or equal to and The minimum value in; where To ensure the minimum power generation of the unit while meeting heat load requirements; To ensure that combined heat and power generation is less energy-efficient than separate heat and power generation, the unit's power generation load must meet certain values; N b Electricity demand in the region; The calculation formula is: （7） in, a’ and b’ All are coefficients. Q h For the regional energy system heat load, MW; The calculation formula is: in, R cost This is the ratio of electricity price to heat price. The method to obtain the maximum benefit of the cogeneration unit is as follows: when the ratio is greater than a set coefficient, the total power generation of the cogeneration unit is the regional demand for electricity; when the ratio is less than the set coefficient, the total power generation of the cogeneration unit is the minimum power generation of the unit while meeting the heat load demand.

2. The power dispatching method for regional cogeneration units according to claim 1, characterized in that, The formula for calculating the net thermal efficiency is: （2） in, η t Gross thermal efficiency, % ξ Let be the heat loss coefficient, %; and the formula for calculating the gross thermal efficiency is: （3）。 3. The power dispatching method for regional cogeneration units according to claim 1, characterized in that, The formula for calculating the total heat consumption of a combined heat and power (CHP) unit is: （4） In the formula: and b All of these are coefficients, which are obtained through calculations based on the unit's heat balance diagram.

4. The power dispatching method for regional cogeneration units according to claim 1, characterized in that, in, （8） （9） In the formula, η hc The heat loss coefficient of the first station of the heating network is %; Net thermal efficiency, %.

5. The power dispatching method for regional cogeneration units according to claim 1, characterized in that, The formula for calculating that the total cost of combined heat and power (CHP) is less than the total cost of separate heat and power (SHP) is as follows: （12） In the formula: F h Heat consumption for heat generation and supply from combined heat and power plants, in MW; F t Combined heat and power (CHP) heat consumption, in MW; N b Regional electricity demand, in MW; N t Combined heat and power (CHP) power generation, in MW; Cost c : Price of heat, yuan / GJ; Cost e Electricity price, yuan / kWh.

6. The power dispatching method for regional cogeneration units according to claim 5, characterized in that, To ensure the validity of equation (12), the following conditions must be met during the design of a combined heat and power plant: （15） in, R cost This is the ratio of electricity price to heat price. F h It is the ratio of the regional energy system's heat load to the efficiency of the heating boiler.

7. The power dispatching method for regional cogeneration units according to claim 1, characterized in that, The condition for a combined heat and power (CHP) unit to achieve maximum benefit is: （22）。

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