New energy power generation water-light combined complementary grid-connected self-adaptive control method

Abstract

According to the new energy power generation water-light combined complementary grid-connected self-adaptive control method, based on centralized photovoltaic power generation characteristics, a centralized grid-connected photovoltaic power station circuit topological structure is established, a water-light complementary dominant model is calculated, and a water-light complementary optimized grid-connected topological structure is constructed; modeling and analyzing each part of the water turbine regulation and control system, constructing a self-adaptive control system structure, and establishing a single-machine self-adaptive control load regulation and control model; a water turbine load regulation and control model is established, an output curve of a photovoltaic power station is optimized, and a hydroelectric generating set is adaptively regulated and controlled to meet the compensation requirement of photovoltaic output fluctuation; establishing a water-light complementary adaptive coordinated power generation and influence model, and optimizing and analyzing the water-light complementary model; according to the method, the output change of photovoltaic power generation can be quickly and stably tracked and compensated, the circuit topology is scientifically arranged to realize water-light complementation combined grid-connected power generation, and the method has the advantages of good economy, safety, reliability, strong water-light complementation control capability and high dispatching intelligence degree.

Description

Technical Field

[0001] The present application relates to a method for controlling a water-photovoltaic combined complementary grid-connected power generation, and in particular to a method for adaptively controlling a water-photovoltaic combined complementary grid-connected power generation for renewable energy, and belongs to the technical field of renewable energy power generation control. Background Art

[0002] New energy is renewable energy developed and utilized on the basis of new technologies, including wind energy, geothermal energy, wave energy, hydropower, solar energy, biomass energy, ocean current energy, tidal energy, and thermal cycles between the surface and deep layers of the ocean. As a new energy source, solar energy has three advantages: abundance, ubiquity, and cleanliness. At present, photovoltaic power generation is developing steadily and rapidly, and has gradually become an effective way to bear loads, reduce environmental pollution, and improve the comprehensive utilization rate of energy. Photovoltaic power generation is easily affected by weather factors and produces sawtooth load fluctuations. Large-scale photovoltaic power stations connected to the grid will threaten the safe operation of the power grid. At present, many photovoltaic operating companies have set their sights on photovoltaic complementary power generation technology, and solving the photovoltaic grid connection problem from the power generation source has also attracted more and more attention.

[0003] Among renewable energy sources, photovoltaic power generation has attracted more and more attention from various countries because it is easy to obtain and does not require transportation. In the past few years, the photovoltaic industry has flourished, and the installed capacity of photovoltaic power has grown "explosively". However, the rapid development of the photovoltaic industry has also brought many chaos and problems, including unstable photovoltaic power generation and insufficient market absorption, among which there is a serious problem of "abandoning light". Photovoltaic power generation output is characterized by volatility, randomness and intermittence. Large-scale grid-connected photovoltaic power generation is bound to pose a huge threat to the safe and stable operation of the power grid. Therefore, when the weather changes drastically and the photovoltaic output cannot be regulated, the power grid dispatcher can only abandon light to protect the grid. To this end, it is of great practical significance to develop efficient photovoltaic complementary grid-connected technology to solve the photovoltaic grid-connected problem from the source.

[0004] There are also some methods for smoothing the grid-connected photovoltaic power generation output in the existing technology, but these methods are mostly used in distributed photovoltaic power generation systems and are difficult to apply in large-scale centralized grid-connected photovoltaic power station projects. There is a lack of methods for using hydropower to compensate for photovoltaic output connected to the grid.

[0005] The problems that need to be solved in the existing large-scale grid-connected photovoltaic power generation and the key technical difficulties of this application include:

[0006] (1) Photovoltaic power generation is easily affected by weather factors and produces sawtooth load fluctuations. Large-scale photovoltaic power station grid connection will threaten the safe operation of the power grid. At present, the photovoltaic industry is booming and the photovoltaic installed capacity is growing explosively. The rapid development of the photovoltaic industry has also brought many chaos and problems. Photovoltaic power generation is unstable and the market absorption is insufficient. Among them, there is a serious problem of abandoned light. Photovoltaic power generation output is characterized by volatility, randomness and intermittence. Large-scale grid-connected photovoltaic power generation is bound to bring huge threats to the safe and stable operation of the power grid. When the weather changes drastically and the photovoltaic output cannot be regulated, the power grid dispatch can only abandon light to protect the network. There are also some methods for smoothing photovoltaic power generation output grid connection in the existing technology, but these methods are mostly used in distributed photovoltaic power generation systems. It is difficult to apply them in large-scale centralized grid-connected photovoltaic power station projects. The regulation effect is not obvious. There is still a large problem of energy waste, or the use of non-clean energy has caused new pollution. The stability of photovoltaic power generation output is poor. It is urgent to take measures to regulate and complement each other to become a smooth and stable active output.

[0007] (2) The existing technology lacks an efficient and reliable adaptive control method for hydro-photovoltaic combined grid-connected power generation. It is unable to establish a centralized grid-connected photovoltaic power station circuit topology based on the characteristics of centralized photovoltaic power generation and in combination with the specific performance of each grid-connected power generation equipment. It is unable to calculate the advantage model of hydro-photovoltaic complementarity and unable to build an optimized grid-connected topology for hydro-photovoltaic complementarity. It lacks modeling and analysis of each part of the turbine control system, unable to build an adaptive control system structure, and unable to establish a single-machine adaptive control load control model. It is unable to establish a turbine load control model in combination with the empirical parameters of the hydropower plant, unable to optimize the output curve of the photovoltaic power station, and unable to build a hydro-photovoltaic complementary joint control model. It is impossible to adaptively control the hydropower units to meet the compensation needs for photovoltaic output fluctuations; it is impossible to establish a hydro-photovoltaic complementary adaptive coordinated power generation and impact model, and it is impossible to optimize and analyze the hydro-photovoltaic complementary model under different control methods and different weather conditions; the randomness, intermittency and volatility of the power output of photovoltaic power generation are prominent, and it has an obvious day and night periodicity. It is impossible to give full play to the characteristics of hydropower such as rapid start-up, fast load control response, flexible operation, and easy grid control. It is impossible to compensate for unstable power supplies and realize the coordinated operation mechanism of hydro-photovoltaic complementarity. The feasibility of the actual application of hydro-photovoltaic combined complementary grid connection is insufficient. Not only is it impossible to coordinate, but new problems are also prone to arise, threatening the security of the power grid.

[0008] (3) The existing technology lacks an adaptive control model for the grid-connected water-photovoltaic joint complementarity. First, it lacks a grid-connected water-photovoltaic joint complementarity system structure, and is unable to utilize the rapid load regulation capability of the hydropower unit and the reservoir regulation capacity of the hydropower station, and is unable to smooth the active output of the photovoltaic power station. It is also unable to transform the low-quality photovoltaic power output into a smooth and stable active output after hydropower complementarity, resulting in a large impact of the output change of the photovoltaic power station on the power grid; second, it lacks an adaptive control strategy for the joint complementarity of water and photovoltaic, lacks an adaptive control method and modeling and analysis of the turbine control system, and is unable to conduct modeling and analysis of the combined pressure water diversion system, turbine, and hydro-generator; third, it lacks an adaptive control load regulation modeling for hydropower plants, lacks an adaptive control cycle, an adaptive control power control model, a single-machine adaptive control model, and a water-photovoltaic complementary joint control system modeling; fourth, it lacks an adaptive coordinated power generation and impact model for water-photovoltaic complementary: it lacks an adaptive control load distribution strategy for water-photovoltaic complementary, an adaptive control safety strategy for water-photovoltaic complementary, and other adaptive control strategies for water-photovoltaic complementary. The control effect of hydropower and photovoltaic complementary grid-connected is not good. It is impossible to timely and accurately control the complementary output of hydropower and photovoltaics, and cannot deal with the problems of abandoned light and instability in time. The regulation ability is weak and the degree of intelligence is low, which is not conducive to ensuring the safety and stability of the power system. Summary of the invention

[0009] The present application proposes a method for adaptive control of water-photovoltaic combined complementary grid-connected new energy power generation. Based on the characteristics of centralized photovoltaic power generation and combined with the specific performance of each grid-connected power generation equipment, a centralized grid-connected photovoltaic power station circuit topology is established, the advantage model of water-photovoltaic complementarity is calculated, and an optimized grid-connected topology of water-photovoltaic complementarity is constructed; each part of the turbine control system is modeled and analyzed respectively, and the system structure of adaptive control is constructed, and a single-machine adaptive control load control model is established; in combination with the empirical parameters of the hydropower plant, a turbine load control model is established, and under typical working conditions, the output curve of the photovoltaic power station is optimized and processed, and a water-photovoltaic complementary joint control model is constructed, and the hydropower units are adaptively controlled to meet the compensation needs of photovoltaic output fluctuations; a water-photovoltaic complementary adaptive coordinated power generation and influence model is established, and the water-photovoltaic complementary model is optimized and analyzed under different control methods and different weather conditions; it can quickly and smoothly track and compensate for the output changes of photovoltaic power generation, scientifically arrange the circuit topology to realize water-photovoltaic complementary combined grid-connected power generation, has good economy, safety, and reliability, strong water-photovoltaic complementary control ability, high degree of intelligent scheduling, and efficiently realizes the complementary advantages of water energy resources and light energy resources.

[0010] In order to achieve the above technical effects, the technical solutions adopted in this application are as follows:

[0011] The adaptive control method for grid-connected water-photovoltaic combined complementation of new energy power generation is as follows: first, based on the characteristics of centralized photovoltaic power generation and combined with the specific performance of each grid-connected power generation equipment, a centralized grid-connected photovoltaic power station circuit topology is established, the advantage model of water-photovoltaic complementation is calculated, and the optimized grid-connected topology of water-photovoltaic complementation is constructed; second, each part of the turbine control system is modeled and analyzed separately, and the system structure of adaptive control is constructed, and a single-machine adaptive control load control model is established; combined with the empirical parameters of the hydropower plant, a turbine load control model is established, and under typical working conditions, the output curve of the photovoltaic power station is optimized, and a water-photovoltaic complementary joint control model is constructed, and the hydropower units are adaptively controlled to meet the compensation needs of photovoltaic output fluctuations; third, a water-photovoltaic complementary adaptive coordinated power generation and impact model is established, and the water-photovoltaic complementary model is optimized and analyzed under different control methods and different weather conditions;

[0012] A. Hydropower-PV combined complementary grid-connected system structure: Utilize the rapid load regulation capability of hydropower units and the reservoir regulation capacity of hydropower stations to smooth the active output of photovoltaic power stations. After hydropower complementation, the low-quality photovoltaic power output is transformed into a smooth and stable active output, reducing the impact of photovoltaic power station output changes on the power grid, including hydropower compensation for photovoltaic and photovoltaic compensation for hydropower;

[0013] B. Hydro-PV joint complementary adaptive control strategy: including adaptive control method and turbine control system modeling and analysis. The turbine control system modeling and analysis are combined with the pressure water diversion system, turbine and turbine generator for modeling and analysis;

[0014] C. Modeling of adaptive load control in hydropower plants: including adaptive control cycle, adaptive power control model, single machine adaptive control model, and modeling of water-solar complementary joint control system;

[0015] D Hydro-PV complementary adaptive coordinated power generation and impact model: including hydro-PV complementary adaptive control load distribution strategy, hydro-PV complementary adaptive control safety strategy, and hydro-PV complementary adaptive control other strategies.

[0016] Preferably, the water-solar combined complementary grid-connected system structure is:

[0017] 1) Compensation of hydropower to photovoltaic power: This is achieved through two compensation processes: the first compensation uses the rapid load regulation capability of hydropower units to smooth the sawtooth output process of photovoltaic power; the second compensation is based on the first compensation, and the intermittent, volatile and random nature of photovoltaic output is further eliminated through the regulation of water energy by reservoir capacity and the rapid regulation of output by hydropower units, so that the combined output of hydropower is maintained at the required value of grid dispatch; the two compensations of hydropower to photovoltaic power are carried out simultaneously, and the quality of photovoltaic power output is improved through the complementary and adaptive control of hydropower and photovoltaic power, and the abandonment rate of photovoltaic power stations is reduced, creating favorable conditions for full grid connection of photovoltaic power generation;

[0018] 2) Photovoltaic compensation for hydropower: First, hydropower stations must maintain a certain flow rate to meet the comprehensive water demand of downstream. At the same time, hydropower also undertakes the task of peak load regulation. When the river water is dry, photovoltaics participate in the complementarity, and use the daytime to make photovoltaics fully generate electricity. Hydropower maintains low load operation so that the reservoir can store more water energy; during the evening peak period of the grid load, hydropower increases its output to compensate photovoltaics and participate in peak load regulation; second, in dry years or winter and spring dry seasons, hydropower water supply restrictions lead to less power generation. At this time, photovoltaics make up for the shortage of hydropower electricity; and in wet years or summer and autumn wet seasons, the large-scale generation of hydropower makes up for the power deficit of photovoltaic power generation caused by rainy weather, and flexibly uses the complementarity of water and light to increase peak load regulation and improve the joint peak load regulation capacity.

[0019] Preferably, the hydro-photovoltaic joint complementary adaptive control strategy includes grid adaptive control, power plant adaptive control and unit control system; it is divided into several control areas according to the location of the power source and the load, and each control area is interconnected by a tie line. The control area has its own perfect adaptive power generation control system. In the control area, the generator set is divided into adaptive control units and non-adaptive control units according to the specific conditions of the generator set and the grid dispatching requirements. The grid dispatching center sets load frequency control software, which collects grid frequency, tie line flow, system time deviation parameters in real time and calculates the regional control deviation of the control area. After filtering, a smooth regional control deviation value is obtained, and then the adaptive control control power value of each unit is calculated according to the actual power, base point power and adaptive control allocation coefficient of each generator set, and sent to each adaptive control unit. The unit changes the output through the control system;

[0020] Adaptive control data flow: The load changes of the power system have certain regularity. The short-term fluctuating load is regulated by the unit's own speed governor, which is the primary regulation. The long-term fluctuating load is regulated by adaptive control, which is the secondary regulation. The long-term load fluctuation is adjusted by the power generation plan, which is the tertiary regulation.

[0021] Adaptive control rules for hydropower plants: First, control the overall active power output of the power plant. Hydropower adaptively controls the start and stop sequence and load distribution of each participating control unit to ensure that the output of the entire plant meets the dispatching requirements; second, ensure the safe operation of the unit. During operation, avoid the vibration area, cavitation area and the unit's poor operating condition area; third, ensure the economical operation of the unit. Reasonable load distribution is carried out according to the efficiency of different units under different heads, so as to minimize the water consumption rate of the entire plant while meeting the dispatching load requirements.

[0022] Preferably, the pressure water diversion system modeling analysis: When the control system has small fluctuations and the length of the pressure pipeline does not exceed 600 to 800 meters, a rigid water hammer model is used. The pressure wave generated by the water hammer will instantly propagate to the entire pressure water diversion pipeline. The water hammer pressure is expressed as:

[0023]

[0024] △H is the water hammer pressure, A is the pipe cross-sectional area, L is the pipe length, Q is the water flow rate in the pipe, where the flow rate Q is the sum of the initial flow rate Q0 and the flow change △Q, and we get:

[0025]

[0026] Taking the relative values ​​on both sides of equation 1, we get:

[0027]

[0028] Where:

[0029] H r is the rated water head, Q r is the rated flow rate, and after taking Laplace transformation of formula 3, we get:

[0030] H(s)=-T w sQ(s) Equation 4

[0031] The transfer function of the water diversion system is obtained as follows:

[0032]

[0033] Where: is the water flow inertia time constant, unit s, T w It is the case that the water flow is at the rated head H without considering the hydraulic loss in the pipeline. r From 0 to rated flow Q r The time required, T w The larger it is, the greater the water hammer pressure is, and the greater the impact on the turbine control system is. The model of the water diversion system under rigid water hammer is obtained.

[0034] Preferably, the turbine modeling analysis: the dynamic characteristics of the turbine are expressed by flow rate Q, head H, guide vane opening a, torque M t , speed n and blade angle φ, and the dynamic characteristics of the turbine are expressed by the torque characteristics and flow characteristics under steady-state conditions:

[0035] Torque: M t =M t (a,n,H);

[0036] Flow rate: Q = Q(a,n,H);

[0037] In the case of small fluctuations, the dynamic parameters only fluctuate slightly under steady-state conditions, which can be approximated by linear equations:

[0038] Torque: mt =e y y+e x x+e h h;

[0039] Flow rate: qt = e qy y+e qx x+e qh h;

[0040] Among them, mt is the relative value of torque deviation, q is the relative value of flow deviation, y is the relative value of guide vane opening deviation, x is the relative value of speed deviation, h is the relative value of head deviation, e y is the transfer coefficient of turbine torque to guide vane opening, e x is the transmission coefficient of turbine torque to speed, e h is the turbine torque to head transfer coefficient, e qy is the transfer coefficient of turbine flow to guide vane opening, e qx is the turbine flow to speed transfer coefficient, e qh is the turbine flow to head transfer coefficient;

[0041] For an ideal turbine, the transfer coefficient is: e y =1,e h =1.5q,e qy =1,e qh =0.5q,e qx =0;

[0042] Let the relative flow rate q = 1.0, and we get e h =1.5, e qh =0.5; integrating the water diversion system and the turbine module, we get:

[0043]

[0044] Equation 6 is the transfer function of the water diversion system and the turbine.

[0045] Preferably, the modeling analysis of the hydro-generator is as follows: the motion equation of the hydro-generator when operating under small fluctuation conditions is:

[0046]

[0047] Where: J is the moment of inertia of the rotating part of the unit, unit: kggm 2 ;ω is the angular velocity of the unit, unit rad / s; M t is the turbine torque, in Ngm; Mg is the generator load torque, in Ngm. The active torque of the turbine is expressed as:

[0048] M t =M t0 +ΔMt Formula 8

[0049] Under steady-state conditions, M g0 =M t0 =M r , M g =M g0 +ΔM g , take the relative value of the deviation, and let Indicates the relative value of the generator load torque deviation; Represents the relative value of the turbine output torque deviation, and we get:

[0050]

[0051] Then the relative value of the deviation is used to express the unit motion equation:

[0052]

[0053] in Where: T a GD is the inertia time constant of the unit, in seconds; 2 Flywheel torque of the rotating part of the unit, unit KNgn 2 ;n r is the rated speed of the unit; N r is the rated output of the unit, T a The size of T is related to the stability of the system. The larger the value, the more conducive it is to the stability of the control system. a It includes not only the mechanical inertia of the generator rotor, but also the mechanical inertia of the rotating part of the turbine and the mechanical inertia of the water in the runner area, namely:

[0054] GD 2 =GD g 2 +GD i 2 +GD w 2 Formula 11

[0055] The change of load resistance moment consists of two parts, expressed in m g0 Indicates the input change of generator load, Expressing the change in resistance torque caused by the change in generator speed, we get:

[0056]

[0057] make It is expressed as the transmission coefficient of the generator load torque deviation to the generator speed deviation, and is the generator load self-regulation coefficient. Its value is greater than 0 and around 1.0. The above formula is simplified to:

[0058] m g=m g0 +e g x formula 13

[0059] The dynamic equation of generator load is:

[0060]

[0061] Use T b Indicates the mechanical inertia in the power grid, m g0 As the disturbance, it is expressed by a step function, let e n =e g -e x , represents the comprehensive self-regulation coefficient of the hydro-generator set, and the generator transfer function is obtained as follows:

[0062]

[0063] The first-order generator and load model are obtained.

[0064] Preferably, adaptive control cycle: adaptive control power instructions are sent to the power plant and the unit according to a certain cycle, and the cycles associated therewith include: adaptive control data acquisition cycle (execution cycle), adaptive control command cycle and unit control command cycle;

[0065] (1) Adaptive control data collection cycle: The adaptive control data collection cycle is 2 to 4 seconds. In each data collection cycle, the adaptive control updates the data once and calculates the regional ACE value and performance monitoring;

[0066] (2) Adaptive control command cycle: Take an integer multiple of the data collection cycle. In addition to completing the tasks of the data collection cycle, it is also necessary to calculate the base power of each unit participating in the adaptive control control, and together with the ACE control power form the target power;

[0067] (3) Unit control command cycle: It is determined by the adaptive control command cycle and the actual control command issued by the unit. The target output is issued within the adaptive control command cycle. If the unit has responded to the last control command, the current control command is issued immediately. If the unit has not responded to the last control command, the current control command will not be issued for the time being. The maximum control amount issued each time can be set manually. For a given value control unit, the control amount should take a larger value or the maximum value to avoid frequent issuance.

[0068] Preferably, the adaptive control power control model:

[0069] (1) Adaptive control power fixed value regulation model: The adaptive control power fixed value regulation mode refers to the adaptive control module directly issuing the power value command that the unit should issue at this moment to the microcomputer speed governor through the host computer. After receiving the command, the speed governor implements it according to the predetermined control law. In the adaptive control power fixed value regulation mode, the host computer only completes the distribution calculation of the unit power, and the closed-loop regulation of active power is realized by the speed governor itself. At this time, the speed governor works in the power regulation mode;

[0070] P C is the target power sent from the dispatching center to the hydropower plant, k l , k2, …, k n is the proportional coefficient of each unit, p cl 、p c2 ,…,p cn The power setting is sent to each unit for adaptive control of the hydropower plant. The primary and secondary frequency regulation of the unit do not interfere with each other. When the secondary frequency regulation of the system ends, the frequency deviation is 0, and the actual power of the unit is equal to the target power.

[0071] (2) Adaptive control power pulse regulation model: In the pulse form adaptive control power closed-loop control mode, the corresponding speed regulator works in the opening control mode. First, the power deviation △P is converted into a series of pulses with adjustable pulse width or period, and connected to the increase and decrease button or dedicated IO interface in the form of switch quantity. When the pulse is at a high level, it is equivalent to the button being closed, and the opening set value changes; when the pulse is at a low level, it is equivalent to the button being disconnected, and the opening set value remains unchanged. If the power deviation △P is positive, only an increase pulse is given if the unit power needs to be increased; if the power deviation △P is negative, only a decrease pulse is given if the unit power needs to be reduced;

[0072] Improve the pulse width modulation method, and use several narrow pulses to equalize a wide pulse in a unit control cycle, that is, the pulse train method. Set up special hardware in the LCU, and the speed regulator reserves a special increase and decrease pulse I / O interface;

[0073] P C To dispatch the given power sent by EMS to the hydropower plant, P1, P2... are the measured power of each hydropower unit, P is the measured total power of the hydropower plant, K1, K2... are the load distribution coefficients of each unit, △P1, △P2... are the incremental power allocated to each unit, P is the power control law formation module, which together with the pulse width generator module and the given integrator module constitutes the power regulator, and its transfer function is:

[0074]

[0075] Where, w P is the power control proportional gain, w Iis the power control integral gain, is the speed regulator opening given value action time constant, T iy is a speed regulator parameter, indicating the time required for the opening given value to change from 0 to 100%; w P 、w I is the adaptive control module parameter in the monitoring system, where w P Indicates the conversion coefficient between power and guide vane opening, w I Indicates the speed of the regulation process. If w I If w, < 1, the action time of the equivalent opening given value increases, and the control process slows down. If w, > 1, the action time of the equivalent opening given value decreases, and the control process speeds up.

[0076] Preferably, the single-machine adaptive control model: the established single-machine adaptive control power regulation model includes PID regulation, pulse generation, given integral link, and dead zone link. The pulse generator receives the power regulation instruction of the upper computer to generate load increase and decrease pulses to control the guide vane opening; the given integral link integrates the pulse sent by the pulse generator to control the guide vane opening; the dead zone link is set to prevent small load deviations from causing frequent regulation of the unit;

[0077] w t represents the pulse generation period, which is 4 to 8 seconds; w tmax Indicates the maximum pulse width, which is 1 to 3 seconds; w tmin Indicates the minimum pulse width, which is about 0.1 seconds, w P 、w I A larger value can speed up the power regulation, but it is easy to cause overshoot. P 、w I If the value is smaller, the power control speed will be slower, resulting in inadequate power control. In addition, a reasonable power control dead zone should be set to prevent the unit from being controlled too frequently. At the same time, under the premise of ensuring safe and stable operation, the control dead zone should be as small as possible to ensure the accuracy of power control, and set to 0.5-1% of the rated power value of the unit.

[0078] Preferably, the load distribution strategy for hydro-photovoltaic complementary adaptive control is as follows: after the dispatching center sends the target load to the hydropower plant adaptive control, the active power between the units is distributed in the following manner;

[0079] (1) Proportional to unit capacity: When the turbine characteristic curve cannot be obtained or the characteristic curve parameters are inaccurate, this method is used to allocate the capacity according to the proportion of each unit capacity to the total capacity under the current water head. The allocation method is as follows:

[0080]

[0081] Where: P i The power value assigned to the i-th unit, Pc To dispatch a given hydropower plant load target value, P imax is the maximum power value of the i-th unit under the current water head;

[0082] (2) Equal incremental rate method: The objective function of adaptive control should be to minimize the total water consumption of the hydropower plant, assuming that the water consumption of the hydropower unit is only proportional to the active power generated by the generator unit P. g Association, objective function:

[0083]

[0084] Constraints:

[0085] P st =P1+P2+…+P n Formula 19

[0086] P gimin ≤P gi ≤P gimax Formula 20

[0087] Q gimin ≤Q gi ≤Q gimax Formula 21

[0088] V imin ≤V i ≤V imax Formula 22

[0089] Where P gi is the actual power generated by the i-th unit, Q gi is the water consumption of the i-th unit, V i is the bus voltage of the i-th unit. The Lagrange multiplier method can be used to solve the conditional extreme value problem of the above formula, and the auxiliary equation is established as follows:

[0090]

[0091] Through differential calculation, the optimal operation mode of the hydropower unit is obtained as follows:

[0092]

[0093] q is the power generated by generator set i, which is P gi The slight increase rate of consumption at that time;

[0094] (3) Multi-objective planning method: The adaptive control multi-objective planning method of hydropower plants allocates loads to meet the following goals: 1) save water and increase power generation; 2) the adaptive control allocation value is as close as possible to the dispatching given value; 3) avoid the unit frequently crossing the vibration zone; 4) the unit load fluctuation caused by two consecutive load adjustments is minimized;

[0095] The equal capacity proportion method is adopted to distribute the unit load. When designing the adaptive control of water-photovoltaic complementary power system, the iterative equal division method is incorporated to make up for the shortcomings of the algorithm.

[0096] Compared with the prior art, the innovations and advantages of this application are:

[0097] (1) The present application proposes a method for adaptive control of water-photovoltaic complementary grid-connected renewable energy power generation. Based on the characteristics of centralized photovoltaic power generation and combined with the specific performance of each grid-connected power generation equipment, a centralized grid-connected photovoltaic power station circuit topology is established, the advantage model of water-photovoltaic complementarity is calculated, and an optimized grid-connected topology of water-photovoltaic complementarity is constructed; each part of the turbine control system is modeled and analyzed respectively, and the system structure of adaptive control is constructed, and a single-machine adaptive control load control model is established; combined with the empirical parameters of the hydropower plant, a turbine load control model is established, and under typical working conditions, the output curve of the photovoltaic power station is optimized and processed, and a water-photovoltaic complementary joint control model is constructed, and the hydropower units are adaptively controlled to meet the compensation needs of photovoltaic output fluctuations; a water-photovoltaic complementary adaptive coordinated power generation and impact model is established, and the water-photovoltaic complementary model is optimized and analyzed under different control methods and different weather conditions; it can quickly and smoothly track and compensate for the output changes of photovoltaic power generation, scientifically arrange the circuit topology to realize water-photovoltaic complementary grid-connected power generation, and has good economy, safety, and reliability. It has strong water-photovoltaic complementary control capabilities and a high degree of intelligent scheduling, and efficiently realizes the complementary advantages of water and light resources.

[0098] (2) This application fully utilizes the advantages of the water-photovoltaic combined complementary power generation system by analyzing the respective characteristics of photovoltaic power generation and hydropower generation; models and analyzes the various parts of the turbine control system, and establishes a single-unit adaptive control load control model for hydropower units that conforms to the actual situation on site; proposes a water-photovoltaic complementary joint control strategy, and establishes a water-photovoltaic complementary joint control model that can quickly and smoothly track and compensate for the output changes of photovoltaic power generation. First, a water-photovoltaic combined complementary grid-connected system structure is proposed, which utilizes the rapid load regulation capability of the hydropower units and the reservoir regulation capacity of the hydropower station to smooth the active output of the photovoltaic power station, and converts the low-quality photovoltaic power output into a smooth and stable active output after hydropower complementation, thereby reducing the impact of photovoltaic power station output changes on the power grid, including the compensation of hydropower to photovoltaic and photovoltaic to hydropower; second, a water-photovoltaic combined complementary adaptive control strategy is proposed; third, a hydropower plant adaptive control load regulation model is proposed, and the hydropower units are adaptively regulated to meet the compensation needs of photovoltaic output fluctuations; fourth, a water-photovoltaic complementary adaptive coordinated power generation and impact model is proposed, and the water-photovoltaic complementary model is optimized and analyzed. The results fully verify the scientificity and feasibility of the water-photovoltaic complementary adaptive control strategy, and the water-photovoltaic complementary application model has positive promotion value in the development and utilization of photovoltaic power stations.

[0099] (3) In view of the many problems caused by the grid connection of large-scale centralized photovoltaic power stations, and based on the objective complementarity of water resources and light energy resources, this application studies the mechanism of water-light complementary coordinated operation, models and analyzes each module of the turbine control system and the photovoltaic array; establishes a single-machine adaptive control load control model of hydropower units that conforms to the actual situation on site; establishes a water-light joint complementary control model; and gives full play to the advantages of water resources and light energy resources. First, it realizes the resource complementarity advantage. Water resources have seasonal periodic changes with abundant water in summer and dry water in winter, and light energy resources are affected by diurnal changes and seasonal changes. In winter, hydropower has to reduce its output and generate less electricity when it enters the dry season. However, due to the dry weather, few clouds and abundant sunshine in winter, it is an excellent time for photovoltaic power generation, thus forming the natural complementary advantages of water energy and light energy. Second, it realizes the equipment complementary advantage. The hydropower station has a complete substation and transmission network. The photovoltaic power station uses the hydropower transmission network to connect to the grid for power generation. On the one hand, it saves the substation and transmission costs of the photovoltaic power station, and on the other hand, it improves the utilization rate of the hydropower transmission equipment. The third is to realize the complementary advantages of technology. The hydropower station has built a complete primary and secondary system, and the photovoltaic power station uses the existing electrical equipment to complete the tasks of grid connection, control and regulation, and dispatch communication. Make full use of the rapid load regulation capability of the hydropower unit and the reservoir regulation capacity of the hydropower station to smooth the active output of the photovoltaic power station, and transform the low-quality photovoltaic power generation output into a smooth and stable active output after hydropower complementation, reduce the impact of the photovoltaic power station output change on the power grid, and improve the safety and stability of photovoltaic grid connection. BRIEF DESCRIPTION OF THE DRAWINGS

[0100] Figure 1 This is the data flow chart of the adaptive control of the power system of this application.

[0101] Figure 2 It is the model block diagram of the water diversion system under rigid water hammer.

[0102] Figure 3 It is the structural block diagram of the water diversion system and turbine module.

[0103] Figure 4 It is a block diagram of the first-order generator and load model.

[0104] Figure 5 It is the principle diagram of adaptive control power constant value adjustment.

[0105] Figure 6 It is a schematic diagram of the adaptive control power pulse regulation method. DETAILED DESCRIPTION

[0106] The following, in conjunction with the accompanying drawings, further describes the technical solution of the adaptive control method for the grid-connected water-photovoltaic combined complementary renewable energy power generation provided in the present application, so that those skilled in the art can better understand the present application and implement it.

[0107] Through modeling and analysis of various parts of the turbine control system, firstly, based on the characteristics of centralized photovoltaic power generation and combined with the specific performance of each grid-connected power generation equipment, a centralized grid-connected photovoltaic power station circuit topology structure is established, the advantage model of water-photovoltaic complementarity is calculated, and the optimized grid-connected topology structure of water-photovoltaic complementarity is constructed; secondly, each part of the turbine control system is modeled and analyzed separately, and the system structure of adaptive control is constructed, and a single-machine adaptive control load control model is established; combined with the empirical parameters of the hydropower plant, a turbine load control model is established, and under typical working conditions, the output curve of the photovoltaic power station is optimized, and a water-photovoltaic complementary joint control model is constructed, and the hydropower units are adaptively controlled to meet the compensation needs of photovoltaic output fluctuations; thirdly, a water-photovoltaic complementary adaptive coordinated power generation and impact model is established, and the water-photovoltaic complementary model is optimized and analyzed under different control methods and different weather conditions;

[0108] 1. Structure of the water-solar combined complementary grid-connected system

[0109] By utilizing the rapid load regulation capability of the hydropower units and the reservoir regulation capacity of the hydropower station, the active output of the photovoltaic power station can be smoothed, and the low-quality photovoltaic power output can be transformed into a smooth and stable active output after hydropower complementation, reducing the impact of photovoltaic power station output changes on the power grid and improving the safety and stability of photovoltaic grid connection.

[0110] (1) Compensation of photovoltaic power by hydropower: This is achieved through two compensation processes: the first compensation uses the rapid load regulation capability of hydropower units to smooth the sawtooth output process of photovoltaic power; the second compensation is based on the first compensation, which further eliminates the intermittent, volatile and random nature of photovoltaic output by regulating water energy through reservoir capacity and rapidly regulating output of hydropower units, so that the combined output of hydropower is maintained at the required value of grid dispatch; the two compensations of photovoltaic power by hydropower are carried out simultaneously, and the quality of photovoltaic power output is improved through the complementary and adaptive control of hydropower and photovoltaic power, reducing the abandonment rate of photovoltaic power stations and creating favorable conditions for full grid connection of photovoltaic power generation.

[0111] (2) Photovoltaic compensation for hydropower: First, hydropower stations must maintain a certain flow rate to meet the comprehensive water demand of the downstream. At the same time, hydropower also undertakes the task of peak load regulation. When the river water flow is dry, photovoltaics participate in the complementary work, using the daytime to make photovoltaics fully generate electricity, and hydropower maintains low load operation so that the reservoir can store more water energy; during the evening peak period of the grid load, hydropower increases its output to compensate photovoltaics and participate in peak load regulation; second, in dry years or winter and spring dry seasons, hydropower water flow restrictions lead to less power generation. At this time, photovoltaics make up for the shortfall in hydropower power; and in wet years or summer and autumn wet seasons, hydropower generation makes up for the power deficit of photovoltaic power generation caused by rainy weather, flexibly utilizing the complementarity of water and photovoltaics to increase peak load regulation and improve the joint peak load regulation capability.

[0112] 2. Water-light joint complementary adaptive control strategy

[0113] 1. Adaptive control method

[0114] It includes grid adaptive control, power plant adaptive control and unit control system; it is divided into several control areas according to the location of power source and load, and each control area is interconnected by interconnection lines. Each control area has its own perfect adaptive power generation control system. In the control area, the generator set is divided into adaptive control units and non-adaptive control units according to the specific conditions of the generator set and the grid dispatching requirements. The grid dispatching center sets up load frequency control software, which collects grid frequency, interconnection line flow, system time deviation parameters in real time and calculates the regional control deviation of the control area. After filtering, a smooth regional control deviation value is obtained, and then the adaptive control control power value of each unit is calculated according to the actual power, base point power and adaptive control allocation coefficient of each generator set, and sent to each adaptive control unit. The unit changes its output through the control system.

[0115] 1. Adaptive control of data flow

[0116] The load changes in the power system have certain regularity. The short-term fluctuating load is regulated by the unit's own speed governor, which is primary regulation. The longer-term fluctuating load is regulated by adaptive control, which is secondary regulation. The long-term load fluctuation is adjusted through the power generation plan, which is tertiary regulation.

[0117] The energy management system of the power grid dispatching center is the core hub for achieving the stability of the power grid frequency. It consists of data acquisition and monitoring, adaptive control, economic dispatching control, and power grid analysis and application. The various systems share information and exchange data through the network. The specific data flow is as follows: Figure 1 shown.

[0118] 2. Adaptive control rules for hydropower plants

[0119] The adaptive control of the hydropower plant determines the number of operating units, the combination of operating units, load distribution and the start-stop sequence between units according to the load distribution requirements of the power system adaptive control, based on the water inflow and discharge of the reservoir, while taking into account the output limit and adverse operating conditions of the units. At the same time, in the process of adjusting to the target load, the adaptive control of the hydropower plant avoids frequent start-stop of units due to short-term load fluctuations of the power system;

[0120] The first is to control the overall active power output of the power plant, and the hydropower adaptively controls the start and stop sequence and load distribution of each participating control unit to ensure that the output of the entire plant meets the dispatching requirements; the second is to ensure the safe operation of the unit, and avoid the vibration area, cavitation area and poor operating condition area of ​​the unit during operation; the third is to ensure the economical operation of the unit, and reasonably distribute the load according to the efficiency of different units under different water heads, so as to minimize the water consumption rate of the entire plant while meeting the dispatching load requirements.

[0121] (II) Modeling and analysis of turbine control system

[0122] 1. Modeling and analysis of pressure water diversion system

[0123] In the case of small fluctuations in the control system, when the length of the pressure pipeline does not exceed 600 to 800m, the rigid water hammer model is used. The pressure wave generated by the water hammer will instantly propagate to the entire pressure water diversion pipeline. The water hammer pressure is expressed as:

[0124]

[0125] △H is the water hammer pressure, A is the pipe cross-sectional area, L is the pipe length, Q is the water flow rate in the pipe, where the flow rate Q is the sum of the initial flow rate Q0 and the flow change △Q, and we get:

[0126]

[0127] Taking the relative values ​​on both sides of equation 1, we get:

[0128]

[0129] Where:

[0130] H r is the rated head, Q r is the rated flow rate, and after taking Laplace transformation of formula 3, we get:

[0131] H(s)=-T w sQ(s) Equation 4

[0132] The transfer function of the water diversion system is obtained as follows:

[0133]

[0134] Where: is the water flow inertia time constant, unit s, T w It is the case that the water flow is at the rated head H without considering the hydraulic loss in the pipeline. r From 0 to rated flow Q r The time required, T w The larger the value, the greater the water hammer pressure, and the greater the impact on the turbine control system. The model block diagram of the water diversion system under rigid water hammer is obtained as follows: Figure 2 shown.

[0135] 2. Turbine modeling analysis

[0136] The dynamic characteristics of the turbine are expressed by flow rate Q, water head H, guide vane opening a, torque Mt, speed n and blade angle φ. The dynamic characteristics of the turbine are expressed by the torque characteristics and flow characteristics under steady-state conditions:

[0137] Torque: M t =M t (a,n,H);

[0138] Flow rate: Q = Q(a,n,H);

[0139] In the case of small fluctuations, the dynamic parameters only fluctuate slightly under steady-state conditions, which can be approximated by linear equations:

[0140] Torque: m t =e y y+e x x+e h h;

[0141] Flow rate: qt = e qy y+e qx x+e qh h;

[0142] Among them, mt is the relative value of torque deviation, q is the relative value of flow deviation, y is the relative value of guide vane opening deviation, x is the relative value of speed deviation, h is the relative value of head deviation, e y is the transfer coefficient of turbine torque to guide vane opening, e x is the transmission coefficient of turbine torque to speed, e h is the turbine torque to head transfer coefficient, e qy is the transfer coefficient of turbine flow to guide vane opening, e qx is the turbine flow to speed transfer coefficient, e qh is the turbine flow to head transfer coefficient;

[0143] For an ideal turbine, the transfer coefficient is: e y =1,e h =1.5q,e qy =1,e qh =0.5q,e qx =0;

[0144] Let the relative flow rate q = 1.0, and we get e h =1.5, e qh =0.5; Combine the water diversion system and turbine module to get the structural block diagram as follows Figure 3 .get:

[0145]

[0146] Equation 6 is the transfer function of the water diversion system and the turbine.

[0147] 3. Hydro-generator modeling analysis

[0148] The motion equation of the hydro-generator when operating under small fluctuation conditions is:

[0149]

[0150] Where: J is the moment of inertia of the rotating part of the unit, unit: kggm 2 ;ω is the angular velocity of the unit, unit rad / s; M t is the turbine torque, in Ngm; Mg is the generator load torque, in Ngm. The active torque of the turbine is expressed as:

[0151] M t =M t0 +ΔM t Formula 8

[0152] Under steady-state conditions, M g0 =M t0 =M r , M g =M g0 +ΔM g , take the relative value of the deviation, and let Indicates the relative value of the generator load torque deviation; Represents the relative value of the turbine output torque deviation, and we get:

[0153]

[0154] Then the relative value of the deviation is used to express the unit motion equation:

[0155]

[0156] in Where: T a GD is the inertia time constant of the unit, in seconds; 2 Flywheel torque of the rotating part of the unit, unit KNgn 2 ;n r is the rated speed of the unit; N r is the rated output of the unit, T a The size of T is related to the stability of the system. The larger the value, the more conducive it is to the stability of the control system. a It includes not only the mechanical inertia of the generator rotor, but also the mechanical inertia of the rotating part of the turbine and the mechanical inertia of the water body in the runner area, namely:

[0157] GD 2 =GD g 2 +GD t 2 +GDw 2 Formula 11

[0158] The change of load resistance moment consists of two parts, expressed in m g0 Indicates the input change of generator load, Expressing the change in resistance torque caused by the change in generator speed, we get:

[0159]

[0160] make It is expressed as the transmission coefficient of the generator load torque deviation to the generator speed deviation, and is the generator load self-regulation coefficient. Its value is greater than 0 and around 1.0. The above formula is simplified to:

[0161] m g =m g0 +e g x formula 13

[0162] The dynamic equation of generator load is:

[0163]

[0164] Use T b Indicates the mechanical inertia in the power grid, m g0 As the disturbance, it is expressed by a step function, let e n =e g -e x , represents the comprehensive self-regulation coefficient of the hydro-generator set, and the generator transfer function is obtained as follows:

[0165]

[0166] The first-order generator and load model is obtained as Figure 4 shown.

[0167] 3. Modeling of adaptive load regulation in hydropower plants

[0168] (I) Adaptive control cycle

[0169] The adaptive control power instructions are sent to the power plant and the units in a certain cycle. The cycles associated with them include: adaptive control data acquisition cycle (execution cycle), adaptive control command cycle and unit control command cycle.

[0170] (1) Adaptive control data collection cycle: The adaptive control data collection cycle is 2 to 4 seconds. In each data collection cycle, the adaptive control updates the data once and calculates the regional ACE value and performance monitoring;

[0171] (2) Adaptive control command cycle: Take an integer multiple of the data collection cycle. In addition to completing the tasks of the data collection cycle, it is also necessary to calculate the base power of each unit participating in the adaptive control control, and together with the ACE control power form the target power;

[0172] (3) Unit control command cycle: It is determined by the adaptive control command cycle and the actual control command issued by the unit. The target output is issued within the adaptive control command cycle. If the unit has responded to the last control command, the current control command is issued immediately. If the unit has not responded to the last control command, the current control command will not be issued for the time being. The maximum control amount issued each time can be set manually. For a given value control unit, the control amount should take a larger value or the maximum value to avoid frequent issuance.

[0173] (II) Adaptive Control Power Control Model

[0174] (1) Adaptive control power constant value regulation model

[0175] The adaptive control power fixed value control mode refers to the adaptive control module directly issuing the power value command that the unit should issue at this moment to the microcomputer speed governor through the host computer (monitoring system). After receiving the command, the speed governor implements it according to the predetermined control law. In the adaptive control power fixed value control mode, the host computer only completes the distribution calculation of the unit power, and the closed-loop control of active power is realized by the speed governor itself. At this time, the speed governor works in the power control mode. The specific principle is as follows Figure 5 shown.

[0176] P C is the target power sent from the dispatching center to the hydropower plant, k l , k2, …, k n is the proportional coefficient of each unit, p cl 、p c2 ,…,p cn The power set by the hydropower plant's adaptive control is sent to each unit. The primary and secondary frequency regulation of the unit do not interfere with each other. When the secondary frequency regulation of the system ends, the frequency deviation is 0, and the actual power of the unit is equal to the target power.

[0177] (2) Adaptive control power pulse regulation model

[0178] In the pulse form adaptive control power closed-loop control mode, the corresponding speed regulator works in the opening control mode. First, the power deviation △P is converted into a series of pulses with adjustable pulse width or period, and connected to the increase and decrease buttons or dedicated IO interface in the form of switch quantity. When the pulse is at a high level, it is equivalent to the button being closed, and the opening set value changes; when the pulse is at a low level, it is equivalent to the button being disconnected, and the opening set value remains unchanged. If the power deviation △P is positive, only an increase pulse is given if the unit power needs to be increased; if the power deviation △P is negative, only a decrease pulse is given if the unit power needs to be reduced.

[0179] Improve the pulse width modulation method, and use several narrow pulses to equalize a wide pulse in a unit control cycle, that is, the pulse train method. Set up special hardware in the LCU, and the speed regulator reserves a special increase and decrease pulse I / O interface. The adaptive control power pulse control method is as follows Figure 6 shown.

[0180] P C To dispatch the given power sent by EMS to the hydropower plant, P1, P2... are the measured power of each hydropower unit, P is the measured total power of the hydropower plant, K1, K2... are the load distribution coefficients of each unit, △P1, △P2... are the incremental power allocated to each unit, P is the power control law formation module, which together with the pulse width generator module and the given integrator module constitutes the power regulator, and its transfer function is:

[0181]

[0182] Where, w P is the power control proportional gain, w I is the power control integral gain, is the speed regulator opening given value action time constant, T iy is a speed regulator parameter, indicating the time required for the opening given value to change from 0 to 100%; w P 、w I is the adaptive control module parameter in the monitoring system, where w P Indicates the conversion coefficient between power and guide vane opening, w I Indicates the speed of the regulation process. If w I <1, the action time of the equivalent opening given value increases, and the control process slows down. If w,>1, the action time of the equivalent opening given value decreases, and the control process speeds up.

[0183] (III) Single-machine adaptive control model

[0184] The established single-machine adaptive control power control model includes PID control, pulse generation, given integral link, and dead zone link. The pulse generator receives the power control command of the upper computer to generate load increase and decrease pulses to control the guide vane opening; the given integral link integrates the pulses sent by the pulse generator to control the guide vane opening; the dead zone link is set to prevent small load deviations from causing frequent control of the unit.

[0185] w t represents the pulse generation period, which is 4 to 8 seconds; w tmax Indicates the maximum pulse width, which is 1 to 3 seconds; w tmin Indicates the minimum pulse width, which is about 0.1 seconds, w P 、w I A larger value can speed up the power regulation, but it is easy to cause overshoot. P 、w I If the value is smaller, the power control speed will be slower, resulting in inadequate power control. In addition, a reasonable power control dead zone should be set to prevent the unit from being controlled too frequently. At the same time, under the premise of ensuring safe and stable operation, the control dead zone should be as small as possible to ensure the accuracy of power control, and set to 0.5-1% of the rated power value of the unit.

[0186] (IV) Modeling of water-photovoltaic complementary joint control system

[0187] The installed capacity of G photovoltaic power station is similar to that of a single unit of L hydropower plant. The rapid regulation capability of the turbine of L hydropower plant is used to compensate for the unstable output of G photovoltaic power station. A single-unit adaptive control load regulation model for hydropower is established. The output curve of photovoltaic power station under typical weather conditions is selected and normalized to establish a complementary regulation model. Under sunny weather conditions, the photovoltaic output is basically in the shape of a steamed bun. The target load of the joint complementary system is given as 0.90.

[0188] After 200s, the photovoltaic output gradually increases from 0 and reaches a peak at around 1000s. In this interval, the complementary hydropower output basically decreases along the same slope. After 1000s, the photovoltaic output gradually decreases until it reaches 0. At this time, the complementary hydropower output basically increases along the same slope. During the time period when the photovoltaic output is 0, the hydropower output runs along the target load curve, and the complementary effect is good.

[0189] 4. Hydro-PV Complementary Adaptive Coordinated Power Generation and Impact Model

[0190] (I) Water-photovoltaic complementary adaptive control load distribution strategy

[0191] After the dispatch center sends the target load to the hydropower plant adaptive control, the active power between the units is distributed in the following way.

[0192] (1) Proportional to unit capacity

[0193] When the turbine characteristic curve cannot be obtained or the characteristic curve parameters are inaccurate, this method is used to allocate the capacity of each unit according to the proportion of the total capacity under the current water head. The allocation method is as follows:

[0194]

[0195] Where: P i The power value assigned to the i-th unit, P C To dispatch a given hydropower plant load target value, P imax is the maximum power value of the i-th unit under the current water head.

[0196] (2) Equal incremental rate method

[0197] The objective function of adaptive control should be to minimize the total water consumption of the hydropower plant, assuming that the water consumption of the hydropower unit is only related to the active power P generated by the generator unit. g Association, objective function:

[0198]

[0199] Constraints:

[0200] P st =P1+P2+…+P n Formula 19

[0201] P gimin ≤P gi ≤P gimax Formula 20

[0202] Q gimin ≤Q gi ≤Q gimax Formula 21

[0203] V imin ≤V i ≤V imax Formula 22

[0204] Where P gi is the actual power generated by the i-th unit, Q gi is the water consumption of the i-th unit, V i is the bus voltage of the i-th unit. The Lagrange multiplier method can be used to solve the conditional extreme value problem of the above formula, and the auxiliary equation is established as follows:

[0205]

[0206] Through differential calculation, the optimal operation mode of the hydropower unit is obtained as follows:

[0207]

[0208] q is the power generated by generator set i, which is P gi The consumption rate increases slightly.

[0209] (3) Multi-objective planning method

[0210] The load allocation method of the adaptive control multi-objective planning of the hydropower plant meets the following goals: 1) saving water and increasing power generation; 2) the adaptive control allocation value is as close as possible to the dispatching given value; 3) avoiding the unit from frequently crossing the vibration zone; 4) the unit load fluctuation caused by two consecutive load adjustments is minimized;

[0211] The equal capacity proportion method is adopted to distribute the unit load. When designing the adaptive control of water-photovoltaic complementary power system, the iterative equal division method is incorporated to make up for the shortcomings of the algorithm.

[0212] (II) Water-photovoltaic hybrid adaptive control security strategy

[0213] (1) Avoiding vibration zones: During the power regulation of the hydro-turbine unit, avoid the non-operating operating zone, including the unit's vibration zone and cavitation zone. The water-solar complementary adaptive control is designed according to the following rules and strategies: the unit cannot operate in the vibration zone and cannot frequently cross the vibration zone. At the same time, the adaptive control sets a dead zone for crossing the vibration zone to avoid frequent crossing of the vibration zone. The adaptive control sets the conditions for crossing the vibration zone: if the target load value cannot be tracked without crossing the vibration zone, then the vibration zone is crossed; when the power shortage reduction value is greater than the dead zone for crossing the vibration zone compared to not crossing the vibration zone, the unit crosses the vibration zone; when the power between units is seriously unbalanced, affecting the economic benefits of the entire plant, the vibration zone is crossed;

[0214] (2) Setting the dead zone and adaptive control response interval: Setting the adaptive control dead zone can prevent the hydropower unit from being frequently adjusted due to small changes in the photovoltaic load, thereby reducing unit wear. At the same time, setting the adaptive control response interval can prevent the frequent adjustment of the unit due to continuous fluctuations in the photovoltaic load caused by weather changes, thereby effectively protecting the unit. The adaptive control dead zone is set to 10MW and the response interval is set to 8s.

[0215] (3) The adaptive control system exits when the following operating conditions are met: failure of the active power measurement channel of the non-maintenance unit, failure of the water-photovoltaic complementary system channel and the PV power station joins the water-photovoltaic complementary adaptive control, speed regulator failure, system frequency over-limit, LCU failure, system or plant failure and accident;

[0216] (4) The adaptive control system is locked and meets the following operating conditions: high frequency increases output, low frequency decreases output, two given over-limit values, and given setting value over-limit.

[0217] (III) Other strategies for adaptive control of water-photovoltaic hybridization

[0218] Set up strategies that meet your own special circumstances: pre-set the appropriate active power control step for each unit; when increasing the load, the unit with the smallest proportion of actual active power to total capacity will be given priority to increase the load; when reducing the load, the unit with the largest proportion of actual active power to total capacity will be given priority to reduce the load; if the control increment is within the control step range and does not enter the vibration zone or exceed the power upper limit, only one unit will be allocated for control.

Claims

1. A method for adaptive control of water-light combined complementary grid connection for renewable energy power generation, characterized in that: First, based on the characteristics of centralized photovoltaic power generation and combined with the specific performance of each grid-connected power generation equipment, the circuit topology of centralized grid-connected photovoltaic power station is established, the advantage model of water-photovoltaic complementarity is calculated, and the optimized grid-connected topology of water-photovoltaic complementarity is constructed; second, each part of the turbine control system is modeled and analyzed separately, and the system structure of adaptive control is constructed, and a single-machine adaptive control load control model is established; combined with the empirical parameters of the hydropower plant, a turbine load control model is established, and under typical working conditions, the output curve of the photovoltaic power station is optimized, and a water-photovoltaic complementary joint control model is constructed, and the hydropower units are adaptively controlled to meet the compensation needs of photovoltaic output fluctuations; third, a water-photovoltaic complementary adaptive coordinated power generation and impact model is established, and the water-photovoltaic complementary model is optimized and analyzed under different control methods and different weather conditions; A. Hydropower-PV combined complementary grid-connected system structure: Utilize the rapid load regulation capability of hydropower units and the reservoir regulation capacity of hydropower stations to smooth the active output of photovoltaic power stations. After hydropower complementation, the low-quality photovoltaic power output is transformed into a smooth and stable active output, reducing the impact of photovoltaic power station output changes on the power grid, including hydropower compensation for photovoltaic and photovoltaic compensation for hydropower; B. Hydro-PV joint complementary adaptive control strategy: including adaptive control method and turbine control system modeling and analysis. The turbine control system modeling and analysis are combined with the pressure water diversion system, turbine and turbine generator for modeling and analysis; C. Modeling of adaptive load control in hydropower plants: including adaptive control cycle, adaptive power control model, single machine adaptive control model, and modeling of water-solar complementary joint control system; D Hydro-PV complementary adaptive coordinated power generation and impact model: including hydro-PV complementary adaptive control load distribution strategy, hydro-PV complementary adaptive control safety strategy, and hydro-PV complementary adaptive control other strategies.

2. According to claim 1, the adaptive control method for the grid-connected water-photovoltaic combined complementary renewable energy power generation is characterized in that: The structure of the water-solar combined complementary grid-connected system: 1) Compensation of hydropower to photovoltaic power: This is achieved through two compensation processes: the first compensation uses the rapid load regulation capability of hydropower units to smooth the sawtooth output process of photovoltaic power; the second compensation is based on the first compensation, and the intermittent, volatile and random nature of photovoltaic output is further eliminated through the regulation of water energy by reservoir capacity and the rapid regulation of output by hydropower units, so that the combined output of hydropower is maintained at the required value of grid dispatch; the two compensations of hydropower to photovoltaic power are carried out simultaneously, and the quality of photovoltaic power output is improved through the complementary and adaptive control of hydropower and photovoltaic power, and the abandonment rate of photovoltaic power stations is reduced, creating favorable conditions for full grid connection of photovoltaic power generation; 2) Photovoltaic compensation for hydropower: First, hydropower stations must maintain a certain flow rate to meet the comprehensive water demand of downstream. At the same time, hydropower also undertakes the task of peak load regulation. When the river water is dry, photovoltaics participate in the complementarity, and use the daytime to make photovoltaics fully generate electricity. Hydropower maintains low load operation so that the reservoir can store more water energy; during the evening peak period of the grid load, hydropower increases its output to compensate photovoltaics and participate in peak load regulation; second, in dry years or winter and spring dry seasons, hydropower water supply restrictions lead to less power generation. At this time, photovoltaics make up for the shortage of hydropower electricity; and in wet years or summer and autumn wet seasons, the large-scale generation of hydropower makes up for the power deficit of photovoltaic power generation caused by rainy weather, and flexibly uses the complementarity of water and light to increase peak load regulation and improve the joint peak load regulation capacity.

3. According to claim 1, the adaptive control method for water-photovoltaic combined complementary grid connection of renewable energy power generation is characterized in that: Hydropower-photovoltaic joint complementary adaptive control strategy: including grid adaptive control, power plant adaptive control and unit control system; divided into several control areas according to the location of power supply and load, each control area is interconnected by tie lines, and the control area has its own perfect adaptive power generation control system. In the control area, the generator set is divided into adaptive control units and non-adaptive control units according to the specific conditions of the generator set and the grid dispatching requirements. The grid dispatching center sets up load frequency control software, which collects grid frequency, tie line flow, system time deviation parameters in real time and calculates the regional control deviation of the control area. After filtering, a smooth regional control deviation value is obtained, and then the adaptive control control power value of each unit is calculated according to the actual power, base point power and adaptive control allocation coefficient of each generator set, and sent to each adaptive control unit. The unit changes its output through the control system; Adaptive control data flow: The load changes of the power system have certain regularity. The short-term fluctuating load is regulated by the unit's own speed governor, which is the primary regulation. The long-term fluctuating load is regulated by adaptive control, which is the secondary regulation. The long-term load fluctuation is adjusted by the power generation plan, which is the tertiary regulation. Adaptive control rules for hydropower plants: First, control the overall active power output of the power plant. Hydropower adaptively controls the start and stop sequence and load distribution of each participating control unit to ensure that the output of the entire plant meets the dispatching requirements; second, ensure the safe operation of the unit. During operation, avoid the vibration area, cavitation area and the unit's poor operating condition area; third, ensure the economical operation of the unit. Reasonable load distribution is carried out according to the efficiency of different units under different heads, so as to minimize the water consumption rate of the entire plant while meeting the dispatching load requirements.

4. According to claim 1, the adaptive control method for the grid-connected water-photovoltaic combined complementary renewable energy power generation is characterized in that: Modeling and analysis of pressure water diversion system: When the control system has small fluctuations and the length of the pressure pipeline does not exceed 600 to 800 meters, a rigid water hammer model is used. The pressure wave generated by the water hammer will instantly propagate to the entire pressure water diversion pipeline. The water hammer pressure is expressed as: △H is the water hammer pressure, A is the pipe cross-sectional area, L is the pipe length, Q is the water flow rate in the pipe, where the flow rate Q is the sum of the initial flow rate Q0 and the flow change △Q, and we get: Taking the relative values ​​on both sides of equation 1, we get: Where: H r is the rated head, Q r is the rated flow rate, and after taking Laplace transformation of formula 3, we get: H(s)=-T w sQ(s) Equation 4 The transfer function of the water diversion system is obtained as follows: Where: is the water flow inertia time constant, unit s, T w It is the case that the water flow is at the rated head H without considering the hydraulic loss in the pipeline. r From 0 to rated flow Q r The time required, T w The larger it is, the greater the water hammer pressure is, and the greater the impact on the turbine control system is. The model of the water diversion system under rigid water hammer is obtained.

5. According to claim 1, the adaptive control method for water-photovoltaic combined complementary grid connection of renewable energy power generation is characterized in that: Turbine modeling analysis: The dynamic characteristics of the turbine are expressed by flow rate Q, head H, guide vane opening a, torque M t , speed n and blade angle φ, and the dynamic characteristics of the turbine are expressed by the torque characteristics and flow characteristics under steady-state conditions: Torque: M t =M t (a,n,H); Flow rate: Q = Q(a,n,H); In the case of small fluctuations, the dynamic parameters only fluctuate slightly under steady-state conditions, which can be approximated by linear equations: Force: m t =e y y+e x x+e h h; Flow rate: qt = e qy y+e qx x+e qh h; Among them, mt is the relative value of torque deviation, q is the relative value of flow deviation, y is the relative value of guide vane opening deviation, x is the relative value of speed deviation, h is the relative value of head deviation, e y is the transfer coefficient of turbine torque to guide vane opening, e x is the transmission coefficient of turbine torque to speed, e h is the turbine torque to head transfer coefficient, e qy is the transfer coefficient of turbine flow to guide vane opening, e qx is the turbine flow to speed transfer coefficient, e qh is the turbine flow to head transfer coefficient; For an ideal turbine, the transfer coefficient is: e y =1,e h =1.5q,e qy =1,e qh =0.5q,e qx =0; Let the relative flow rate q = 1.0, and we get e h =1.5, e qh =0.5; integrating the water diversion system and the turbine module, we get: Equation 6 is the transfer function of the water diversion system and the turbine.

6. The adaptive control method for grid-connected water-photovoltaic combined complementary renewable energy power generation according to claim 1 is characterized in that: Modeling and analysis of hydro-generator: The motion equation of the hydro-generator when operating under small fluctuation conditions is: Where: J is the moment of inertia of the rotating part of the unit, unit: kggm 2 ;ω is the angular velocity of the unit, unit rad / s; M t is the turbine torque, in Ngm; M g is the generator load torque, in Ngm, and the turbine active torque is expressed as: M t = M t0 + ΔM t Equation 8 Under steady-state conditions, M g0 =M t0 =M r , M g =M g0 +ΔM g , take the relative value of the deviation, and let Indicates the relative value of the generator load torque deviation; Represents the relative value of the turbine output torque deviation, and we get: Then the relative value of the deviation is used to express the unit motion equation: in Where: T a GD is the inertia time constant of the unit, in seconds; 2 Flywheel torque of the rotating part of the unit, unit KNgn 2 ;n r is the rated speed of the unit; N r is the rated output of the unit, T a The size of T is related to the stability of the system. The larger the value, the more conducive it is to the stability of the control system. a It includes not only the mechanical inertia of the generator rotor, but also the mechanical inertia of the rotating part of the turbine and the mechanical inertia of the water body in the runner area, namely: GD 2 = GD g 2 + GD t 2 + GD w 2 Equation 11 The change of load resistance moment consists of two parts, expressed in m g0 Indicates the input change of generator load, Expressing the change in resistance torque caused by the change in generator speed, we get: make It is expressed as the transmission coefficient of the generator load torque deviation to the generator speed deviation, and is the generator load self-regulation coefficient. Its value is greater than 0 and around 1.

0. The above formula is simplified to: m g =m g0 +e g x formula 13 The dynamic equation of generator load is: Use T b Indicates the mechanical inertia in the power grid, m g0 As the disturbance, it is expressed by a step function, let e n =e g -e x , represents the comprehensive self-regulation coefficient of the hydro-generator set, and the generator transfer function is obtained as follows: The first-order generator and load model are obtained.

7. The adaptive control method for grid-connected water-photovoltaic combined complementary renewable energy power generation according to claim 1 is characterized in that: Adaptive control cycle: The adaptive control power command is sent to the power plant and the unit according to a certain cycle. The associated cycles include: adaptive control data acquisition cycle (execution cycle), adaptive control command cycle and unit control command cycle; (1) Adaptive control data collection cycle: The adaptive control data collection cycle is 2 to 4 seconds. In each data collection cycle, the adaptive control updates the data once and calculates the regional ACE value and performance monitoring; (2) Adaptive control command cycle: Take an integer multiple of the data collection cycle. In addition to completing the tasks of the data collection cycle, it is also necessary to calculate the base power of each unit participating in the adaptive control control, and together with the ACE control power form the target power; (3) Unit control command cycle: It is determined by the adaptive control command cycle and the actual control command issued by the unit. The target output is issued within the adaptive control command cycle. If the unit has responded to the last control command, the current control command is issued immediately. If the unit has not responded to the last control command, the current control command will not be issued for the time being. The maximum control amount issued each time can be set manually. For a given value control unit, the control amount should take a larger value or the maximum value to avoid frequent issuance.

8. The adaptive control method for grid-connected water-photovoltaic combined complementary renewable energy power generation according to claim 1 is characterized in that: Adaptive control power control model: (1) Adaptive control power fixed value regulation model: The adaptive control power fixed value regulation mode refers to the adaptive control module directly issuing the power value command that the unit should issue at this moment to the microcomputer speed governor through the host computer. After receiving the command, the speed governor implements it according to the predetermined control law. In the adaptive control power fixed value regulation mode, the host computer only completes the distribution calculation of the unit power, and the closed-loop regulation of active power is realized by the speed governor itself. At this time, the speed governor works in the power regulation mode; P C is the target power sent from the dispatching center to the hydropower plant, k l , k2, …, k n is the proportional coefficient of each unit, p cl 、p c2 ,…,p cn The power setting is sent to each unit for adaptive control of the hydropower plant. The primary and secondary frequency regulation of the unit do not interfere with each other. When the secondary frequency regulation of the system ends, the frequency deviation is 0, and the actual power of the unit is equal to the target power. (2) Adaptive control power pulse regulation model: In the pulse form adaptive control power closed-loop control mode, the corresponding speed regulator works in the opening control mode. First, the power deviation △P is converted into a series of pulses with adjustable pulse width or period, and connected to the increase and decrease button or dedicated IO interface in the form of switch quantity. When the pulse is at a high level, it is equivalent to the button being closed, and the opening set value changes; when the pulse is at a low level, it is equivalent to the button being disconnected, and the opening set value remains unchanged. If the power deviation △P is positive, only an increase pulse is given if the unit power needs to be increased; if the power deviation △P is negative, only a decrease pulse is given if the unit power needs to be reduced; Improve the pulse width modulation method, and use several narrow pulses to equalize a wide pulse in a unit control cycle, that is, the pulse train method. Set up special hardware in the LCU, and the speed regulator reserves a special increase and decrease pulse I / O interface; P C To dispatch the given power sent by EMS to the hydropower plant, P1, P2... are the measured power of each hydropower unit, P is the measured total power of the hydropower plant, K1, K2... are the load distribution coefficients of each unit, △P1, △P2... are the incremental power allocated to each unit, P is the power control law formation module, which together with the pulse width generator module and the given integrator module constitutes the power regulator, and its transfer function is: Where, w P is the power control proportional gain, w I is the power control integral gain, is the speed regulator opening given value action time constant, T iy It is a speed regulator parameter, indicating the time required for the opening given value to change from 0 to 100%; w P 、w I is the adaptive control module parameter in the monitoring system, where w P Indicates the conversion coefficient between power and guide vane opening, w I Indicates the speed of the regulation process. If w I If w, < 1, the action time of the equivalent opening given value increases, and the control process slows down. If w, > 1, the action time of the equivalent opening given value decreases, and the control process speeds up.

9. The adaptive control method for grid-connected water-photovoltaic combined complementary renewable energy power generation according to claim 1 is characterized in that: Single-machine adaptive control model: The established single-machine adaptive control power regulation model includes PID regulation, pulse generation, given integral link, and dead zone link. The pulse generator receives the power regulation command of the host computer to generate load increase and decrease pulses to control the guide vane opening. The given integral link integrates the pulses sent by the pulse generator to control the guide vane opening; The dead zone setting is to prevent small load deviations from causing frequent adjustments of the unit; w t represents the pulse generation period, which is 4 to 8 seconds; w tmax Indicates the maximum pulse width, which is 1 to 3 seconds; w tmin Indicates the minimum pulse width, which is about 0.1 seconds, w P 、w I A larger value can speed up the power regulation, but it is easy to cause overshoot. P 、w I If the value is smaller, the power control speed will be slower, resulting in inadequate power control. In addition, a reasonable power control dead zone should be set to prevent the unit from being controlled too frequently. At the same time, under the premise of ensuring safe and stable operation, the control dead zone should be as small as possible to ensure the accuracy of power control, and set to 0.5-1% of the unit rated power value.

10. The adaptive control method for grid-connected water-photovoltaic combined complementary renewable energy power generation according to claim 1 is characterized in that: Load distribution strategy for hydro-photovoltaic complementary adaptive control: After the dispatch center sends the target load to the hydropower plant adaptive control, the active power between the units is distributed in the following way; (1) Proportional to unit capacity: When the turbine characteristic curve cannot be obtained or the characteristic curve parameters are inaccurate, this method is used to allocate the capacity according to the proportion of each unit capacity to the total capacity under the current water head. The allocation method is as follows: Where: P i The power value assigned to the i-th unit, P C To dispatch a given hydropower plant load target value, P imax is the maximum power value of the i-th unit under the current water head; (2) Equal incremental rate method: The objective function of adaptive control should be to minimize the total water consumption of the hydropower plant, assuming that the water consumption of the hydropower unit is only proportional to the active power generated by the generator unit P. g Association, objective function: Constraints: P st =P1+P2+...+P n Formula 19 P gimin ≤P gi ≤P gimax Formula 20 Q gimin ≤Q gi ≤Q gimax Formula 21 V imin ≤V i ≤V imax Formula 22 Where P gi is the actual power generated by the i-th unit, Q gi is the water consumption of the i-th unit, V i is the bus voltage of the i-th unit. The Lagrange multiplier method can be used to solve the conditional extreme value problem of the above formula, and the auxiliary equation is established as follows: Through differential calculation, the optimal operation mode of the hydropower unit is obtained as follows: q is the power generated by generator set i, which is P gi The slight increase rate of consumption at that time; (3) Multi-objective planning method: The adaptive control multi-objective planning method of hydropower plants allocates loads to meet the following goals: 1) save water and increase power generation; 2) the adaptive control allocation value is as close as possible to the dispatching given value; 3) avoid the unit frequently crossing the vibration zone; 4) the unit load fluctuation caused by two consecutive load adjustments is minimized; The equal capacity proportion method is adopted to distribute the unit load. When designing the adaptive control of water-photovoltaic complementary power system, the iterative equal division method is incorporated to make up for the shortcomings of the algorithm.

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