A pricing method for hydropower in the electricity spot market

Abstract

The present invention discloses a pricing method for hydropower in the electricity spot market, comprising the following steps: S1, performing a simulation clearing of the electricity spot market on a monthly basis, namely: performing a simulation clearing on a monthly basis based on a safety-constrained unit combination model (SCUC) and a safety-constrained economic dispatch model (SCED), and obtaining a hydropower unit output curve; S2, determining a storage capacity hydropower unit output curve based on the monthly clearing result, performing a day-ahead spot market clearing under a fixed hydropower output, and determining the market electricity price and the output of other units. The present invention can optimize resource allocation, reduce spot market electricity prices, increase hydropower consumption, and accelerate the market-oriented reform process of my country's power system.

Description

Technical Field

[0001] The present invention belongs to the field of electrical engineering, and more specifically, relates to a pricing method for hydropower in a spot electricity market. Background Art

[0002] For provinces with a high proportion of hydropower installed capacity, how hydropower can participate in the spot market is a major problem that needs to be solved urgently. Reservoir-type hydropower stations can store natural water in reservoirs and release water to generate electricity when needed, which has a certain peak-shaving capacity. Reasonable use of its reservoir capacity regulation capacity in the spot market can optimize the resource allocation on the power generation side and reduce the total social electricity cost. However, in the day-ahead spot market, how to determine the starting and ending reservoir capacity of the hydropower unit and maximize the use of its reservoir capacity regulation capacity is a major problem currently faced. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a pricing method for hydropower in the electricity spot market, which can optimize the resource allocation on the power generation side and reduce the total electricity cost of the society.

[0004] The technical solution adopted by the present invention to solve the technical problem is: constructing a pricing method for hydropower in the electricity spot market, comprising the following steps:

[0005] S1. Conduct electricity spot market simulation and clearing on a monthly basis, specifically:

[0006] Based on the safety constrained unit commitment model (SCUC) and the safety constrained economic dispatch model (SCED), the clearing simulation is carried out on a monthly basis to obtain the output curve of the hydropower units.

[0007] S2. Determine the output curve of storage capacity hydropower units based on the monthly clearing results, conduct day-ahead spot market clearing under fixed hydropower output, and determine the market electricity price and output of other units.

[0008] According to the above scheme, in step S1, the safety constrained unit commitment model (SCUC) and the safety constrained economic dispatch model (SCED) are planned under the following constraints and objective functions, specifically:

[0009] The system load balance constraint is described as follows: in each period t, the sum of the power generated by the generator and the planned power of the tie line is equal to the system load, which is:

[0010]

[0011] Among them, P i，t 、T j，t are the output of unit i and tie line j in time period t, D tis the system load in time period t, N and NT are the total number of units and the total number of tie lines respectively;

[0012] The positive and negative capacity constraints of the system are to prevent the imbalance between supply and demand caused by load forecast deviation and various actual operation accidents. The positive and negative reserve capacity of the system is described as:

[0013]

[0014]

[0015] Among them, α i，t is the start and stop status of unit i in period t, 0 is used to indicate shutdown and 1 is used to indicate startup. They represent the maximum and minimum output of unit i in time period t, They represent the positive and negative reserve capacity requirements of the system in time period t respectively;

[0016] The upper and lower limits of the unit output are described as follows:

[0017]

[0018] set up is the maximum ramp rate of unit i, is the maximum ramp rate of unit i, and the unit ramp constraint is described as:

[0019]

[0020]

[0021] The minimum continuous start-stop time constraint is due to the physical properties of the unit and the actual operation needs. The unit is required to be started or stopped continuously for at least a certain period of time. The minimum continuous start-stop time constraint is expressed as:

[0022]

[0023]

[0024] Among them, T U 、T D They are the minimum continuous start time and minimum continuous shutdown time of the unit, are the continuous start-up and shutdown time of unit i in time period t, It is expressed as:

[0025]

[0026]

[0027] Hydropower unit output Spare capacity of hydropower units Assembled capacity of Heshui electric machine Satisfy the constraints:

[0028]

[0029]

[0030] Assume that the amount of water discarded by the hydropower unit is The hydropower output relationship must meet the following requirements:

[0031]

[0032] Among them, E i，t is the energy stored in the reservoir capacity of hydropower unit i at time t, is the natural water energy of hydropower unit i at time t;

[0033] The storage capacity of the hydropower unit meets the upper and lower limit constraints and the water quantity equation constraints:

[0034]

[0035]

[0036] in, is the hydropower reservoir capacity, υ h are the maximum and minimum storage capacity ratios respectively;

[0037] Line power flow constraints To ensure that the transmission line power does not exceed the rated value, the line power flow constraints are expressed as:

[0038]

[0039] in, is the power transmission limit of line l, G l-i , G l-j , G l-k are the generator output power transfer distribution factors of the node where unit i is located, the node where tie line j is located, and node k to line l, respectively. K is the number of system nodes, and D k，t is the bus load of node k in period t, are the positive and negative power flow relaxation variables of line l respectively;

[0040] The section power flow constraint is to ensure that the section transmission power does not exceed its limit value. The section power flow constraint is expressed as:

[0041]

[0042] in, are the power flow transmission limit of section s, G s-i , G s-j , G s-k are the generator output power transfer distribution factors of the node where unit i is located, the node where tie line j is located, and node k to section s, respectively. are the positive and negative flow relaxation variables of section s respectively;

[0043] The objective function of the safety constrained unit commitment model (SCUC) is to minimize the total power generation cost. The objective function formula is:

[0044]

[0045] Where T represents the total number of time periods considered, G i，t (P i，t ), are the operating cost and startup cost of unit i in period t, respectively. i，t (P i，t ) is a multi-segment linear function related to the output ranges and corresponding prices reported by the unit, and M is the penalty factor for the relaxation of the network power flow constraint;

[0046] The safety constrained unit commitment model (SCUC) is similar to the safety constrained economic dispatch model (SCED). The model takes the unit start-stop plan solved by SCUC as a known quantity, and re-takes minimizing the total power generation cost as the goal. It solves the optimal power flow under the consideration of various technical constraints and obtains the output curve of the unit in each period. The load balance constraint, unit output upper and lower limit constraints, line power flow constraint, section power flow constraint and objective function of the SCED model are the same as those of the SCUC model. Since the unit start-stop plan becomes a known quantity, the unit climbing constraint is modified as follows:

[0047]

[0048]

[0049] The spot market adopts a node electricity price pricing mechanism. The node electricity price of node i in time period t can be expressed as:

[0050]

[0051] Among them, λ t is the Lagrange multiplier of system load balance in period t, are the maximum positive and negative power flow constraint Lagrange multipliers of line l and section s respectively. When the corresponding line or section power flow exceeds the limit, the Lagrange multiplier is the network power flow constraint relaxation penalty factor.

[0052] According to the above scheme, in step S2, the output of the hydropower units is fixed according to the monthly clearing results and then the spot market is cleared daily.

[0053] The method for pricing hydropower in the electricity spot market according to the present invention has the following beneficial effects:

[0054] The pricing method of hydropower in the electricity spot market of the present invention firstly performs spot market clearing on a monthly basis based on load forecast data and reservoir water inflow forecast data, then performs spot market daily clearing based on fixed hydropower output, and determines the clearing electricity price and unit output based on this result. The method can optimize resource allocation, reduce spot market electricity prices, increase hydropower consumption, and accelerate the market-oriented reform process of the power system. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 It is a schematic diagram of the output curve of the hydropower unit in January in an embodiment of the present invention;

[0056] Figure 2 Schematic diagram of the annual hydropower unit storage capacity variation curve in the embodiment of the present invention;

[0057] Figure 3 It is a schematic diagram comparing the market electricity price continuous curves determined by the existing method and the method in the embodiment of the present invention. DETAILED DESCRIPTION

[0058] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, specific embodiments of the present invention are now described in detail with reference to the accompanying drawings.

[0059] The massive power user clustering algorithm based on data-physical feature joint drive of the present invention comprises the following steps:

[0060] S1. Conduct electricity spot market simulation clearing on a monthly basis, specifically:

[0061] The power spot market simulation clearing model uses the security constrained unit commitment model (SCUC) and the security constrained economic dispatch model (SCED) to solve the optimal power flow. The constraints and objective functions are as follows:

[0062] The system load balance constraint is described as follows: in each period t, the sum of the power generated by the generator and the planned power of the tie line is equal to the system load, that is:

[0063]

[0064] Among them, P i，t 、T j，t are the output of unit i and tie line j in time period t, D tis the system load in time period t, N and NT are the total number of units and the total number of tie lines respectively;

[0065] The positive and negative capacity constraints of the system are to prevent the imbalance between supply and demand caused by load forecast deviation and various actual operation accidents. The positive and negative reserve capacity of the system is described as:

[0066]

[0067]

[0068] Among them, α i，t is the start and stop status of unit i in period t, 0 is used to indicate shutdown and 1 is used to indicate startup. They represent the maximum and minimum output of unit i in time period t, They represent the positive and negative reserve capacity requirements of the system in time period t respectively;

[0069] The upper and lower limits of the unit output are described as follows:

[0070]

[0071] set up is the maximum ramp rate of unit i, is the maximum ramp rate of unit i, and the unit ramp constraint is described as:

[0072]

[0073]

[0074] The minimum continuous start-stop time constraint is due to the physical properties of the unit and the actual operation needs. The unit is required to be started or stopped continuously for at least a certain period of time. The minimum continuous start-stop time constraint is expressed as:

[0075]

[0076]

[0077] Among them, T U 、T D They are the minimum continuous start time and minimum continuous shutdown time of the unit, are the continuous start-up and shutdown time of unit i in time period t, It is expressed as:

[0078]

[0079]

[0080] Hydropower unit output Spare capacity of hydropower units Assembled capacity of Heshui electric machine Satisfy the constraints:

[0081]

[0082]

[0083] Assume that the amount of water discarded by the hydropower unit is The hydropower output relationship must meet the following requirements:

[0084]

[0085] Among them, E i，t is the energy stored in the reservoir capacity of hydropower unit i at time t, is the natural water energy of hydropower unit i at time t;

[0086] The storage capacity of the hydropower unit must also meet the upper and lower limit constraints and the water quantity equation constraints:

[0087]

[0088]

[0089] in, is the hydropower reservoir capacity, υ h are the maximum and minimum storage capacity ratios respectively.

[0090] Line power flow constraints To ensure that the transmission line power does not exceed the rated value, the line power flow constraints are expressed as:

[0091]

[0092] in, is the power transmission limit of line l, G l-i , G l-j , G l-k are the generator output power transfer distribution factors of the node where unit i is located, the node where tie line j is located, and node k to line l, respectively. K is the number of system nodes, and D k，t is the bus load of node k in period t, are the positive and negative power flow relaxation variables of line l respectively.

[0093] The section power flow constraint is to ensure that the section transmission power does not exceed its limit value. The section power flow constraint is expressed as:

[0094]

[0095] in, are the power flow transmission limit of section s, G s-i , G s-j , G s-k are the generator output power transfer distribution factors of the node where unit i is located, the node where tie line j is located, and node k to section s, respectively. are the positive and negative flow relaxation variables of section s respectively.

[0096] The objective function of the SCUC model is to minimize the total power generation cost. The objective function formula is:

[0097]

[0098] Where T represents the total number of time periods considered, C i，t (P i，t ), are the operating cost and startup cost of unit i in period t, respectively. i，t (P i，t ) is a multi-segment linear function related to the output ranges reported by the unit and the corresponding prices, and M is the penalty factor for the relaxation of the network power flow constraint.

[0099] The safety constrained economic dispatch model (SCED) is similar to the safety constrained unit combination model (SCUC). The model takes the unit start-stop plan solved by SCUC as a known quantity, and re-takes minimizing the total power generation cost as the goal. It solves the optimal power flow while considering various technical constraints and obtains the output curve of the unit in each period. The load balance constraint, upper and lower limit constraints of unit output, line power flow constraint, section power flow constraint and objective function of the SCED model are the same as those of the SCUC model. Since the unit start-stop plan becomes a known quantity, the unit climbing constraint is modified to:

[0100]

[0101]

[0102] The spot market adopts a node electricity price pricing mechanism. The node electricity price of node i in time period t is expressed as:

[0103]

[0104] Among them, λ t is the Lagrange multiplier of system load balance in period t, are the maximum positive and negative power flow constraint Lagrange multipliers of line l and section s respectively. When the corresponding line or section power flow exceeds the limit, these Lagrange multipliers are the network power flow constraint relaxation penalty factors.

[0105] By solving the above SCUC and SCED models, the electricity spot market output results on a monthly basis can be obtained.

[0106] S2. Determine the output curve of the reservoir-type hydropower unit based on the monthly clearing results, conduct day-ahead spot market clearing, and determine the market electricity price and output of other units.

[0107] From step S1, the output curve of the hydropower unit in each time period can be obtained. When performing daily scheduling in the day-ahead spot market, the output of the fixed hydropower unit is cleared. The constraints and objective functions are the same as (1) to (10) and (16) to (21). The market electricity price and the output curves of other units can be obtained from the daily clearing results.

[0108] Example

[0109] like Figure 1-2 As shown, taking the actual electricity market data of a certain place as an example, firstly, the market is cleared on a monthly basis, and the annual output curve and reservoir capacity change curve of the hydropower units in the place can be obtained.

[0110] like Figure 3 As shown in the figure, after the output of the hydropower unit is determined, the output of the hydropower unit is fixed during the daily spot market dispatch, and the spot market daily clearing is performed again to obtain the market electricity price and other unit output curves. The market electricity price continuous curve determined by the conventional method and the method of the present invention. Using the method of the present invention to determine the output of the hydropower unit can reasonably utilize the hydropower storage capacity price adjustment capacity, reduce the market electricity price, optimize resource allocation, and reduce the total electricity cost of the whole society.

[0111] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation modes, which are merely illustrative rather than restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the present invention and the claims, all of which are within the protection of the present invention.

Claims

1. A method for pricing hydropower in the electricity spot market, characterized in that: The following steps are involved: S1. Conduct electricity spot market simulation and clearing on a monthly basis, specifically: Based on the safety constrained unit commitment model (SCUC) and the safety constrained economic dispatch model (SCED), the clearing simulation is carried out on a monthly basis to obtain the output curve of the hydropower units. The safety constrained unit commitment model (SCUC) and the safety constrained economic dispatch model (SCED) are planned by the following constraints and objective functions: The system load balancing constraint is described as follows: The sum of the electric energy generated by the generator and the planned power of the tie line is equal to the system load, which is: in, , For each unit , contact line In the period of efforts, For the period The system load, , They are the total number of units and the total number of tie lines respectively; The positive and negative capacity constraints of the system are to prevent the imbalance between supply and demand caused by load forecast deviation and various actual operation accidents. The positive and negative reserve capacity of the system is described as: in, For the crew In the period The start and stop status, 0 is used to indicate shutdown, and 1 is used to indicate startup. , Respectively represent the unit In the period The maximum and minimum output of , Respectively indicate time periods Positive and negative spare capacity requirements of the system; The upper and lower limits of the unit output are described as follows: set up For the crew Maximum climbing rate, For the crew The maximum down-climbing rate and the unit climbing constraint are described as: The minimum continuous start-stop time constraint is due to the physical properties of the unit and the actual operation needs. The unit is required to be started or stopped continuously for at least a certain period of time. The minimum continuous start-stop time constraint is expressed as: in, , They are the minimum continuous start time and minimum continuous shutdown time of the unit, , For each unit In the period Continuous startup and shutdown time, , It is expressed as: Hydropower unit output , Spare capacity of hydropower units Assembled capacity of Heshui electric machine Satisfy the constraints: Assume that the amount of water discarded by the hydropower unit is , then the hydropower output relationship must satisfy: in, For hydroelectric units At the moment The energy stored in the reservoir capacity is For hydroelectric units At the moment of natural water energy; The storage capacity of the hydropower unit meets the upper and lower limit constraints and the water quantity equation constraints: in, is the hydropower reservoir capacity, , are the maximum and minimum storage capacity ratios respectively; Line power flow constraints To ensure that the transmission line power does not exceed the rated value, the line power flow constraints are expressed as: in, For line The power transmission limit of , , For each unit Nodes and contact lines Node and node To line The generator output power transfer distribution factor, is the number of system nodes, For Node In the period The busbar load, , Line The positive and negative power flow relaxation variables; The section power flow constraint is to ensure that the section transmission power does not exceed its limit value. The section power flow constraint is expressed as: in, , Section The power transmission limit of , , For each unit Nodes and contact lines Node, Node Cross-section The generator output power transfer distribution factor, , Section The positive and negative power flow relaxation variables; The objective function of the safety constrained unit commitment model (SCUC) is to minimize the total power generation cost. The objective function formula is: in, represents the total number of time periods considered, , For each unit In the period Operating costs and startup costs, unit operating costs It is a multi-segment linear function related to the output ranges and corresponding prices reported by the unit. is the penalty factor for network power constraint relaxation; The safety constrained unit commitment model (SCUC) is similar to the safety constrained economic dispatch model (SCED). The model takes the unit start-stop plan solved by SCUC as a known quantity, and re-takes minimizing the total power generation cost as the goal. It solves the optimal power flow under the consideration of various technical constraints and obtains the output curve of the unit in each period. The load balance constraint, unit output upper and lower limit constraints, line power flow constraint, section power flow constraint and objective function of the SCED model are the same as those of the SCUC model. Since the unit start-stop plan becomes a known quantity, the unit climbing constraint is modified as follows: The spot market adopts a node electricity price pricing mechanism. In the period The node electricity price can be expressed as: in, For the period Lagrange multiplier for system load balancing, , , , Line and cross section The maximum forward and reverse power flow constraint Lagrange multiplier, when the corresponding line or section power flow exceeds the limit, the Lagrange multiplier is the network power flow constraint relaxation penalty factor; S2. Determine the output curve of storage capacity hydropower units based on the monthly clearing results, conduct day-ahead spot market clearing under fixed hydropower output, and determine the market electricity price and output of other units.

2. The method for pricing hydropower in the electricity spot market according to claim 1, characterized in that: In step S2, the output of the hydropower units is fixed according to the monthly clearing results and then the spot market is cleared daily.

Images