Water and electricity dominated multi-energy isolated network system frequency control method

Abstract

The invention relates to a frequency control method for a hydroelectric-dominated multi-energy isolated network system, and belongs to the technical field of frequency modulation of isolated network systems. According to the method, various power supplies such as hydroelectric power and wind power are connected to a centralized control platform, the centralized control platform overall optimizes control strategies of all the power supplies, and through an isolated network side AGC control method and a multi-energy load distribution strategy, part of main hydroelectric generating units serve as dominant frequency modulation units, and other power supplies assist in adjustment, frequency control of the multi-energy isolated network system dominant by hydroelectric power is achieved. According to the method, the phenomenon of disordered fluctuation of the system caused by load pulling, asynchronous adjustment and the like after various power supplies all participate in adjustment is prevented, a new control strategy is provided for stable control of the multi-energy isolated network system, and the method has engineering application value.

Description

Technical Field

[0001] The invention belongs to the technical field of frequency regulation of isolated grid systems, and in particular relates to a frequency control method for a multi-energy isolated grid system dominated by hydropower. Background Art

[0002] In recent years, with the massive access of new energy sources to regional power grids, the risk of passive grid isolation has become increasingly high. There have been a number of consecutive grid isolation and voltage loss events in regions where a high proportion of small hydropower and new energy sources have been connected to the grid. Representative examples include the "6.6" 500kV Liping regional grid voltage loss in Guizhou Power Grid and the "7.22" 110kV Xinggu transformer isolated grid operation event in Yunnan Power Grid. The operating characteristics of the power grids in these regions are complex, with large outputs of small hydropower and new energy sources, weak grid structures within the isolated grids, and differences in hydropower, new energy control, grid stability control strategies, and load types within the isolated grids, resulting in complex characteristics after passive grid isolation. Load grabbing often occurs between units, and the system cannot be restarted due to insufficient load after stable machine cutting, causing large fluctuations or collapse of the system frequency.

[0003] Therefore, how to overcome the shortcomings of the existing technology and prevent the system from disorderly fluctuations caused by load pulling and asynchronous regulation after all multiple power sources are involved in the regulation is an urgent problem to be solved in the field of frequency regulation of isolated coating grid systems. Summary of the invention

[0004] The purpose of the present invention is to solve the deficiencies of the prior art and provide an easy-to-implement frequency control method for a multi-energy isolated grid system dominated by hydropower. The method connects multiple power sources such as hydropower and wind power to a centralized control platform, which coordinates and optimizes the control strategies of each power source, and uses the AGC control method on the isolated grid side and the multi-energy load distribution strategy to take some main hydropower units as the dominant frequency regulation units to achieve frequency control dominated by hydropower in the multi-energy isolated grid system.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0006] A frequency control method for a multi-energy isolated grid system dominated by hydropower, comprising the following steps:

[0007] Step (1), establishing an AGC control model for an isolated grid system with hydropower-dominated frequency regulation;

[0008] Step (2), using the hydropower unit regulation system model, the wind power regulation system model and the isolated grid system AGC control model constructed in step (1), to establish an isolated grid system frequency regulation closed-loop control overall model;

[0009] Step (3), establishing a load distribution method for the leading frequency regulating unit;

[0010] Step (4): based on the isolated grid system frequency regulation closed-loop control overall model constructed in step (2), the frequency static characteristic coefficient is obtained according to the active power and frequency rating of the isolated grid system collected by the centralized control platform, and the shortage or excess active power that needs to be adjusted is calculated through the isolated grid system AGC control model; the load distribution method of the leading frequency regulation unit established in step (3) is used to distribute the corresponding active power disturbance according to the current regulation capacity of each unit, and the hydropower unit is used to superimpose the shortage or excess negative active power that needs to be adjusted on the basis of the current output active power, so as to control the isolated grid system accordingly.

[0011] Further, preferably, the isolated grid system frequency regulation closed-loop control overall model includes a hydropower unit regulation system, a wind power regulation system, an isolated grid system AGC control model, a centralized control platform and an isolated grid load;

[0012] The centralized control platform is connected to the hydropower unit regulation system, wind power regulation system, isolated grid system AGC control model, and isolated grid load respectively;

[0013] The hydropower unit regulation system includes the leading frequency-regulated hydropower unit and other hydropower units;

[0014] The wind power regulation system includes a plurality of wind turbines;

[0015] The AGC control model of the isolated grid system is connected to the dominant frequency-regulated hydropower unit.

[0016] Further, preferably, in step (1), the AGC control model of the isolated grid system is:

[0017] First, the load of the isolated grid system is divided by the rated frequency to obtain the load and frequency static characteristic coefficient, and then multiplied by the frequency deviation of the isolated grid system. After smoothing through K parameter correction, PI control and response time, the system shortage or excess load value is obtained. The expression is:

[0018] ΔP to =K×B×Δf×(K P '+K I ' / s)×1 / (Ts+1) (1)

[0019] B=P GL / f g

[0020] Δf=f g -f ref

[0021] Where B is the load and frequency static characteristic coefficient, ΔP to is the system shortage or excess load value, P G L is the load of the isolated grid system, K is the correction factor, KP ' is the system AGC proportional gain, K I ' is the system AGC integral gain, T is the response time constant, s is the Laplace operator, Δf is the frequency deviation of the isolated grid system, f ref is the frequency feedback value, f g is the frequency rating.

[0022] Furthermore, preferably, the value of T is 0.1s-1s, and the value of K is 0.8-0.95.

[0023] Further, preferably, the relationship between the system load and frequency static characteristics is:

[0024] According to the static characteristics of system load and frequency, when the frequency deviates from the given value and remains unchanged, the approximate linear relationship is achieved. When the system frequency target is determined, P can be used near the given frequency value. GL / f g Indicates the relationship between frequency and load.

[0025] Further, preferably, in step (3), the load distribution method of the leading frequency regulating unit is:

[0026] The load distribution method of the leading frequency regulating unit is:

[0027] Collect data for the load distribution of frequency-regulating units connected to the centralized control platform. Use the centralized control platform to collect in real time the total load of the isolated grid system, frequency change, active power capacity of each hydropower unit connected to the isolated grid system, real-time active power, and the number of units participating in the load distribution of the leading frequency-regulating units;

[0028] When the system load is disturbed, the system adjustable active power meets the system load disturbance active power, that is:

[0029]

[0030] Among them, P′ Gi is the lower limit of adjustable capacity (real-time active power) of the i-th leading frequency-regulated hydropower unit, P″ Gi is the upper limit of adjustable capacity (active power capacity) of the i-th dominant frequency-regulated hydropower unit; ΔP Gi is the regulating capacity of one of the hydropower units, and n is the number of hydropower units involved in the regulation;

[0031] The load disturbance power is shared by the frequency modulation unit, and the shared active power does not exceed the adjustable active power range of the unit;

[0032] The maximum regulation capacity of each unit is related to the regulation margin of the unit. The unit with a large regulation margin undertakes more load disturbance active power regulation tasks. The maximum regulation capacity of the unit is normalized and the active power is allocated to each unit according to the current regulation capacity of the unit, that is,

[0033]

[0034]

[0035] is the active power allocated to regulating unit i.

[0036] The present invention connects multiple power sources such as hydropower and wind power to a centralized control platform. The centralized control platform coordinates and optimizes the control strategies of various power sources. Through the AGC control method on the isolated grid side and the multi-energy load distribution strategy, some main hydropower units are used as the leading frequency regulation units, and other power sources are used for auxiliary regulation, thereby realizing frequency control dominated by hydropower in the multi-energy isolated grid system.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] (1) The frequency control method for a multi-energy isolated grid system dominated by hydropower provided by the present invention solves the problem of disorderly fluctuations caused by load pulling and asynchronous regulation of hydropower, wind power and other multi-energy co-regulation in the current isolated grid system;

[0039] (2) The AGC control model and unit load distribution method of the isolated grid system with hydropower-dominated frequency regulation designed by the present invention can respond to the shortage or excess load of the isolated grid system and effectively compensate or reduce the load, while ensuring smooth regulation of the entire dynamic process;

[0040] (3) The present invention contributes to the safe and stable operation of a multi-energy isolated grid system; the method of the present invention is simple, the logic is clear, the computer program is easy to implement, and it has practical value.

[0041] In summary, the frequency control method for a multi-energy isolated grid system proposed in the present invention effectively solves the problems of disordered fluctuations such as load pulling and asynchronous regulation after all multiple power sources in the isolated grid system participate in the regulation. Through the simulation of load mutation of a certain isolated grid system, the isolated grid system centralized control platform is connected to 3 hydropower units and 2 wind farms (i.e., wind turbines). The frequency of the isolated grid system before the load mutation is 49.51Hz, and the load sudden frequency is stabilized at 50.68Hz. The load of one hydropower unit is reduced from 50MW to 34.2MW, and the load of one hydropower unit is reduced from 40MW to 24.3MW, with a total load reduction of 31.5MW. The regulation time is about 45s, and the simulation results achieve the expected effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 This is a schematic diagram of the AGC control model of an isolated grid system with hydropower-dominated frequency regulation;

[0043] Figure 2 It is a schematic diagram of the overall model of frequency regulation closed-loop control of isolated grid system;

[0044] Figure 3It is a simulation waveform diagram of load mutation of isolated grid system; (a) is the waveform of load mutation of isolated grid system, (b) is the frequency waveform of isolated grid system, (c) is the active power waveform of the first hydropower unit involved in regulation, and (d) is the active power waveform of the second hydropower unit involved in regulation;

[0045] Figure 4 This is the simulated waveform of the gradual wind change of the wind farm station in the isolated grid system. (a) is the waveform of the gradual wind change active power of the wind farm station in the isolated grid system, (b) is the frequency waveform of the isolated grid system, (c) is the active power waveform of the first hydropower unit involved in the regulation, and (d) is the active power waveform of the second hydropower unit involved in the regulation. DETAILED DESCRIPTION

[0046] The present invention is further described in detail below in conjunction with embodiments.

[0047] Those skilled in the art will appreciate that the following examples are only used to illustrate the present invention and should not be considered to limit the scope of the present invention. If no specific techniques or conditions are specified in the examples, the techniques or conditions described in the literature in the art or the product specifications are used. If the manufacturer of the materials or equipment used is not specified, they are all conventional products that can be purchased.

[0048] Example 1

[0049] A frequency control method for a multi-energy isolated grid system dominated by hydropower, comprising the following steps:

[0050] Step (1), establishing an AGC control model for an isolated grid system with hydropower-dominated frequency regulation;

[0051] Step (2), using the hydropower unit regulation system model, the wind power regulation system model and the isolated grid system AGC control model constructed in step (1), to establish an isolated grid system frequency regulation closed-loop control overall model;

[0052] Step (3), establishing a load distribution method for the leading frequency regulating unit;

[0053] Step (4): based on the isolated grid system frequency regulation closed-loop control overall model constructed in step (2), the frequency static characteristic coefficient is obtained according to the active power and frequency rating of the isolated grid system collected by the centralized control platform, and the shortage or excess active power that needs to be adjusted is calculated through the isolated grid system AGC control model; the load distribution method of the leading frequency regulation unit established in step (3) is used to distribute the corresponding active power disturbance according to the current regulation capacity of each unit, and the hydropower unit is used to superimpose the shortage or excess negative active power that needs to be adjusted on the basis of the current output active power, so as to control the isolated grid system accordingly.

[0054] Example 2

[0055] A frequency control method for a multi-energy isolated grid system dominated by hydropower, comprising the following steps:

[0056] Step (1), establishing an AGC control model for an isolated grid system with hydropower-dominated frequency regulation;

[0057] Step (2), using the hydropower unit regulation system model, the wind power regulation system model and the isolated grid system AGC control model constructed in step (1), to establish an isolated grid system frequency regulation closed-loop control overall model;

[0058] Step (3), establishing a load distribution method for the leading frequency regulating unit;

[0059] Step (4): based on the isolated grid system frequency regulation closed-loop control overall model constructed in step (2), the frequency static characteristic coefficient is obtained according to the active power and frequency rating of the isolated grid system collected by the centralized control platform, and the shortage or excess active power that needs to be adjusted is calculated through the isolated grid system AGC control model; the load distribution method of the leading frequency regulation unit established in step (3) is used to distribute the corresponding active power disturbance according to the current regulation capacity of each unit, and the hydropower unit is used to superimpose the shortage or excess negative active power that needs to be adjusted on the basis of the current output active power, so as to control the isolated grid system accordingly.

[0060] The overall model of frequency regulation closed-loop control of isolated grid system includes hydropower unit regulation system, wind power regulation system, isolated grid system AGC control model, centralized control platform and isolated grid load;

[0061] The centralized control platform is connected to the hydropower unit regulation system, wind power regulation system, isolated grid system AGC control model, and isolated grid load respectively;

[0062] The hydropower unit regulation system includes the leading frequency-regulated hydropower unit and other hydropower units;

[0063] The wind power regulation system includes a plurality of wind turbines;

[0064] The AGC control model of the isolated grid system is connected to the dominant frequency-regulated hydropower unit.

[0065] In step (1), the AGC control model of the isolated grid system is:

[0066] First, the load of the isolated grid system is divided by the rated frequency to obtain the load and frequency static characteristic coefficient, and then multiplied by the frequency deviation of the isolated grid system. After smoothing through K parameter correction, PI control and response time, the system shortage or excess load value is obtained. The expression is:

[0067] ΔP to =K×B×Δf×(K P '+K I ' / s)×1 / (Ts+1) (1)

[0068] B=P GL / f g

[0069] Δf=f g -f ref

[0070] Where B is the load and frequency static characteristic coefficient, ΔP to is the system shortage or excess load value, P G L is the load of the isolated grid system, K is the correction factor, K P ' is the system AGC proportional gain, K I ' is the system AGC integral gain, T is the response time constant, s is the Laplace operator, Δf is the frequency deviation of the isolated grid system, f ref is the frequency feedback value, f g is the frequency rating.

[0071] The T value is 0.1s-1s, and the K value is 0.8-0.95.

[0072] The relationship between the system load and frequency static characteristics is:

[0073] According to the static characteristics of system load and frequency, when the frequency deviates from the given value and remains unchanged, the approximate linear relationship is achieved. When the system frequency target is determined, P can be used near the given frequency value. GL / f g Indicates the relationship between frequency and load.

[0074] In step (3), the load distribution method of the leading frequency regulating unit is:

[0075] The load distribution method of the leading frequency regulating unit is:

[0076] Collect data for the load distribution of frequency-regulating units connected to the centralized control platform. Use the centralized control platform to collect in real time the total load of the isolated grid system, frequency change, active power capacity of each hydropower unit connected to the isolated grid system, real-time active power, and the number of units participating in the load distribution of the leading frequency-regulating units;

[0077] When the system load is disturbed, the system adjustable active power meets the system load disturbance active power, that is:

[0078]

[0079] Among them, P′ Gi is the lower limit of adjustable capacity of No. i dominant frequency regulation hydropower unit, P″ Gi is the upper limit of the adjustable capacity of the i-th dominant frequency-regulating hydropower unit; ΔP Gi is the regulating capacity of one of the hydropower units, and n is the number of hydropower units involved in the regulation;

[0080] The load disturbance power is shared by the frequency modulation unit, and the shared active power does not exceed the adjustable active power range of the unit;

[0081] The maximum regulating capacity of the unit is normalized, and the active power allocated to each unit is calculated according to the current regulating capacity of the unit, that is,

[0082]

[0083]

[0084] is the active power allocated to regulating unit i.

[0085] Example 3

[0086] The frequency control method of a multi-energy isolated grid system dominated by hydropower comprises the following steps:

[0087] Step (1), establishing an AGC control model for an isolated grid system with hydropower-dominated frequency regulation;

[0088] Step (2), using the hydropower unit regulation system model, the wind power regulation system model and the isolated grid system AGC control model constructed in step (1), to establish an isolated grid system frequency regulation closed-loop control overall model;

[0089] Step (3), establishing a load distribution method for the leading frequency regulating unit;

[0090] Step (4): based on the isolated grid system frequency regulation closed-loop control overall model constructed in step (2), the frequency static characteristic coefficient is obtained according to the active power and frequency rating of the isolated grid system collected by the centralized control platform, and the shortage or excess active power that needs to be adjusted is calculated through the isolated grid system AGC control model; the load distribution method of the leading frequency regulation unit established in step (3) is used to distribute the corresponding active power disturbance according to the current regulation capacity of each unit, and the hydropower unit is used to superimpose the shortage or excess negative active power that needs to be adjusted on the basis of the current output active power, so as to control the isolated grid system accordingly.

[0091] The frequency control method of the multi-energy isolated grid system dominated by hydropower is characterized in that the isolated grid system frequency regulation closed-loop control overall model includes a hydropower unit regulation system, a wind power regulation system, an isolated grid system AGC control model, a centralized control platform and an isolated grid load;

[0092] The centralized control platform is connected to the hydropower unit regulation system, wind power regulation system, isolated grid system AGC control model, and isolated grid load respectively;

[0093] The hydropower unit regulation system includes the leading frequency-regulated hydropower unit and other hydropower units;

[0094] The wind power regulation system includes a plurality of wind turbines;

[0095] The AGC control model of the isolated grid system is connected to the dominant frequency-regulated hydropower unit.

[0096] The frequency control method of the multi-energy isolated grid system dominated by hydropower is characterized in that, in step (1), the AGC control model of the isolated grid system is:

[0097] First, the load of the isolated grid system is divided by the rated frequency to obtain the load and frequency static characteristic coefficient, and then multiplied by the frequency deviation of the isolated grid system. After smoothing through K parameter correction, PI control and response time, the system shortage or excess load value is obtained. The expression is:

[0098] ΔP to =K×B×Δf×(K P '+K I ' / s)×1 / (Ts+1) (1)

[0099] B=P GL / f g

[0100] Δf=f g -f ref

[0101] Where B is the load and frequency static characteristic coefficient, ΔP to is the system shortage or excess load value, P G L is the load of the isolated grid system, K is the correction factor, K P ' is the system AGC proportional gain, K I ' is the system AGC integral gain, T is the response time constant, s is the Laplace operator, Δf is the frequency deviation of the isolated grid system, f ref is the frequency feedback value, f g is the frequency rating.

[0102] The frequency control method of the multi-energy isolated grid system dominated by hydropower is characterized in that the value of T is 0.1s-1s and the value of K is 0.8-0.95.

[0103] The frequency control method of the multi-energy isolated grid system dominated by hydropower is characterized in that the relationship between the system load and the frequency static characteristic is:

[0104] According to the static characteristics of system load and frequency, when the frequency deviates from the given value and remains unchanged, the approximate linear relationship is achieved. When the system frequency target is determined, P can be used near the given frequency value. GL / f g Indicates the relationship between frequency and load.

[0105] The frequency control method of a multi-energy isolated grid system dominated by hydropower is characterized in that, in step (3), the load distribution method of the dominant frequency modulation unit is:

[0106] The load distribution method of the leading frequency regulating unit is:

[0107] To collect data for load distribution of frequency-regulating units connected to the centralized control platform, the centralized control platform is used to collect in real time the total load of the isolated grid system, frequency change, active power capacity of each hydropower unit connected to the isolated grid system, real-time active power, and the number of units participating in the load distribution of the dominant frequency-regulating units.

[0108] When the system load is disturbed, the system adjustable active power meets the system load disturbance active power, that is:

[0109]

[0110] Among them, P′ Gi is the lower limit of adjustable capacity (real-time active power) of the i-th leading frequency-regulated hydropower unit, P″ Gi ΔP is the upper limit of the adjustable capacity (active power capacity) of the i-th dominant frequency-regulated hydropower unit. Gi is the regulating capacity of one of the hydropower units, and n is the number of hydropower units involved in the regulation.

[0111] The load disturbance power is shared by the frequency modulation unit, and the shared active power does not exceed the adjustable active power range of the unit.

[0112] The maximum regulation capacity of each unit is related to the regulation margin of the unit. The unit with a large regulation margin undertakes more load disturbance active power regulation tasks. The maximum regulation capacity of the unit is normalized and the active power is allocated to each unit according to the current regulation capacity of the unit, that is,

[0113]

[0114]

[0115] is the active power allocated to regulating unit i.

[0116] Application Examples

[0117] Taking a multi-energy isolated grid system as an example, there are three hydropower units connected to the isolated grid system, with capacities of 30MW for Unit 1, 60MW for Unit 2, and 50MW for Unit 3. Two wind farms are connected to the isolated grid system, with capacities of 50MW for Wind Turbine Station 1 and 40MW for Wind Turbine Station 2. The proposed frequency control method for the multi-energy isolated grid system is simulated and verified by simulating the load shedding of the units, sudden load changes in the isolated grid system, and gusts and gradual wind characteristics of the wind turbines.

[0118] Simulation 1: Simulation of load mutation of isolated grid system: At a certain time, the operating load of the isolated grid system is 180MW, of which the load of hydropower units is 30MW for unit 1, 50MW for unit 2, and 40MW for unit 3. The load of wind farms is 30MW for station 1 and 30MW for station 2. The load of the isolated grid system suddenly changes by 20%, that is, 36MW. Units 2 and 3 participate in AGC regulation, and other units do not participate in frequency regulation. The K coefficient is 0.9. The simulation results are as follows: Figure 3 :

[0119] The frequency of the isolated grid system was 49.51Hz before the sudden load change, and the load sudden frequency was stabilized at 50.68Hz. The load of Unit 1 decreased from 50MW to 34.2MW, and the load of Unit 2 decreased from 40MW to 24.3MW. The total load reduction of the two units was 31.5MW. The adjustment time was about 45s, and the simulation results achieved the expected effect.

[0120] Simulation 2: Simulation of gradually changing wind speed at wind farms: At a certain time, the operating load of the isolated grid system is 180MW, of which the hydropower units are respectively loaded with 30MW for Unit 1, 50MW for Unit 2, and 40MW for Unit 3. The wind farm is loaded with 20MW for Station 1 and 40MW for Station 2. The gradually changing wind speed at Station 1 of the isolated grid system changes from 9m / s to 12m / s. Units 2 and 3 participate in AGC regulation, and other units do not participate in frequency regulation. The K coefficient is 0.9. The simulation results are as follows: Figure 4 :

[0121] After the load of the No. 1 station of the isolated grid system gradually changed from 20MW to 50MW, the frequency reached a maximum of 50.8Hz and a minimum of 49.4Hz. The frequency change was small and remained within the controllable range. The load of Unit 1 decreased from 50MW to 38.4MW, and the load of Unit 2 decreased from 40MW to 24.9MW. The total load reduction of the two units was 26.7MW, and the simulation results achieved the expected effect.

[0122] In summary, the existing frequency control method for multi-energy isolated grid system is still dominated by hydropower units, and all hydropower units are synchronously adjusted according to the frequency difference, without considering the influence of unit adjustment characteristics, such as frequency dead zone, response time, etc. The frequency control method for multi-energy isolated grid system dominated by hydropower units proposed in the present invention preferably uses units with better adjustment performance as the leading frequency adjustment units, and other base load operations or auxiliary adjustments, to prevent disordered fluctuations such as load pulling and asynchronous adjustment after all multiple power sources in the isolated grid system participate in the adjustment, and has practical value.

[0123] The above shows and describes the basic principles, main features and advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A frequency control method for a multi-energy isolated grid system dominated by hydropower, characterized in that: These include: Step (1), establishing an AGC control model for an isolated grid system with hydropower-dominated frequency regulation; Step (2), using the hydropower unit regulation system model, the wind power regulation system model and the isolated grid system AGC control model constructed in step (1), to establish an isolated grid system frequency regulation closed-loop control overall model; Step (3), establishing a load distribution method for the leading frequency regulating unit; Step (4): based on the isolated grid system frequency regulation closed-loop control overall model constructed in step (2), the frequency static characteristic coefficient is obtained according to the active power and frequency rating of the isolated grid system collected by the centralized control platform, and the shortage or excess active power that needs to be adjusted is calculated through the isolated grid system AGC control model; the load distribution method of the leading frequency regulation unit established in step (3) is used to distribute the corresponding active power disturbance according to the current regulation capacity of each unit, and the hydropower unit is used to superimpose the shortage or excess negative active power that needs to be adjusted on the basis of the current output active power, so as to control the isolated grid system accordingly.

2. The frequency control method of multi-energy isolated grid system dominated by hydropower according to claim 1 is characterized in that: The overall model of frequency regulation closed-loop control of isolated grid system includes hydropower unit regulation system, wind power regulation system, isolated grid system AGC control model, centralized control platform and isolated grid load; The centralized control platform is connected to the hydropower unit regulation system, wind power regulation system, isolated grid system AGC control model, and isolated grid load respectively; The hydropower unit regulation system includes the leading frequency-regulated hydropower unit and other hydropower units; The wind power regulation system includes a plurality of wind turbines; The AGC control model of the isolated grid system is connected to the dominant frequency-regulated hydropower unit.

3. The frequency control method of multi-energy isolated grid system dominated by hydropower according to claim 1 is characterized in that: In step (1), the AGC control model of the isolated grid system is: First, the load of the isolated grid system is divided by the rated frequency to obtain the load and frequency static characteristic coefficient, and then multiplied by the frequency deviation of the isolated grid system. After smoothing through K parameter correction, PI control and response time, the system shortage or excess load value is obtained. The expression is: ΔP to =K×B×Δf×(K P ’+K I ’ / s)×1 / (Ts+1) (1) B=P GL / f g Δf=f g -f ref Where B is the load and frequency static characteristic coefficient, ΔP to is the system shortage or excess load value, P GL is the load of the isolated grid system, K is the correction factor, K P ' is the system AGC proportional gain, K I ' is the system AGC integral gain, T is the response time constant, s is the Laplace operator, Δf is the frequency deviation of the isolated grid system, f ref is the frequency feedback value, f g is the frequency rating.

4. The frequency control method of multi-energy isolated grid system dominated by hydropower according to claim 3 is characterized in that: The T value is 0.1s-1s, and the K value is 0.8-0.

95.

5. The frequency control method of multi-energy isolated grid system dominated by hydropower according to claim 3 is characterized in that: The relationship between the system load and frequency static characteristics is: According to the static characteristics of system load and frequency, when the frequency deviates from the given value and remains unchanged, the approximate linear relationship is achieved. When the system frequency target is determined, P can be used near the given frequency value. GL / f g Indicates the relationship between frequency and load.

6. The frequency control method of multi-energy isolated grid system dominated by hydropower according to claim 1 is characterized in that: In step (3), the load distribution method of the leading frequency regulating unit is: The load distribution method of the leading frequency regulating unit is: Collect data for the load distribution of frequency-regulating units connected to the centralized control platform. Use the centralized control platform to collect in real time the total load of the isolated grid system, frequency change, active power capacity of each hydropower unit connected to the isolated grid system, real-time active power, and the number of units participating in the load distribution of the leading frequency-regulating units; When the system load is disturbed, the system adjustable active power meets the system load disturbance active power, that is: ΔP Gi =P″ Gi -P′ Gi Among them, P′ Gi is the lower limit of adjustable capacity of No. i dominant frequency regulation hydropower unit, P″ Gi is the upper limit of the adjustable capacity of the i-th dominant frequency-regulating hydropower unit; ΔP Gi is the regulating capacity of one of the hydropower units, and n is the number of hydropower units involved in the regulation; The load disturbance power is shared by the frequency modulation unit, and the shared active power does not exceed the adjustable active power range of the unit; The maximum regulating capacity of the unit is normalized, and the active power allocated to each unit is calculated according to the current regulating capacity of the unit, that is, is the active power allocated to regulating unit i.

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