Power grid dispatching method based on dynamic frequency security constraint and program product

Abstract

The embodiment of the invention provides a power grid dispatching method based on dynamic frequency security constraint and a program product. The method comprises the following steps: determining system frequency response information of the power system according to hydroelectric generating set frequency response information of the power system, photovoltaic / wind generating set frequency response information of the power system and battery energy storage frequency response information of the power system; the system frequency response information represents response conditions of the power system under different load changes; determining the minimum operation cost and the minimum voltage deviation value of the power system according to the system frequency response information of the power system; wherein the minimum voltage deviation value represents the change condition of the voltage when the power system receives disturbance; and determining a power dispatching strategy of the power system according to the minimum operation cost and the minimum voltage deviation value of the power system. The method is used for achieving the effects of giving consideration to the safety of the dynamic frequency and the steady-state voltage of the system and improving the safety and stability level of the frequency voltage of the island micro-grid.

Description

Technical Field

[0001] The present application relates to the field of power grid dispatching, and in particular to a power grid dispatching method and program product based on dynamic frequency security constraints. Background Art

[0002] With the transformation of the global energy mix and the rapid development of renewable energy, the proportion of renewable energy sources such as wind and solar in power systems has increased year by year. However, the integration of a high proportion of renewable energy into the grid poses a severe challenge to the safe and stable operation of power systems, especially in isolated microgrids. Due to their small size and low inertia, the high uncertainty and volatility of renewable energy sources can easily lead to frequency and voltage stability issues.

[0003] Traditional power system optimization and dispatching models usually take economy as the main goal, ignore dynamic frequency security constraints, and are unable to cope with the frequency fluctuation problems caused by the high proportion of renewable energy grid connection.

[0004] Therefore, there is an urgent need for a method that can take into account both the system dynamic frequency and steady-state voltage security and optimize the scheduling method to improve the frequency and voltage safety and stability level of the isolated island microgrid. Summary of the Invention

[0005] The embodiments of the present application provide a power grid dispatching method and program product based on dynamic frequency safety constraints, so as to achieve the effect of taking into account both the dynamic frequency and steady-state voltage safety of the system and improving the frequency and voltage safety and stability level of the isolated island microgrid.

[0006] In a first aspect, an embodiment of the present application provides a power grid dispatching method based on dynamic frequency security constraints, including: determining the system frequency response information of the power system based on the frequency response information of the hydropower units of the power system, the frequency response information of the photovoltaic / wind power units of the power system, and the battery energy storage frequency response information of the power system; the system frequency response information characterizes the response of the power system under different load changes; based on the system frequency response information of the power system, determining the minimum operating cost and the minimum voltage offset value of the power system; wherein the minimum voltage offset value characterizes the change in voltage when the power system receives a disturbance; and determining the power dispatching strategy of the power system based on the minimum operating cost and the minimum voltage offset value of the power system.

[0007] In a possible implementation, the frequency response information of the hydropower unit, the frequency response information of the photovoltaic / wind power unit, and the frequency response information of the battery energy storage are determined based on the preset inertial response power and system frequency deviation of the hydropower unit, the inertial response power and system frequency deviation of the photovoltaic / wind power unit, the inertial response power of the battery energy storage, and the system frequency deviation; and the system frequency response information of the power system is determined based on the frequency response information of the hydropower unit, the frequency response information of the photovoltaic / wind power unit, and the battery energy storage frequency response information.

[0008] In one possible implementation, a first constraint condition of the power system is determined based on the system frequency response information of the power system, wherein the first constraint condition represents a preliminary condition that needs to be met for the operation of the power system; the first constraint condition corresponds to an objective function; based on the first constraint condition and the objective function, the system frequency response information of the power system is calculated and processed to obtain the minimum operating cost and minimum voltage offset value of the power system.

[0009] In one possible implementation, based on the first constraint of the power system, the operating cost information of the power system is determined; wherein the operating cost information indicates the operating costs of the hydropower units, photovoltaic / wind power units, and battery energy storage in the system; based on the operating cost information of the power system, the minimum operating cost of the power system is determined; the minimum operating cost of the power system represents the minimum cost required for the normal operation of the power system; the voltage amplitude and standard voltage value of the node in the power system are obtained; and based on the voltage amplitude and standard voltage value of the node in the power system, the minimum voltage offset value is determined.

[0010] In one possible implementation, a second constraint is determined based on the frequency response information of the hydropower unit, the frequency response information of the photovoltaic / wind power unit, and the battery energy storage frequency response information; wherein, the second constraint represents the conditions satisfied by the operation of each unit; based on the first constraint and the second constraint, a third constraint of the power system is determined; wherein, the first constraint represents the preliminary conditions that need to be satisfied for the operation of the power system, and the third constraint represents the target conditions that need to be satisfied for the normal operation of the power system; based on the third constraint, the minimum operating cost and the minimum voltage offset value of the power system are calculated and processed to obtain the power dispatching strategy of the power system.

[0011] In a second aspect, an embodiment of the present application provides a power grid dispatching device based on dynamic frequency security constraints, including: a response module, used to determine the system frequency response information of the power system based on the frequency response information of the hydropower units of the power system, the frequency response information of the photovoltaic / wind power units of the power system, and the battery energy storage frequency response information of the power system; the system frequency response information characterizes the response of the power system under different load changes; a first determination module, used to determine the minimum operating cost and the minimum voltage offset value of the power system based on the system frequency response information of the power system; wherein the minimum voltage offset value characterizes the change in voltage when the power system receives a disturbance; a second determination module, used to determine the power dispatching strategy of the power system based on the minimum operating cost and the minimum voltage offset value of the power system.

[0012] In one possible embodiment, the response module includes: a determination unit for determining the frequency response information of the hydropower unit, the frequency response information of the photovoltaic / wind power unit, and the frequency response information of the battery energy storage based on the preset inertial response power and system frequency deviation of the hydropower unit, the inertial response power and system frequency deviation of the photovoltaic / wind power unit, the inertial response power of the battery energy storage, and the system frequency deviation; and a response unit for determining the system frequency response information of the power system based on the frequency response information of the hydropower unit, the frequency response information of the photovoltaic / wind power unit, and the frequency response information of the battery energy storage.

[0013] In a third aspect, an embodiment of the present application provides a power grid dispatching device based on dynamic frequency security constraints, including: a memory, a processor;

[0014] The memory stores computer-executable instructions;

[0015] The processor executes the computer-executable instructions stored in the memory, so that the processor executes the above first aspect and / or various possible implementations of the first aspect.

[0016] In a fourth aspect, an embodiment of the present application provides a computer-readable storage medium, in which computer-executable instructions are stored. When the computer-executable instructions are executed by a processor, they are used to implement the first aspect above and / or various possible implementation methods of the first aspect.

[0017] In a fifth aspect, an embodiment of the present application provides a computer program product, including a computer program, which, when executed by a processor, implements the above first aspect and / or various possible implementation methods of the first aspect.

[0018] The embodiments of the present application provide a power grid dispatching method and program product based on dynamic frequency security constraints, which determines the system frequency response information of the power system based on the frequency response information of the hydropower units in the power system, the frequency response information of the photovoltaic / wind power units in the power system, and the battery energy storage frequency response information of the power system; the system frequency response information represents the response of the power system under different load changes; based on the system frequency response information of the power system, the minimum operating cost and the minimum voltage offset value of the power system are determined; wherein the minimum voltage offset value represents the change in voltage when the power system receives a disturbance; based on the minimum operating cost and the minimum voltage offset value of the power system, the power dispatching strategy of the power system is determined. This method is used to achieve the effect of taking into account both the dynamic frequency and steady-state voltage safety of the system and improving the frequency and voltage safety and stability level of the isolated island microgrid. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0020] Figure 1 Schematic diagram of the process of the power grid dispatching method based on dynamic frequency security constraints provided in this application Figure 1 ;

[0021] Figure 2 Schematic diagram of the process of the power grid dispatching method based on dynamic frequency security constraints provided in this application Figure 2 ;

[0022] Figure 3 Schematic diagram of power grid dispatch simulation based on dynamic frequency security constraints provided by this application;

[0023] Figure 4 A schematic diagram of the voltage amplitudes of various nodes in the system provided by this application;

[0024] Figure 5 Schematic diagram of system active power balance provided for this application;

[0025] Figure 6 Schematic diagram of reactive power balance of distribution network provided for this application;

[0026] Figure 7 Schematic diagram of the output and upper reserve power of the hydropower unit provided for this application;

[0027] Figure 8 Schematic diagram of the disturbance provided for this application;

[0028] Figure 9 Schematic diagram of wind, solar, and hydropower distributed energy frequency response power provided for this application;

[0029] Figure 10 A schematic diagram of the architecture of the power grid dispatching method based on dynamic frequency security constraints provided in this application;

[0030] Figure 11 A schematic diagram of the structure of a power grid dispatching device based on dynamic frequency security constraints provided in this application;

[0031] Figure 12 A schematic diagram of the structure of the power grid dispatching equipment based on dynamic frequency security constraints provided in this application.

[0032] The above drawings illustrate specific embodiments of the present application, which will be described in more detail below. These drawings and the textual description are not intended to limit the scope of the present application in any way, but rather to illustrate the concepts of the present application to those skilled in the art by reference to specific embodiments. DETAILED DESCRIPTION

[0033] Exemplary embodiments will be described in detail herein, with examples illustrated in the accompanying drawings. In the following description, when referring to the drawings, identical numerals in different figures represent identical or similar elements, unless otherwise indicated. The embodiments described in the following exemplary embodiments are not intended to represent all embodiments consistent with the present application. Rather, they are merely examples of apparatus and methods consistent with certain aspects of the present application, as detailed in the appended claims.

[0034] Figure 1 Schematic diagram of the process of the power grid dispatching method based on dynamic frequency security constraints provided in this application Figure 1 ,like Figure 1 As shown, the method includes:

[0035] S101, determining system frequency response information of the power system based on frequency response information of the hydropower units of the power system, frequency response information of the photovoltaic / wind power units of the power system, and frequency response information of the battery energy storage of the power system; the system frequency response information represents the response of the power system under different load changes;

[0036] It should be noted that the frequency stability of the power system depends on the real-time balance of active power (i.e., the balance between generation and load). When the load changes suddenly (such as a sudden increase or decrease), the system frequency will deviate from the rated value (such as 50Hz). At this time, the power supply needs to quickly adjust the active power output to restore the balance.

[0037] Frequency response information can indicate the ability of various power sources (hydropower, wind power / photovoltaic, and energy storage) in the power system to quickly adjust their active output to balance power when the system frequency deviates (such as when a sudden load change causes the frequency to rise or fall).

[0038] By using system frequency response information and integrating the frequency response characteristics of various power sources, the dynamic regulation capability of the entire power system under different load changes (such as sudden increases or decreases) is evaluated, including regulation speed, regulation capacity and stability.

[0039] Optionally, the frequency response information may be the ability of various power sources (hydropower, wind power / photovoltaic, energy storage) in the power system to quickly adjust active output to balance power when the system frequency deviates (such as a sudden load change causing the frequency to rise or fall).

[0040] S102. Determine a minimum operating cost and a minimum voltage offset value of the power system based on the system frequency response information of the power system; wherein the minimum voltage offset value represents a change in voltage when the power system receives a disturbance;

[0041] For example, the minimum operating cost is to minimize the total operating cost of the power system by optimizing the scheduling strategy (such as the output distribution of hydropower, new energy, and energy storage) under the premise of meeting the system frequency stability and voltage safety.

[0042] The minimum voltage deviation value is used to minimize the deviation of the bus voltage from the rated value through reactive power regulation (such as new energy inverters, energy storage, and reactive power compensation equipment) when the system is disturbed (such as sudden load changes).

[0043] S103: Determine a power dispatching strategy for the power system according to the minimum operating cost and the minimum voltage offset value of the power system.

[0044] It should be noted that considering the minimum voltage offset value ensures frequency stability and voltage safety in the dispatch strategy. Considering the minimum operating cost can also reduce the cost of the dispatch strategy. The power system's minimum operating cost and minimum voltage offset value are combined to formulate a power dispatch strategy. Through optimized dispatch, the use of high-cost power sources (such as hydropower) is reduced, and low-cost power sources (such as renewable energy) and energy storage are prioritized. This helps avoid curtailment of wind and solar power, and improves the capacity to absorb renewable energy.

[0045] The grid dispatching method based on dynamic frequency security constraints provided in the embodiment of the present application determines the system frequency response information of the power system based on the frequency response information of the hydropower units of the power system, the frequency response information of the photovoltaic / wind power units of the power system, and the battery energy storage frequency response information of the power system; the system frequency response information characterizes the response of the power system under different load changes; based on the system frequency response information of the power system, the minimum operating cost and the minimum voltage offset value of the power system are determined; wherein, the minimum voltage offset value characterizes the change in voltage when the power system receives a disturbance; based on the minimum operating cost and the minimum voltage offset value of the power system, the power dispatching strategy means of the power system is determined to achieve (the beneficial effect corresponding to the technical problem).

[0046] Figure 2 Schematic diagram of the process of the power grid dispatching method based on dynamic frequency security constraints provided in this application Figure 2 ,like Figure 2 As shown, this embodiment Figure 1 Based on the embodiment, a power grid dispatching method based on dynamic frequency security constraints is described in detail. The method includes:

[0047] S201, determining the frequency response information of the hydropower unit, the frequency response information of the photovoltaic / wind power unit, and the frequency response information of the battery energy storage according to the preset inertial response power and system frequency deviation of the hydropower unit, the inertial response power and system frequency deviation of the photovoltaic / wind power unit, and the inertial response power and system frequency deviation of the battery energy storage;

[0048] S202: Determine system frequency response information of the power system according to the frequency response information of the hydropower generator set, the frequency response information of the photovoltaic / wind generator set, and the battery energy storage frequency response information.

[0049] For example:

[0050] (1) The frequency response model of the hydropower unit is as follows:

[0051] When a power disturbance occurs in the system, the hydroelectric generator can use part of the rotor kinetic energy to quickly respond to the system power disturbance. The inertial response power of the hydroelectric unit can be expressed as:

[0052]

[0053] Where, t is the dispatch period number; m is the hydropower unit number; ΔP IR Hm is the inertia response power of the hydropower unit; H Hm is the inertia constant of the hydropower unit; Δf is the system frequency deviation.

[0054] The main consideration for hydropower units is the water hammer effect. The primary frequency regulation process can be expressed using the first-order inertia link:

[0055]

[0056] Where, ΔP PFR Hm is the primary frequency regulation power of the hydropower unit; T Hm is the water hammer effect coefficient; R Hm It is the regulation coefficient of hydropower unit.

[0057] (2) Photovoltaic / wind turbine frequency response model:

[0058] Based on virtual inertia control and virtual droop control strategies, photovoltaic / wind turbines can provide inertia response power and primary frequency regulation response power to the system.

[0059] 1) Virtual inertia control:

[0060]

[0061] Where n is the number of photovoltaic / wind turbine; ΔP IR V / Wn is the inertial response power of the photovoltaic / wind turbine generator set; H V / Wn is the virtual inertia response coefficient of the photovoltaic / wind turbine group.

[0062] 2) Virtual droop control:

[0063]

[0064] Where, ΔP PFR V / Wn is the primary frequency modulation response power of the photovoltaic / wind turbine generator set; K V / Wn is the virtual droop control coefficient of the PV / wind turbine.

[0065] (3) Battery energy storage frequency response model:

[0066] Similarly, battery energy storage can also provide the system with inertial response power and primary frequency modulation response power, which are expressed as:

[0067]

[0068] Where s is the battery energy storage number; is the virtual inertia response power of battery energy storage; H Es is the virtual inertia constant of battery energy storage; ΔP PFR Es The primary frequency modulation response power of the battery energy storage; K Es is the virtual droop control coefficient of battery energy storage.

[0069] Combining the above formula, we can get the frequency response equation of the system:

[0070]

[0071] in,

[0072]

[0073] Where, ΔP L is the disturbance power of the system; K D is the system damping frequency adjustment coefficient; H SYS is the equivalent inertia constant of the system; U Hm The start / stop status of the hydropower unit is a 0 / 1 type variable, 1 means start, 0 means stop; S Hm is the capacity of the hydropower unit; S V / Wn is the capacity of photovoltaic / wind turbine; S Es is the battery energy storage capacity; S B For the baseline capacity.

[0074] By presetting the relationship between the inertial response power of different power sources and system frequency deviation, the frequency response information of hydropower, renewable energy, and energy storage can be accurately determined. The rapid response capabilities of energy storage and renewable energy can be leveraged to reduce frequency fluctuations. The large-capacity regulation capabilities of hydropower units can be leveraged to prevent secondary frequency fluctuations. Coordinating the output of multiple power sources reduces the frequency of high-cost power calls and achieves economical operation.

[0075] S203: Determine a first constraint condition of the power system based on the system frequency response information of the power system, wherein the first constraint condition represents a preliminary condition that needs to be met for the operation of the power system; and the first constraint condition corresponds to an objective function;

[0076] S204 : Based on the first constraint condition and the objective function, calculate and process the system frequency response information of the power system to obtain a minimum operating cost and a minimum voltage offset value of the power system.

[0077] Optionally, the first constraint condition is a preliminary condition that the power system must satisfy for operation. The first constraint condition may be composed of multiple sub-constraints, for example:

[0078] The first constraint conditions include: maximum frequency change rate constraint, quasi-steady-state frequency deviation constraint, and frequency minimum point constraint.

[0079] Maximum frequency change rate constraint: The rate of change of the system frequency (e.g., the change per second) must not exceed the maximum allowed value. This prevents rapid frequency fluctuations from causing equipment damage or malfunctioning of protective devices.

[0080] Quasi-steady-state frequency deviation constraint: After frequency regulation is completed, the deviation between the system frequency and the rated frequency must be within the allowable range. This ensures long-term frequency stability and avoids impacts on users and equipment.

[0081] Frequency minimum point constraint: During frequency regulation, the system frequency must not fall below a safety threshold. This prevents low frequencies from causing equipment downtime or system crashes.

[0082] For example:

[0083] Maximum frequency change rate constraint:

[0084]

[0085] Where, It is the maximum allowable value of the system frequency change rate.

[0086] Quasi-steady-state frequency deviation constraint:

[0087]

[0088] Where, It is the allowable value of the system's quasi-steady-state frequency deviation.

[0089] Frequency minimum point constraint:

[0090]

[0091] Where, t m It is the time of the lowest frequency point on the frequency deviation curve.

[0092] Exemplarily, operating cost information of the power system is determined based on a first constraint condition of the power system; wherein the operating cost information indicates operating costs of hydropower units, photovoltaic / wind power units, and battery energy storage in the power system;

[0093] Optionally, the operating costs of battery energy storage are as follows:

[0094] The operating cost of the isolated microgrid includes the start-up and shutdown costs of the hydropower units f U , unit operation and maintenance cost f O , wind / solar curtailment cost f S As well as energy storage operation, maintenance and charging and discharging costs E .

[0095]

[0096] Start-up and shutdown costs of hydropower units:

[0097]

[0098] Where cu m and cd m are the startup and shutdown cost coefficients of the hydropower unit, respectively.

[0099] Unit operation and maintenance costs:

[0100]

[0101] Where c h is the operation and maintenance cost coefficient of the hydropower unit; c v / w P is the operation and maintenance cost coefficient of photovoltaic / wind turbine. Hm , is the active power output by the hydropower unit.

[0102] Cost of curtailing wind / solar power:

[0103]

[0104] Where c s Ppre is the predicted power of photovoltaic or wind turbine.

[0105] Energy storage operation, maintenance, charging and discharging costs:

[0106]

[0107] Where c b is the operation and maintenance cost coefficient of battery energy storage; c p P is the electricity price for battery energy storage charging and discharging. cha Es 、P dis Es are the active power absorbed or released by the battery energy storage;

[0108] Based on the operating cost information of the power system, the minimum operating cost of the power system is determined; the minimum operating cost of the power system represents the minimum cost required for the normal operation of the power system; the voltage amplitude and standard voltage value of the node in the power system are obtained; based on the voltage amplitude and standard voltage value of the node in the power system, the minimum voltage offset value is determined.

[0109] Exemplarily, a second constraint condition is determined based on the frequency response information of the hydropower unit, the frequency response information of the photovoltaic / wind power unit, and the frequency response information of the battery energy storage unit; wherein the second constraint condition represents a condition satisfied by the operation of each unit;

[0110] Determining a third constraint condition for the power system based on the first constraint condition and the second constraint condition; wherein the first constraint condition represents a preliminary condition that needs to be met for the operation of the power system, and the third constraint condition represents a target condition that needs to be met for the normal operation of the power system;

[0111] The minimum operating cost and the minimum voltage offset value of the power system are calculated based on the third constraint condition to obtain a power dispatching strategy for the power system.

[0112] Optionally, the second constraint may be composed of multiple sub-constraints, for example, including a hydropower unit constraint, a photovoltaic / wind power unit constraint, and a battery energy storage constraint:

[0113] (1) Hydropower units:

[0114] The active power and reactive power constraints of the hydropower unit are:

[0115]

[0116] Where, P Hm , Q Hm are respectively the active / reactive power output by the hydropower unit, Q max Hm , Q min Hm are the maximum and minimum reactive power output by the hydropower unit, P max Hm 、P min Hm They are the maximum and minimum active power output of the hydropower unit respectively.

[0117] Active power ramp constraint:

[0118]

[0119] Where, P rate Hm is the maximum climbing power of the hydropower unit.

[0120] Spinning reserve power constraints:

[0121]

[0122] Where D L is the spinning reserve ratio of the system load; P L is the system active load power.

[0123] Start and stop time constraints:

[0124]

[0125] Where, T on Hm 、T off Hm The minimum start-up and shutdown time of the hydropower unit.

[0126] (2) Photovoltaic / wind turbines:

[0127] Based on the constant power factor control method, photovoltaic / wind power inverters have a certain reactive power regulation capability. However, the output active power and reactive power are coupled and affected by the rated capacity of the inverter. The active and reactive power output model of the photovoltaic / wind power inverter can be expressed as follows:

[0128] 0≤D V / Wn (t)≤1

[0129]

[0130] Under the condition that the inverter capacity does not exceed the limit, the maximum active output of the photovoltaic / wind turbine is:

[0131]

[0132] Subtracting the conventional active power output of the photovoltaic / wind turbine, the maximum additional active power that can be generated by the photovoltaic / wind turbine is:

[0133]

[0134] Where D V / Wn is the solar / wind curtailment rate; P V / Wn , Q V / Wn are the actual active power output and reactive power output of photovoltaic / wind turbine respectively; θ V / Wn is the power factor angle of photovoltaic / wind turbine; P max V / Wn To ensure that the capacity does not exceed the limit, the maximum active power output of the photovoltaic / wind turbine group; S N V / Wn is the inverter capacity of the photovoltaic / wind turbine; ΔP max V / Wn The maximum additional active power that can be generated by the photovoltaic / wind turbine generator set.

[0135] (3) Battery energy storage:

[0136] Battery energy storage can operate flexibly in four quadrants within the converter capacity range. Its active and reactive output can be expressed as:

[0137]

[0138] Where, P Es The active power exchanged by the battery energy storage; P cha Es 、P dis Es are the active power absorbed or released by the battery energy storage; Q Es Reactive power exchanged for battery energy storage; Q cha Es , Q dis Es are the reactive power absorbed or released by the battery energy storage; α cha Es , α dis Es are the states of the battery energy storage absorbing or releasing active power; βcha Es and βdis Es are the states of the battery energy storage absorbing or releasing reactive power, which are 0 / 1 type variables, 1 represents charging and 0 represents discharging; Smax Es is the maximum apparent power of the energy storage converter.

[0139] Similarly, considering the capacity limitation of the converter, the maximum active output of the battery energy storage is:

[0140]

[0141] Subtracting the conventional active power output of battery energy storage, the maximum active power that can be generated by battery energy storage is:

[0142]

[0143] The remaining capacity of the battery energy storage can be expressed as:

[0144]

[0145] Where, T is the end of the scheduling period; E s is the amount of battery energy storage at time t; Emax s and Emin s are the upper and lower limits of the remaining amount of battery energy storage, respectively; ηcha Es and ηdis Es are the active charge and discharge efficiencies of the battery energy storage, respectively.

[0146] Optionally, when wind, solar, hydro and storage distributed energy sources provide frequency support, the impact of unit spare capacity, ramp rate or converter remaining capacity needs to be considered:

[0147]

[0148] Where, ΔP nadirV / W n. They represent the frequency response power provided by hydropower, photovoltaic / wind power, and energy storage at the lowest frequency point respectively; They respectively represent the frequency response power provided by hydropower, photovoltaic / wind power, and energy storage when the frequency reaches a steady state.

[0149] Therefore, to ensure that the system's maximum frequency deviation and maximum steady-state frequency deviation do not exceed the safety threshold, the third constraint must be met:

[0150]

[0151] Optionally, Figure 10 Schematic diagram of the architecture of the power grid dispatching method based on dynamic frequency security constraints provided in this application:

[0152] The dynamic frequency response model and frequency security constraint construction of the island microgrid include:

[0153] Active frequency support mechanism of distributed energy sources including wind, solar and storage: including virtual inertia response and virtual droop control.

[0154] Dynamic frequency response model (ASF model): includes hydropower unit frequency response model, wind turbine unit frequency response model and battery energy storage frequency response model.

[0155] Dynamic frequency safety constraints (linearization): including maximum frequency change rate constraints, maximum frequency deviation constraints, and steady-state frequency deviation.

[0156] The multi-source coordinated optimization dispatch model of wind, solar, hydro and storage in isolated microgrids includes:

[0157] Objective function: including minimizing economic operation cost and minimizing node voltage deviation.

[0158] Conventional constraints: including power balance constraints, ramp rate constraints, power flow safety constraints, start and stop time constraints, unit output constraints and reserve constraints.

[0159] A multi-source collaborative optimization scheduling model for wind, solar, hydro and storage in isolated microgrids considering dynamic frequency security constraints.

[0160] Methods for solving complex nonlinear optimization models, including:

[0161] Mixed-integer nonlinear programming models: Using linearization techniques.

[0162] Mixed integer linear programming model: solved using MATLAB / Gurobi solver.

[0163] Through the above method, the coordinated optimization scheduling of multiple sources of wind, solar, hydro and storage in the isolated island microgrid can be achieved to ensure the frequency stability and economy of the system.

[0164] Figure 3 This application provides a schematic diagram of a grid dispatch simulation based on dynamic frequency security constraints. This simulation analysis uses a modified IEEE 33 (a standard distribution network) node system as an example. This system is connected to five hydroelectric generators, two wind turbines, three photovoltaic generators, and one energy storage device. The voltage regulators include one SVC, two SCs, and one OLTC. The SVC's reactive power compensation range is -1Mvar to 1Mvar, the SC's maximum reactive power compensation is 0.5Mvar, the unit shunt capacitor's compensation power is 0.05Mvar, and the OLTC's adjustable ratio range is 0.95 to 1.05, with an adjustment step size of 0.01. Each generator and voltage regulator is connected to a node.

[0165] To verify the effectiveness of the proposed method for optimizing the coordinated dispatch of wind, solar, hydro, and storage power in an island microgrid, taking into account dynamic frequency security constraints, this example uses the Gurobi solver to solve the constructed optimization dispatch model. The system voltage amplitudes at each node, the active and reactive output of the wind, solar, hydro, and storage distributed energy resources, and their active power spinning reserve are analyzed. The optimization results are then input into an island microgrid frequency response model constructed on the MATLAB / Simulink platform, further investigating the impact of disturbance power on the system's dynamic frequency security. The results demonstrate that incorporating the strategy of wind, solar, hydro, and storage power participating in active system frequency support, along with dynamic frequency security constraints, into the optimized dispatch model significantly improves the frequency security and stability of the island microgrid, validating the effectiveness of the proposed method.

[0166] Figure 4 The schematic diagram of the voltage amplitude of each node in the system provided for this application shows that in most operating periods, the node voltage amplitude is generally higher than the rated voltage, and the maximum voltage deviation of some nodes reaches about 2%. However, all node voltage amplitudes are strictly controlled within the safe allowable operating range (±5%), indicating that the coordinated optimization operation of wind, solar, hydropower and storage distributed energy and voltage regulation devices can effectively reduce system node voltage deviations, significantly improve voltage quality, and increase the grid voltage safety margin.

[0167] Figure 5 The system active power balance diagram provided for this application shows that hydropower units, as the primary power generation unit, bear the majority of the load power supply demand. Wind turbine output exhibits significant fluctuations, while the "daytime power generation and nighttime shutdown" operating characteristics of photovoltaic units increase the difficulty of peak load shaving and valley filling in the system. The battery energy storage system effectively mitigates the peak-to-valley difference in load power by optimizing the charging and discharging time, discharging during peak load periods and charging during valley periods.

[0168] Figure 6 The reactive power balance diagram of the distribution network provided for this application shows that during peak load periods, the system's reactive power demand increases significantly. During this period, the hydropower units, battery energy storage system, static compensator (SC), and static VAR compensator (SVC) jointly shoulder the primary reactive power support responsibility. To optimize network power flow distribution, the battery energy storage system's reactive power is largely maintained throughout the day.

[0169] Figure 7 The schematic diagram of the hydroelectric generator output and upper reserve power provided for this application shows that during peak electricity demand, to meet load demand, the hydroelectric generator output increases, resulting in a decrease in its upper reserve power, which in turn weakens the system's flexibility and regulation capabilities. Limited by the maximum adjustable power, the hydroelectric generator's frequency regulation capability is low. During low electricity demand periods, however, the hydroelectric generator has ample upper reserve power, resulting in stronger primary frequency regulation capabilities.

[0170] At the beginning of each period, set an 8% active load step disturbance and record the system frequency response process in the first 30 seconds, such as Figure 8 As shown in the figure, it can be seen that under different disturbance powers, the system's frequency drop rate, minimum frequency point, and steady-state frequency all vary. However, the system's dynamic frequency can enter a steady-state process within 20 seconds after the disturbance occurs, and the maximum frequency deviation (maximum allowable value is 0.5Hz) and quasi-steady-state frequency deviation (maximum allowable value is 0.2Hz) are both maintained within the safe allowable range, further demonstrating the effectiveness of the wind, solar, hydropower and storage multi-source coordinated frequency support strategy and frequency and voltage security constraints.

[0171] Figure 9The wind, solar, and hydropower distributed energy frequency response power diagram provided for this application shows the wind, solar, and hydropower distributed energy frequency response power situation in 15 time periods. It can be seen that the frequency response power of the wind and solar units is zero. This is because the system does not produce wind and solar power abandonment in order to maximize energy utilization and reduce operating costs, resulting in the wind and solar units having almost no frequency regulation capability. Therefore, the system frequency support mainly relies on hydropower units and battery energy storage devices. Among them, the frequency regulation power response speed of hydropower units is significantly slower than that of battery energy storage devices due to the influence of the speed regulator time constant.

[0172] The embodiment of the present application provides a power grid dispatching method based on dynamic frequency security constraints, which determines the system frequency response information of the power system based on the frequency response information of the hydropower units in the power system, the frequency response information of the photovoltaic / wind power units in the power system, and the battery energy storage frequency response information of the power system; the system frequency response information represents the response of the power system under different load changes; based on the system frequency response information of the power system, the minimum operating cost and the minimum voltage offset value of the power system are determined; wherein the minimum voltage offset value represents the change in voltage when the power system receives a disturbance; based on the minimum operating cost and the minimum voltage offset value of the power system, the power dispatching strategy means of the power system is determined. This method is used to achieve the effect of taking into account both the dynamic frequency and steady-state voltage safety of the system and improving the frequency and voltage safety and stability level of the isolated island microgrid.

[0173] Figure 11 The schematic diagram of the structure of the power grid dispatching device based on dynamic frequency security constraints provided by this application is as follows: Figure 11 As shown, the power grid dispatching device 40 based on dynamic frequency security constraints provided in this embodiment includes:

[0174] A response module 401 is configured to determine system frequency response information of the power system based on frequency response information of the hydropower units in the power system, frequency response information of the photovoltaic / wind turbine units in the power system, and frequency response information of the battery energy storage in the power system; the system frequency response information represents the response of the power system under different load changes;

[0175] A first determining module 402 is configured to determine a minimum operating cost and a minimum voltage offset value of the power system based on the system frequency response information of the power system; wherein the minimum voltage offset value represents a voltage change when the power system receives a disturbance;

[0176] The second determining module 403 is configured to determine a power dispatching strategy for the power system according to the minimum operating cost and the minimum voltage offset value of the power system.

[0177] In one possible implementation, the response module 401 includes: a determination unit, configured to determine frequency response information of the hydropower unit, frequency response information of the photovoltaic / wind power unit, and frequency response information of the battery energy storage based on preset inertial response power and system frequency deviation of the hydropower unit, inertial response power and system frequency deviation of the photovoltaic / wind power unit, inertial response power of the battery energy storage, and system frequency deviation; and a response unit, configured to determine system frequency response information of the power system based on the frequency response information of the hydropower unit, the frequency response information of the photovoltaic / wind power unit, and the frequency response information of the battery energy storage.

[0178] In one possible implementation, the first determination module 402 is used to determine a first constraint condition of the power system based on the system frequency response information of the power system, wherein the first constraint condition represents a preliminary condition that needs to be met for the operation of the power system; the first constraint condition corresponds to an objective function; based on the first constraint condition and the objective function, the system frequency response information of the power system is calculated and processed to obtain the minimum operating cost and minimum voltage offset value of the power system.

[0179] In one possible implementation, the first determination module 402 is further used to determine the operating cost information of the power system based on the first constraint condition of the power system; wherein the operating cost information indicates the operating costs of the hydropower units, photovoltaic / wind power units, and battery energy storage in the system; determine the minimum operating cost of the power system based on the operating cost information of the power system; the minimum operating cost of the power system represents the minimum cost required for the normal operation of the power system; obtain the voltage amplitude and standard voltage value of the node in the power system; determine the minimum voltage offset value based on the voltage amplitude and standard voltage value of the node in the power system.

[0180] In one possible implementation, the device also includes: a third determination module, used to determine a second constraint condition based on the frequency response information of the hydropower unit, the frequency response information of the photovoltaic / wind power unit, and the battery energy storage frequency response information; wherein, the second constraint condition represents the conditions satisfied by the operation of each unit; based on the first constraint condition and the second constraint condition, a third constraint condition of the power system is determined; wherein, the first constraint condition represents the preliminary conditions that need to be satisfied for the operation of the power system, and the third constraint condition represents the target conditions that need to be satisfied for the normal operation of the power system; based on the third constraint condition, the minimum operating cost and minimum voltage offset value of the power system are calculated and processed to obtain the power dispatching strategy of the power system.

[0181] The power grid dispatching device based on dynamic frequency security constraints provided in this embodiment can execute the method provided in the above method embodiment. Its implementation principle and technical effects are similar, and are not described in detail in this embodiment.

[0182] Figure 12 This is a schematic diagram of the structure of the power grid dispatching equipment based on dynamic frequency security constraints provided by this application. Figure 12 As shown, the electronic device 50 provided in this embodiment includes: at least one processor 501 and a memory 502. Optionally, the device 50 further includes a communication component 503. The processor 501, the memory 502 and the communication component 503 are connected via a bus 504.

[0183] In a specific implementation process, at least one processor 501 executes the computer-executable instructions stored in the memory 502, so that the at least one processor 501 performs the above method.

[0184] The specific implementation process of the processor 501 can be found in the above method embodiment. Its implementation principle and technical effects are similar and will not be repeated here in this embodiment.

[0185] In the above embodiments, it should be understood that the processor may be a central processing unit (CPU), other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), etc. A general-purpose processor may be a microprocessor or any conventional processor. The steps of the method disclosed in the present invention may be directly implemented by a hardware processor or implemented by a combination of hardware and software modules in the processor.

[0186] The memory may include a high-speed memory (Random Access Memory, RAM), and may also include a non-volatile memory (NVM), such as at least one disk memory.

[0187] The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, or an Extended Industry Standard Architecture (EISA) bus. Buses can be classified into address buses, data buses, and control buses. For ease of illustration, the buses in the drawings of this application are not limited to just one bus or just one type of bus.

[0188] The present application also provides a computer program product, including a computer program, which implements the above method when executed by a processor.

[0189] The present application also provides a computer-readable storage medium, in which computer-executable instructions are stored. When a processor executes the computer-executable instructions, the above method is implemented.

[0190] The above-mentioned readable storage medium can be implemented by any type of volatile or non-volatile memory device or a combination thereof, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic memory, flash memory, magnetic disk or optical disk. The readable storage medium can be any available medium that can be accessed by a general-purpose or special-purpose computer.

[0191] An exemplary readable storage medium is coupled to a processor so that the processor can read information from the readable storage medium and write information to the readable storage medium. Of course, the readable storage medium can also be an integral part of the processor. The processor and the readable storage medium can be located in an application specific integrated circuit (ASIC). Of course, the processor and the readable storage medium can also exist in the device as discrete components.

[0192] The division of units is merely a logical functional division; actual implementations may employ alternative divisions, such as combining or integrating multiple units or components into another system, or omitting or disabling certain features. Furthermore, any direct coupling or communication connection shown or discussed may be an indirect coupling or communication connection between devices or units, either through an interface, electrical, mechanical, or other means.

[0193] Units described as separate components may or may not be physically separate, and components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of these units may be selected to achieve the purpose of this embodiment according to actual needs.

[0194] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0195] If the function is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, server, or network device, etc.) to execute all or part of the steps of the various embodiments of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, and other media that can store program code.

[0196] Those skilled in the art will appreciate that all or part of the steps in the above-described method embodiments can be implemented using hardware associated with program instructions. The aforementioned program can be stored in a computer-readable storage medium. When executed, the program performs the steps of the above-described method embodiments. The aforementioned storage medium includes various media capable of storing program code, such as ROM, RAM, magnetic disks, or optical disks.

[0197] Finally, it should be noted that those skilled in the art will readily identify other embodiments of the present invention after considering the specification and practicing the invention disclosed herein. The present invention is intended to cover any variations, uses, or adaptations of the present invention that follow the general principles of the present invention and include common knowledge or customary techniques in the art not disclosed herein. The present invention is not limited to the precise structure described above and illustrated in the accompanying drawings, and various modifications and variations may be made without departing from the scope thereof. The scope of the present invention is limited solely by the appended claims.

Claims

1. A power grid dispatching method based on dynamic frequency security constraints, characterized in that: include: Determining system frequency response information of the power system based on frequency response information of the hydropower units in the power system, frequency response information of the photovoltaic / wind power units in the power system, and frequency response information of the battery energy storage in the power system; The system frequency response information represents the response of the power system under different load changes; Determining a minimum operating cost and a minimum voltage offset value of the power system based on the system frequency response information of the power system; wherein the minimum voltage offset value represents a change in voltage when the power system receives a disturbance; A power dispatching strategy for the power system is determined according to the minimum operating cost and the minimum voltage offset value of the power system.

2. The method according to claim 1, characterized in that Determining system frequency response information of the power system based on frequency response information of the hydropower generating units of the power system, frequency response information of the photovoltaic / wind generating units of the power system, and frequency response information of the battery energy storage of the power system, including: Determine the frequency response information of the hydropower unit, the frequency response information of the photovoltaic / wind power unit, and the frequency response information of the battery energy storage according to the preset inertial response power and system frequency deviation of the hydropower unit, the inertial response power and system frequency deviation of the photovoltaic / wind power unit, the inertial response power of the battery energy storage, and the system frequency deviation; System frequency response information of the power system is determined according to the frequency response information of the hydropower generator set, the frequency response information of the photovoltaic / wind generator set, and the battery energy storage frequency response information.

3. The method according to claim 1, characterized in that Determining a minimum operating cost and a minimum voltage offset value of the power system according to system frequency response information of the power system includes: determining a first constraint condition of the power system based on the system frequency response information of the power system, wherein the first constraint condition represents a preliminary condition that needs to be satisfied for the operation of the power system; and the first constraint condition corresponds to an objective function; Based on the first constraint condition and the objective function, the system frequency response information of the power system is calculated and processed to obtain the minimum operating cost and the minimum voltage offset value of the power system.

4. The method according to claim 3, characterized in that Calculating and processing the system frequency response information of the power system based on the first constraint condition and the objective function to obtain a minimum operating cost and a minimum voltage offset value of the power system includes: Determining operating cost information of the power system based on a first constraint condition of the power system; wherein the operating cost information indicates operating costs of the hydropower units, photovoltaic / wind power units, and battery energy storage in the store system; Determining a minimum operating cost of the power system based on the operating cost information of the power system; the minimum operating cost of the power system represents the minimum cost required for normal operation of the power system; Obtaining voltage amplitudes and standard voltage values ​​of nodes in the power system; The minimum voltage offset value is determined according to the voltage amplitude and the standard voltage value of the node in the power system.

5. The method according to any one of claims 1 to 4, characterized in that The method further comprises: Determining a second constraint condition based on the frequency response information of the hydropower unit, the frequency response information of the photovoltaic / wind power unit, and the frequency response information of the battery energy storage unit; wherein the second constraint condition represents a condition satisfied by the operation of each unit; Determining a third constraint condition for the power system based on the first constraint condition and the second constraint condition; wherein the first constraint condition represents a preliminary condition that needs to be met for the operation of the power system, and the third constraint condition represents a target condition that needs to be met for the normal operation of the power system; The minimum operating cost and the minimum voltage offset value of the power system are calculated based on the third constraint condition to obtain a power dispatching strategy for the power system.

6. A power grid dispatching device based on dynamic frequency security constraints, characterized in that: include: a response module, configured to determine system frequency response information of the power system based on frequency response information of the hydropower generating units of the power system, frequency response information of the photovoltaic / wind generating units of the power system, and frequency response information of the battery energy storage of the power system; The system frequency response information represents the response of the power system under different load changes; A first determining module is configured to determine a minimum operating cost and a minimum voltage offset value of the power system based on system frequency response information of the power system; wherein the minimum voltage offset value represents a change in voltage when the power system receives a disturbance; The second determining module is used to determine the power dispatching strategy of the power system according to the minimum operating cost and the minimum voltage offset value of the power system.

7. The device according to claim 6, characterized in that Response modules, including: a determination unit, configured to determine the frequency response information of the hydropower unit, the frequency response information of the photovoltaic / wind power unit, and the frequency response information of the battery energy storage according to the preset inertial response power and system frequency deviation of the hydropower unit, the inertial response power and system frequency deviation of the photovoltaic / wind power unit, and the inertial response power and system frequency deviation of the battery energy storage; The response unit is used to determine the system frequency response information of the power system according to the frequency response information of the hydropower unit, the frequency response information of the photovoltaic / wind power unit, and the battery energy storage frequency response information.

8. A power grid dispatching method and device based on dynamic frequency security constraints, characterized in that: include: Memory, processor; The memory stores computer-executable instructions; The processor executes the computer-executable instructions stored in the memory, so that the processor performs the method according to any one of claims 1 to 5.

9. A computer-readable storage medium, characterized in that The computer-readable storage medium stores computer-executable instructions, which are used to implement the method according to any one of claims 1 to 5 when executed by a processor.

10. A computer program product, characterized in that The invention comprises a computer program, which implements the method according to any one of claims 1 to 5 when executed by a processor.

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