CN114899880A

CN114899880A - Flexible power system time sequence production simulation method based on linearization solution method

Info

Publication number: CN114899880A
Application number: CN202210431066.0A
Authority: CN
Inventors: 谈健; 吴垠; 薛贵元; 吴晨; 牛文娟; 陈琛; 南开辉; 马龙鹏
Original assignee: Economic and Technological Research Institute of State Grid Jiangsu Electric Power Co Ltd
Current assignee: Economic and Technological Research Institute of State Grid Jiangsu Electric Power Co Ltd
Priority date: 2022-04-22
Filing date: 2022-04-22
Publication date: 2022-08-12

Abstract

The invention relates to a flexible power system time sequence production simulation method based on a linearization solution method, which belongs to the technical field of power system simulation analysis, takes the minimum integral operation cost of a power system in an optimized time period as an objective function, comprehensively considers constraints such as thermal power unit output, new energy output, unit climbing, energy storage, wind and light abandoning and the like, linearizes coal cost and power flow calculation by using the linearization solution method, performs actual case analysis, and proves that the new energy achieves full-scale consumption through empirical simulation. The thermal power flexibility transformation energy efficiency of the time sequence production simulation model provided by the invention is verified to be remarkable. The time sequence production simulation model can be subjected to targeted constraint adjustment aiming at power systems with serious new energy discarding, obvious load fluctuation and the like so as to adapt to the test. Has stronger portability, tailorability and robustness.

Description

Flexible power system time sequence production simulation method based on linearization solution method

Technical Field

The invention belongs to the technical field of power system simulation analysis, and particularly relates to a flexible power system time sequence production simulation method based on a linearization solution method.

Background

With the continuous consumption and exhaustion of fossil energy, the ecological environment is becoming more serious and worse, the demand of new energy is gradually increased, an electric power system is undergoing an intelligent and clean energy revolution, and a power grid is gradually transformed from a power supply structure mainly based on traditional thermal power to a clean power supply structure mainly based on new energy such as wind power, photovoltaic and the like. Under the promotion of the construction of flexible power systems and power markets in China, common small-scale distributed power sources such as wind power generation and photovoltaic power generation are heavier and heavier, and a plurality of households are built and used by themselves in advanced cities in China. Due to the fact that renewable clean energy such as wind and light is easy to collect, abundant wind power generation and photovoltaic power generation can be put into a power grid, but due to the fact that load requirements change in real time, and the flexibility of a traditional thermal power unit is poor, the output of the traditional thermal power unit is difficult to adjust greatly in a short time, the phenomenon that wind and light are abandoned is serious when the load requirements are low, and therefore reasonable planning on flexible resources is urgently needed.

Therefore, at present, a flexible power system time sequence production simulation method based on a linearization solution method needs to be designed to solve the above problems.

Disclosure of Invention

The invention aims to provide a flexible power system time sequence production simulation method based on a linear solving method, which is used for solving the technical problems in the prior art, and the method has the advantages that wind, light and other renewable clean energy sources are easy to collect, so that abundant wind power generation and photovoltaic power generation can be put into a power grid, but the load demand is difficult to adjust greatly in a short time due to the uncertainty of real-time change of the load demand and poor flexibility of the traditional thermal power unit, so that the phenomenon of wind abandoning and light abandoning is particularly serious when the load demand is low, and therefore, the reasonable planning on the flexible resources is urgently needed.

In order to achieve the purpose, the technical scheme of the invention is as follows:

the flexible power system time sequence production simulation method based on the linearization solution method comprises the following steps:

s1: providing a power system time sequence production simulation model, and taking the minimum overall operation cost of the power system in an optimized time period as a target function;

s2: on the basis of the step S1, comprehensively considering thermal power output modification constraint, new energy output constraint, unit climbing constraint, energy storage constraint, load power range constraint, interruptible load constraint, power balance, branch flow balance, node voltage phase angle constraint and wind and light abandoning constraint;

s3: and on the basis of the step S2, a linearization solution method is used for linearizing the coal cost and load flow calculation.

Further, step S1 is specifically as follows:

in order to minimize the total operation cost during the whole operation period of the power system, the total fuel consumption and the total power generation cost of each unit in the optimization time period, the cost of the fire power transformation, the energy storage investment and the load side demand response in the planning period are considered, namely, the cost comprises the new energy installation and maintenance cost, the conventional unit power generation cost and the fire power transformation cost C _Gm Wind power, photovoltaic power generation cost and conventional unit CO ₂ The overall result of the emission cost is optimal, and an objective function with the aim of minimizing the overall operation cost of the power system in the optimization time period is provided, as shown in formula (1):

wherein C is _FBS And C _Fu Respectively representing the power generation cost of a conventional unit and considering the start-stop cost and the coal consumption cost of a thermal power unit; t and nG respectively represent the operation of the thermal power generating unitTime and amount, C _RP The penalty cost of wind and light abandonment is considered for representing the power generation cost of new energy; the new energy installation and maintenance cost mainly comprises equipment cost, construction cost, maintenance cost and discount value to a target year, and the long-term property of planning installation is considered, C _R，IM The installation and maintenance cost of the new energy is assumed to be equal annual value relative to the optimization year limit; c _S，IM Indicating that the installed cost, maintenance cost, and discount value of the energy storage device will also be utilized for the equal-year value; when considering the flexible resource scheduling, the system can not meet the peak load demand, the response of the flexible resource scheduling of the demand side is considered, wherein the demand side response comprises load reduction and load transfer, the cost of the demand response of the load side comprises the early cost and the transfer cost of transferring the response resource, and the compensation cost of the interruptible load is also included, and the generated compensation cost is marked as C _IL (ii) a Wherein C is _FBS Can be expressed as

C _FBS ＝C _B S _Bi,t +C _F S _Fi,t (37)

Wherein S _Bi，t And S _Fi，t Respectively represents the starting state and the stopping state of the thermal power generating unit i at the moment t, and is an integer ranging from 0 to 1, namely S _Bi，t 1 stands for on, S _Fi，t 1 represents shutdown; c _B And C _F The starting cost and the stopping cost of the unit are respectively;

the coal consumption cost of the conventional thermal power generating unit is expressed as the actual output P of the unit i at the moment t _i,t In the form of a quadratic function of the argument:

C _Fu (P _i,t )＝a _i (P _i,t ) ² +b _i P _i,t +c _i (38)

wherein a is _i 、b _i 、c _i The coal consumption coefficient of the unit i is obtained;

wind and light abandoning penalty cost C of new energy _RP Expressed by the following formula:

wherein C is _W,pu Represents the cost per MWh of abandoned wind, C _S,pu The cost of each MWh of abandoned light is represented, and delta T represents the measuring time interval of the power generation output; p _RW，i，t And P _RS，i，t Respectively representing the air abandon amount and the light abandon amount of the unit i as a standby system at the moment t; NRW and NRS represent the number of wind turbines and solar photovoltaic sets, respectively.

Further, the wind and light abandoning penalty cost C of new energy _RP An alternative to the following formula:

where ρ is _p，w ，ρ _p，s Respectively representing a wind curtailment penalty factor, a light curtailment penalty factor, P _{RW，i，t，max} Amount of available resources representing wind farm production, and P _RW，i，t The difference is the actual air abandon quantity; p _{RS，i，t，max} Represents the amount of available resources of the photovoltaic, which is related to P _RS，i，t The difference is the actual amount of light lost.

Further, step S2 is specifically as follows:

thermal power output reconstruction constraint:

the thermal power output reconstruction constraint is represented by that the output power of the thermal power generating unit i at the moment t is limited between the minimum output limit and the maximum output limit; wherein, P _i，min The lower limit of the output force before transformation; p is _i*，min The lower limit of output force after transformation; p _i，max The upper limit of the output of the unit; x is the number of _i The proportion is modified for the thermal power generating unit;

and (3) new energy output constraint:

wherein the content of the first and second substances,

representing the starting and stopping states of the wind turbine generator i at the moment t;

representing the starting and stopping states of the photovoltaic unit i at the moment t; p _i,min,RW Representing the minimum output of the wind turbine generator i; p _i,max,RW Representing the maximum output of the wind turbine generator i; p _i,min,RS Represents the minimum output of the photovoltaic i, P _i,max,RS Represents the maximum output of the photovoltaic i;

representing the output of the wind turbine generator i at the moment t;

representing the output of the photovoltaic i at the moment t; s _i，t 1 represents the starting and stopping states of the unit i at the time t (the superscripts RW and RS represent wind power and photovoltaic main bodies respectively); s. the _i，t 1 denotes start-up, S _i，t 0 means off; p _i，min And P _i，max Respectively representing the minimum and maximum output requirements of the unit i;

unit climbing restraint:

taking unit time as a dimension, wherein the value of the output power variation in certain unit time is between the lower climbing limit and the upper climbing limit; the unit time is represented by a delta T,

wherein the content of the first and second substances,

and

respectively representing the downward climbing rate and the upward climbing rate of the conventional unit per minute;

and

respectively representing the downward slope rate and the upward slope rate of the wind turbine generator per minute;

and

respectively representing the downward climbing rate and the upward climbing rate of the photovoltaic per minute;

and

respectively representing the downward climbing rate and the upward climbing rate of the energy storage device per minute; equations (9) - (12) represent the ramp rate limits for conventional units, wind turbines, photovoltaic units, and energy storage devices, respectively;

representing the variation value of the output power of the photovoltaic unit in unit time;

representing the variation value of the output power of the wind generating set in unit time; p _i,t -P _i,t-1 Representing the variation value of the output power of the conventional unit in unit time;

representing the variation value of the output power of the energy storage device in unit time;

energy storage restraint:

the charging power or the discharging power at the time t is required to be within a maximum allowable range; p _C，max ，P _DC，max Respectively representing the maximum power of energy storage charging and discharging;

0≤P _C,t ≤P _C，max (48)

0≤P _DC,t ≤P _DC,max (49)

wherein, P ^S _dc，i，t 、P ^S _c，i，t Respectively the discharge and charge power, P, of the energy storage unit ^grid _i，t For injecting power into the grid; s ^S _dc，i，t 、S ^S _c，i，t The discharge state and the charge state of the energy storage unit are respectively an integer in the range of 0-1, namely S ^S _dc，i，t Is in discharge state when 1 isState, S ^S _c，i，t 1 is in a charged state; e ^S _i，t Storing electric energy for the energy storage unit i at the moment t; eta ^S _c，i 、η ^S _dc，i Respectively the energy conversion rate of the energy storage device i during charging and discharging; e ^S _i，min 、E ^S _i，max The minimum and maximum stored electric energy of the energy storage unit i are respectively set;

load power range constraint:

wherein, P _in，sl，t 、P _out，sl，t Representing the in-and out-going power of the transferable load at time t, respectively; t represents the duration of the planning period;

the following constraints are upper and lower limits on load power; wherein, P _sl，t Representing the capacity of the transferable load; s _t Indicating the state of transferable loads, i.e. s _t 1 means that the transferable coincidences are operational within time period t; p _sl，min ，P _sl，max Representing transferable compliant allowed maximum and minimum load power values, respectively;

s _t P _sl,min ≤P _sl,t ≤s _t P _sl,max (54)；

interruptible load constraint:

the power requirement for interruptible loads is that their values should be within the minimum and maximum allowed ranges, i.e.

P _il,min,t ≤P _il,i,t ≤P _il,max,t (55)

Wherein, P _il，min，t ，P _il，max，t Respectively the minimum value and the maximum value of the interruptible load at the time t;

power balance:

the above formula is an expression representing power balance; p _l，t Is an important load, i.e. a load that cannot be powered off; p _sl，t Is a translatable load capacity; p _il，t Is an interruptible load; p _R，t The total light quantity is abandoned for wind abandonment; p _SCRW，i，t 、P _SCRS，k，t 、P _SCG ， _s，t 、P _SCS，m，t Respectively representing the output values of the wind turbine generator, the photovoltaic generator, the conventional generator and the energy storage generator at the moment t;

branch tidal current balance:

branch flow balance constraints are to be considered

Bθ＝P _G +P _W +P _ess +P _L (57)

Wherein, P _G The method comprises the following steps of (1) providing an output matrix for a conventional thermal power generating unit; p _W The output matrix of the wind turbine is P _i，t A matrix of compositions; p _ess The vector of output power of the energy storage device is P _C，t A matrix of compositions; p is _L Is a load power matrix, which is the sum matrix of the important load and the translatable load minus the interruptible load matrix; b is a node admittance matrix; theta is a node voltage phase angle vector;

node voltage phase angle constraint:

the constraint on the phase angle of the node voltage is to constrain its upper and lower limits, i.e. to constrain

Wherein, theta _i ，

Respectively the minimum value and the maximum value of the node voltage phase angle;

abandoning wind and abandoning light restraint:

introducing a abandoned wind-solar variable as a control variable; in order to limit the amount of abandoned wind and light, starting from the capacity of the new energy unit which can be output at each moment, the proportion of abandoned wind and light values in the capacity of the output is limited;

wherein x is a percentage coefficient, and the meaning of the percentage coefficient is that the ratio of the abandoned wind and the light quantity to the possible value is limited; p _RS，t ，P _RW ， _t And the total amount of abandoned wind and abandoned light of the wind turbine generator and the photovoltaic generator at the moment t respectively.

Further, step S3 is specifically as follows:

coal cost linearization:

the coal consumption cost in the model is in a quadratic function form, and sectional linearization processing is needed, namely, the quadratic function is divided into a plurality of sections of linear functions;

C _0,i ＝a _i (P _i,min ) ² +b _i P _i,min +c _i (62)

wherein m is the total number of segments; k _i，s The slope of each section of the coal consumption function after the piecewise linearization is adopted; p _i，min 、P _i，max Respectively the minimum and maximum output of the wind turbine; p _i，t，s The output of each section of the unit;

and (3) carrying out load flow calculation linearization:

when considering the power flow constraint, the power balance at the node is considered, i.e. the apparent power flowing into the node is equal to the voltage across the branch times the conjugate of the current, as shown in the following equation:

in the formula I ^* Represents the conjugation of I, U _i Is the voltage at node i; r is the resistance on the branch circuit; x is reactance on the branch; theta _i And theta _j The voltage phase angles at two nodes are respectively; in addition, according to equation (30), the active power and the reactive power flowing into the node are expressed by two equations, respectively, as follows:

consider the linearization of the power flow balance of equation (30):

(1) considering a large-scale power grid system environment; q is 0;

(2) on the transmission line, R < < X;

(3) the difference between the phase angles of the voltages of the two nodes connected to each other is 0, i.e. theta _i -θ _j ＝θ _ij ＝0；

(4) The per unit values of the node voltages are all 1, i.e. | u _i |＝|u _j |＝1；

Wherein, | u _i I represents the per unit value of the voltage amplitude of the node i, and u _j And | represents the per unit value of the voltage amplitude of the node j.

The simplified power flow balance formula is as follows:

so according to the lobida rule, i.e.

The formula of the power flow calculation is converted into the following form to linearize it:

compared with the prior art, the invention has the beneficial effects that:

one of the beneficial effects of the scheme is that in the scheme, the minimum overall operation cost of the power system in the optimized time period is taken as an objective function, constraints such as thermal power unit output, new energy output, unit climbing, energy storage, wind and light abandonment and the like are comprehensively considered, a linearization solving method is used for carrying out linearization on coal cost and trend calculation, actual case analysis is carried out on the data of the power system in 2020 of a certain province, and the result shows that the new energy achieves full-scale consumption through empirical simulation. The thermal power flexibility transformation energy efficiency of the time sequence production simulation model provided by the invention is verified to be remarkable. It should be noted that the flexible power system time sequence production simulation method provided by the invention is not limited to the embodiment, and the time sequence production simulation model can be subjected to targeted constraint adjustment to adapt to the test aiming at power systems with serious new energy discard, obvious load fluctuation and the like. Therefore, the method has stronger transportability, tailorability and robustness.

Drawings

Fig. 1 is a schematic diagram of a 2020 wind power output and load power utilization curve of a certain province in the embodiment of the application.

Fig. 2 is a schematic diagram of a 2020 time series production simulation analysis in a certain province according to an embodiment of the present application.

Fig. 3 is a flowchart illustrating steps according to an embodiment of the present disclosure.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. The components of embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.

Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present invention without making any creative effort, shall fall within the protection scope of the present invention. It is noted that relational terms such as "first" and "second," and the like, may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions.

Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.

The features and properties of the present invention are described in further detail below with reference to examples.

Due to the fact that renewable clean energy such as wind and light is easy to collect, abundant wind power generation and photovoltaic power generation can be put into a power grid, but due to the fact that load requirements change in real time, and the flexibility of a traditional thermal power unit is poor, the output of the traditional thermal power unit is difficult to adjust greatly in a short time, the phenomenon that wind and light are abandoned is serious when the load requirements are low, and therefore reasonable planning on flexible resources is urgently needed.

As shown in fig. 3, a flexible power system time sequence production simulation method based on a linearization solution method is provided, which includes the following steps:

An objective function part:

in order to minimize the total operation cost during the whole operation period of the power system, the total fuel consumption and the total power generation cost of each unit in an optimization period, the cost of the fire-electricity transformation, the energy storage investment and the load side demand response in a planning period are considered; namely, the installation and maintenance cost of new energy, the power generation cost of a conventional unit and the thermal power transformation cost C _Gm Wind power and photovoltaic power generation cost and CO of conventional unit ₂ The overall result of the emission cost is optimal, and an objective function with the aim of minimizing the overall operation cost of the power system in an optimization time period is provided, as shown in formula (1).

In addition, the power generation cost of the conventional unit mainly considers the start-stop cost C of the thermal power unit _FBS And coal consumption cost C _Fu (ii) a Power generation cost of new energy mainly considering punishment cost C of abandoned wind and light _RP (ii) a The new energy installation and maintenance cost mainly includes equipment cost, construction cost, maintenance cost and the discount value to the target age, and the installation and maintenance cost of the new energy is assumed to be relative to the optimization age and the like in consideration of the long-term property of planning installationAnnual value C _R，IM In addition, similar to new energy installation, the installation cost, maintenance cost and discount value of the energy storage device will also be expressed by the annual value C _S，IM 。

In addition, when considering flexible resource scheduling, a time when the system cannot meet peak shaving requirements may occur, and response of flexible resource scheduling on the demand side is to be considered, wherein the demand side response includes load shedding and load shifting, which is a lower-cost way for providing flexibility for the power system, but due to the limitation of demand side flexibility, the proportion of participation on the actual demand side is lower, and needs to be used in combination with other flexible resources. The cost of the load-side demand response includes the upfront cost and the transfer cost of the transfer response resource, and also includes the compensation cost of the interruptible load, and the generated compensation cost is marked as C _IL 。

Wherein C is _FBS Can be expressed as

C _FBS ＝C _B S _Bi,t +C _F S _Fi,t (72)

Wherein S _Bi，t And S _Fi，t Respectively represents the starting state and the stopping state of the thermal power generating unit i at the moment t, and is an integer ranging from 0 to 1, namely S _Bi，t 1 stands for on, S _Fi，t 1 represents shutdown. C _B And C _F The start-up cost and the shut-down cost of the unit are respectively.

The coal consumption cost of the conventional thermal power generating unit can be expressed in the form of a quadratic function taking the actual output of the unit i at the moment t as an independent variable:

C _Fu (P _i,t )＝a _i (P _i,t ) ² +b _i P _i,t +c _i (73)

wherein a is _i 、b _i 、c _i And (4) the coal consumption coefficient of the unit i.

In addition, the wind and light abandoning penalty cost C of new energy _RP Can be represented by the following equation:

wherein C is _W,pu Represents the cost per MWh of abandoned wind, C _S,pu Represents the cost per MWh of reject light, and Δ T represents the measurement interval (e.g., 15 minutes) of the power generation output. P _{RW，i，t，r} And P _{RS，i，t，r} And respectively representing the air abandon amount and the light abandon amount of the unit i as a system standby under regulation at the time t. NRW and NRS represent the number of wind turbines and solar photovoltaic sets, respectively.

Wind and light abandoning penalty cost C of new energy _RP It can also be expressed by the following method:

where ρ is _p，w ，ρ _p，s Respectively representing a wind curtailment penalty factor, a light curtailment penalty factor, P _{RW，i，t，max} Amount of available resources representing wind farm production, and P _RW，i，t The difference is the actual air reject rate. P _{RS，i，t，max} Represents the amount of available resources of the photovoltaic, which is related to P _RS，i，t The difference is the actual amount of light lost.

The constraint part:

thermal power output reconstruction constraint

The thermal power output constraint is represented by that the output power of the thermal power generating unit i at the moment t is limited between the minimum output limit and the maximum output limit. In order to improve the flexible processing capacity of the unit, the lowest output value of the thermal power unit is improved, wherein P is _i，min The lower limit of the output force before transformation; p _i*，min The lower limit of output force after transformation; p _i，max The upper limit of the output of the unit; x is the number of _i The method is a modification proportion of a thermal power generating unit.

Upper and lower limit restraint of output of new energy machine set

The constraints here take into account the output limits of the wind turbine and the photovoltaic generator, the actual output at each moment being within the output range formed by the minimum and maximum output. The upper and lower output limits of each unit are generally fixed characteristics, so that time elements are omitted for the definition of the upper and lower output limits.

Wherein S is _i，t 1 represents the start-stop state of the unit i at the moment t, S _i，t 1 denotes start-up, S _i，t 0 means off; p _i，min And P _i，max Respectively representing the minimum and maximum output requirements of the unit i.

Unit climbing restraint

The climbing constraint is an important constraint considering the construction of a flexible unit model, and reflects the output level of an actual unit. The output power variation per unit time is between the down-hill limit and the up-hill limit, with the unit time being the dimension. The unit time is denoted by Δ T, where Δ T is 1 h.

Wherein R is _id And R _iu The lower climbing rate and the upper climbing rate of each minute are represented respectively, and the upper formula represents the climbing rate limit of the conventional unit, the wind turbine unit, the photovoltaic unit and the energy storage device respectively. P _i，t -P _i，t-1 Representing the variation value of the unit output power in unit time.

Restraint of stored energy

The energy storage constraint mainly aims at the charge and discharge power of an energy storage power station, and the charge power or the discharge power of the energy storage power station at the time t is required to be within a maximum allowable range. P _C，max ，P _DC，max Respectively representing the maximum power of energy storage charging and discharging.

0≤P _C,t ≤P _C，max (83)

0≤P _DC,t ≤P _DC,max (84)

Wherein, P ^S _dc，i，t 、P ^S _c，i，t Respectively the discharge and charge power, P, of the energy storage unit ^grid _i，t For injecting power into the grid; s ^S _dc，i，t 、S ^S _c，i，t The values of the discharge state and the charge state of the energy storage unit are integers in the range of 0-1, namely S ^S _dc，i，t 1 is in discharge state, S ^S _c，i，t 1 is in a charged state; e ^S _i，t Storing electric energy for the energy storage unit i at the moment t; eta ^S _c，i 、η ^S _dc，i Respectively the energy conversion rate of the energy storage device i during charging and discharging; e ^S _i，min 、E ^S _i，max The energy storage units i are respectively the minimum and the maximum stored electric energy of the energy storage unit i.

Load power range constraints

The constraint on load power means that the capacity for transferable loads is to be within the lowest and highest capacity allowed by the system. The transferable load changes the electricity utilization time period of the load through economic incentive, and the transferable load only changes the electricity utilization time of the load and has no influence on the total electricity utilization amount, so that the total electricity utilization amount of the transferable load in the planning cycle is ensured to be kept unchanged.

Wherein, P _in，sl，t 、P _out，sl，t Representing the in-and out-going power of the transferable load at time t, respectively; t denotes the duration of the planning period.

The following constraints are upper and lower limit constraints on the load power. Wherein, P _sl，t Representing the capacity of the transferable load; s is _t Indicating the state of transferable load, i.e. s _t 1 means that the transferable coincidences are operational within time period t; p _sl，min ，P _sl，max Representing maximum and minimum load power values, respectively, which may be transferred in compliance with the allowance.

s _t P _sl,min ≤P _sl,t ≤s _t P _sl,max (89)

Interruptible load constraints

P _il,min,t ≤P _il,i,t ≤P _il,max,t (90)

Wherein, P _il，min，t ，P _il，max，t Respectively the minimum and maximum value of the interruptible load at time t.

Power balancing

The above equation is an expression representing power balance. P _l，t Important loads, i.e. loads that cannot be powered off for a significant time; p _sl，t Is a translatable load capacity; p _il，t Is an interruptible load; p _R，t The total light quantity is abandoned for wind abandonment; p _SCRW，i，t 、P _SCRS，k，t 、P _SCG，s，t 、P _SCS，m，t Respectively are the output values of the wind turbine generator, the photovoltaic generator, the conventional generator and the energy storage generator at the moment t.

Branch tidal current balance

Branch flow constraints will be taken into account

Bθ＝P _G +P _W +P _ess +P _L (92)

Wherein, P _G The method comprises the following steps of (1) providing an output matrix for a conventional thermal power generating unit; p _W The output matrix of the wind turbine is P _i，t A matrix of compositions; p _ess The vector of output power for the energy storage device is represented by P _C，t A matrix of compositions; p is _L Is a load power matrix, which subtracts an interruptible load matrix from a sum matrix of the important loads and the translatable loads; b is a node admittance matrix; theta is the node voltage phase angle vector.

Node voltage phase angle constraint

The constraints on the phase angle of the node voltage are mainly the upper and lower limit values thereof, i.e.

Wherein the content of the first and second substances,θ _i ，

respectively, the minimum and maximum values of the phase angle of the node voltage.

Wind and light rejection restraint

In order to meet the requirement of good new energy consumption, the abandoned wind and the light quantity are controlled to a certain extent, and a abandoned wind-solar variable is introduced into the model as a control variable. This variable has two implications: firstly, the method is used as a relaxation variable in a mathematical sense to ensure that a unit combination model has a feasible solution; on the other hand, in a physical sense, the constraints on the abandoned wind and the light quantity are the expression of effective control and good consumption of new energy. In order to limit the amount of abandoned wind and light, the proportion of abandoned wind and light values in the capacity of the new energy machine set is limited by starting from the capacity of the new energy machine set which can output power at each moment.

Wherein x is a percentage coefficient, and the meaning of the percentage coefficient is that the ratio of the abandoned wind and the light quantity to the possible value is limited. P is _RS，t ，P _RW，t And the total amount of abandoned wind and abandoned light of the wind turbine generator and the photovoltaic generator at the moment t are respectively.

The linearization solution method part:

coal cost linearization

The coal consumption cost in the model is in a quadratic function form, and the piecewise linearization processing is needed, namely the quadratic function is divided into a plurality of sections of linear functions. The reason for the linearized output is that CPLEX can only solve the linearized model optimally.

C _0,i ＝a _i (P _i,min ) ² +b _i P _i,min +c _i (97)

Wherein m is the total number of segments; k _i，s The slope of each section of the coal consumption function after the piecewise linearization is adopted; p _i，min 、

P _i，max The minimum output and the maximum output of the wind turbine are respectively; p _i，t，s Is the output of each section of the unit.

Load flow calculation linearization

When considering the power flow constraint, the power balance at the node is mainly considered, i.e. the apparent power flowing into the node is equal to the voltage across the branch multiplied by the conjugate of the current, as shown in the following equation.

In the formula of U _i Is the voltage at node i; r is the resistance on the branch circuit; x is reactance on the branch; theta _i And theta _j Which are the phase angles of the voltages at the two nodes, respectively. In addition, according to equation (30), the active power and the reactive power flowing into the node can be expressed by two equations, respectively, as shown below.

However, since the node voltage phase angle is considered when calculating the power flow, the nonlinear trigonometric function form can be obviously seen after the polar coordinate form of the voltage is simplified by using the euler formula, and the optimization is complicated by the nonlinearity. In order to enable linear optimization using CPLEX, the power flow balance of equation (30) will be considered to be linearized:

(1) consider a large grid system environment. In large grids, little reactive power is transmitted because the reactive power is essentially balanced locally, i.e. Q-0.

(2) On the transmission line, the resistance value is much smaller than the reactance value, i.e., R < < X.

(3) The difference in voltage phase angle between two nodes connected to each other is almost 0, i.e., theta _i -θ _j ＝θ _ij ＝0。

(4) The voltage at the node is almost 1 per unit, i.e. | u _i |＝|u _j |＝1。

The simplified power flow balance formula is shown as follows.

It can be found that the expression of the active power still exists in a non-linear form, so according to the law of lobida, i.e.

The formula of the power flow calculation can be converted into the following form to linearize it.

Namely, the linearized power flow calculation considers the ratio of the phase angle difference and the reactance of two ends of the node, and is independent of the voltage.

Case analysis:

in order to verify the correctness of the model provided by the project, the load and wind power output of 2020 years of a certain province are analyzed, a typical wind power output and load power utilization per unit value is selected, a curve of the wind power output and load power utilization of 2020 years of the certain province can be obtained through simulation, and the number of the generator sets with different installed capacities and the installed capacity are shown in a table 1.

TABLE 1 analysis of the number of generator sets and installed capacity (non-new energy) of different installed capacities in 2020 of a province

volume/MW	≥600	[300,350]	[150,200]	[100,150)	<100
						Number of units/unit	21	236	81	36	229
Rated total power/MW	13260	72570	14490	4297.8	4788.28

Statistical analysis shows that the number of generator sets with the capacity of 300-350 MW and the capacity of less than 100MW is the largest, and the generator sets account for 39% and 38% respectively; however, further combined with the installed capacity analysis, the installed capacity of the generator with the capacity of 300-350 MW is up to 72570MW, which accounts for 66% of the total installed capacity, while the installed capacity of the generator with the capacity of less than 100MW is only 4788.28MW, which only accounts for 5% of the total installed capacity. By combining the adjustable coefficients of thermal power generating units with different capacities shown in table 2, the unit combination analysis of 2020 in a certain province can be obtained through analysis, and is shown in fig. 2.

According to simulation results, although the installed capacity of the new energy reaches 17000MW, the utilization hours of the fan are low, the maximum output is only 6889MW, the maximum output only accounts for 40.5% of the installed capacity, the annual wind power utilization hours are only 1209 hours, and the annual load power consumption reaches 6461.42 hundred million kilowatt hours.

TABLE 2 Adjustable output coefficient of thermal power generating units of different capacities

Type of unit	>30 ten thousand kW	20 ten thousand kW	<20 ten thousand kW
				Heat supply unit	0.2	0.15	0.1
Non-heat supply unit	0.5	0.4	0.3

As can be seen from fig. 2, at the current wind installation and load level, the new energy can be consumed by 100%.

The above are preferred embodiments of the present invention, and all changes made according to the technical solutions of the present invention that produce functional effects do not exceed the scope of the technical solutions of the present invention belong to the protection scope of the present invention.

Claims

1. The flexible power system time sequence production simulation method based on the linearization solution method is characterized by comprising the following steps:

2. The method for simulating the time series production of the flexible power system based on the linearized solution as set forth in claim 1, wherein the step S1 is as follows:

in order to minimize the total operation cost during the whole operation period of the power system, the total fuel consumption and the total power generation cost of each unit in the optimization time period, the cost of the fire power transformation, the energy storage investment and the load side demand response in the planning period are considered, namely, the cost comprises the new energy installation and maintenance cost, the conventional unit power generation cost and the fire power transformation cost C _Gm Wind power and photovoltaic power generation cost and CO of conventional unit ₂ The overall result of the emission cost is optimal, and an objective function with the aim of minimizing the overall operation cost of the power system in the optimization time period is provided, as shown in formula (1):

wherein C is _FBS And C _Fu Respectively representing the power generation cost of a conventional unit and considering the start-stop cost and the coal consumption cost of a thermal power unit; t and nG respectively represent the running time and the number of the thermal power generating units, C _RP Representing the cost of electricity generation of new energyConsidering the punishment cost of abandoned wind and light; the new energy installation and maintenance cost mainly comprises equipment cost, construction cost, maintenance cost and discount value to a target year, and the long-term property of planning installation is considered, C _R，IM The installation and maintenance cost of the new energy is assumed to be equal annual value relative to the optimization year limit; c _S，IM Indicating that the installed cost, maintenance cost, and discount value of the energy storage device will also be utilized for the equal-year value; when considering the flexible resource scheduling, the system can not meet the peak load demand, the response of the flexible resource scheduling of the demand side is considered, wherein the demand side response comprises load reduction and load transfer, the cost of the demand response of the load side comprises the early cost and the transfer cost of transferring the response resource, and the compensation cost of the interruptible load is also included, and the generated compensation cost is marked as C _IL (ii) a Wherein C is _FBS Can be expressed as

C _FBS ＝C _B S _Bi,t +C _F S _Fi,t (2)

Wherein S _Bi，t And S _Fi，t Respectively represent the starting state and the stopping state of the thermal power generating unit i at the moment t, and are integers in the range of 0-1, namely S _Bi，t 1 stands for on, S _Fi，t 1 represents shutdown; c _B And C _F Respectively the starting cost and the stopping cost of the unit;

C _Fu (P _i,t )＝a _i (P _i,t ) ² +b _i P _i,t +c _i (3)

wherein C is _W,pu Represents the cost per MWh of abandoned wind, C _S,pu The cost of each MWh of abandoned light is represented, and delta T represents the measuring time interval of the power generation output; p _RW，i，t And P _RS，i，t Respectively representing the air abandon amount and the light abandon amount of the unit i which is used as a system lower standby at the time t; NRW and NRS represent the number of wind turbines and solar photovoltaic sets, respectively.

3. The method for simulating the time series production of the flexible power system based on the linear solving method as claimed in claim 2, wherein the wind curtailment and light penalty cost C of new energy _RP An alternative to the following formula:

4. The method for simulating the time series production of the flexible power system based on the linearized solution as set forth in claim 2, wherein the step S2 is as follows:

thermal power output reconstruction constraint:

the thermal power output reconstruction constraint is represented by that the output power of the thermal power generating unit i at the moment t is limited between the minimum output limit and the maximum output limit; wherein, P _i，min The lower limit of the output force before transformation; p is _i*，min The lower limit of output force after transformation; p is _i，max The output upper limit of the unit is set; x is a radical of a fluorine atom _i The proportion is modified for the thermal power generating unit;

and (3) new energy output constraint:

wherein the content of the first and second substances,

representing the output of the wind turbine generator i at the moment t;

representing the output of the photovoltaic i at the moment t; s _i，t 1 represents the starting and stopping states of the unit i at the time t (the superscripts RW and RS represent wind power and photovoltaic main bodies respectively); s _i，t 1 denotes start-up, S _i，t 0 means off; p _i，min And P _i，max Respectively representing the minimum and maximum output requirements of the unit i;

unit climbing restraint:

taking unit time as a dimension, wherein the value of the output power variation in certain unit time is between the lower climbing limit and the upper climbing limit; the unit time is represented by deltat,

wherein the content of the first and second substances,

and

and

respectively representing the downward climbing rate and the upward climbing rate of the wind turbine generator per minute;

and

and

energy storage restraint:

0≤P _C,t ≤P _C，max (13)

0≤P _DC,t ≤P _DC,max (14)

wherein, P ^S _dc，i，t 、P ^S _c，i，t Respectively the discharge and charge power, P, of the energy storage unit ^grid _i，t For injecting power into the grid; s ^S _dc，i，t 、S ^S _c，i，t The values of the discharge state and the charge state of the energy storage unit are integers in the range of 0-1, namely S ^S _dc，i，t 1 is in discharge state, S ^S _c，i，t 1 is in a charged state; e ^S _i，t Storing electric energy for the energy storage unit i at the moment t; eta ^S _c，i 、η ^S _dc，i Respectively the energy conversion rate of the energy storage device i during charging and discharging; e ^S _i，min 、E ^S _i，max The minimum and maximum stored electric energy of the energy storage unit i are respectively set;

and (3) load power range constraint:

s _t P _sl,min ≤P _sl,t ≤s _t P _sl,max (19)；

interruptible load constraint:

P _il,min,t ≤P _il,i,t ≤P _il,max,t (20)

Wherein, P _il，min，t ，P _il，max，t Respectively the minimum value and the maximum value of the interruptible load at the moment t;

power balance:

the above formula is an expression representing power balance; p _l，t Is an important load, i.e. a load that cannot be powered off; p _sl，t Is a translatable load capacity; p _il，t Is an interruptible load; p _R，t The total light quantity is abandoned for wind abandonment; p _SCRW，i，t 、P _SCRS，k，t 、P _SCG，s，t 、P _SCS，m，t Output values of the wind turbine generator set, the photovoltaic generator set, the conventional generator set and the energy storage generator set i, k, s and m at the moment t are respectively;

branch tidal current balance:

branch flow balance constraints are to be considered

Bθ＝P _G +P _W +P _ess +P _L (22)

Wherein, P _G An output matrix is provided for a conventional thermal power generating unit; p _W The output matrix of the wind turbine is P _i，t A matrix of compositions; p _ess The vector of output power of the energy storage device is P _C，t A matrix of compositions; p _L Is a load power matrix, which subtracts an interruptible load matrix from a sum matrix of the important loads and the translatable loads; b is a node admittance matrix; theta is a node voltage phase angle vector;

node voltage phase angle constraint:

the constraint on the phase angle of the node voltage is to constrain its upper and lower limits, i.e. to limit the phase angle of the node voltage

Wherein, the first and the second end of the pipe are connected with each other,θ _i ，

respectively the minimum value and the maximum value of the phase angle of the node voltage;

abandoning wind and abandoning light restraint:

introducing a wind and light abandoning variable as a control variable; in order to limit the amount of abandoned wind and light, starting from the capacity of the new energy unit which can be output at each moment, the proportion of abandoned wind and light values in the capacity of the output is limited;

wherein x is a percentage coefficient, and the meaning of the percentage coefficient is that the ratio of the abandoned wind and the light quantity to the possible value is limited; p _RS，t ，P _RW，t And the total amount of abandoned wind and abandoned light of the wind turbine generator and the photovoltaic generator at the moment t respectively.

5. The method for simulating the time series production of the flexible power system based on the linearized solution as set forth in claim 4, wherein the step S3 is as follows:

coal cost linearization:

the coal consumption cost in the model is in a quadratic function form, and piecewise linearization processing is needed, namely the quadratic function is divided into a plurality of sections of linear functions;

C _0,i ＝a _i (P _i,min ) ² +b _i P _i,min +c _i (27)

wherein m is the total number of segments; k _i，s The slope of each section of the coal consumption function after the piecewise linearization is adopted; p _i，min 、P _i，max Respectively the minimum and maximum output of the wind turbine; p is _i，t，s The output of each section of the unit;

and (3) carrying out load flow calculation linearization:

in the formula I ^* Represents the conjugation of I, U _i Is the voltage at node i; r is the resistance on the branch circuit; x is the reactance on the branch; theta _i And theta _j The voltage phase angles at two nodes are respectively; in addition, according to equation (30), the active power and the reactive power flowing into the node are expressed by two equations, respectively, as follows:

consider the linearization of the power flow balance of equation (30):

(1) considering a large-scale power grid system environment; q is 0;

(2) on the transmission line, R < < X;

Wherein, | u _i I represents the per unit value of the voltage amplitude of the node i, | u _j And | represents the per unit value of the voltage amplitude of the node j. The simplified power flow balance formula is as follows:

so according to the lobida law, i.e.