CN112491079B

CN112491079B - Method for rapidly controlling power of photovoltaic power station inverter

Info

Publication number: CN112491079B
Application number: CN201910862673.0A
Authority: CN
Inventors: 米高祥; 陶征; 丁勇; 石祥建; 刘为群
Original assignee: NR Electric Co Ltd; NR Engineering Co Ltd
Current assignee: NR Electric Co Ltd; NR Engineering Co Ltd
Priority date: 2019-09-12
Filing date: 2019-09-12
Publication date: 2022-10-28
Anticipated expiration: 2039-09-12
Also published as: CN112491079A

Abstract

The invention discloses a method for rapidly controlling the power of a photovoltaic power station inverter, which comprises the following steps: step 1, an inverter automatically records the maximum power point voltage Vmpp in an unlimited power operation period, and automatically records and updates the Vmpp in an unlimited power state; step 2, in a power limiting state, the inverter receives a power up-regulation instruction and performs a fast spanning type power regulation response according to a power lifting target value Pt1 and a maximum power point voltage Vmpp; and when the inverter receives the power reduction command, the inverter refers to the target power value Pt2 to perform quick power reduction regulation response. The method can enable the inverter in the photovoltaic power station to perform quick execution response, the relevant parameters of the maximum power point voltage point are recorded through the inverter in a self-adaptive intelligent mode, the maximum power point can be located in one step in the quick power control of the inverter, and the execution speed of the power regulation of the photovoltaic inverter in the whole station is within 30 ms.

Description

Method for rapidly controlling power of photovoltaic power station inverter

Technical Field

The invention belongs to the field of new energy power generation control, and particularly relates to rapid power control of a photovoltaic inverter in a photovoltaic power station.

Background

Along with the increasing occupation ratio of new energy in a power grid, the installed capacity of the new energy in the 'three north' region is close to or even exceeds 30% in some cases, the high proportion of the new energy seriously extrudes the primary frequency modulation rapid reserve capacity space of conventional energy, so that the operation of the power grid faces a series of challenges, the new energy such as a photovoltaic power station is urgently needed to accelerate the power regulation response speed so as to meet the power regulation rapid response requirement in the fault or disturbance process of the power grid, and the new energy participates in the primary frequency modulation of the power grid to become a power supply of a 'friendly type' of the power grid. If the active/reactive power of part of photovoltaic power stations can be adjusted and controlled within one hundred milliseconds, the active control method has a remarkable positive effect on relieving the overvoltage problem of the direct-current blocking transmission end power grid, can effectively improve the frequency and voltage control capability of the power grid, and enhances the stability level of the power grid.

However, the current new energy wind power and photovoltaic power stations usually perform power regulation response control through an automatic generation power control system (AGC system for short), the in-station control start response time of the system is as long as 20 seconds, the execution response time of the inverter end is as long as 1-3 seconds, and even if the time of other links is compressed to 0, the demand of the stable control system on hundreds of milliseconds regulation control response of the new energy photovoltaic power station cannot be met. The reason of the inverter is analyzed, when the target power is reduced, the target power can be reached certainly, gradual iterative algorithm tracking is not needed, and the algorithm is easy to realize; when the target power is increased, because the inverter in the limited power state does not know the current maximum power generation capacity of the photovoltaic array connected with the inverter, the maximum power value or the target power value can be usually found only through an MPPT algorithm; the conventional MPPT tracking process is slow, gradual iteration (about 100ms per step) tracking is needed, the inverter system is ensured to track safely and stably, and the whole MPPT tracking process generally lasts for 1-3 seconds; on the other hand, if the inverter is blindly subjected to fast power boost tracking, once the boosted target power exceeds the current natural maximum power of the photovoltaic array to which the inverter is connected, the inverter dc bus voltage is likely to collapse, which in turn leads to the risk of trip. The speed and the greater trip risk of the conventional MPPT algorithm of the inverter obviously do not meet the requirement of system level power response within hundred milliseconds to the photovoltaic plant at the time of grid fault or disturbance.

At present, the scheme proposes to adopt temperature and illumination intensity data of an environment monitoring instrument to evaluate the actual maximum power point of a whole photovoltaic inverter, and further researches propose to adopt partial sample inverters to naturally generate power without limit, and to evaluate the maximum power points of all other inverters of the whole photovoltaic power station through the running states of the partial sample inverters. However, the two schemes have low power tracking accuracy, are only suitable for ideal photovoltaic power stations with flat and consistent potentials in the power station, and have good parameter characteristic consistency of solar photovoltaic cells, inverters, cable wiring and the like of all grid-connected units in the power station, and the defect of narrow scheme application range is obvious. By adopting the scheme of the sample inverter, the sample inverter cannot participate in power regulation control, so that the capacity of overall power regulation of the power station is reduced; the power station control system must firstly obtain the running state parameters of the sample inverters through communication and issue the parameters to each inverter through communication, the controlled inverters can start to perform power regulation response, two links of the up-sending and the down-sending of the parameters of the sample inverters are added in the control process, and the power regulation rate of the whole photovoltaic power station is not influenced.

The following problems are prevalent in most existing photovoltaic power plants:

(1) The topography of the photovoltaic power station is uneven, the directions of the photovoltaic components are not completely consistent, and the problem of local shadow shielding exists;

(2) The power station is built in multiple stages, different types and brands of solar cells exist in the same photovoltaic power station, and the cell characteristics have larger difference;

(3) Along with the power generation of the power station, the attenuation degree of the solar photovoltaic cell of the same photovoltaic power station is inconsistent, and the difference becomes larger continuously.

The normal operation power generation cycle of the photovoltaic power station reaches 20-30 years, and the existing two schemes can not self-adaptively meet the discrete difference problems of different power station geographical layouts, photovoltaic cell differences and battery power generation performance attenuation.

Disclosure of Invention

The invention aims to provide a method for quickly controlling the power of a photovoltaic power station inverter, which can be used for quickly executing a response method for the inverter in the photovoltaic power station, the relevant parameters of a maximum power point voltage point are intelligently recorded in a self-adaptive manner through the inverter, the maximum power point can be positioned in one step in the quick power control of the inverter, and the execution speed of the power regulation of the photovoltaic inverter in the whole station is realized within 30 ms.

The technical problem to be solved by the invention is as follows:

1) The problem that when the photovoltaic inverter of the photovoltaic power station is in a power limiting state, the power is improved, and the execution response of the conventional MPPT algorithm is slow is solved;

2) The problem that the direct-current voltage of the inverter is likely to collapse and trip due to blind and quick power setting in the MPPT power climbing process of the photovoltaic inverter is solved;

3) The problem that under the conditions that environmental conditions such as different terrain layouts and different shadow shelters exist in the same photovoltaic power station and the brands or specifications of different photovoltaic cell assemblies and the service life attenuation degrees of photovoltaic cells are inconsistent, uniform environmental monitoring data or sample inverter data are adopted to control the power of each inverter monomer, and large deviation exists is solved;

4) The problem of communication delay of obtaining environment monitoring data or sample inverter data through communication is solved, and the power rapid regulation rate is further improved;

5) The problem that part of sample inverters arranged in a power station need to naturally run at the maximum power point all the time and cannot participate in power rapid control is solved;

6) The problem that the maximum power point voltage parameter needs to be dynamically adaptively changed and refreshed in order to ensure the tracking control precision along with the continuous change of the weather conditions of the four-season environment and the continuous attenuation of the solar photovoltaic cell in the long-term operation process of the photovoltaic power station is solved;

7) The problem of photovoltaic inverter because overhauls, the fault shutdown leads to maximum power point voltage coefficient can't obtain or the error influences actual power tracking control accuracy greatly is solved.

In order to achieve the above object and solve the above technical problems, the solution of the present invention is:

a method for rapidly controlling the power of a photovoltaic power station inverter comprises the following steps:

step 1, an inverter automatically records the maximum power point voltage Vmpp in an unlimited power operation period, and automatically records and updates the Vmpp in an unlimited power state;

step 2, in a power limiting state, the inverter receives an up-regulation power instruction, and fast spanning type power regulation response is carried out according to a lifting power target value Pt1 and a maximum power point voltage Vmpp; and when the inverter receives the power reduction command, the inverter refers to the target power value Pt2 to perform quick power reduction regulation response.

In the step 1, the value of Vmpp is in a specified inverter output power interval, and the power interval has a single-side limit value or upper and lower limit double-side limit values.

In step 1, the Vmpp value is averaged over the whole day, or averaged over a fixed period of time per day, or averaged over a weighted average over different periods of time, or averaged over a sliding window over n days.

In the step 1, the inverters upload the value of the maximum power point voltage Vmpp of the inverters through a wired or wireless communication means, a Vmpp deviation threshold value is set for each inverter, and when the Vmpp data of the inverter on the day cannot be obtained or the deviation is larger and more limited, the Vmpp recent average value stored in the previous day of the inverter or the Vmpp average value of the inverter on the total station on the day is used as the Vmpp data of the inverter on the day.

The communication protocol adopts GOOSE/UDP or TCP.

In the step 2, the power up instruction or the power down instruction received by the inverter is sent by the photovoltaic power station fast power control device or directly issued by a power grid superior control system, and the power grid superior control system comprises a power grid safety and stability control system and a power grid dispatching system.

In the step 2, when the inverter receives the power-up instruction, the direct-current voltage of the inverter is set at Vmpp +. DELTA.U and is used for controlling the inverter, wherein the. DELTA.U is the safe threshold of the direct-current voltage of the inverter; directly switching the power of the inverter to a secondary maximum power value Pm ' corresponding to the direct-current voltage Vmpp plus delta U, starting from the Pm ' point, and carrying out next adjustment on the inverter based on the sizes of the power adjustment instructions Pt1 and Pm ': when Pt1 is larger than Pm', the inverter continues MPPT tracking; and when the Pt1 is less than or equal to Pm', directly adjusting the inverter power to the target power Pt1.

In the step 2, when the inverter receives the power up command, the target value Pt1 of the boost power is compared with the sub-maximum power value Pm 'to which the inverter is switched in the first step, and when Pt1 is less than or equal to Pm', the output power is adjusted to the target value Pt1 of the boost power in the execution process; and when Pt1 is greater than Pm', the output power is adjusted to the natural maximum power value of the inverter in the execution process.

The value of delta U is 0.5-5% of the rated value of the DC bus voltage of the inverter.

After the scheme is adopted, the invention has the beneficial effects that:

(1) By adopting the method, the inverter crosses to the maximum power point in one step by virtue of the electrical parameters of the maximum power point recorded by the inverter, meanwhile, the communication delay of the mutual information of a third-party environment monitoring instrument or a sample inverter is avoided, the target power or the maximum power value can be quickly tracked within 30ms, the execution response speed of the photovoltaic inverter is obviously improved, the power execution response of a total station is enabled to be realized, and the requirement of a stability control system for quickly adjusting the response within hundred milliseconds of a new energy photovoltaic power station is met;

(2) By adopting the method, the problem that the execution of the diffuse purposeless exploration type climbing process is slow in the climbing execution process of the MPPT power climbing algorithm of the photovoltaic inverter can be solved, a relatively accurate maximum power point tracking basis is provided, and the equipment safety in the maximum power point tracking process is ensured;

(3) By adopting the method, the meteorological conditions, the geographical layout, the photovoltaic cell parameters and the inverter running state difference caused by the performance attenuation difference in the long-term running process of the photovoltaic cell in the same photovoltaic power station can be adaptively met, the independent power control is adaptively carried out aiming at different individual running conditions of the inverter, and the control precision and the practicability of the scheme are improved;

(4) After the method is adopted, a large number of established new energy photovoltaic power stations can be subjected to compatibility upgrading, so that the controllability and rapidity of frequency modulation and voltage regulation responses of the system participated by the new energy stations can be obviously improved, the operation control characteristics of conventional power plants such as thermal power plants, hydroelectric power plants and the like can be further approached and surpassed by the large number of photovoltaic power stations, and the improvement of the access absorption capacity of new energy in a power grid is facilitated.

Drawings

Fig. 1 is a schematic diagram of a photovoltaic maximum power point voltage Vmpp under different illumination intensities;

FIG. 2 is a flow diagram of a method of Vmpp recording and updating;

FIG. 3 is a diagram of a photovoltaic power plant implementation communication architecture;

fig. 4 is a communication transmission diagram of the new energy fast power control system;

FIG. 5 is a schematic diagram of a one-step positioning switching MPPT power control algorithm based on the maximum power point voltage Vmpp of the inverter;

FIG. 6 is a photovoltaic inverter fast power control topology;

FIG. 7 is a graph of inverter stand-alone power fast regulation response;

fig. 8 is a graph of a response to rapid power regulation of a photovoltaic power plant total station.

Detailed Description

The invention provides a method for rapidly controlling the power of a photovoltaic power station inverter, which comprises the following three parts:

firstly, dynamically tracking, recording and updating the maximum power point parameter of an inverter by an intelligent self-adaptive maximum power point recording and updating method in the operation process of the inverter;

the intelligent self-adaptive maximum power point recording and updating method is realized by automatically recording and updating the value of the maximum power point voltage Vmpp of the photovoltaic inverter in the process of automatically starting and operating the inverter every day within the time of unlimited power and natural power generation operation.

The Vmpp sampling and recording can be carried out in a specified inverter output power interval according to the inverter output power value, and the power interval can have a single-side limit value or an upper limit value and a lower limit value.

The value of Vmpp can be taken as the average value of all days according to the time value, or can be taken as the average value of fixed time periods every day or the weighted average value of different time periods based on the Vmpp data of multiple days in the near term, or can be taken as the sliding window average value of n days, and the value of n can be set through the fixed value. Therefore, the influence of the Vmpp data on the day power quick control function cannot be obtained when the inverter is overhauled and stopped due to failure is avoided.

When the maximum power point voltage of the inverter is recorded and updated, the inverter sends the value of the maximum power point voltage Vmpp of the inverter through a wired or wireless communication means, the upper computer or the power station monitoring system carries out various average value calculation checks on the value of the maximum power point voltage Vmpp of the total station inverter, a deviation threshold value is set, and the maximum power point voltage Vmpp of the inverter with the deviation out of limit is updated to the recent average value of the Vmpp stored one day before the inverter or the average value of the Vmpp of the total station inverter on the same day; the communication protocol can adopt GOOSE/UDP or TCP.

The following data error correction prevention method can be adopted: and a Vmpp deviation threshold value is set for each inverter, when the Vmpp data on the same day cannot be obtained or the deviation is larger and larger because of reasons such as maintenance, fault shutdown and the like on the same day of the inverter, the Vmpp data on the same day does not enter a recent Vmpp mean value calculation link needing to be recorded, the Vmpp value exceeding the deviation limit on the same day is replaced by the mean value recorded by the recent Vmpp, the Vmpp data enters the recent Vmpp calculation link needing to be recorded, the regular automatic refreshing of the Vmpp value is kept, and more accurate power tracking control is realized.

Secondly, in a power limiting state, when a power grid fails or is abnormal and power shortage occurs and the photovoltaic power station needs to rapidly increase power, the inverter acquires a recent maximum power point voltage reference value Vmpp recorded by the inverter, receives a power increase target value Pt1 sent by a rapid power control device or a superior stability control and regulation system at a plant end, and performs rapid spanning type power regulation response under the combined action of the Vmpp and the Pt1.

The method for rapidly controlling the power boost of the inverter in the power limiting state comprises the following steps that after the inverter receives a power up-regulation instruction, the DC voltage of the inverter is set to Vmpp plus delta U and is supplied to the inverter to control the voltage outer ring to be executed, wherein the delta U is the DC voltage safety threshold of the inverter and takes the value of 0.5-5% of the rated value of the DC bus voltage of the inverter; directly switching the power of the inverter to secondary maximum power Pm ' corresponding to the direct-current voltage Vmpp plus delta U in one step, starting from the Pm ' point, and carrying out next adjustment based on the sizes of the upper power adjustment instructions Pt1 and Pm ': when Pt1 is greater than Pm ', the inverter continues the conventional MPPT tracking algorithm, and when Pt1 is less than or equal to Pm', the inverter power is directly adjusted to the target power Pt1.

The inverter performs power fast-boost response in two cases: (1) When the lifting power target value Pt1 is smaller than or equal to the actual maximum power value Pmpp of the inverter, in the execution process, the power control of the inverter compares the Pmpp and the Pt1 in real time, and the output power is adjusted to the lifting power target value Pt1; (2) When the target value Pt1 of the boost power is larger than the actual maximum power value Pmpp, the Pmpp and Pt1 are compared in real time in the power control of the inverter in the execution process, and the output power is adjusted to the natural maximum power value of the inverter.

Thirdly, when the power grid fails or is abnormal, the power grid regulates and controls the photovoltaic power station to reduce power quickly, the inverter receives a power reduction command, the inverter performs power reduction regulation response quickly by directly referring to a target power value Pt2, and when the inverter executes an active power reduction command Pt2, namely the active power Pt2 of the power reduction target value is smaller than the current generating power of the inverter, the inverter directly outputs active power and adjusts the active power to the power reduction target value Pt2.

In the second part and the third part, the fast power control command received by the inverter can be sent by a fast power control device of the photovoltaic power station, or can be directly issued by a power grid superior control system including a power grid safety and stability control system and a power grid dispatching system, the fast power control device of the photovoltaic power station is installed at a grid-connected point of the photovoltaic power station, and is in high-speed communication with the power grid superior control system including the power grid safety and stability control system and the power grid dispatching system, receives a superior plant station total regulation command, and is in fast communication with each inverter after corresponding power decomposition and processing.

Because two communication delay links of data communication transmission and data communication transmission between the inverter and an environment monitoring instrument or a sample inverter are avoided, the power speed of the inverter can be further improved, the single-machine power lifting or descending regulation execution response time of the inverter is less than 30 milliseconds, and the power lifting or descending regulation execution response time of a full photovoltaic power station is less than 50 milliseconds.

The technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be obtained by a person skilled in the art without making any creative effort based on the embodiments in the present invention, belong to the protection scope of the present invention.

1) As shown in fig. 3, a centralized photovoltaic power station of 50MWp is taken as an example for illustration, the photovoltaic power station is designed into 1MW square matrix, each square matrix contains two typical photovoltaic inverters of 500kW, and the total photovoltaic power station contains 100 photovoltaic inverters in total. All inverters develop a GOOSE protocol supporting network, and the inverters receive and send external GOOSE.

2) At the plant end of the photovoltaic power station, as shown in fig. 4, a new energy fast power control device is developed and erected, the device can perform high-speed GOOSE communication with 100 inverters of the total station, and mainly achieves receiving of a superior power regulation command, decomposition of the total station power command, power acquisition and calculation of a grid-connected point, receiving and sending of maximum power point voltages Vmpp of all the inverters, and high-speed dispatch of a single power regulation command and an average value of the maximum power point voltages Vmpp of the total station inverters to the 100 inverters.

3) After each inverter is started and operated, the 100 inverters automatically record the Vmpp parameters of the inverter in a non-limited power state, synthesize recent Vmpp data for multiple days, calculate the Vmpp mean value by adopting modes such as arithmetic mean, weighted mean, multi-day sliding window mean or different operating power interval average aiming at the inverters, and automatically update the original stored data for later use after the data calculated every day. Fig. 2 shows a procedure of calculating and updating the Vmpp by taking the Vmpp sliding window average value of 7 days as an example and referring to the inverter operating power point interval to take a value of the Vmpp.

4) The 100 photovoltaic inverters support GOOSE fast communication, and also support a conventional TCP manner to perform information state upload communication with a higher-level device or system including a new energy fast power control device. Specific protocols can be selected and matched, and some communication protocols based on Ethernet, such as MMS, MODBUS, IEC103, IEC104, OPC and the like, mainly exist.

5) Under normal conditions, the inverter operates in an adjustable power generation state controlled by a superior plant station system; when the power grid fails or is abnormal and the photovoltaic power station needs to reduce power quickly, the power generation power of the inverter at the whole station is reduced preferentially, and the inverter performs power quick reduction response based on a power reduction target value Pt2 issued by the rapid power control device at the plant station end; when a power grid fails or is abnormal and power shortage needs rapid power boost of a photovoltaic power station, the inverter rapidly communicates with and receives a rapid power boost power target value Pt1 sent by a rapid power control device at a station end, and simultaneously reads a 7-day sliding window average value Vmpp of maximum power point voltage recorded in the inverter, and the inverter performs one-step positioning type tracking and execution rapid response based on the coaction of the Pt1 value and the Vmpp value so as to solve the key problem of rapid power boost in photovoltaic rapid power response control; meanwhile, for convenience of description, when the power reduction target value Pt2 and the power boost target value Pt1 are not distinguished, they are collectively referred to as the power target value Pt, that is, pt represents Pt1 or Pt2;

6) After the inverter acquires the maximum power point voltage Vmpp of the local machine and the power boost power target value Pt1, as shown in FIG. 5, the first step of the MPPT power climbing tracking algorithm of the inverter is to set the direct current bus voltage of the inverter at the Vmpp plus delta U value to provide the voltage outer loop of the MPPT power climbing algorithm for execution, the delta U value range is 0.5% -5% of the rated value of the direct current bus voltage Udc of the inverter of the model, in practice, the delta U takes a typical value of 10V, the inverter power is boosted to the corresponding sub-maximum power value Pm 'through execution, then the target inverter starts from the Pm' point and performs small-step tracking based on the MPPT algorithm, and finally the power is stopped at the target power value.

7) As shown in fig. 6, for the power control topology of the photovoltaic inverter, for the power execution speed of the photovoltaic inverter, after receiving a new power target instruction, the DSP performs sampling, PQ operation, phase-locked loop, positive-negative sequence decomposition, dq conversion, dual-loop PI regulation, and the like, and finally can control the consumed time within 30 ms.

8) And after the power of the target inverter is quickly increased to the sub-maximum power value Pm', the increased target power value is converted into the limit value of a current loop and is fed.

9) The direct-current voltage control target and the power target which are clear in one step are achieved without step-by-step iterative tracking, and the power tracking speed of the inverter power control target is improved.

10 And) the upper computer or the monitoring system at the plant station side continuously receives Vmpp values of the inverters, refreshes and stores the Vmpp values, and sends the average value of the Vmpp values to each inverter through an optical fiber ring network of the photovoltaic power station through corresponding weighted average calculation.

11 Considering that the fast power control has coordination problem with the conventional AGC power system in the station, when the fast power control response of the whole station is performed, the new energy fast power control system at the station end needs to send a remote signaling signal to the AGC system immediately, and the AGC system locks the conventional AGC control immediately after receiving the signal until the signal is cleared.

12 ) the measures of the steps are integrated, and the related technology is put into operation at a certain photovoltaic power station in Tibet. Based on the above-mentioned related systems and techniques, a fast power response curve of the in-station 1# inverter is shown in fig. 7, in which the horizontal axis represents the inverter power execution relative time, where the time 0 is the time when the inverter receives the adjustment command and starts the power execution; the vertical axis represents the ac power generation value of the inverter.

A) Single drop power response

Curve 1 in fig. 7 is the power curve waveform of the implementation process in which the inverter receives the regulating command of the control device and reduces from 450kW to 20kW. The time delay from 450kW down to 63kW (90% adjustment) is approximately 15ms from the waveform. Thereafter, the power was slightly overshot to 0kW, and then ramped back up to 20kW.

B) Boosted power response for stand-alone target values below maximum power values

Curve 2 in fig. 7 is the power-up response for the case where the current maximum generated power of the inverter (i.e., the current maximum power of the photovoltaic panel cells) is higher than the target power, corresponding to the power curve of the implementation process where the inverter is boosted from 50kW to the target value of 400kW (when the maximum power value of the adjacent inverter is above 450 kW). In the early stage of the regulation process, the inverter is instantaneously and slightly overshot to be close to 450kW. Thereafter, the power was gradually decreased to 400kW, and the response time was 15 to 25ms.

C) Boosted power response for stand-alone target values above maximum power value

Curve 3 in fig. 7 is a power execution curve of the inverter in another case where the current maximum generated power (about 400 kW) of the inverter cannot satisfy the target power (500 kW). From the actual response curve, in the process that the inverter is forcibly increased to 500kW from 0kW, a top rushing process with the height exceeding the natural maximum power (400 kW) and even exceeding the target power (500 kW) exists within 6-8 ms instantaneously, and analysis shows that the phenomenon is caused by instantaneous overpower due to temporary energy release of capacitive energy storage in a direct-current bus circuit of the inverter. And then, the AC output power value of the inverter oscillates downwards in a small amplitude manner and finally stabilizes near the maximum power value.

Fig. 8 records total-station power response curves of three typical situations in a network-related commissioning test process of a new energy rapid control system of a certain photovoltaic power station in tibet. In the figure, the horizontal axis is power execution relative time, the time 0 is the time when the control device receives the instruction of the upper stable control system, and the vertical axis is the real-time power acquisition calculation value of the grid-connected point.

A) Total station derate response

Fig. 8, curve 1 is a power execution process curve of the high-voltage station receiving the command of 4.4MW regulated by the steady-state master station, and controlling the inverters to regulate the total power from 17MW to 12.6MW, so as to regulate the response time by about 28ms (to a regulated value of 90%, the same applies below);

b) Total station power-up response with target value below maximum power value

Fig. 8, curve 2 is a power execution process curve of 3.2MW up-regulation by the total station when the current natural maximum generated power of the high station satisfies the target power condition, and the response time is about 33ms;

c) Total station power-up response with target value higher than maximum power value

Fig. 8, curve 3 is a power execution process curve for adjusting the target value to exceed the current natural maximum power value of the elevation station. The natural maximum power of the total station at that time was about 14.5MW, while the commanded goal was to boost 5MW to 15.3MW. From curve 3, it can be seen that the total station power generation value has a short-term 5-8 ms rise-towards-height process, and then gradually falls back to be stabilized to be near the maximum power value. Calculated at the natural maximum power value that the total station will eventually reach, in this case the total station response time is about 22ms. Furthermore, from the curve comparison, the total-station response is much smoother than the stand-alone power response curve.

Based on the steps and the field verification of the related technology, the aims that the response time of the single-machine power boosting or descending regulation execution of the inverter is less than 30 milliseconds, and the response time of the full photovoltaic power station power boosting or descending regulation execution is less than 50 milliseconds are achieved. The system-level quick support response requirements of a power grid stability control and dispatching center or other superior systems on the new energy photovoltaic power station system level are met.

In the method, the inverter is not influenced by condition deviation such as terrain distribution difference, shadow shielding, illumination meteorological conditions, inconsistent attenuation degree of a photovoltaic cell assembly and the like on the maximum power point of different inverters through an intelligent self-adaptive algorithm, and the maximum power point parameter of a photovoltaic array at the input side of the inverter can be dynamically tracked, recorded and updated. When the rapid power control and regulation of the power station is carried out, a power target value sent by the rapid power control device at the plant station end is received, rapid power descending or ascending execution response is carried out through the voltage outer ring and the current inner ring regulation of the inverter, the rapid power control target within 30 milliseconds of a single inverter and 50 milliseconds of a total station is achieved, the requirement of hundred-millisecond regulation response of a system to a photovoltaic power station is met when the power grid is disturbed or abnormal, and therefore the stability of the power grid and the friendliness and economy of photovoltaic grid connection are improved.

The above embodiments are only for illustrating the technical idea of the present invention, and the protection scope of the present invention is not limited thereby, and any modifications made on the basis of the technical scheme according to the technical idea of the present invention fall within the protection scope of the present invention.

Claims

1. A method for rapidly controlling the power of a photovoltaic power station inverter is characterized by comprising the following steps:

step 2, in a power limiting state, the inverter receives an up-regulation power instruction, and fast spanning type power regulation response is carried out according to a lifting power target value Pt1 and a maximum power point voltage Vmpp; when the inverter receives a power reduction command, quickly reducing power and adjusting response by referring to a target power value Pt2;

in the step 1, the value of Vmpp is in a specified inverter output power interval, the power interval has a single-side limit value or has upper and lower-side limit values, the Vmpp value adopts an average value of all days, or adopts an average value of a fixed time period every day, or adopts a weighted average value of different time periods, or adopts a sliding window average value of n days, the inverter sends the value of the maximum power point voltage Vmpp of the inverter by means of wired or wireless communication, vmpp deviation threshold values are respectively set for each inverter, and when the current-day Vmpp data of the inverter cannot be obtained or the deviation is larger and more limited, the Vmpp near-term average value stored in the previous day of the inverter or the current-day inverter Vmpp average value is used as the current-day Vmpp data of the inverter;

in the step 2, when the inverter receives the power up-regulation instruction, firstly, the direct-current voltage of the inverter is set at Vmpp +. DELTA.U and is used for controlling the inverter, wherein the DELTA.U is the safe threshold of the direct-current voltage of the inverter; directly switching the power of the inverter to a secondary maximum power value Pm ' corresponding to the direct-current voltage Vmpp plus delta U, starting from the Pm ' point, and carrying out next adjustment on the inverter based on the sizes of the power adjustment instructions Pt1 and Pm ': when Pt1 is greater than Pm', the inverter continues MPPT tracking; when Pt1 is less than or equal to Pm', directly regulating the power of the inverter to the target power Pt1,

when the inverter receives the power-up instruction, comparing the target value Pt1 of the boosted power with the actual maximum power value Pmpp of the inverter, and when Pt1 is less than or equal to Pmpp, adjusting the output power to the target value Pt1 of the boosted power in the execution process; and when Pt1 is larger than Pmpp, adjusting the output power to the natural maximum power value of the inverter in the execution process.

2. The method for rapidly controlling the power of the photovoltaic power station inverter as claimed in claim 1, characterized in that: the communication protocol adopts GOOSE/UDP or TCP.

3. The method for rapidly controlling the power of the photovoltaic power station inverter as claimed in claim 1, wherein the method comprises the following steps: in the step 2, the power-up instruction or the power-down instruction received by the inverter is sent by the photovoltaic power station rapid power control device or directly issued by a power grid superior control system, wherein the power grid superior control system comprises a power grid safety and stability control system and a power grid dispatching system.

4. The method for rapidly controlling the power of the photovoltaic power station inverter as claimed in claim 1, wherein the method comprises the following steps: the delta U value is 0.5% -5% of the rated value of the DC bus voltage of the inverter.