Active power control method and apparatus for converter-interfaced generators, and electronic device

Abstract

Provided in the present application are an active control method and apparatus for converter-interfaced generators, and an electronic device. The method comprises: when a system total power reserve value is greater than a disturbance power value and some converter-interfaced generators go beyond a feasible power region, on the basis of power deviations of some converter-interfaced generators, distributedly controlling active power outputted by some converter-interfaced generators, such that all the converter-interfaced generators operate within the feasible power region or a power limit, and a system steady-state frequency is at a rated value; and on the basis of a phase angle reference value issued by a power grid control center, centrally controlling the active power outputted by each converter-interfaced generator, so as to adjust a power grid flow. The method enables the frequency of a converter-interfaced generator-dominated system to remain almost constantly at a rated value in the case of a power disturbance, and also brings about good synchronous stability characteristics under both small and large disturbances, and the converter-interfaced generators can also achieve good compatibility with an existing power source, so as to adapt to gradual transformation of a power grid.

Description

Active control method and device of converter interfaced power supply and electronic equipment

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to the Chinese patent application No. 202411123538.1, filed on August 15, 2024, and entitled “Active control method and device of converter interfaced power supply and electronic equipment”, which is incorporated by reference in its entirety. TECHNICAL FIELD

[0003] The present application relates to the technical field of power system control, and in particular to an active control method and device of converter interfaced power supply and electronic equipment. BACKGROUND

[0004] In 1788, James Watt invented the flyball governor for regulating the speed of a rotating steam engine, establishing a speed-based power regulation architecture.

[0005] In the late 19th century, with the advent of alternating current power systems, synchronous generators became the main power producers. The stator voltage frequency of a synchronous generator is directly determined by the rotational speed of the rotor, which is influenced by the mechanical and electromagnetic power balance. Therefore, the method of regulating the active power balance based on the frequency regulation system has been adopted to this day. Active power control and frequency control are closely linked together, known as active power-frequency control.

[0006] In recent years, with the low-carbon transformation of energy systems, more and more wind power, photovoltaic and energy storage are connected to the grid through converters. Converter interfaced power sources (CIGs) are gradually replacing synchronous machines and becoming the main form of power generation. The working principle of this form of power generation is different from that of traditional synchronous machines, and its frequency is determined by the modulation wave generated by the controller, which can be decoupled from the active power.

[0007] Although converters provide new possibilities, many existing control strategies still bind active power control and frequency control together, failing to take advantage of the high customizability of power electronic converters. For example, virtual synchronous machines attempt to mimic the behavior of synchronous generators by controlling active power through frequency response. This not only inherits the problem of frequency fluctuations in synchronous machine-dominated systems and the problem of large disturbance synchronous stability, but also leads to various new problems caused by inverters, especially oscillations.

[0008] Amplitude-phase control is an exception that decouples active power and frequency, allowing power to absorb or release unbalanced power in the system while maintaining constant voltage amplitude and frequency. However, in this case, other power sources that couple active power control with frequency cannot perceive imbalance through frequency changes, so they do not actively participate in active power control. At this time, all unbalanced power in the system is borne by the amplitude-phase controlled unit.

[0009] Therefore, how to solve the problem of frequency fluctuation caused by the existing active control method, and the problem of low synchronous stability of small disturbance and large disturbance, is an important task in the field of power system control that needs to be solved.

[0010] SUMMARY

[0011] The present application provides an active control method, device and electronic equipment of a converter interface power supply, to overcome the defects of the existing active control method that cannot completely decouple active power control and frequency control, low synchronous stability of small disturbance and large disturbance, realize complete decoupling of active power control and frequency, make the system frequency almost always be the rated value, avoid the problem of frequency fluctuation, and improve the small disturbance and large disturbance synchronous stability characteristics of the power system.

[0012] In one aspect, the present application provides an active control method of a converter interface power supply, comprising: in the case that the total power reserve value of the system is greater than the disturbance power value, and part of the converter interface power supply exceeds the feasible power region, adjusting the phase angle based on the power deviation amount of the part of the converter interface power supply, realizing distributed control of the active output of the part of the converter interface power supply, so that all converter interface power supplies operate within the feasible power region or at the power limit, and the system frequency is finally maintained at the rated value; based on the phase angle reference value issued by the grid control center, centrally controlling the active power output of each converter interface power supply to adjust the grid flow.

[0013] Further, the adjusting the phase angle based on the power deviation amount of the part of the converter interface power supply, realizing the distributed control of the active output of the part of the converter interface power supply, comprises: for each converter interface power supply in the part of the converter interface power supply, obtaining the actual output power of the converter interface power supply; determining the power deviation amount of the converter interface power supply according to the actual output power and its corresponding feasible power region; calculating the internal potential phase of the converter interface power supply according to the power deviation amount and the given phase angle reference value of the grid control center; adjusting the phase angle according to the internal potential phase and the given voltage amplitude to control the active power output of the converter interface power supply.

[0014] Further, the active power output of the centralized control converter interface power supply based on the phase angle reference value issued by the power grid control center comprises: obtaining the target output power of each converter interface power supply calculated by the power grid control center; generating the phase angle reference value of each converter interface power supply according to the power difference between the target output power and the actual output power of each converter interface power supply; and controlling the active power output of each alternating current interface power supply according to the phase angle reference value.

[0015] Further, the calculation formula of the power deviation amount is as follows:

[0016] Wherein, u represents the power deviation amount, P e represents the actual output power of the converter interface power supply, P min represents the minimum power limit value in the feasible power region of the converter interface power supply, P max represents the maximum power limit value in the feasible power region of the converter interface power supply.

[0017] The calculation formula of the internal potential phase is as follows:

[0018] Wherein, represents the internal potential phase of the converter interface power supply, ω0 represents the rated angular frequency, t represents time, δ represents the phase shift amount, δ SAC represents the phase angle reference value given by the power grid control center.

[0019] Further, the phase angle reference value is calculated by the PI controller based on the deviation value between the actual output power and the target output power of the converter interface power supply, and the specific calculation formula is as follows:

[0020] Wherein, δ SAC represents the phase angle reference value issued by the power grid control center to the converter interface power supply, K PS represents the proportional gain, K IS represents the integral gain, s represents the differential operator, P cmd represents the target output power of the converter interface power supply calculated by the power grid control center, P e represents the actual output power of the converter interface power supply.

[0021] Further, the step of controlling the active power output of the converter interface power supply specifically comprises: setting the converter control parameter of the converter interface power supply according to the grid frequency requirement and / or the ability of the converter interface power supply to maintain the output power exceeding the feasible power region for a certain time; wherein the grid frequency requirement comprises the system frequency drop rate requirement and the system frequency recovery time requirement; the higher the system frequency drop rate requirement, the smaller the corresponding converter control parameter; the higher the system frequency recovery time requirement, the larger the corresponding converter control parameter; the stronger the ability of the converter interface power supply to maintain the output power exceeding the feasible power region for a certain time, the smaller the corresponding converter control parameter.

[0022] Further, when the converter interface power supply is operated together with the existing power supply, the converter interface power supply participates in the grid frequency modulation process in different ways according to the proportion of the converter interface power supply in the grid; wherein when the proportion of the converter interface power supply in the grid is lower than a set proportion, the converter interface power supply participates in the primary frequency modulation process of the grid, and the calculation formula of the active power output by the converter interface power supply is as follows:

[0023] wherein P e represents the active power output by the converter interface power supply when participating in the primary frequency modulation process of the grid, P max represents the maximum power limit in the feasible power region of the converter interface power supply, K IP represents the converter control parameter of the converter interface power supply, and Δf represents the steady-state frequency difference.

[0024] In a second aspect, the present application further provides an active power control device of a converter interface power supply, comprising: a primary power control module, configured to, in the case that the system total power backup value is greater than the disturbance power value and part of the converter interface power supply exceeds the feasible power region, adjust the phase angle based on the power deviation of the part of the converter interface power supply, implement distributed control of the active power output of the part of the converter interface power supply, so that all the converter interface power supplies are operated within the feasible power region or at the power limit, and the system frequency is finally maintained at the rated value; and a secondary power control module, configured to, based on the phase angle reference value issued by the grid control center, centrally control the active power output of each converter interface power supply to adjust the grid power flow.

[0025] In a third aspect, the present application further provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the active power control method of the converter interface power supply as described above.

[0026] In a fourth aspect, the present application provides a non-transitory computer-readable storage medium having stored thereon a computer program which, when executed by a processor, implements the active power control method of the converter interface power supply as described above.

[0027] The active power control method of the converter interface power supply provided by the present application can realize distributed control of the active power output of the partial converter interface power supply by adjusting the phase angle based on the power deviation of the partial converter interface power supply when the system total power backup value is greater than the disturbance power value and the partial converter interface power supply exceeds the feasible power region, so that all the converter interface power supplies operate within the feasible power region or at the power limit, and the system frequency is ultimately maintained at the rated value, and then the active power output of each converter interface power supply is centrally controlled based on the phase angle reference value issued by the power grid control center to adjust the power flow of the power grid. This method can make the converter interface power supply dominant system have a rated value almost all the time when facing power disturbance, and at the same time, good small disturbance and large disturbance synchronous stability characteristics are brought, and the converter interface power supply can also realize good compatibility with existing power supplies to adapt to the gradual transformation of the power grid. BRIEF DESCRIPTION OF DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without any creative effort based on these drawings.

[0029] FIG. 1 is a flowchart of the active power control method of the converter interface power supply provided by the present application.

[0030] FIG. 2 is a schematic diagram of primary active power control of the converter interface power supply provided by the present application.

[0031] FIG. 3 is a schematic diagram of centralized secondary active power control of the converter interface power supply provided by the present application.

[0032] FIG. 4 is a topological diagram of a 3-machine 9-node system provided by the present application.

[0033] FIG. 5 is a schematic diagram of system response under primary active power control provided by the present application.

[0034] FIG. 6 is a schematic diagram of system response under primary active power control provided by the present application.

[0035] FIG. 7 is a schematic diagram of system response under primary active power control provided by the present application.

[0036] FIG. 8 is a schematic diagram of a response of a converter interface power supply under secondary active power control according to an embodiment of the present application.

[0037] FIG. 9 is a schematic diagram of a response of a converter interface power supply under different converter control parameters according to an embodiment of the present application.

[0038] FIG. 10 is a schematic diagram of a structure of an active control device of a converter interface power supply according to an embodiment of the present application.

[0039] FIG. 11 is a schematic diagram of a physical structure of an electronic device according to an embodiment of the present application. DETAILED DESCRIPTION

[0040] For the purpose, technical solutions and advantages of the present application to be clearer, the technical solutions of the present application will be described clearly and completely below with reference to the drawings in the present application. Obviously, the described embodiments are some, but not all, of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the scope of protection of the present application.

[0041] It should be noted that the traditional active control strategy cannot exert the high customizability of the power electronic converter, and in a frequency-fixed system, the power imbalance cannot be reflected, and the power supply cannot participate in active control, and the existing amplitude-phase control strategy cannot completely decouple active power control and frequency control, resulting in unreasonable imbalance power processing.

[0042] In view of this, the present application provides a new active control method of a converter interface power supply. Specifically, FIG. 1 shows a flowchart of an active control method of a converter interface power supply according to an embodiment of the present application.

[0043] As shown in FIG. 1, the method comprises steps S110-S120, which will be described in detail below.

[0044] S110, in a case where the total power reserve value of the system is greater than the disturbance power value and part of the converter interface power supply exceeds the feasible power region, adjusting the phase angle based on the power deviation of the part of the converter interface power supply to realize distributed control of active output of the part of the converter interface power supply, so that all the converter interface power supplies operate in the feasible power region or at the power limit, and the system frequency is finally maintained at the rated value.

[0045] It can be understood that this step describes a distributed fast primary active power control process, and before this, the total power reserve value of the system needs to satisfy a prerequisite condition that the total power reserve value of the system is greater than the disturbance power value.

[0046] Specifically, according to the relative size of the total system power reserve value and the disturbance power value, there are the following case 1, case 2 and case 3.

[0047] Case 1: After the disturbance occurs, the disturbance power is distributed among the converter interface power sources according to the synchronous power coefficient, and all the converter interface power sources do not exceed their feasible power regions. Therefore, the phase angles of all the converter interface power sources controlled by pulse width modulation (PMW) remain unchanged. According to the definition of instantaneous power The internal potential frequency of all the converter interface power sources remains unchanged. Wherein, f represents frequency, φ represents phase, and t represents time, Δφ represents the change amount of the phase.

[0048] Case 2: After the disturbance occurs, part of the converter interface power sources exceeds the corresponding feasible power region. Subsequently, the output power of the part of the converter interface power sources gradually decreases to the power limit P min , and the remaining power is borne by other converter interface power sources, so that all the converter interface power sources are located within the power limit or the feasible power region. When part of the converter interface power sources temporarily exceeds the feasible power region, the phase changes, so the grid frequency temporarily drops, and finally the steady-state frequency of the whole system returns to the rated value.

[0049] Case 3: When the total system power reserve value is less than the disturbance power value, all the converter interface power sources exceed the feasible power region, and the system has a steady-state frequency difference. This working condition is actually caused by the fact that the system power is insufficient to meet the load requirement, and cannot be changed by adjusting the control strategy.

[0050] In the embodiment, not only is it required that the total system power reserve value is greater than the disturbance power value, but also it is required that part of the converter interface power sources in the grid exceeds the feasible power region (i.e., corresponding to “case 2”). The number of the converter interface power sources that exceed the feasible power region is determined according to the actual situation, and is not specifically limited here.

[0051] Wherein, each of the converter interface power sources has a corresponding feasible power region, and the feasible power region is set according to the maximum power limit and the minimum power limit of the converter interface power source. In a specific embodiment, the feasible power region is [P min ,P max ], the maximum power limit P max and the minimum power limit P min are set according to the nature of the converter interface power source, and are not specifically limited here.

[0052] In the case that the total power reserve value of the system is greater than the disturbance power value and part of the converter interface power supply exceeds the feasible power region, the unbalanced power is distributed according to the synchronous power coefficient and the reserve power capacity of the converter interface power supply. If no converter interface power supply exceeds the feasible power region, the unbalanced power is directly distributed according to the synchronous power system.

[0053] Specifically, according to the actual output power of the converter interface power supply, the power deviation amount corresponding to the converter interface power supply is determined, and then a series of control amounts are generated according to the power deviation amount, and then the internal potential phase is generated through an integral element, and the active power output by the converter interface power supply is controlled according to the internal potential phase, so as to realize power distribution after disturbance, so that part of the converter interface power supply exceeding the feasible power region can operate in the feasible power region.

[0054] It should be noted that the feasible power region in this step includes power limit values (maximum power limit value and minimum power limit value of the converter interface power supply).

[0055] It is also worth mentioning that this step emphasizes the distributed primary active power control of each converter interface power supply.

[0056] S120, based on the phase angle reference value issued by the power grid control center, the active power output by each converter interface power supply is centrally controlled to adjust the power grid flow.

[0057] It can be understood that on the basis of the distributed and rapid primary power control in step S110, further, step S120 will perform centralized secondary active power control.

[0058] Specifically, the power grid control center will first calculate the power grid flow it expects and the target output power of each converter interface power supply. Then, the converter interface power supply with the most power reserve is selected as the balancing node to bear the unbalanced power.

[0059] Then, the power grid control center obtains the actual output power of each converter interface power supply once every preset time period, and obtains the power difference value by subtracting the target output power. Then, the phase angle reference value of each converter interface power supply except the slack node is generated through a proportional-integral controller (PIC).

[0060] The preset time period can be set according to actual needs, which is not specifically limited here.

[0061] For example, in a specific embodiment, the power grid control center obtains the actual output power of each converter interface power supply once every 5 seconds.

[0062] Finally, the grid control center sends the calculated phase angle reference value of each converter interface power supply to the corresponding converter interface power supply, thereby centrally controlling the active power output of the converter interface power supply to achieve the adjustment of the grid power flow.

[0063] It should be noted that the secondary frequency control of the traditional power system is to make the system frequency return to the rated value, while in the embodiment, the system frequency is error-regulated. Therefore, the secondary frequency control is replaced by the secondary active power control, and the purpose is to achieve the power flow adjustment of the power system.

[0064] It is also worth mentioning that this step emphasizes the centralized secondary active power control of the grid control center on each converter interface power supply.

[0065] In this embodiment, by adjusting the phase angle based on the power deviation of part of the converter interface power supplies when the total system power reserve value is greater than the disturbance power value and part of the converter interface power supplies exceeds the feasible power region, distributed control of the active output of part of the converter interface power supplies is realized, so that all converter interface power supplies operate within the feasible power region or at the power limit, and the system frequency is finally maintained at the rated value, and then based on the phase angle reference value sent by the grid control center, the active power output of each converter interface power supply is centrally controlled to adjust the grid power flow. This method can make the converter interface power supply dominant system have a rated frequency almost all the time when facing power disturbances, while bringing good small disturbance and large disturbance synchronous stability characteristics, and the converter interface power supply can also realize good compatibility with existing power supplies to adapt to the gradual transformation of the grid.

[0066] On the basis of the above embodiment, further, the distributed primary active power control process of the converter interface power supply will be described in detail below.

[0067] Adjusting the phase angle based on the power deviation of part of the converter interface power supplies to realize distributed control of the active output of part of the converter interface power supplies includes: for each converter interface power supply in part of the converter interface power supplies, obtaining the actual output power of the converter interface power supply; determining the power deviation of the converter interface power supply according to the actual output power and its corresponding feasible power region; calculating the internal potential phase of the converter interface power supply according to the power deviation and the given phase angle reference value of the grid control center; and adjusting the phase angle according to the internal potential phase and the given voltage amplitude to control the active power output of the converter interface power supply.

[0068] It can be understood that the converter interface power supply in this embodiment uses pulse width modulation technology to generate an alternating voltage according to the amplitude of the modulation wave and the internal potential phase, thereby controlling the active power output of the alternating current interface power supply.

[0069] Correspondingly, Fig. 2 shows a schematic diagram of primary active power control of the AC interface power supply provided by the embodiment of the application.

[0070] According to Fig. 2, first, the actual output power P e of the converter interface power supply is obtained.

[0071] In formula (1), u represents the power deviation amount, P e actual output power of the converter interface power supply, P min represents the minimum power limit in the feasible power region of the converter interface power supply, P max represents the maximum power limit in the feasible power region of the converter interface power supply, [P min , P max ] represents the feasible power region, which is variable according to the working condition.

[0072] It should be noted here that the converter interface power supply has the ability to temporarily exceed the feasible power region, and when the system does not participate in primary power frequency modulation or has no power reserve, P min , P max , P ref , and P ref are set as the target output power (expected output power) of the AC interface power supply.

[0073] After the power deviation amount is calculated, the phase shift amount δ is calculated according to the converter control parameter K IP . Then, combined with the phase angle reference value δ SAC given by the grid control center and the rated angular frequency ω0 given by the system, the internal potential phase of the converter interface power supply is calculated.

[0074] The calculation formula of the internal potential phase is as follows.

[0075] In formula (2), φ represents the internal potential phase of the converter interface power supply, ω0 represents the rated angular frequency, t represents time, δ represents the phase shift amount, and δ SAC represents the phase angle reference value issued by the grid control center in the secondary active power control process.

[0076] Regarding the rated angular frequency ω0, for a 50Hz system, ω0 takes the value of 100π rad / s; for a 60Hz system, ω0 takes the value of 120π rad / s.

[0077] According to the calculated internal potential phase and the given voltage amplitude E to adjust the phase angle, generate an alternating voltage, and further control the active power output by the converter interface power supply, so that the converter interface power supply runs in the feasible power region.

[0078] In the embodiment, for each of the converter interface power supplies, the actual output power of the converter interface power supply is obtained, and the power deviation of the converter interface power supply is determined according to the actual output power and the corresponding feasible power region, and then the internal potential phase of the converter interface power supply is calculated according to the power deviation and the given phase angle reference value given by the grid control center, so that the active power output by the converter interface power supply is controlled according to the internal potential phase and the given voltage amplitude E to adjust the phase angle, and the converter interface power supply runs in the feasible power region. The method can make the converter interface power supply dominant system have a frequency of a rated value almost all the time when facing power disturbance, and also bring good small disturbance and large disturbance synchronization stability characteristics, and the converter interface power supply can also realize good compatibility with existing power supplies to adapt to the gradual transformation of the power grid.

[0079] On the basis of the above embodiment, further, the centralized secondary active power control process of the converter interface power supply will be described in detail below.

[0080] Based on the phase angle reference value given by the grid control center, the active power output by the converter interface power supply is centrally controlled, including: obtaining the target output power of each converter interface power supply calculated by the grid control center; generating a phase angle reference value of each converter interface power supply according to the power difference between the target output power and the actual output power of each converter interface power supply; and centrally controlling the active power output by each converter interface power supply according to the phase angle reference value.

[0081] Specifically, the secondary active power control includes the following steps S121-S124.

[0082] Step S121, the grid control center calculates the desired power flow of the grid and the output of each power supply, i.e., the target output power of the converter interface power supply.

[0083] Step S122, the converter interface power supply with the most power reserve at present is selected as the balancing node to bear the unbalanced power.

[0084] Step S123, the grid control center obtains the actual output power of each converter interface power supply once every 5s, and the power difference is formed by subtracting the target output power, and the phase angle reference value δ of each converter interface power supply except the slack node is generated by PI. SAC .

[0085] Step S124, according to the phase angle reference value, the active power output of each AC interface power supply is controlled to realize the adjustment of power grid flow.

[0086] Correspondingly, Fig. 3 shows a centralized secondary active power control diagram of the converter interface power supply provided by the embodiment of the application.

[0087] According to Fig. 3, first, the target output power P cmd of each converter interface power supply calculated by the power grid control center is obtained.

[0088] Then, according to the power difference between the target output power P cmd and the actual output power P e of each converter interface power supply, the phase angle reference value δ SAC of each converter interface power supply is generated.

[0089] The phase angle reference value δ SAC is calculated by the PI controller from the deviation value of the actual output power and the target output power of the converter interface power supply, and the specific calculation formula is as follows formula (3).

[0090] In formula (3), δ SAC represents the phase angle reference value of the converter interface power supply issued by the power grid control center, K PS represents the proportional gain, K IS represents the integral gain, s represents the differential operator, P cmd represents the target output power of the converter interface power supply calculated by the power grid control center, and P e represents the actual output power of the converter interface power supply.

[0091] Finally, according to the phase angle reference value δ SAC , the active power output of each AC interface power supply is controlled, and the effect of adjusting the power grid flow is achieved.

[0092] In this embodiment, by obtaining the target output power of each converter interface power supply calculated by the power grid control center, and according to the power difference between the target output power and the actual output power of each converter interface power supply, the phase angle reference value of each converter interface power supply is generated, and then according to the phase angle reference value, the active power output of each AC interface power supply is controlled. This method can make the converter interface power supply dominant system have a frequency of almost the rated value when facing power disturbance, while bringing good small disturbance and large disturbance synchronous stability characteristics, and the converter interface power supply can also realize good compatibility with existing power supply to adapt to the gradual transformation of the power grid.

[0093] On the basis of the above-mentioned embodiments, further, the following will be described in detail for the setting process of the converter control parameter of the converter interface power supply.

[0094] The step of controlling the active power output by the converter interface power supply specifically comprises: setting the converter control parameter of the converter interface power supply according to the grid frequency requirement, and / or the ability of the converter interface power supply to maintain the output power to exceed the feasible power region for a time; wherein the grid frequency requirement comprises the system frequency drop rate requirement and the system frequency recovery time requirement.

[0095] It can be understood that the converter control parameter K IP will affect the control speed of the dynamic process, but will not affect the control structure. Taking the primary active power control as an example, the larger the converter control parameter is, the shorter the system frequency recovery time is, and the more intense the fluctuation is; accordingly, the time for which the output power of the converter interface power supply exceeds the feasible power region is also shorter.

[0096] In view of this, the present embodiment makes the following three limitations for the setting process of the converter control parameter.

[0097] Limitation 1: the more stringent the system frequency drop rate requirement is, the smaller the converter control parameter corresponding to the primary power control of the converter is.

[0098] That is to say, in the grid in which the system frequency drop rate requirement is relatively stringent, or in which the system frequency drop rate is expected to be as small as possible, the converter control parameter of the converter interface power supply is set to a relatively small direction.

[0099] In this case, the smaller converter control parameter can slow down the response speed of the converter interface power supply, thereby reducing the excessive fluctuation of the system frequency due to the rapid response.

[0100] Limitation 2: the more stringent the system frequency recovery time requirement is, the larger the converter control parameter corresponding to the primary power control of the converter is.

[0101] That is to say, in the grid in which the system frequency recovery time requirement is relatively stringent, the converter control parameter of the converter interface power supply is set to a relatively large direction.

[0102] In this case, the larger converter control parameter can make the converter interface power supply respond to the system frequency change more quickly, thereby shortening the system frequency recovery time, which is helpful to quickly restore the steady state of the system, especially after the grid fault.

[0103] Limitation 3: the stronger the ability of the converter interface power supply to maintain the output power to exceed the feasible power region for a time is, the smaller the converter control parameter is.

[0104] That is to say, for the converter interface power supply that maintains the output power beyond the feasible power region for a long time, the converter control parameter of the converter interface power supply is set to a relatively small value.

[0105] In this case, the small converter control parameter can reduce the probability and time of the converter interface power supply beyond the feasible power region, thereby reducing the risk of overload and protecting the equipment from damage.

[0106] In the embodiment, by setting the converter control parameter of the converter interface power supply according to the grid frequency demand and / or the ability of the converter interface power supply to maintain the output power beyond the feasible power region, different system frequency demands can be effectively responded to, thereby improving the overall stability of the system.

[0107] On the basis of the above embodiment, further, the compatibility of the converter interface power supply with the existing power supply will be described in detail below.

[0108] It can be understood that the active power control method of the converter interface power supply provided in the embodiment can be well compatible with the existing power supply to adapt to the demand of gradual transformation of the grid. When the converter interface power supply operates together with the existing power supply, according to the proportion of the converter interface power supply in the grid, the converter interface power supply participates in the grid frequency regulation process in different ways.

[0109] For example, in a specific embodiment, at the initial stage of system transformation, when the proportion of the converter interface power supply in the grid is low, the frequency characteristics of the system are mainly dominated by the existing power supply, and the response process is close to the primary frequency regulation of the existing grid. Since the standby power capacity of the converter interface power supply is usually less than the system disturbance power in this case, after the disturbance, the steady-state frequency of the system cannot return to the rated value, but there is a steady-state frequency difference Δf.

[0110] At this time, the converter interface power supply also operates beyond the feasible power region, and the active power output by the converter interface power supply can be seen from the following formula (4).

[0111] In formula (4), P e represents the active power output by the converter interface power supply when participating in the primary frequency regulation process of the grid, P max represents the maximum power limit in the feasible power region of the converter interface power supply, K IP represents the converter control parameter of the converter interface power supply, and Δf represents the steady-state frequency difference.

[0112] After the secondary frequency regulation, the frequency of the system returns to the rated value, and the converter interface power supply also returns to operate within the feasible power region.

[0113] It should be noted that the converter interface power supply mentioned in the embodiment refers to the power supply that executes the control strategy provided in the embodiment.

[0114] In another specific embodiment, when the converter interfaced power has a high share in the grid, the reserve power capacity of the converter interfaced power is sufficient to meet the disturbance power in most scenarios, and the frequency characteristic of the system is close to the case where "there is no steady-state frequency difference in the system".

[0115] After the disturbance, the synchronous machines and other existing frequency-active coupling power sources only provide transient support, not steady-state support, and return to the pre-disturbance active power output after the frequency returns to the rated value.

[0116] Therefore, the active power control method of the converter interfaced power provided in the embodiment can achieve good compatibility with existing power sources to adapt to the gradual transformation of the grid.

[0117] In some embodiments, an application example of the active power control method of the converter interfaced power provided in the present application is given.

[0118] Specifically, FIG. 4 shows a topological schematic diagram of a 3-machine 9-node system provided in an embodiment of the present application.

[0119] In FIG. 4, the lines, transformers, initial power flow are consistent with the WSCC 9-node system, and all synchronous machines are replaced with converter interfaced power sources that perform the control strategy provided in the present application.

[0120] The parameters of each converter interfaced power source in FIG. 4 are as follows.

[0121] In the embodiment, the total power reserve value of the system is 54.45 MW, and a power disturbance of 30 MW, 50 MW and 70 MW is respectively applied at node 8 in FIG. 4 to simulate three working conditions that may occur in primary power control.

[0122] Working condition 1: the disturbance power is 30 MW, and FIG. 5 shows one of the schematic diagrams of the system response under the primary active power control provided in an embodiment of the present application. As shown in FIG. 5, the converter interfaced power sources CIG2 and CIG3 closest to the load disturbance point (node 8) bear the most unbalanced power, and CIG1, CIG2 and CIG3 all do not cross the feasible power region, so the internal potential frequency is maintained at the rated value.

[0123] Case 2: The disturbance power is 50MW, and Fig. 6 shows a second schematic diagram of system response under the primary active power control provided by the embodiment. As shown in Fig. 6, the converter interface power supply CIG3 first crosses the feasible power region, and then reduces the output until it reaches the power limit, while the converter interface power supply CIG1 increases its output. When the converter interface power supply CIG3 crosses the feasible power region, the terminal frequency drops temporarily and is lower than the rated value. Finally, the converter interface power supplies CIG1 and CIG3 both operate at the upper power limit, and the CIG2 operates in the feasible power region, and the system steady-state frequency difference is 0.

[0124] Case 3: The disturbance power is 70MW, and Fig. 7 shows a third schematic diagram of system response under the primary active power control provided by the embodiment. The disturbance power exceeds the system total power reserve. As shown in Fig. 7, all the converter interface power supplies cross the feasible power region, and the system steady-state frequency is lower than the rated value, which is 59.97Hz.

[0125] According to the above, in the case where the system power reserve value is greater than the disturbance power, the active control method of the converter interface power supply provided by the embodiment is adopted, and the system frequency is almost always maintained at the rated value.

[0126] Further, centralized secondary active power control is performed under the above-mentioned case 2, and the grid control center obtains the expected power flow as follows: the converter interface power supply CIG1 adjusts the output (target output power) to 80.49MW, and the converter interface power supply CIG3 adjusts the output to 96.65MW, and all the converter interface power supplies are pulled back to the feasible power region to meet the next power disturbance requirement. At the same time, the converter interface power supply CIG2 with the most sufficient power reserve is selected as the balancing node.

[0127] Then, according to the secondary power control process described in the above embodiment, a phase angle command is issued to the converter interface power supplies CIG1 and CIG3 every 5 seconds, and each converter interface power supply responds. Specifically, Fig. 8 shows a schematic diagram of the response of the converter interface power supply under the secondary active power control provided by the embodiment.

[0128] According to Fig. 8, after about 60 seconds, the outputs of the converter interface power supplies CIG1 and CIG3 are adjusted to be consistent with the target output power. It can be seen that the centralized secondary active power control provided by the embodiment relatively quickly and accurately realizes the power flow distribution.

[0129] Further, the converter control parameter K of the converter interface power supply CIG3 is adjusted under the above-mentioned case 2. IP The responses of the converter interface power supplies under different converter control parameters are different.

[0130] Specifically, FIG. 9 shows a response diagram of the converter interface power supply under different converter control parameters according to an embodiment of the present application.

[0131] According to FIG. 9, in a system with strict requirements on system frequency recovery time, the converter control parameter K IP is set to 10, and the system frequency is recovered to the rated value at about 0.1 s; in a system with relatively strict requirements on system frequency drop rate, the converter control parameter K IP is set to 1, and the system frequency drop rate is significantly reduced. In addition, the larger the converter control parameter K IP is, the shorter the time for the converter interface power supply CIG3 to output power beyond the feasible power region.

[0132] In addition, the embodiment also provides stability analysis. Specifically, the small disturbance stability problem focuses on the characteristics of the system near the equilibrium point. In most cases, when the converter interface power supply operates in the feasible power region, the converter interface power supply will not change the initial phase under small disturbance, which can be represented by an algebraic equation in the electromechanical scale; and at the power limit, it is similar to droop control. Therefore, the system has good small disturbance stability by using the active power control method of the converter interface power supply provided by the embodiment of the present application.

[0133] At the same time, the system also has significant advantages compared with the synchronous machine and the power supply with the characteristics of the analog synchronous machine in the large disturbance synchronous stability problem. Taking a two-machine system as an example, the system is almost globally stable. In a more complex system, the limit removal time of the fault is also longer than that of the traditional synchronous machine dominant system.

[0134] Corresponding to the active power control method of the converter interface power supply described in the above embodiments, the present application also provides an active power control device of the converter interface power supply. Specifically, FIG. 10 shows a structure diagram of the active power control device of the converter interface power supply according to an embodiment of the present application.

[0135] As shown in FIG. 10, the device comprises: a primary power control module 1010, configured to, in a case that the total power reserve value of the system is greater than the disturbance power value and part of the converter interface power supply is beyond the feasible power region, adjust the phase angle based on the power deviation amount of the part of the converter interface power supply, implement distributed control of the active output of the part of the converter interface power supply, so that all the converter interface power supplies operate in the feasible power region or at the power limit, and finally maintain the system frequency at the rated value; and a secondary power control module 1020, configured to centrally control the active power output of each converter interface power supply based on the phase angle reference value issued by the power grid control center, so as to adjust the power flow of the power grid.

[0136] In the embodiment, the primary power control module 1010 adjusts the phase angle based on the power deviation of the partial converter interface power supply to realize distributed control of the active output of the partial converter interface power supply, so that all converter interface power supplies operate within the feasible power region or at the power limit, and the system frequency is finally maintained at the rated value, in the case that the system total power reserve value is greater than the disturbance power value, and the partial converter interface power supply exceeds the feasible power region. The secondary power control module 1020 centrally controls the active power output of each converter interface power supply based on the phase angle reference value issued by the grid control center to adjust the grid power flow. The method can make the converter interface power supply dominant system have a rated frequency almost all the time when facing power disturbance, while bringing good small disturbance and large disturbance synchronous stability characteristics. The converter interface power supply can also realize good compatibility with existing power supplies to adapt to the gradual transformation of the grid.

[0137] It should be noted that the active control device of the converter interface power supply provided in the embodiment can be correspondingly referred to the active control method of the converter interface power supply described in the above embodiments, which will not be described here.

[0138] FIG. 11 illustrates an example of an electronic device, as shown in FIG. 11, which can include a processor 1110, a communications interface 1120, a memory 1130, and a communications bus 1140, wherein the processor 1110, the communications interface 1120, and the memory 1130 can communicate with each other through the communications bus 1140. The processor 1110 can invoke the logical instructions in the memory 1130 to execute the active control method of the converter interface power supply, which includes: in the case that the system total power reserve value is greater than the disturbance power value, and the partial converter interface power supply exceeds the feasible power region, adjusting the phase angle based on the power deviation of the partial converter interface power supply to realize distributed control of the active output of the partial converter interface power supply, so that all converter interface power supplies operate within the feasible power region or at the power limit, and the system frequency is finally maintained at the rated value; and centrally controlling the active power output of each converter interface power supply based on the phase angle reference value issued by the grid control center to adjust the grid power flow.

[0139] In addition, the logic instructions in the memory 1130 described above can be implemented in the form of a software function unit and sold or used as an independent product, and can be stored in a computer readable storage medium. Based on such understanding, the technical solutions of the present application essentially or the parts that contribute to the prior art or parts of the technical solutions can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a plurality of instructions to make a computer device (which can be a personal computer, a server, or a network device, etc.) execute all or part of the steps of the methods described in various embodiments of the present application. The foregoing storage medium includes: a U disk, a mobile hard disk, a read-only memory (ROM, Read-Only Memory), a random access memory (RAM, Random Access Memory), a magnetic disk or an optical disk, and various media that can store program codes.

[0140] In another aspect, the present application also provides a non-transitory computer readable storage medium having a computer program stored thereon, the computer program being executed by a processor to implement the active control method of the converter interface power supply provided by the above method, the method comprising: in the case that the system total power backup value is greater than the disturbance power value, and part of the converter interface power supply exceeds the feasible power region, adjusting the phase angle based on the power deviation amount of the part of the converter interface power supply, realizing distributed control of the active output of the part of the converter interface power supply, so that all converter interface power supplies operate within the feasible power region or at the power limit, and the system frequency is finally maintained at the rated value; based on the phase angle reference value issued by the power grid control center, centralized control of the active power output of each converter interface power supply is realized to adjust the power flow of the power grid.

[0141] The device embodiments described above are only schematic, wherein the units described as separate components can or can not be physically separated, and the components displayed as units can or can not be physical units, i.e. they can be located in one place, or distributed on a plurality of network units. Part or all of the modules can be selected according to actual needs to achieve the purpose of the present embodiment. Those skilled in the art can understand and implement without creative labor.

[0142] Those skilled in the art can clearly understand the implementation of the various embodiments by means of software and necessary general hardware platforms through the description of the above embodiments, and of course, the various embodiments can also be implemented by hardware. Based on such understanding, the above technical solutions, essentially or in other words, the part of the prior art that contributes to the technical solutions can be embodied in the form of a software product. The computer software product can be stored in a computer readable storage medium, such as a ROM / RAM, a magnetic disk, an optical disk, and the like, and includes a plurality of instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments.

[0143] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. An active power control method of a converter interface power supply, comprising: in a case where a system total power reserve value is greater than a disturbance power value and part of the converter interface power supplies exceeds a feasible power region, adjusting a phase angle based on a power deviation amount of the part of the converter interface power supplies to realize distributed control of active power output of the part of the converter interface power supplies, so that all of the converter interface power supplies operate within the feasible power region or at a power limit, and so that a system frequency is finally maintained at a rated value; based on a phase angle reference value issued by a power grid control center, centrally controlling active power output of the converter interface power supplies to adjust power grid power flow.

2. The method of active control of a current interface power supply according to claim 1, wherein, The adjusting of the phase angle based on the power deviation amount of the part of the converter interface power supplies to realize the distributed control of the active power output of the part of the converter interface power supplies comprises: for each of the part of the converter interface power supplies, obtaining actual output power of the converter interface power supply; determining a power deviation amount of the converter interface power supply according to the actual output power and a corresponding feasible power region of the converter interface power supply; calculating an internal potential phase of the converter interface power supply according to the power deviation amount and a given phase angle reference value of the power grid control center; adjusting the phase angle according to the internal potential phase and a given voltage amplitude to control the active power output of the converter interface power supply.

3. The method of active control of a current interface power supply according to claim 1, wherein, The centrally controlling of the active power output of the converter interface power supplies based on the phase angle reference value issued by the power grid control center comprises: obtaining target output power of each of the converter interface power supplies calculated by the power grid control center; generating a phase angle reference value of each of the converter interface power supplies according to a power difference between the target output power and actual output power of each of the converter interface power supplies; centrally controlling the active power output of each of the converter interface power supplies according to the phase angle reference value.

4. The method of active control of a current interface power supply according to claim 2, wherein, The formula for calculating the power deviation amount is as follows: where u represents the power deviation amount, P e represents the actual output power of the converter interface power supply, P min represents the minimum power limit value in the feasible power region of the converter interface power supply, P max represents the maximum power limit value in the feasible power region of the converter interface power supply; The calculation formula of the internal potential phase is as follows: wherein, denotes the internal potential phase of the converter interface power supply, ω0denotes the nominal angular frequency, t denotes time, δ denotes the phase shift, δ SAC denotes the phase angle reference value given by the grid control center.

5. The method of active control of a current interface power supply according to claim 3, wherein, The phase angle reference value is calculated by a PI controller from the deviation of the actual output power of the converter interface power supply from the target output power, and the specific calculation formula is as follows: wherein δ SAC represents the phase angle reference value issued by the grid control center to the converter interface power supply, K PS represents the proportional gain, K IS represents the integral gain, s represents the differential operator, P cmd represents the target output power of the converter interface power supply calculated by the grid control center, P e represents the actual output power of the converter interface power supply.

6. The method of active control of a current interface power supply according to any of claims 1-5, wherein, The step of controlling the active power output of the converter interface power supply specifically comprises: adjusting a converter control parameter of the converter interface power supply according to a power grid frequency demand and / or a capability of the converter interface power supply to maintain output exceeding the feasible power region for a time; wherein the power grid frequency demand comprises a system frequency drop rate demand and a system frequency recovery time demand; the higher the system frequency drop rate demand, the smaller the corresponding converter control parameter; the higher the system frequency recovery time demand, the larger the corresponding converter control parameter; the stronger the capability of the converter interface power supply to maintain output exceeding the feasible power region for a time, the smaller the corresponding converter control parameter.

7. The active power control method of the converter interface power supply according to any one of claims 1-5, wherein, when the converter interface power supply operates together with an existing power supply, participating in a power grid frequency modulation process in different ways according to a proportion of the converter interface power supply in the power grid. In the case that the proportion of the converter interface power supply in the power grid is lower than a set proportion, the converter interface power supply participates in the primary frequency modulation process of the power grid, and the calculation formula of the active power output by the converter interface power supply is as follows: where P e represents the active power output by the converter interfaced power source when participating in primary frequency regulation of the power grid, P max represents the maximum power limit in the feasible power region of the converter interfaced power source, K IP represents the converter control parameter of the converter interfaced power source, and Δf represents the steady state frequency deviation.

8. An active power control device of a converter interface power supply, comprising: a primary power control module, configured to adjust phase angle based on power deviation of the partial converter-interfaced power source to realize distributed control of active power output of the partial converter-interfaced power source, so that all converter-interfaced power sources operate within the feasible power region or at the power limit, and so that the system frequency is finally maintained at the rated value, when the total system power backup value is greater than the disturbance power value and the partial converter-interfaced power source exceeds the feasible power region; a secondary power control module, configured to centrally control active power output of each converter-interfaced power source based on phase angle reference values issued by the power grid control center to adjust power flow of the power grid.

9. An electronic device comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, wherein, The processor implements the active control method of the converter-interfaced power source according to any one of claims 1 to 7 when executing the program.

10. A non-transitory computer readable storage medium having stored thereon a computer program, wherein, The computer program implements the active control method of the converter-interfaced power source according to any one of claims 1 to 7 when executed by the processor.

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