Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a new energy grid-connected power system multi-time scale scheduling method based on robust optimization, solves the technical problem that the scheduling plan is frequently adjusted in actual operation because the uncertainty of a new energy predicted value is not considered in multi-time scale scheduling in the prior art, can effectively reduce the influence of uncertainty factors on the scheduling plan of the new energy grid-connected power system, has good robustness, and realizes the balance of safety and economy.
In order to solve the technical problems, the technical scheme of the invention is as follows: a new energy grid-connected power system multi-time scale scheduling method based on robust optimization is disclosed, wherein the new energy grid-connected power system comprises new energy and schedulable energy, and the method comprises the following steps:
step 1: respectively establishing a target function of each time scale dispatching plan by taking the dispatchable energy output in the new energy grid-connected power system as a decision variable;
step 2: respectively establishing constraint conditions including robust constraint and traditional physical constraint of each time scale scheduling plan; the robust constraint is established according to uncertainty factors and a robust level value, wherein the uncertainty factors comprise new energy output and load;
and step 3: establishing a robust optimization scheduling model of each time scale according to each objective function and corresponding constraint conditions;
and 4, step 4: selecting robust level values under each time scale according to a robust level value adjustment rule, and respectively inputting the robust level values into robust optimization scheduling models of each time scale so as to obtain decision variables meeting the objective function under constraint conditions;
and 5: and adjusting the dispatching plan according to the decision variable so as to dispatch the dispatchable energy.
Preferably, before the robust constraint is established, a robust constraint condition set J is established according to uncertainty factors, and the method comprises the following steps:
step 201: using uncertainty constraint as element for building robust constraint set J, Aj∈J,AjJ belongs to { 1.,..,. N }, and N is the number of uncertainty constraint conditions in the jth uncertainty constraint condition in the robust constraint condition set J;
step 202: establishing a set of uncertainty factors for each uncertainty constraint, wherein the jth uncertainty constraint AjThe uncertainty factor set on is Ij,Bl∈Ij,BlIs a set of uncertainty factors IjThe l-th uncertainty factor in (1), l ∈ { 1.
Preferably, the robust optimized scheduling model for each time scale has the following general formula:
wherein x is a decision variable; minf (x) is an objective function of the current time scale scheduling plan;
is the jth uncertainty constraint A
jA coefficient matrix of an upper decision variable x; u. of
ljIs the jth uncertainty constraint A
jThe parameter of the l uncertainty factor of (1) above is
A nominal value of (d);
is the jth uncertainty constraint A
jThe parameter of the l uncertainty factor of (1) above is
The amount of disturbance of; z is a radical of
jFor the jth uncertainty constraint A in the current dispatch plan
jMaximum value of disturbance quantity of upper uncertainty factor; p
max、P
minRespectively is the upper limit and the lower limit of the output of the schedulable energy; and gamma is the robust level value of the current time scale scheduling plan selected according to the robust level value adjustment rule.
Preferably, the new energy comprises wind power output and photovoltaic output, and the schedulable energy comprises hydroelectric output and thermal power output; n is 2, and the robust constraint condition set J comprises two uncertain constraint conditions; the number of uncertainty factors in the uncertainty factor set of each uncertainty constraint condition is M to 3, and the three uncertainty factors are wind power output, photovoltaic output and load respectively;
uncertainty constraint A when j is 11To power balance constraints:
uncertainty constraint A when j is 22Rotating the standby constraint for the system:
wherein z is1Is the maximum value of disturbance quantity of uncertainty factor of power balance constraint in current scheduling plan, z2For in the current scheduling planMaximum value of disturbance quantity of uncertainty factor of system rotation standby constraint; z is a radical of1=z2(ii) a Gamma is the robust level value of the current time scale scheduling plan selected according to the robust level value adjustment rule, and gamma belongs to [0, M ∈];
PG.i.tDetermining the output condition of the thermal power generating unit i at the moment t for the current scheduling plan; ph.tDetermining the output condition of the hydroelectric generating set at the moment t for the current scheduling plan; pw.tDetermining the output condition of the wind turbine generator at the moment t for the current scheduling plan; pL.tLoad at time t determined for the current dispatch plan; pmax.iThe output upper limit is the thermal power generating unit i; ph.maxThe output upper limit of the hydroelectric generating set; and R is the spare capacity of the new energy grid-connected power system.
Preferably, the robust level value adjustment rule is: and adjusting the robust level value by adjusting the confidence level, wherein the robust level value and the confidence level are adjusted in the following relation:
wherein epsilon is the confidence level selected under the current time scale plan.
Preferably, the confidence level is adjusted according to the following principle:
first, the basic rule is determined: as the time scale is gradually reduced, the robust level value should be gradually increased;
secondly, on the basis of meeting the basic rule, the following adjustments are carried out according to the disturbance quantity of each uncertain factor and the new energy access proportion:
if the disturbance quantity values of all uncertain factors are closer, the robust level value of the maximum time scale plan is increased, and if the disturbance quantity values of all uncertain factors are larger in difference, the robust water value of the maximum time scale plan is reduced;
and if the new energy access proportion is increased, the robust level value of each time scale scheduling plan is increased.
Compared with the prior art, the invention has the following beneficial effects:
1. the method carries out robust modeling on the wind, light and load predicted values of each time scale, converts deterministic constraints under each time scale into robust constraints for considering uncertainty, and establishes a multi-time scale robust economic dispatching model, so that the uncertainty of the predicted values of different time scales of the wind, light and load is fully considered when a dispatching plan is made, and the influence of the wind, light and load predictive uncertainty is effectively reduced.
2. The invention sets the robustness level which is increased step by step along with the reduction of the time scale so as to reflect the reduction of the tolerance of the system to the worst case of uncertainty factors and the improvement of the attention degree of safety along with the approach of the actual scheduling time, thereby replacing the scheduling plan with larger safety guarantee at smaller economic cost and realizing the balance of safety and economy.
3. The whole scheduling model can effectively reduce the influence of wind, light and load prediction uncertainty, effectively reduce frequent start and stop of a unit, relieve scheduling pressure, and reduce the level of abandoned wind and load shedding, and meanwhile, compared with the traditional robust scheduling model in the day, the whole scheduling model has better economy and realizes coordination of economy and safety.
Detailed Description
A new energy grid-connected power system multi-time scale scheduling method based on robust optimization is disclosed, wherein the new energy grid-connected power system comprises new energy and schedulable energy, and the method comprises the following steps:
step 1: respectively establishing a target function of each time scale dispatching plan by taking the dispatchable energy output in the new energy grid-connected power system as a decision variable;
step 2: respectively establishing constraint conditions including robust constraint and traditional physical constraint of each time scale scheduling plan; the robust constraint is established according to uncertainty factors and a robust level value, wherein the uncertainty factors comprise new energy output and load;
and step 3: establishing a robust optimization scheduling model of each time scale according to each objective function and corresponding constraint conditions;
and 4, step 4: selecting robust level values under each time scale according to a robust level value adjustment rule, and respectively inputting the robust level values into robust optimization scheduling models of each time scale so as to obtain decision variables meeting the objective function under constraint conditions;
and 5: and adjusting the dispatching plan according to the decision variable so as to dispatch the dispatchable energy.
In this embodiment, the following three time scale scheduling plans are included: a 24-hour day-ahead scheduling plan, a 4-hour day-in scheduling plan and a real-time 15-min scheduling plan;
24h schedule plan day by day 24: 00, once formulating, and configuring wind power output, photovoltaic output and hydropower output into a virtual power supply by using short-term predicted values of wind power output, photovoltaic output and load for 24h in the future, and participating in scheduling with thermal power output;
rolling and making a 4h scheduling plan every 15min in the day, and preferentially calling hydropower to adjust power deviation according to the latest future 4h wind power output, photovoltaic output and ultra-short-term predicted value of load on the basis of a 24h scheduling plan in the day, so as to correct the schedulable energy output and the thermal power unit combination state;
and the real-time 15-min scheduling plan is also made in a rolling mode once every 15min, and on the basis of the 4-hour scheduling plan in the day, the schedulable energy unit output in the future 15min, namely the next scheduling moment, is corrected according to the latest real-time predicted values of the wind power output, the photovoltaic output and the load in the future 15 min.
The 24h day-ahead scheduling plan provides a virtual power supply and a thermal power output power operation point for a 4h day scheduling plan, and the 4h day scheduling plan provides a thermal power output, a thermal power output and a thermal power unit combination state for a real-time 15min scheduling plan; the real-time 15min scheduling plan arrangement can schedule the real-time output adjustment of the energy unit, and all the rings are buckled and orderly and effectively connected.
The 4h scheduling plan and the real-time 15min scheduling plan in the day are rolling scheduling plans, and the respective previous time scale scheduling plans are rolled and corrected, so that the effective connection and stable transition of the scheduling plans in different time scales are effectively ensured, and the uncertain influence caused by the output of new energy can be better overcome.
In the specific embodiment, before the robust constraint is established, a robust constraint condition set J needs to be established according to uncertainty factors, and the following steps are performed:
step 201: using uncertainty constraint as element for building robust constraint set J, Aj∈J,AjJ belongs to { 1.,..,. N }, and N is the number of uncertainty constraint conditions in the jth uncertainty constraint condition in the robust constraint condition set J;
step 202: establishing a set of uncertainty factors for each uncertainty constraint, wherein the jth uncertainty constraint AjThe uncertainty factor set on is Ij,Bl∈Ij,BlIs a set of uncertainty factors IjThe l-th uncertainty factor in (1), l ∈ { 1.
In this embodiment, the general formula of the robust optimized scheduling model for each time scale is as follows:
wherein x is a decision variable; minf (x) is an objective function of the current time scale scheduling plan;
is the jth uncertainty constraint A
jA coefficient matrix of an upper decision variable x; u. of
ljIs the jth uncertainty constraint A
jThe parameter of the l uncertainty factor of (1) above is
A nominal value of (d);
is the jth uncertainty constraint A
jThe parameter of the l uncertainty factor of (1) above is
The amount of disturbance of; z is a radical of
jFor the jth uncertainty constraint A in the current dispatch plan
jMaximum value of disturbance quantity of upper uncertainty factor; p
max、P
minRespectively is the upper limit and the lower limit of the output of the schedulable energy; and gamma is the robust level value of the current time scale scheduling plan selected according to the robust level value adjustment rule.
In the specific embodiment, the new energy comprises wind power output and photovoltaic output, and the schedulable energy comprises hydroelectric output and thermal power output; n is 2, and the robust constraint condition set J comprises two uncertain constraint conditions; the number of uncertainty factors in the uncertainty factor set of each uncertainty constraint condition is M to 3, and the three uncertainty factors are wind power output, photovoltaic output and load respectively;
uncertainty constraint A when j is 11To power balance constraints:
uncertainty constraint A when j is 22Rotating the standby constraint for the system:
wherein z is1Is the maximum value of disturbance quantity of uncertainty factor of power balance constraint in current scheduling plan, z2The maximum value of the disturbance quantity of the uncertainty factor of the system rotation standby constraint in the current scheduling plan is obtained; z is a radical of1=z2(ii) a Gamma is the robust level value of the current time scale scheduling plan selected according to the robust level value adjustment rule, and gamma belongs to [0, M ∈];
PG.i.tOutput condition of thermal power generating unit i at time t determined for current scheduling plan;Ph.tDetermining the output condition of the hydroelectric generating set at the moment t for the current scheduling plan; pw.tDetermining the output condition of the wind turbine generator at the moment t for the current scheduling plan; pL.tLoad at time t determined for the current dispatch plan; pmax.iThe output upper limit is the thermal power generating unit i; ph.maxThe output upper limit of the hydroelectric generating set; and R is the spare capacity of the new energy grid-connected power system.
In this specific embodiment, the robust constraints of the 24h day-ahead scheduling plan include a power balance constraint and a system rotation standby constraint, which are respectively as follows:
and power balance constraint:
and (3) system rotation standby constraint:
wherein the content of the first and second substances,
for the maximum value of the disturbance quantity of uncertainty factors of the power balance constraint in the 24h scheduling plan,
the maximum value of the disturbance quantity of the uncertainty factor of the system rotation standby constraint in the 24h dispatching plan,
Γ
24hthe robust level value of the scheduling plan 24h before the day is selected according to the robust level value adjustment rule;
planning the determined output condition of the thermal power generating unit i at the moment t for 24h before the day;
the output condition of the hydroelectric generating set at the moment t is planned and determined 24h before the day;
the output condition of the wind turbine generator at the time t is determined for 24h before the day;
the determined load at time t is planned for 24h before the day.
In this specific embodiment, the robust constraints of the intra-day 4h scheduling plan include a power balance constraint and a system rotation standby constraint, which are respectively as follows:
and power balance constraint:
and (3) system rotation standby constraint:
wherein the content of the first and second substances,
the maximum value of the disturbance quantity of the uncertainty factor of the power balance constraint in the 4h scheduling plan in the day,
the maximum value of the disturbance quantity of the uncertainty factor of the system rotation standby constraint in the 4h scheduling plan in the day,
Γ
4hthe robust level value of the scheduling plan of 4h in a day selected according to the robust level value adjustment rule;
fire determined for 4h dispatch plan within dayThe output condition of the motor set i at the moment t;
the output condition of the hydroelectric generating set at the time t determined by the scheduling plan for 4 hours in the day;
the output condition of the wind turbine generator at the time t is determined for a 4h scheduling plan in the day;
the load at time t is determined for the 4h scheduling plan in the day.
In this embodiment, the robust constraints of the real-time 15min scheduling plan include a power balance constraint and a system rotation standby constraint, which are respectively as follows:
and power balance constraint:
and (3) system rotation standby constraint:
wherein the content of the first and second substances,
the maximum value of the disturbance quantity of the uncertainty factor of the power balance constraint in the real-time 15min scheduling plan,
the maximum value of the disturbance quantity of the uncertainty factor of the system rotation standby constraint in the day real-time 15min scheduling plan,
Γ
15minthe robust level value of the real-time 15min scheduling plan selected according to the robust level value adjustment rule;
the output condition of the thermal power generating unit i at the moment t is determined for a real-time 15min scheduling plan;
the output condition of the hydroelectric generating set at the time t determined by the real-time 15min scheduling plan;
the output condition of the wind turbine generator at the time t is determined for a real-time 15min scheduling plan;
the load at time t is determined for the real-time 15min dispatch plan.
In the specific embodiment, the objective function of the 24-hour day-ahead scheduling plan is established according to the following steps:
step 501: the wind power output, the photovoltaic output and the hydroelectric output are configured into a virtual power supply, and the index N is tracked by the load of the virtual power supplyrThe minimum is used as a first layer objective function, and a virtual power output curve VP and an optimized load curve P are obtained under the condition of meeting the first layer objective functionr(ii) a The first layer objective function is as follows:
minNr=Dt+Ds+Dc;
wherein D istFor the rate of fluctuation of new energy output with respect to load, DsAs standard deviation of load fluctuation, DcIs the load power rate of change; dtThe smaller the output curve of the virtual power supply VP is, the closer the output curve of the virtual power supply VP is to the load curve, namely the better the tracking capability of the virtual power supply VP on the load is; dsAs standard deviation of load fluctuation, DcFor the load power change rate, the two indexes jointly represent the optimized load curve P after the output curve VP of the virtual power supply is stabilizedrThe smaller the value, the more the optimized load curve P is representedrThe smoother and smaller the fluctuation;
step 502: with thermal power machineThe lowest group total power generation cost is the second layer objective function and is in the optimized load curve PrArranging working positions of thermal power output meeting the second layer of objective function; the second layer objective function is as follows:
wherein the content of the first and second substances,
the number of time segments divided for the 24h scheduling plan day ahead; n is a radical of
gThe total number of the thermal power generating units; u shape
i,tThe starting and stopping state, U, of the thermal power generating unit i at the moment t determined for the current scheduling plan
i,t∈{0,1};U
i,t-1The starting and stopping state, U, of the thermal power generating unit i at the moment t-1 determined for the current scheduling plan
i,t-1∈{0,1};
Planning the determined output condition of the thermal power generating unit i at the moment t for 24h before the day; s
iThe starting cost of the thermal power generating unit i is obtained; a is
i、b
i、c
iThe first economic characteristic parameter, the first economic characteristic parameter and the third economic characteristic parameter of the thermal power generating unit i are respectively.
In the specific embodiment, hydropower is preferentially called by a 4h scheduling plan in a day to adjust power deviation, the lowest hydropower output adjustment cost and the lowest start-stop cost in the period are taken as target functions, and the fine adjustment of the combined state of the thermal power generating units is mainly used for arranging the quick start-stop of the small thermal power generating units according to the unit start-up priority determined by a priority method;
the objective function of the intra-day 4h dispatch plan is as follows:
wherein the content of the first and second substances,
hours divided for 4h scheduling plan in dayThe number of stages; epsilon
i.tAdjusting the cost for the unit output of the thermal power generating unit; delta P
G.i.tThe output adjustment quantity delta P is the output adjustment quantity of the thermal power generating unit i at the moment t
G′
.i.tThe difference value of the output condition of the medium-voltage generator set i in the 4h scheduling plan in the day and the output condition of the medium-voltage generator set i in the 24h scheduling in the day.
In the specific embodiment, the real-time 15-min scheduling plan preferentially calls hydropower to correct the power deviation, and meanwhile, due to the fact that the ultra-short-term prediction accuracy under the last time scale is high, the hydropower and thermal power output adjustment amount under the time scale is small, and the unit combination state is not adjusted; the minimum real-time adjustment cost of the thermal power generating unit is taken as a target, and no start-stop expense item exists; the objective function of the real-time 15min dispatch plan is as follows:
wherein N isgThe total number of the thermal power generating units; u shapei,tThe starting and stopping state, U, of the thermal power generating unit i at the moment t determined for the current scheduling plani,t∈{0,1};εi.tAdjusting the cost for the unit output of the thermal power generating unit; delta PG.i.tThe output adjustment quantity of the thermal power generating unit i at the moment t, the output adjustment quantity delta P ″)G.i.tThe difference value of the output condition of the I-type live-wire generator set in the real-time 15-min dispatching plan and the output condition of the I-type live-wire generator set in the 4-hour dispatching plan in the day is shown.
In the specific embodiment, the traditional physical constraints of each time scale scheduling plan include unit active output constraints, unit climbing capacity constraints, unit minimum on-off time constraints and wind/light abandoning constraints;
active power output constraint of the current time scale scheduling plan:
unit climbing capacity constraint of the current time scale scheduling plan:
wind/light curtailment constraints of the current time scale scheduling plan:
the minimum on-off time constraint of the unit of the current time scale scheduling plan is divided into the following two cases:
the minimum on-off time constraints of the unit of the 24h hour day-ahead scheduling plan and the real-time 15min scheduling plan are as follows:
the minimum start-up and shut-down time constraint of the unit of the 4h scheduling plan in the day is as follows:
in the above formula, the parameters have the following meanings: t is
start.i、T
stop.iRespectively scheduling the starting and stopping time of the fire generator set i in the plan for 4h in a day; p
G.i.t、P
G.i.t-1Respectively determining the output conditions of the thermal power generating unit i at the time t and the time t-1 determined by the current scheduling plan; u shape
i,t、U
i,t-1The starting and stopping states, U, of the thermal power generating unit i at the time t and the time t-1 determined by the current scheduling plan respectively
i,t∈{0,1},U
i,t-1∈{0,1};P
h.tDetermining the output condition of the hydroelectric generating set at the moment t for the current scheduling plan; p
w.tDetermining the output condition of the wind turbine generator at the moment t for the current scheduling plan; p
L.tLoad at time t determined for the current dispatch plan; p
max.i、P
min.iRespectively representing the upper output limit and the lower output limit of the thermal power generating unit i; p
h.max、P
h.minRespectively representing the upper output limit and the lower output limit of the hydroelectric generating set; r
u.i、R
d.iClimbing rate and slip of thermal power generating unit iA ramp rate;
respectively the continuous startup time and the continuous shutdown time of the thermal power generating unit from the moment i to the moment t-1;
respectively determining the minimum continuous starting time and the minimum continuous stopping time of the thermal power generating unit i; delta
1、δ
2Respectively the allowed maximum wind abandoning rate and the maximum light abandoning rate;
and
the maximum wind power and the photovoltaic available output at the moment t are respectively.
In this embodiment, the robust level value adjustment rule is as follows: and adjusting the robust level value by adjusting the confidence level, wherein the robust level value and the confidence level are adjusted in the following relation:
wherein epsilon is a confidence level selected under a current time scale plan, and a robust level value can be adjusted by adjusting the confidence level, so that robust optimization of multi-time scale scheduling is realized, the higher the robust level value is, the higher the system security is, and the lower the robust level value is, the better the system economy is, therefore, an appropriate robust level value needs to be selected to realize balance of the system economy and the security, and therefore, the following robust level value adjustment rule is established:
in this embodiment, the confidence level is adjusted according to the following principle:
first, the basic rule is determined: as the time scale is gradually reduced, the robust level value should be gradually increased; and the robust level value of the 24h day-ahead dispatch plan does not need to be set too high. The robust level value of the scheduling plan 24h before the day can be set to be smaller properly, and the robust level value is increased step by step in the subsequent time scale scheduling plan, so that the system scheduling safety is increased step by step at relatively lower economic cost, and the balance between the safety and the economy is realized;
secondly, on the basis of meeting the basic rule, the following adjustments are carried out according to the disturbance quantity of each uncertain factor and the new energy access proportion:
if the disturbance quantity values of all uncertain factors are closer, the robust level value of the maximum time scale plan, namely the day-ahead 24h scheduling plan, is increased, and if the disturbance quantity values of all uncertain factors are larger in difference, the robust water value of the maximum time scale plan is reduced to be close to the actual worst condition;
if the new energy access proportion is increased, the robust level value of each time scale scheduling plan is increased; the higher the new energy access proportion is, the larger the value of the predicted deviation value of the new energy output is, the more difficult the system can not cope with the bad situation, and the more difficult the system safety is to be ensured, so a higher robust level is set to improve the conservative degree of a scheduling plan, and the system safety is ensured as much as possible.
Finally, the above embodiments are only intended to illustrate the technical solutions of the present invention and not to limit the present invention, and although the present invention has been described in detail with reference to the preferred embodiments, it will be understood by those skilled in the art that modifications or equivalent substitutions may be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, which should be covered by the claims of the present invention.