Power grid frequency modulation control method and device for coordinating gravity energy storage and electrochemical energy storage

Abstract

The invention discloses a power grid frequency modulation control method and device for coordinating gravity energy storage and electrochemical energy storage, and the method comprises the steps: obtaining the frequency modulation demand power of a power grid side, and determining an input scheme of gravity energy storage; based on the input scheme of the gravity energy storage and the power output characteristics of the gravity energy storage, a power transmission strategy of the gravity energy storage is given; determining an electrochemical energy storage power transmission strategy based on the power transmission strategy of gravity energy storage and the required power of power grid side frequency modulation; based on a power transmission strategy of gravity energy storage and electrochemical energy storage, power output of gravity energy storage and electrochemical energy storage is controlled. The peak regulation and frequency modulation requirements of the power grid can be quickly met.

Description

Technical Field

[0001] The present invention belongs to the technical field of power grid frequency regulation, and in particular relates to a power grid frequency regulation control method and device for coordinating gravity energy storage and electrochemical energy storage. Background Art

[0002] In order to support large-scale access to new energy and ensure the safe and stable operation of the power grid, the new power system needs to comprehensively improve its flexible adjustment capabilities at different time scales, such as seconds, minutes, hours, and even weeks and quarters. Mechanical energy storage technology can provide an effective means to solve the multi-time scale power and energy balance problem of new power systems with new energy as the main body. Mechanical energy storage is one of the important types of energy storage, and its types include flywheel energy storage, compressed air energy storage, pumped storage, and gravity energy storage. By utilizing the differentiated technical advantages of mechanical energy storage, the regulation needs of future new power systems for inertial support and long-term energy storage can be better filled.

[0003] Gravity energy storage is a new type of mechanical energy storage technology that is gradually reaching the conditions for commercial application. Its energy storage medium is solid material. It uses a generator / motor to use the height difference to lift and lower the energy storage medium to realize the charging and discharging process of the energy storage system, and can provide a certain inertial support for the power system. It has the advantages of being environmentally friendly, flexible in site selection, long cycle life, low overall cost, no attenuation of energy storage medium, and no fire risk. Gravity energy storage can be benchmarked against pumped storage and salt cavern compressed air energy storage to achieve system-level and large-scale applications. At the same time, there is no need to build reservoirs, water culverts, gas storage chambers and other projects, which greatly reduces the amount of engineering.

[0004] In the prior art, there has been no research on the grid-connected control of vertical matrix-type gravity energy storage. Current research is mostly focused on modeling assumptions based on mountain slope or mine-type gravity energy storage entities, and no modeling of vertical matrix-type gravity energy storage entities has been seen. Moreover, current related research does not involve grid-connected control. Therefore, it is of great significance to study a grid-connected control method and system for a vertical matrix gravity energy storage system.

[0005] The large-scale centralized grid connection of renewable energy power systems such as wind power and photovoltaic power has brought challenges to the safe and stable operation of the power grid system. Since the output of renewable energy power systems is random, intermittent and volatile, the power grid system needs to have rapid adjustment capabilities.

[0006] The large-scale application of energy storage systems is conducive to improving the flexibility, economy and safety of power grid systems. Gravity energy storage systems have the advantages of high safety, clean and environmental protection, flexible site selection, and low overall cost. They are the key supporting technology for peak load shaving and valley filling of power grids and maintaining safe and stable operation of power grid systems. The existing vertical matrix gravity energy storage system converts the potential energy generated by the lifting of the weight block into electrical energy. For example, patent CN118412882A discloses a frequency modulation method of a gravity energy storage system, which uses a gravity energy storage frequency modulation unit for frequency modulation. The gravity energy storage frequency modulation unit includes an electric generator, which is connected to a friction wheel, which is connected to the weight through a wire rope, and the weight is movably located in an energy conversion channel formed by a high-structured structure; the electric generator is connected to the power grid through a bidirectional converter and a transformer in turn; the frequency modulation method includes the following steps: realizing power grid frequency detection through a bidirectional converter at the PCC point; when the power grid frequency is stable, the weight is in a suspended state; when the power grid frequency fluctuates, the power grid frequency is calculated and compared with a preset reference value, and a corresponding adjustment instruction is generated, and the frequency of the power grid is quickly adjusted by charging and discharging the gravity energy storage frequency modulation unit. However, the power increase per unit weight block of the gravity energy storage system is large. When the power demand on the grid side falls between the step output power of the gravity energy storage, gravity energy storage alone cannot meet the power demand on the grid side. It is necessary to design a hybrid energy storage system that connects gravity energy storage and electrochemical energy storage in parallel to better meet the power demand on the grid side.

[0007] Therefore, how to provide a grid frequency regulation method combining gravity energy storage and electrochemical energy storage is an urgent problem to be solved by technicians in this field. Summary of the invention

[0008] In view of the defects existing in the above-mentioned prior art, the present invention provides a method and device for controlling power grid frequency regulation by coordinating gravity energy storage and electrochemical energy storage, which can quickly meet the peak load and frequency regulation requirements of the power grid.

[0009] In a first aspect, the present invention provides a method for controlling power grid frequency regulation by coordinating gravity energy storage and electrochemical energy storage, comprising:

[0010] Obtain the power demand for grid-side frequency regulation and determine the investment plan for gravity energy storage;

[0011] Based on the investment plan of gravity energy storage and the power output characteristics of gravity energy storage, the power transfer strategy of gravity energy storage is given;

[0012] Determine the power transfer strategy of electrochemical energy storage based on the power transfer strategy of gravity energy storage and the power demand of grid-side frequency regulation;

[0013] A power transfer strategy based on gravity energy storage and electrochemical energy storage controls the power output of gravity energy storage and electrochemical energy storage.

[0014] Furthermore, the investment plan for gravity energy storage is determined, including:

[0015] Obtain the output power of a single weight block in the gravity energy storage unit corresponding to the gravity energy storage;

[0016] The number of weight blocks to be put into use is determined based on the power demand of the grid-side frequency regulation and the output power of a single weight block.

[0017] Furthermore, based on the power demand of the grid-side frequency regulation and the output power of a single weight block, the number of weight blocks to be put into use is determined, including:

[0018] The output power of the weight blocks in the gravity energy storage unit is superimposed in the order in which they are put into use, until the difference between the power demand for frequency regulation on the grid side and the output power of the superimposed weight blocks is the smallest and the difference is not negative, and the corresponding number of superimposed weight blocks is given.

[0019] Further, the gravity energy storage unit corresponding to the gravity energy storage includes a synchronous generator unit and a plurality of weight blocks;

[0020] Based on the investment scheme of gravity energy storage and the power output characteristics of gravity energy storage, the power transfer strategy of gravity energy storage is given, including:

[0021] According to the number of weight blocks put into the gravity energy storage unit and the corresponding power output characteristics, the time interval for adjacent weight blocks put into the gravity energy storage unit to start working in sequence is determined;

[0022] Based on the time interval when adjacent weight blocks in the gravity energy storage unit start to work in sequence, and the output power of the corresponding synchronous generator set when each weight block works, the power transmission strategy of gravity energy storage is given.

[0023] Furthermore, based on the time intervals at which adjacent weight blocks in the gravity energy storage unit start to work in sequence, and the output power of the corresponding synchronous generator set when each weight block works, a power transfer strategy for gravity energy storage is given, including:

[0024] Based on the number of weight blocks put into the gravity energy storage unit and the time intervals for starting to work in sequence, determine the time nodes for starting to work of the weight blocks put into the unit;

[0025] Based on the starting time node of the weight block, the output power of the synchronous generator set corresponding to the weight block at different time nodes is superimposed, and a power transfer strategy of the gravity energy storage unit corresponding to the gravity energy storage that changes with time is constructed.

[0026] Furthermore, based on the power transfer strategy of gravity energy storage and the power demand of grid-side frequency regulation, the power transfer strategy of electrochemical energy storage is determined, including:

[0027] According to the power transfer strategy of gravity energy storage, determine the output power of gravity energy storage at different time nodes;

[0028] Based on the difference between the power demand of grid-side frequency regulation and the output power of gravity energy storage at different time nodes, the output power of electrochemical energy storage at different time nodes is determined;

[0029] Based on the output power of the electrochemical energy storage at different time nodes, the power transfer strategy of the electrochemical energy storage is determined.

[0030] Further, the electrochemical energy storage includes an electrochemical energy storage device, and an electrochemical energy storage converter connecting the electrochemical energy storage device and a power grid, and the electrochemical energy storage converter includes a converter outer loop controller and a converter current inner loop controller;

[0031] Power delivery strategy based on electrochemical energy storage to control the power output of electrochemical energy storage, including:

[0032] Based on the power transfer strategy of electrochemical energy storage, the output power of electrochemical energy storage at different time nodes is given;

[0033] Based on the output power of electrochemical energy storage and combined with the converter outer loop controller, a current reference value of the converter outer loop controller is given;

[0034] Based on the current reference value of the converter outer loop controller, and the converter current inner loop controller, a modulation voltage output by the converter current inner loop controller is given;

[0035] Based on the modulation voltage output by the converter current inner loop controller, the actual voltage output by the converter current inner loop controller is controlled to control the power output of the electrochemical energy storage.

[0036] Furthermore, based on the output power of the electrochemical energy storage and in combination with the converter outer loop controller, a current reference value of the converter outer loop controller is given, including:

[0037] Based on the converter outer loop controller, determine its proportional gain and integral gain;

[0038] Based on the proportional gain and integral gain of the converter outer loop controller and combined with the Laplace operator, the transfer function of the converter outer loop controller is given;

[0039] Based on the difference between the active power reference value of the converter outer loop controller and the actual output power of the electrochemical energy storage, and combined with the transfer function of the converter outer loop controller, a current reference value of the converter outer loop controller is given.

[0040] Further, based on the current reference value of the converter outer loop controller, and the converter current inner loop controller, a modulation voltage output by the converter current inner loop controller is given, including:

[0041] Obtaining the grid voltage angular velocity, the filter inductance of the electrochemical energy storage converter and the voltage of the electrochemical energy storage grid connection point;

[0042] Determine the first intermediate state coefficient based on the grid voltage angular velocity and the filter inductance of the electrochemical energy storage converter, and in combination with the actual current value of the converter outer loop controller;

[0043] Based on the converter current inner loop controller, determine its proportional gain and integral gain;

[0044] Based on the proportional gain and integral gain of the converter current inner loop controller and combined with the Laplace operator, the transfer function of the converter current inner loop controller is given;

[0045] Based on the difference between the current reference value of the converter outer loop controller and the current actual value of the converter outer loop controller, and in combination with the transfer function of the converter current inner loop controller, a second intermediate state coefficient is given;

[0046] Based on the voltage of the electrochemical energy storage grid-connected point, a difference between the first intermediate state coefficient and the second intermediate state coefficient is processed to obtain a modulation voltage output by the converter current inner loop controller.

[0047] In a second aspect, the present invention further provides a power grid frequency regulation control device for coordinating gravity energy storage and electrochemical energy storage, and adopts the above-mentioned power grid frequency regulation control method for coordinating gravity energy storage and electrochemical energy storage, and the power grid frequency regulation control device comprises:

[0048] An investment determination module is used to obtain the power demand for grid-side frequency regulation and determine the investment plan for gravity energy storage;

[0049] A first strategy module, which is used to provide a power transfer strategy for the gravity energy storage based on the investment plan of the gravity energy storage and the power output characteristics of the gravity energy storage;

[0050] A second strategy module is used to determine the electrochemical energy storage power transfer strategy based on the power transfer strategy of the gravity energy storage and the power demand of the grid-side frequency regulation;

[0051] The control output module is used to control the power output of the gravity energy storage and the electrochemical energy storage based on the power transmission strategy of the gravity energy storage and the electrochemical energy storage.

[0052] Furthermore, the investment determination module includes:

[0053] Obtain the output power of a single weight block in the gravity energy storage unit corresponding to the gravity energy storage;

[0054] The number of weight blocks to be put into use is determined based on the power demand of the grid-side frequency regulation and the output power of a single weight block.

[0055] Furthermore, the investment determination module also includes:

[0056] The output power of the weight blocks in the gravity energy storage unit is superimposed in the order in which they are put into use, until the difference between the power demand for frequency regulation on the grid side and the output power of the superimposed weight blocks is the smallest and the difference is not negative, and the corresponding number of superimposed weight blocks is given.

[0057] Furthermore, the first strategy module includes:

[0058] According to the number of weight blocks put into the gravity energy storage unit and the corresponding power output characteristics, the time interval for adjacent weight blocks put into the gravity energy storage unit to start working in sequence is determined;

[0059] Based on the time interval when adjacent weight blocks in the gravity energy storage unit start to work in sequence, and the output power of the corresponding synchronous generator set when each weight block works, the power transmission strategy of gravity energy storage is given.

[0060] Furthermore, the first strategy module also includes:

[0061] Based on the number of weight blocks put into the gravity energy storage unit and the time intervals for starting to work in sequence, determine the time nodes for starting to work of the weight blocks put into the unit;

[0062] Based on the starting time node of the weight block, the output power of the synchronous generator set corresponding to the weight block at different time nodes is superimposed, and a power transfer strategy of the gravity energy storage unit corresponding to the gravity energy storage that changes with time is constructed.

[0063] Furthermore, the second strategy module includes:

[0064] According to the power transfer strategy of gravity energy storage, determine the output power of gravity energy storage at different time nodes;

[0065] Based on the difference between the power demand of grid-side frequency regulation and the output power of gravity energy storage at different time nodes, the output power of electrochemical energy storage at different time nodes is determined;

[0066] Based on the output power of the electrochemical energy storage at different time nodes, the power transfer strategy of the electrochemical energy storage is determined.

[0067] Furthermore, the control output module includes:

[0068] Based on the power transfer strategy of electrochemical energy storage, the output power of electrochemical energy storage at different time nodes is given;

[0069] Based on the output power of electrochemical energy storage and combined with the converter outer loop controller, a current reference value of the converter outer loop controller is given;

[0070] Based on the current reference value of the converter outer loop controller, and the converter current inner loop controller, a modulation voltage output by the converter current inner loop controller is given;

[0071] Based on the modulation voltage output by the converter current inner loop controller, the actual voltage output by the converter current inner loop controller is controlled to control the power output of the electrochemical energy storage.

[0072] Furthermore, the control output module includes:

[0073] Based on the converter outer loop controller, determine its proportional gain and integral gain;

[0074] Based on the proportional gain and integral gain of the converter outer loop controller and combined with the Laplace operator, the transfer function of the converter outer loop controller is given;

[0075] Based on the difference between the active power reference value of the converter outer loop controller and the actual output power of the electrochemical energy storage, and combined with the transfer function of the converter outer loop controller, a current reference value of the converter outer loop controller is given.

[0076] Furthermore, the control output module also includes:

[0077] Obtaining the grid voltage angular velocity, the filter inductance of the electrochemical energy storage converter and the voltage of the electrochemical energy storage grid connection point;

[0078] Determine the first intermediate state coefficient based on the grid voltage angular velocity and the filter inductance of the electrochemical energy storage converter, and in combination with the actual current value of the converter outer loop controller;

[0079] Based on the converter current inner loop controller, determine its proportional gain and integral gain;

[0080] Based on the proportional gain and integral gain of the converter current inner loop controller and combined with the Laplace operator, the transfer function of the converter current inner loop controller is given;

[0081] Based on the difference between the current reference value of the converter outer loop controller and the current actual value of the converter outer loop controller, and in combination with the transfer function of the converter current inner loop controller, a second intermediate state coefficient is given;

[0082] Based on the voltage of the electrochemical energy storage grid-connected point, a difference between the first intermediate state coefficient and the second intermediate state coefficient is processed to obtain a modulation voltage output by the converter current inner loop controller.

[0083] The present invention provides a method and device for controlling power grid frequency regulation by coordinating gravity energy storage and electrochemical energy storage, which at least has the following beneficial effects:

[0084] In response to the power demand of grid-side frequency regulation, based on the step output power characteristics of gravity energy storage, during the interval of heavy blocks being put into gravity energy storage, the output power of the gravity energy storage unit is used as a benchmark, and the electrochemical energy storage is used to supplement the shortfall between the power demand of the grid-side and the output power of the gravity energy storage. A time-sequential collaborative control strategy for gravity energy storage and electrochemical energy storage is designed, and the "gravity-electrochemical" hybrid energy storage works together to achieve the power demand of peak load and frequency regulation on the grid side. BRIEF DESCRIPTION OF THE DRAWINGS

[0085] Figure 1 A flow chart of a grid frequency modulation control method for coordinating gravity energy storage and electrochemical energy storage provided by the present invention;

[0086] Figure 2 A flow chart of a power transfer strategy for gravity energy storage provided in accordance with an embodiment of the present invention;

[0087] Figure 3 A flow chart for determining an electrochemical energy storage power transfer strategy provided by an embodiment of the present invention;

[0088] Figure 4 A flow chart of controlling the power output of electrochemical energy storage provided by an embodiment of the present invention;

[0089] Figure 5 A schematic diagram of a power grid frequency regulation control device for coordinating gravity energy storage and electrochemical energy storage provided by the present invention. DETAILED DESCRIPTION

[0090] In order to better understand the above technical solution, the above technical solution will be described in detail below in conjunction with the accompanying drawings and specific implementation methods. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0091] The terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments, and are not intended to limit the present invention. The singular forms "a", "said" and "the" used in the embodiments of the present invention and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings, and "multiple" generally includes at least two.

[0092] It should also be noted that the term "includes", "comprising" or any other variation thereof is intended to cover non-exclusive inclusion, so that a commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprising a ..." do not exclude the existence of other identical elements in the commodity or device including the elements.

[0093] Due to the limitation of its own mechanical structure, the output power characteristic of gravity energy storage presents a step output characteristic. On the one hand, there is a fixed interval time for the weight block to be put into gravity energy storage, and a single gravity energy storage device is difficult to meet the real-time power demand of the grid side; on the other hand, there is a minimum output power limit for the gravity energy storage device. If the power demand on the grid side is not an integer multiple of the minimum output power of the gravity energy storage device, it is difficult to meet the power demand on the grid side by relying solely on the gravity energy storage device, and there is a power shortage. Based on this, if Figure 1 As shown, the present invention provides a grid frequency regulation control method for coordinating gravity energy storage and electrochemical energy storage, which may include:

[0094] Obtain the power demand for grid-side frequency regulation and determine the investment plan for gravity energy storage;

[0095] Based on the investment plan of gravity energy storage and the power output characteristics of gravity energy storage, the power transfer strategy of gravity energy storage is given;

[0096] Determine the power transfer strategy of electrochemical energy storage based on the power transfer strategy of gravity energy storage and the power demand of grid-side frequency regulation;

[0097] A power transfer strategy based on gravity energy storage and electrochemical energy storage controls the power output of gravity energy storage and electrochemical energy storage.

[0098] The present invention aims at the power demand of grid-side frequency regulation based on the step output power characteristics of gravity energy storage. During the interval time when the heavy blocks are put into the gravity energy storage, the output power of the gravity energy storage unit is used as a benchmark, and the electrochemical energy storage is used to supplement the shortfall between the power demand of the grid-side and the output power of the gravity energy storage. A time-sequential coordinated control strategy for gravity energy storage and electrochemical energy storage is designed, and the "gravity-electrochemical" hybrid energy storage works together to achieve the power demand of grid-side peak-shaving and frequency regulation.

[0099] The gravity energy storage unit corresponding to the gravity energy storage includes a synchronous generator set and a plurality of weight blocks. When determining the investment plan for gravity energy storage, it can include:

[0100] Obtain the output power of a single weight block in the gravity energy storage unit corresponding to the gravity energy storage;

[0101] The number of weight blocks to be put into use is determined based on the power demand of the grid-side frequency regulation and the output power of a single weight block.

[0102] Specifically, based on the power demand of the grid-side frequency regulation and the output power of a single weight block, determining the number of weight blocks to be put in may include:

[0103] The output power of the weight blocks in the gravity energy storage unit is superimposed in the order in which they are put into use, until the difference between the power demand for frequency regulation on the grid side and the output power of the superimposed weight blocks is the smallest and the difference is not negative, and the corresponding number of superimposed weight blocks is given.

[0104] By determining the number of weight blocks required for power grid frequency modulation according to the working order of the weight blocks of the gravity energy storage unit, it can be applied to different application scenarios; for example, it can be applied to the situation where the weights of the weight blocks in the gravity energy storage unit are different. Under the condition that the working order of all the weight blocks in the gravity energy storage unit is fixed, the number of weight blocks can still be determined. Among them, when the gravity energy storage unit is used to output power to achieve the frequency modulation of the power grid, the forward work of each weight block in the gravity energy storage unit is used to achieve the frequency modulation of the power grid. The forward work is the process of finally converting the gravitational potential energy of the weight block into the electric energy of the power grid. In this process, the order of inputting the weight blocks is the forward work order of the weight blocks in sequence. When it is necessary to convert and store the excess power in the power grid, the gravity energy storage unit is used to perform reverse work to achieve the frequency modulation of the power grid. The reverse work is the process of finally converting the electric energy of the power grid into the gravitational potential energy of the weight blocks. In this process, the order of inputting the weight blocks is the reverse work order of the weight blocks in sequence.

[0105] like Figure 2 As shown, after determining the investment scheme of gravity energy storage, the power transfer strategy of gravity energy storage can be given based on the investment scheme of gravity energy storage and the power output characteristics of gravity energy storage, including:

[0106] According to the number of weight blocks put into the gravity energy storage unit and the corresponding power output characteristics, the time interval for adjacent weight blocks put into the gravity energy storage unit to start working in sequence is determined;

[0107] Based on the time intervals when adjacent weight blocks in the gravity energy storage unit start to work in sequence, and the output power of the corresponding synchronous generator set when each weight block works, the power transmission strategy of gravity energy storage is given, including:

[0108] Based on the number of weight blocks put into the gravity energy storage unit and the time intervals for starting to work in sequence, determine the time nodes for starting to work of the weight blocks put into the unit;

[0109] Based on the starting time node of the weight block, the output power of the synchronous generator set corresponding to the weight block at different time nodes is superimposed, and a power transfer strategy of the gravity energy storage unit corresponding to the gravity energy storage that changes with time is constructed.

[0110] like Figure 3 As shown, based on the power transfer strategy of gravity energy storage and the power demand of grid-side frequency regulation, the power transfer strategy of electrochemical energy storage is determined, which may include:

[0111] According to the power transfer strategy of gravity energy storage, determine the output power of gravity energy storage at different time nodes;

[0112] Based on the difference between the power demand of grid-side frequency regulation and the output power of gravity energy storage at different time nodes, the output power of electrochemical energy storage at different time nodes is determined;

[0113] Based on the output power of the electrochemical energy storage at different time nodes, the power transfer strategy of the electrochemical energy storage is determined.

[0114] The electrochemical energy storage includes an electrochemical energy storage device and an electrochemical energy storage converter connecting the electrochemical energy storage device and a power grid, and the electrochemical energy storage converter includes a converter outer loop controller and a converter current inner loop controller;

[0115] like Figure 4 As shown, after determining the power transfer strategy of the electrochemical energy storage, the power output of the electrochemical energy storage can be controlled based on the power transfer strategy of the electrochemical energy storage, including:

[0116] Based on the power transfer strategy of electrochemical energy storage, the output power of electrochemical energy storage at different time nodes is given;

[0117] Based on the output power of electrochemical energy storage and combined with the converter outer loop controller, a current reference value of the converter outer loop controller is given;

[0118] Based on the current reference value of the converter outer loop controller, and the converter current inner loop controller, a modulation voltage output by the converter current inner loop controller is given;

[0119] Based on the modulation voltage output by the converter current inner loop controller, the actual voltage output by the converter current inner loop controller is controlled to control the power output of the electrochemical energy storage.

[0120] That is, the present invention controls the modulation voltage output by the converter current inner loop controller to control the actual current value of the converter outer loop controller, and finally realizes the power output control of the electrochemical energy storage. Among them, based on the output power of the electrochemical energy storage, combined with the converter outer loop controller, the current reference value of the converter outer loop controller is given, including:

[0121] Based on the converter outer loop controller, determine its proportional gain and integral gain;

[0122] Based on the proportional gain and integral gain of the converter outer loop controller and combined with the Laplace operator, the transfer function of the converter outer loop controller is given;

[0123] Based on the difference between the active power reference value of the converter outer loop controller and the actual output power of the electrochemical energy storage, and combined with the transfer function of the converter outer loop controller, a current reference value of the converter outer loop controller is given.

[0124] The current reference value of the converter outer loop controller given is a d-axis current reference value of the converter outer loop controller.

[0125] Based on the current reference value of the converter outer loop controller, the converter current inner loop controller is used to provide a modulation voltage output by the converter current inner loop controller, including:

[0126] Obtaining the grid voltage angular velocity, the filter inductance of the electrochemical energy storage converter and the voltage of the electrochemical energy storage grid connection point;

[0127] Determine the first intermediate state coefficient based on the grid voltage angular velocity and the filter inductance of the electrochemical energy storage converter, and in combination with the actual current value of the converter outer loop controller;

[0128] Based on the converter current inner loop controller, determine its proportional gain and integral gain;

[0129] Based on the proportional gain and integral gain of the converter current inner loop controller and combined with the Laplace operator, the transfer function of the converter current inner loop controller is given;

[0130] Based on the difference between the current reference value of the converter outer loop controller and the current actual value of the converter outer loop controller, and in combination with the transfer function of the converter current inner loop controller, a second intermediate state coefficient is given;

[0131] Based on the voltage of the electrochemical energy storage grid-connected point, a difference between the first intermediate state coefficient and the second intermediate state coefficient is processed to obtain a modulation voltage output by the converter current inner loop controller.

[0132] Among them, the proportional gain and integral gain of the converter current inner loop controller are respectively the proportional gain and integral gain of the d-axis of the converter current inner loop controller; when determining the first intermediate state coefficient, the actual current value of the combined converter outer loop controller is the actual current value of the q-axis of the converter outer loop controller; when determining the second intermediate state coefficient, the actual current value of the combined converter outer loop controller is the actual current value of the d-axis of the converter outer loop controller, and the voltage of the electrochemical energy storage grid connection point is the d-axis voltage of the electrochemical energy storage grid connection point. In addition, based on the voltage of the electrochemical energy storage grid connection point, the difference between the first intermediate state coefficient and the second intermediate state coefficient is subjected to difference processing, specifically: the voltage of the electrochemical energy storage grid connection point and the difference between the first intermediate state coefficient and the second intermediate state coefficient are subjected to difference processing.

[0133] In addition, in addition to the above-mentioned control of the active power output of the electrochemical energy storage, the present invention can also realize the control of the reactive power output of the electrochemical energy storage. Specifically, the current reference value of the converter outer loop controller also includes the q-axis current reference value of the converter outer loop controller. Among them, the determination of the q-axis current reference value of the converter outer loop controller includes:

[0134] Based on the converter outer loop reactive power controller, determine its proportional gain and integral gain;

[0135] Based on the proportional gain and integral gain of the converter outer loop reactive controller and combined with the Laplace operator, the transfer function of the converter outer loop reactive controller is given.

[0136] Based on the difference between the reactive power reference value of the converter outer loop reactive controller and the actual output reactive power of the converter outer loop reactive controller and combined with the transfer function of the converter outer loop reactive controller, a q-axis current reference value of the converter outer loop controller is given.

[0137] After determining the q-axis current reference value of the converter outer loop controller, the q-axis component decoupling control can be implemented through feedforward control based on the converter current inner loop controller. Specifically, it includes:

[0138] Obtaining the q-axis voltage of the electrochemical energy storage grid connection point;

[0139] Determine the third intermediate state coefficient based on the grid voltage angular velocity and the filter inductance of the electrochemical energy storage converter and in combination with the actual value of the d-axis current of the converter outer loop controller;

[0140] Based on the current inner loop reactive controller of the converter, the proportional gain and integral gain of the q axis are determined;

[0141] Based on the proportional gain and integral gain of the q-axis of the converter current inner loop reactive controller and combined with the Laplace operator, the transfer function of the converter current inner loop reactive controller is given.

[0142] Based on the difference between the q-axis current reference value of the converter outer loop controller and the actual value of the q-axis current of the converter outer loop controller, and in combination with the transfer function of the converter current inner loop reactive controller, a fourth intermediate state coefficient is given;

[0143] Based on the q-axis voltage of the electrochemical energy storage grid-connected point, and superimposed with the third intermediate state coefficient and the fourth intermediate state coefficient, the q-axis component of the modulation voltage output by the converter current inner loop controller is obtained.

[0144] Based on the above determination of the current reference value of the converter outer loop controller, it is also possible to obtain the output power based on the electrochemical energy storage and combine the converter outer loop controller to give the current reference value of the converter outer loop controller, including:

[0145] Based on the converter outer loop controller and the converter outer loop reactive controller, determine the proportional gain and integral gain of the converter outer loop controller, as well as the proportional gain and integral gain of the converter outer loop reactive controller;

[0146] Based on the proportional gain and integral gain of the converter outer loop controller and combined with the Laplace operator, the transfer function of the converter outer loop controller is given; Based on the proportional gain and integral gain of the converter outer loop reactive controller and combined with the Laplace operator, the transfer function of the converter outer loop reactive controller is given;

[0147] Based on the difference between the active power reference value of the converter outer loop controller and the actual output power of the electrochemical energy storage, and in combination with the transfer function of the converter outer loop controller, a d-axis current reference value of the converter outer loop controller is given; based on the difference between the reactive power reference value of the converter outer loop reactive controller and the actual output reactive power of the converter outer loop reactive controller, and in combination with the transfer function of the converter outer loop reactive controller, a q-axis current reference value of the converter outer loop controller is given;

[0148] Based on the d-axis current reference value and the q-axis current reference value of the converter outer loop controller, a current reference value of the converter outer loop controller is determined.

[0149] The present invention simulates a "vertical matrix gravity energy storage-electrochemical" hybrid energy storage system to implement the grid frequency control method of the present invention. The hybrid energy storage system is provided with a gravity energy storage direct grid-connected unit, and the electrochemical energy storage is connected to the grid through the converter. Its grid-connected topology is that the gravity energy storage corresponding gravity energy storage unit includes a number of weights and a synchronous generator, and the several weights are connected to the grid through the synchronous generator; the electrochemical energy storage is connected to the grid after connecting the transformer through the converter. Several weights are correspondingly arranged in the gravity energy storage unit, and the mass of a single weight block is m=27.64 tons, and the maximum operating speed during ascent / descent is 2m / s. The synchronous generator set in the unit is a permanent magnet synchronous generator, and the maximum power output of the synchronous generator is 6.5MW. The electrochemical energy storage adopts a grid-following control strategy with a capacity of 6MW.

[0150] According to the grid-connected topology, a simulation model is constructed. At 20s in the simulation, the power demand instruction on the grid side changes from 0MW to 1.7MW. Based on the power demand instruction on the grid side, during the time interval when the gravity energy storage puts three weight blocks into operation, the power allocation strategy between the gravity energy storage and the electrochemical energy storage is used to allocate the timing power instructions to the gravity energy storage and the electrochemical energy storage. The output power of the "gravity-electrochemical" hybrid energy storage system meets the power demand of the grid side during the operation period. The output power of the gravity energy storage unit gradually increases in a step-like manner, while the output power of the electrochemical energy storage unit gradually decreases in a step-like manner. Moreover, the step-like shape of the gravity energy storage unit and the step-like shape of the electrochemical energy storage are approximately mirror-symmetrical. In this example, the gravity energy storage unit puts in the first weight block at 20 seconds, and the second and third weight blocks are put in at intervals of 4 seconds. During this period of time, the difference between the power demand on the grid side and the actual power generated by the gravity energy storage is realized by the electrochemical energy storage. As the weight blocks are put in one by one, the output power of the gravity energy storage increases in a step-by-step manner, and the electrochemical energy storage gradually decreases, thereby achieving the hybrid energy storage output power unchanged to track the power demand on the grid side.

[0151] like Figure 5 As shown, the present invention also provides a power grid frequency regulation control device for coordinating gravity energy storage and electrochemical energy storage, and adopts the power grid frequency regulation control method for coordinating gravity energy storage and electrochemical energy storage, and the power grid frequency regulation control device comprises:

[0152] An investment determination module is used to obtain the power demand for grid-side frequency regulation and determine the investment plan for gravity energy storage;

[0153] A first strategy module, which is used to provide a power transfer strategy for the gravity energy storage based on the investment plan of the gravity energy storage and the power output characteristics of the gravity energy storage;

[0154] A second strategy module is used to determine the electrochemical energy storage power transfer strategy based on the power transfer strategy of the gravity energy storage and the power demand of the grid-side frequency regulation;

[0155] The control output module is used to control the power output of the gravity energy storage and the electrochemical energy storage based on the power transmission strategy of the gravity energy storage and the electrochemical energy storage.

[0156] Furthermore, the investment determination module includes:

[0157] Obtain the output power of a single weight block in the gravity energy storage unit corresponding to the gravity energy storage;

[0158] The number of weight blocks to be put into use is determined based on the power demand of the grid-side frequency regulation and the output power of a single weight block.

[0159] Furthermore, the investment determination module also includes:

[0160] The output power of the weight blocks in the gravity energy storage unit is superimposed in the order in which they are put into use, until the difference between the power demand for frequency regulation on the grid side and the output power of the superimposed weight blocks is the smallest and the difference is not negative, and the corresponding number of superimposed weight blocks is given.

[0161] Furthermore, the first strategy module includes:

[0162] According to the number of weight blocks put into the gravity energy storage unit and the corresponding power output characteristics, the time interval for adjacent weight blocks put into the gravity energy storage unit to start working in sequence is determined;

[0163] Based on the time interval when adjacent weight blocks in the gravity energy storage unit start to work in sequence, and the output power of the corresponding synchronous generator set when each weight block works, the power transmission strategy of gravity energy storage is given.

[0164] Furthermore, the first strategy module also includes:

[0165] Based on the number of weight blocks put into the gravity energy storage unit and the time intervals for starting to work in sequence, determine the time nodes for starting to work of the weight blocks put into the unit;

[0166] Based on the starting time node of the weight block, the output power of the synchronous generator set corresponding to the weight block at different time nodes is superimposed, and a power transfer strategy of the gravity energy storage unit corresponding to the gravity energy storage that changes with time is constructed.

[0167] Furthermore, the second strategy module includes:

[0168] According to the power transfer strategy of gravity energy storage, determine the output power of gravity energy storage at different time nodes;

[0169] Based on the difference between the power demand of grid-side frequency regulation and the output power of gravity energy storage at different time nodes, the output power of electrochemical energy storage at different time nodes is determined;

[0170] Based on the output power of the electrochemical energy storage at different time nodes, the power transfer strategy of the electrochemical energy storage is determined.

[0171] Furthermore, the control output module includes:

[0172] Based on the power transfer strategy of electrochemical energy storage, the output power of electrochemical energy storage at different time nodes is given;

[0173] Based on the output power of electrochemical energy storage and combined with the converter outer loop controller, a current reference value of the converter outer loop controller is given;

[0174] Based on the current reference value of the converter outer loop controller, and the converter current inner loop controller, a modulation voltage output by the converter current inner loop controller is given;

[0175] Based on the modulation voltage output by the converter current inner loop controller, the actual voltage output by the converter current inner loop controller is controlled to control the power output of the electrochemical energy storage.

[0176] Furthermore, the control output module includes:

[0177] Based on the converter outer loop controller, determine its proportional gain and integral gain;

[0178] Based on the proportional gain and integral gain of the converter outer loop controller and combined with the Laplace operator, the transfer function of the converter outer loop controller is given;

[0179] Based on the difference between the active power reference value of the converter outer loop controller and the actual output power of the electrochemical energy storage, and combined with the transfer function of the converter outer loop controller, a current reference value of the converter outer loop controller is given.

[0180] Furthermore, the control output module also includes:

[0181] Obtaining the grid voltage angular velocity, the filter inductance of the electrochemical energy storage converter and the voltage of the electrochemical energy storage grid connection point;

[0182] Determine the first intermediate state coefficient based on the grid voltage angular velocity and the filter inductance of the electrochemical energy storage converter, and in combination with the actual current value of the converter outer loop controller;

[0183] Based on the converter current inner loop controller, determine its proportional gain and integral gain;

[0184] Based on the proportional gain and integral gain of the converter current inner loop controller and combined with the Laplace operator, the transfer function of the converter current inner loop controller is given;

[0185] Based on the difference between the current reference value of the converter outer loop controller and the current actual value of the converter outer loop controller, and in combination with the transfer function of the converter current inner loop controller, a second intermediate state coefficient is given;

[0186] Based on the voltage of the electrochemical energy storage grid-connected point, a difference between the first intermediate state coefficient and the second intermediate state coefficient is processed to obtain a modulation voltage output by the converter current inner loop controller.

[0187] Although preferred embodiments of the present invention have been described, additional changes and modifications may be made to these embodiments by those skilled in the art once the basic inventive concepts are known. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention. Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A method for controlling power grid frequency regulation by coordinating gravity energy storage and electrochemical energy storage, characterized in that: include: Obtain the power demand for grid-side frequency regulation and determine the investment plan for gravity energy storage; Based on the investment plan of gravity energy storage and the power output characteristics of gravity energy storage, the power transfer strategy of gravity energy storage is given; Determine the power transfer strategy of electrochemical energy storage based on the power transfer strategy of gravity energy storage and the power demand of grid-side frequency regulation; A power transfer strategy based on gravity energy storage and electrochemical energy storage controls the power output of gravity energy storage and electrochemical energy storage.

2. The power grid frequency modulation control method according to claim 1, characterized in that: Determine the investment plan for gravity energy storage, including: Obtain the output power of a single weight block in the gravity energy storage unit corresponding to the gravity energy storage; The number of weight blocks to be put into use is determined based on the power demand of the grid-side frequency regulation and the output power of a single weight block.

3. The power grid frequency modulation control method according to claim 2, characterized in that: Based on the power demand of grid-side frequency regulation and the output power of a single weight block, the number of weight blocks to be put into use is determined, including: The output power of the weight blocks in the gravity energy storage unit is superimposed in the order in which they are put into use, until the difference between the power demand for frequency regulation on the grid side and the output power of the superimposed weight blocks is the smallest and the difference is not negative, and the corresponding number of superimposed weight blocks is given.

4. The power grid frequency modulation control method according to claim 1, characterized in that: The gravity energy storage unit corresponding to the gravity energy storage includes a synchronous generator set and a plurality of weight blocks; Based on the investment scheme of gravity energy storage and the power output characteristics of gravity energy storage, the power transfer strategy of gravity energy storage is given, including: According to the number of weight blocks put into the gravity energy storage unit and the corresponding power output characteristics, the time interval for adjacent weight blocks put into the gravity energy storage unit to start working in sequence is determined; Based on the time interval when adjacent weight blocks in the gravity energy storage unit start to work in sequence, and the output power of the corresponding synchronous generator set when each weight block works, the power transmission strategy of gravity energy storage is given.

5. The power grid frequency control method according to claim 4, characterized in that: Based on the time intervals when adjacent weight blocks in the gravity energy storage unit start to work in sequence, and the output power of the corresponding synchronous generator set when each weight block works, the power transmission strategy of gravity energy storage is given, including: Based on the number of weight blocks put into the gravity energy storage unit and the time intervals for starting to work in sequence, determine the time nodes for starting to work of the weight blocks put into the unit; Based on the starting time node of the weight block, the output power of the synchronous generator set corresponding to the weight block at different time nodes is superimposed, and a power transfer strategy of the gravity energy storage unit corresponding to the gravity energy storage that changes with time is constructed.

6. The power grid frequency modulation control method according to claim 1, characterized in that: Based on the power transfer strategy of gravity energy storage and the power demand of grid-side frequency regulation, the power transfer strategy of electrochemical energy storage is determined, including: According to the power transfer strategy of gravity energy storage, determine the output power of gravity energy storage at different time nodes; Based on the difference between the power demand of grid-side frequency regulation and the output power of gravity energy storage at different time nodes, the output power of electrochemical energy storage at different time nodes is determined; Based on the output power of the electrochemical energy storage at different time nodes, the power transfer strategy of the electrochemical energy storage is determined.

7. The power grid frequency modulation control method according to claim 6, characterized in that: The electrochemical energy storage includes an electrochemical energy storage device and an electrochemical energy storage converter connecting the electrochemical energy storage device and a power grid, wherein the electrochemical energy storage converter includes a converter outer loop controller and a converter current inner loop controller; Power transfer strategy based on electrochemical energy storage to control the power output of electrochemical energy storage, including: Based on the power transfer strategy of electrochemical energy storage, the output power of electrochemical energy storage at different time nodes is given; Based on the output power of electrochemical energy storage and combined with the converter outer loop controller, a current reference value of the converter outer loop controller is given; Based on the current reference value of the converter outer loop controller, and the converter current inner loop controller, a modulation voltage output by the converter current inner loop controller is given; Based on the modulation voltage output by the converter current inner loop controller, the actual voltage output by the converter current inner loop controller is controlled to control the power output of the electrochemical energy storage.

8. The power grid frequency control method according to claim 7, characterized in that: Based on the output power of electrochemical energy storage and combined with the converter outer loop controller, the current reference value of the converter outer loop controller is given, including: Based on the converter outer loop controller, determine its proportional gain and integral gain; Based on the proportional gain and integral gain of the converter outer loop controller and combined with the Laplace operator, the transfer function of the converter outer loop controller is given; Based on the difference between the active power reference value of the converter outer loop controller and the actual output power of the electrochemical energy storage, and combined with the transfer function of the converter outer loop controller, a current reference value of the converter outer loop controller is given.

9. The power grid frequency control method according to claim 7, characterized in that: Based on the current reference value of the converter outer loop controller, the converter current inner loop controller is used to provide a modulation voltage output by the converter current inner loop controller, including: Obtaining the grid voltage angular velocity, the filter inductance of the electrochemical energy storage converter and the voltage of the electrochemical energy storage grid connection point; Determine the first intermediate state coefficient based on the grid voltage angular velocity and the filter inductance of the electrochemical energy storage converter, and in combination with the actual current value of the converter outer loop controller; Based on the converter current inner loop controller, determine its proportional gain and integral gain; Based on the proportional gain and integral gain of the converter current inner loop controller and combined with the Laplace operator, the transfer function of the converter current inner loop controller is given; Based on the difference between the current reference value of the converter outer loop controller and the current actual value of the converter outer loop controller, and in combination with the transfer function of the converter current inner loop controller, a second intermediate state coefficient is given; Based on the voltage of the electrochemical energy storage grid-connected point, a difference between the first intermediate state coefficient and the second intermediate state coefficient is processed to obtain a modulation voltage output by the converter current inner loop controller.

10. A power grid frequency control device for coordinating gravity energy storage and electrochemical energy storage, characterized in that: The grid frequency regulation control method for coordinating gravity energy storage and electrochemical energy storage as claimed in any one of claims 1 to 9 is adopted, and the grid frequency regulation control device comprises: An investment determination module is used to obtain the power demand for grid-side frequency regulation and determine the investment plan for gravity energy storage; A first strategy module, which is used to provide a power transfer strategy for the gravity energy storage based on the investment plan of the gravity energy storage and the power output characteristics of the gravity energy storage; A second strategy module is used to determine the electrochemical energy storage power transfer strategy based on the power transfer strategy of the gravity energy storage and the power demand of the grid-side frequency regulation; The control output module is used to control the power output of the gravity energy storage and the electrochemical energy storage based on the power transmission strategy of the gravity energy storage and the electrochemical energy storage.

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