A Method for Controlling Active Power of a Photovoltaic Power Station Based on Complementary Water and Light

Abstract

The present invention provides a method for controlling the active power of a photovoltaic power station based on the complementary use of water and light, comprising the following steps: Step 1, the hydropower station monitoring system schedules the active power target value of the hydropower unit issued by the AGC master station; Step 2, according to the limit transmission capacity of the outgoing channel and the active power target value of the hydropower unit, calculate the maximum limit value of the active power of the current photovoltaic power station; Step 3, according to the relationship between the real-time active power of the photovoltaic power station and the current planned value or the current maximum limit value of the photovoltaic power station, judge whether power reduction regulation is required; Step 4, judge whether the active power difference ΔP AGC is within the regulation dead zone; Step 5, distribute the active power target value of the inverter according to the equal proportion principle of capacity; Step 6, after all inverters complete the regulation according to the instruction, return to Step 4; Step 7, return to Step 1. Under the condition of taking into account the grid safety, the maximum consumption of the photovoltaic power station is achieved through automatic control.

Description

Technical Field

[0001] The invention relates to the technical field of photovoltaic power generation control, and in particular to an active power control method of a photovoltaic power station based on water-photovoltaic complementarity. Background Art

[0002] In accordance with the requirements of the national "14th Five-Year Plan" for integrated renewable energy development bases for wind, solar and water, we plan to build integrated renewable energy development bases for wind, solar and water, and promote the complementary development of wind, solar and water in reservoir power stations in other river basins.

[0003] The current hydro-photovoltaic complementary projects mainly connect the photovoltaic power plants within a certain range around the cascade hydropower stations in the basin to the nearest hydropower stations, and use the hydropower station's complementary regulation and its channel transmission to improve the transmission channel utilization rate. Since the access of photovoltaic power stations has squeezed the transmission channel of the hydropower station, it will weaken the peak-shaving and frequency-regulating capabilities of the hydropower station to a certain extent. Overall, it is of great significance to the safety of power grid operation to not change the position of the hydropower station in the system in the hydro-photovoltaic complementary project and give priority to meeting the overall peak-shaving and frequency-regulating needs of the entire network. Therefore, in this case, how to control the active power of the photovoltaic power station in the hydro-photovoltaic complementary project and realize the maximum absorption of the photovoltaic power station by limiting the photovoltaic output is an urgent problem to be solved. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a method for controlling active power of a photovoltaic power station based on water-photovoltaic complementarity, which realizes maximum absorption of the photovoltaic power station through automatic control while taking into account the safety of the power grid.

[0005] The technical solution adopted by the present invention to solve its technical problem is:

[0006] A method for controlling active power of a photovoltaic power station based on water-photovoltaic complementarity comprises the following steps:

[0007] Step 1: The hydropower station monitoring system dispatches the active power target value of the hydropower unit issued by the AGC master station;

[0008] Step 2: Calculate the maximum limit of the current active power of the photovoltaic power station according to the maximum transmission capacity of the transmission channel and the active power target value of the hydropower unit;

[0009] Step 3: Determine whether power reduction control is required based on the relationship between the real-time active power of the photovoltaic power station and the current planned value or the current maximum limit of the photovoltaic power station;

[0010] Step 4: Determine the difference in active power ΔP AGC Whether it is within the dead zone of adjustment, if not, proceed to step 5, otherwise proceed to step 7;

[0011] Step 5: Allocate the active power target value of the adjustable inverter according to the principle of equal proportion of capacity;

[0012] Step 6: After all adjustable inverters have been regulated according to the instructions, return to step 4;

[0013] Step 7: Return to step 1 and enter the next control cycle.

[0014] In step 2, the maximum limit value P of the current active power of the photovoltaic power station limit,t The calculation formula is as follows:

[0015] P limit,t =P Lmax -P safe -P h,t (one)

[0016] In formula (1), P Lmax P is the maximum conveying capacity of the delivery channel; safe is the active power safety margin; P h,t is the target value of the active power of the hydropower unit issued by the AGC master station at time t; P limit,t It is the maximum limit of the active power of the photovoltaic power station at time t.

[0017] In step 3, the determination of whether power reduction control is required includes the following steps:

[0018] S3.1, when P limit,t ≥P plant,t Go to step 3.2 when it is true, otherwise go to step 3.3;

[0019] S3.2, Active power P of the photovoltaic power station at time t t The restriction condition is P plant,t , when p t >P plant,t When , the power is reduced and the process goes to step 4, otherwise it goes to step 7;

[0020] S3.3, Active power P of the photovoltaic power station at time t t The restriction condition is P limit,t , when p t >P limit,t , then the power reduction control is carried out to enter step 4, otherwise it enters step 7;

[0021] Among them, P plant,t is the current planned value of the photovoltaic power station at time t, P t It is the real-time active power of the photovoltaic power station.

[0022] In step 4, the difference in active power ΔP AGC The calculation method is as follows:

[0023] K1. When entering step 4 from step 3.2, then ΔP AGC = P plant,t - p t ;

[0024] K2. When entering step 4 from step 3.3, then ΔP AGC = P limit,t - p t .

[0025] In step 5, the calculation method of the active power target value of the inverter is as follows;

[0026]

[0027] In formula (2), P itarget is the target value of the active power of the i-th inverter; P i,t is the real-time active power of the i-th inverter; n is the number of inverters participating in the regulation; is the sum of the real-time powers of all inverters participating in the regulation; P iN is the rated active power of the i-th inverter; is the sum of the rated active powers of all inverters participating in the regulation.

[0028] In step 7, the entry into the next regulation cycle is as follows: If within the regulation cycle of the photovoltaic power station, the dispatching AGC master station issues a new active power target value to the hydropower unit, the photovoltaic power station exits the current round of regulation and directly enters the next regulation cycle.

[0029] The beneficial effects of the present invention are:

[0030] 1. Through the current plan limitations of the hydropower station and the photovoltaic power station, it can meet the current power generation balance requirements of the entire network; when the dispatching AGC master station issues an active power regulation instruction to the hydropower unit, the photovoltaic power station can judge whether active power regulation is required according to the transmission channel capacity. Under the premise of taking into account the grid safety, the maximum consumption of the photovoltaic power station is achieved through automatic control. Description of the Drawings

[0031] Figure 1 is the flow chart of the present invention. Detailed Embodiments

[0032] The present invention will be further described below in conjunction with the drawings and embodiments.

[0033] Embodiment 1

[0034] As Figure 1 shown, a method for controlling the active power of a photovoltaic power station based on water-light complementarity includes the following steps;

[0035] Step 1: The active power target value of the hydropower unit issued by the dispatching AGC master station of the hydropower station monitoring system;

[0036] Step 2: Calculate the maximum limit value of the active power of the current PV power station according to the limit transmission capacity of the transmission channel and the active power target value of the hydropower unit;

[0037] Step 3: Judge whether power reduction regulation is required according to the relationship between the real-time active power of the PV power station and the current planned value or the current maximum limit value of the PV power station;

[0038] Step 4: Judge the difference ΔP of the active power AGC Whether it is within the regulation dead zone. If it is not within the regulation dead zone, go to Step 5; otherwise, go to Step 7;

[0039] Step 5: Allocate the active power target value of the adjustable inverter according to the equal proportion principle of capacity;

[0040] Step 6: After all adjustable inverters complete the regulation according to the instruction, return to Step 4;

[0041] Step 7: Return to Step 1 and enter the next regulation cycle.

[0042] In Step 2, the calculation formula of the maximum limit value P of the active power of the current PV power station limit,t is as follows:

[0043] P limit,t = P Lmax - P safe - P h,t (1)

[0044] In formula (1), P Lmax is the limit transmission capacity of the transmission channel; P safe is the active power safety margin; P h,t is the target value of the active power of the hydropower unit issued by the AGC master station at time t; P limit,t is the maximum limit value of the active power of the PV power station at time t.

[0045] By calculating the maximum limit value P limit,t through formula (1), the constraint of the active power safety margin limit of P safe is increased. Advantages: 1. Considering that the active power regulation rates of hydropower units and PV inverters are different, if P safe is not increased, there may be a situation where the total output of water and light exceeds the thermal stability limit of the transmission channel due to different regulation speeds; 2. Since the current combined operation of water and light is considered according to the total output of water and light not exceeding the installed capacity of hydropower, when the system is short of power, the total output of water and light can exceed the installed capacity of hydropower but cannot exceed the limit of the transmission channel, P safeThe setting of the value can be determined according to the actual requirements of the dispatching, making the operation more flexible and safe.

[0046] In step 3, the determination of whether power reduction regulation is required includes the following steps:

[0047] S3.1. When P limit,t ≥P plant,t , go to step 3.2; otherwise, go to step 3.3.

[0048] S3.2. The active power P of the PV power station at time t t The limit condition is P plant,t . When p t >P plant,t , perform power reduction regulation and go to step 4; otherwise, go to step 7.

[0049] S3.3. The active power P of the PV power station at time t t The limit condition is P limit,t . When p t >P limit,t , perform power reduction regulation and go to step 4; otherwise, go to step 7.

[0050] Among them, P plant,t is the current planned value of the PV power station at time t, and P t is the real-time active power of the PV power station.

[0051] By judging the power reduction regulation, the limitation of the PV power station's daily plan curve is increased. When the dispatching formulates the daily plan and the PV power station participates in the overall network balance, the output curve of each moment of the PV may exceed or be lower than the maximum limit value of the PV active power. Therefore, the active power control strategy needs to be adjusted according to different situations.

[0052] In step 4, the calculation method of the difference ΔP AGC of the active power is as follows:

[0053] K1. When entering step 4 from step 3.2, then ΔP AGC =P plant,t -p t ;

[0054] K2. When entering step 4 from step 3.3, then ΔP AGC =P limit,t -p t .

[0055] In step 5, the calculation method of the target value of the inverter active power is;

[0056]

[0057] In formula (2), P itargetis the target value of the active power of the i-th inverter; P i,t is the real-time active power of the i-th inverter; n is the number of inverters participating in the regulation; is the sum of the real-time powers of all inverters participating in the regulation; P iN is the rated active power of the i-th inverter; is the sum of the rated active powers of all inverters participating in the regulation.

[0058] By calculating the target value of the active power of the inverter and adopting the principle of equal proportion distribution of capacity, a fixed coefficient can be set without real-time calculation of the adjustable capacity of each inverter, which has low requirements for the hardware processing ability and calculation speed, and improves the control speed.

[0059] In step 7, the entry into the next regulation cycle is as follows: If the dispatching AGC master station issues a new target value of active power to the hydropower unit within the regulation cycle of the photovoltaic power station, the photovoltaic power station exits this round of regulation and directly enters the next regulation cycle.

[0060] Embodiment 2

[0061] A method for controlling the active power of a photovoltaic power station based on the complementarity of water and light, comprising the following steps;

[0062] Step 1, the hydropower station monitoring system forwards the output of the hydropower unit or the target value of the active power of the hydropower unit issued by the dispatching AGC master station to the photovoltaic power station in real time;

[0063] Step 2, calculate the maximum limit value of the active power of the current photovoltaic power station according to the limit transmission capacity of the outgoing channel and the real-time value and target value of the active power of the hydropower unit;

[0064] P limit,t = P Lmax - P safe - P h,t (1)

[0065] In formula (1), P Lmax is the limit transmission capacity of the outgoing channel; P safe is the active power safety margin, which can be set according to dispatching requirements, the ramp rate of hydropower units, photovoltaic power stations, etc.; P h,t is the target value of the active power of the hydropower unit issued by the AGC master station at time t; P limit,t is the maximum limit value of the active power of the photovoltaic power station at time t.

[0066] Step 3, judge whether power reduction regulation is required according to the relationship between the real-time active power of the photovoltaic power station and the current planned value or the current maximum limit value of the photovoltaic power station, which is divided into the following situations;

[0067] When P limit,t ≥ P plant,tWhen the PV active power \(P_t\) is restricted, the condition is \(P\) limit,t , when \(p\) t \(>\) \(P\) plant,t , power reduction control is required to enter Step 4, otherwise enter Step 7;

[0068] When \(P\) limit,t \(<\) \(P\) plant,t , the PV active power \(P\) t restriction condition is \(P\) limit,t , when \(P\) t \(>\) \(P\) limit,t , power reduction control is required to enter Step 4, otherwise enter Step 7;

[0069] Among them, \(P\) plant,t is the current planned value of the PV power station at time \(t\), and \(P\) t is the real-time active power of the PV power station;

[0070] Step 4: Judge whether the difference \(\Delta P\) AGC is within the regulation dead zone. If it is not within the regulation dead zone, then go to Step 5, otherwise go to Step 7. The calculation method of \(\Delta P\) AGC is as follows;

[0071] 1) If the PV active power \(P\) t restriction condition is \(P\) plant,t , then \(\Delta P\) AGC \(=\) \(P\) plant,t \(-\) \(p\) t ;

[0072] 2) If the PV active power \(P\) t restriction condition is \(P\) limit,t , then \(\Delta P\) AGC \(=\) \(P\) limit,t \(-\) \(p\) t .

[0073] Step 5: Allocate the target value of the adjustable inverter active power according to the capacity equal-proportion principle;

[0074] Excluding the inverters with communication interruptions and those already at the lowest lower limit from participating in the regulation, other inverters are allocated according to the capacity equal-proportion allocation principle:

[0075]

[0076] In formula (2), \(P\) itarget is the target value of the active power of the \(i\)-th inverter; \(P\) i,t is the real-time active power of the \(i\)-th inverter; \(n\) is the number of inverters participating in the regulation; is the sum of the real-time powers of all inverters participating in the regulation; \(P\) iN is the rated active power of the \(i\)-th inverter; It is the sum of the rated active powers regulated by all participating inverters;

[0077] Step 6: After all adjustable inverters complete the regulation according to the instruction, perform Step 4;

[0078] Step 7: Return to Step 1 to enter the next regulation cycle. If, within the regulation cycle of the photovoltaic power station, the dispatching AGC master station issues a new active power target value to the hydropower unit, the photovoltaic power station exits the current regulation cycle and directly enters the next regulation cycle.

[0079] Through the current plan limitations of the hydropower station and the photovoltaic power station, the current power generation balance requirements of the entire network can be met; when the dispatching AGC master station issues an active power regulation instruction to the hydropower unit, the photovoltaic power station can judge whether active power regulation is required based on the transmission channel capacity. Under the condition of taking into account the grid safety, the maximum consumption of the photovoltaic power station is achieved through automatic control.

[0080] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for controlling active power of a photovoltaic power station based on water-photovoltaic complementarity, characterized in that: The steps include: Step 1: The hydropower station monitoring system dispatches the active power target value of the hydropower unit issued by the AGC master station; Step 2: Calculate the maximum limit of the current active power of the photovoltaic power station according to the maximum transmission capacity of the transmission channel and the active power target value of the hydropower unit; Step 3: Determine whether power reduction control is required based on the relationship between the active power of the photovoltaic power station and the current planned value and the current maximum limit of the photovoltaic power station; Step 4: Determine the difference in active power △P AGC Whether it is within the dead zone of adjustment, if not, proceed to step 5, otherwise proceed to step 7; Step 5: Allocate the inverter active power target value according to the principle of equal proportion of capacity; Step 6: After all inverters have completed control according to the instructions, return to step 4; Step 7: Return to step 1 and enter the next regulation cycle; In step 2, the maximum limit value P of the current active power of the photovoltaic power station limit,t The calculation formula is as follows: P limit,t =P Lmax -P safe -P h,t (one) In formula (1), P Lmax P is the maximum conveying capacity of the delivery channel; safe is the active power safety margin; P h,t is the target value of the active power of the hydropower unit issued by the AGC master station at time t; P limit,t is the maximum limit of the active power of the photovoltaic power station at time t; In step 3, the step of determining whether power reduction control is required includes the following steps: S3.1, when P limit,t ≥P plant,t Go to step 3.2 when it is true, otherwise go to step 3.3; S3.2, Active power P of the photovoltaic power station at time t t The restriction condition is P plant,t , when p t >P plant,t When , the power is reduced and the process goes to step 4, otherwise it goes to step 7; S3.3, Active power P of the photovoltaic power station at time t t The restriction condition is P limit,t , when p t >P limit,t , then the power reduction control is carried out to enter step 4, otherwise it enters step 7; Among them, P plant,t is the current planned value of the photovoltaic power station at time t, P t The real-time active power of the photovoltaic power station; In step 4, the active power difference △P AGC The calculation method is as follows: K1. When step 3.2 enters step 4, then △P AGC =P plant,t -p t ; K2. When step 3.3 enters step 4, then △P AGC =P limit,t -p t .

2. The active power control method of a photovoltaic power station based on water-photovoltaic complementarity according to claim 1, characterized in that: In step 5, the calculation method of the inverter active power target value is: In formula (II), P itarget is the target value of active power of the i-th inverter; P i,t is the real-time active power of the i-th inverter; n is the number of inverters involved in the regulation; is the sum of the real-time powers of all inverters involved in regulation; P iN is the rated active power of the i-th inverter; It is the sum of the rated active powers of all inverters involved in the regulation.

3. The active power control method of a photovoltaic power station based on water-photovoltaic complementarity according to claim 1, characterized in that: In step 7, the step of entering the next regulation cycle is: if the AGC master station issues a new active power target value to the hydropower unit during the regulation cycle of the photovoltaic power station, the photovoltaic power station exits the current regulation and directly enters the next regulation cycle.

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