Control method of battery energy storage converter based on error model and electronic device

Abstract

Provided is a control method of a battery energy storage converter based on an error model and an electronic device. The method includes: acquiring voltage and current values in a battery energy stora

Description

[0001] The invention relates to the technical field of controlling a battery energy storage converter, and in particular to a control method of a battery energy storage converter based on an error model and an electronic device. BACKGROUND

[0002] The battery energy storage system is the important component of the new energy power generation system, which can be used to reduce peaks and fill valleys, thereby compensating fluctuation of new energy power generation. Batteries generally output a direct current and cannot be directly connected to the grid. Therefore, it is necessary to introduce the battery energy storage converter device. Through the high-frequency operation of the device such as the semiconductor transducer, electric energy can be converted into the alternating current with the industrial standard frequency to be connected to the grid, achieving bidirectional power flow, and ultimately achieving the function of storing or releasing the electric energy generated by new energy. The electric energy quality and the response speed are the core parameters of the battery energy storage converter. On the other hand, as a typical nonlinear control method, sliding mode control has a wide range of applications in many fields including battery energy storage converters.

[0003] However, there are risks such as uncertain convergence time and buffeting near the sliding surface in the traditional sliding mode control. In order to ensure the dynamic response time of the battery energy storage converter, take into account the steady-state electric energy quality, and prevent buffeting and filter resonance, the existing sliding mode control method of the battery energy storage converter should be improved to achieve the finite time convergence sliding mode control that can ensure the rapid convergence of the control loop. The finite time convergence sliding mode control can further ensure the convergence response speed in the control process, and has obvious advantages in applications with high convergence time requirements compared with traditional proportional integral differential control and sliding mode control. However, such algorithm cannot be directly applied to the battery energy storage system.

[0004] How to complete the convergence control of the battery energy storage converter in finite time has become a technical problem to be solved. SUMMARY

[0005] The purpose of the invention is to provide a control method of a battery energy storage converter based on an error model and an electronic device in order to overcome the defects of the prior art.

[0006] The purpose of the invention can be achieved by the following technical scheme.

[0007] According to one aspect of the invention, there is provided a control method of a battery energy storage converter based on an error model, wherein the method includes:

[0008] acquiring voltage and current values in a battery energy storage converter in an abc coordinate system, and converting the voltage and current values into voltage and current values in an aP coordinate system through Clark transformation;

[0009] calculating reference values of the voltage and current values in the aP coordinate system, respectively, according to the voltage and current values in the aP coordinate system;

[0010] calculating errors between the reference values and actual values of the voltage and current values in the aP coordinate system, respectively, and constructing an error model; and

[0011] solving an output voltage at an alternating current side in the aP coordinate system in finite convergence time based on the error model to achieve control of the battery energy storage converter;

[0012] wherein the voltage and current values include a filter capacitor voltage, an inner current and an outer current.

[0013] In one embodiment, calculating a reference value of the outer current in the aP coordinate system specifically includes: sin(0g+^) sin(0+^-9O ) where hn denotes an effective value of a phase current of an expected grid current; 9g denotes a grid angle; (p denotes a power factor angle between the grid voltage and the grid current signal; i2a and i* denote reference values of the components of the outer current on a and P axes, respectively.

[0014] In one embodiment, calculating reference values of the filter capacitor voltage and the inner current in the aP coordinate system specifically includes: u =--------(u + 0Ln\[2Lcos(0 + m 1-0 L3C v u =---------(z / + «4^2 / 003(0 + cp 1-0 L2Cf v 02LC 1--2-^- 1 -02LC 02L2Cf 1 - 02L3Cf 4^12R sin 0C ------------u 1 2 T P"1 1-0 L^C aC ---------u 1 2 T P"1 Y-co L3Cf * * where uca and uiR denote reference values of the components of the filter capacitor voltage on the a and P axes, respectively; ila and i* denote reference values of the components of the inner current on the a and P axes, respectively; a denotes the grid angular velocity; uga and ugp denote the components of the grid voltage in the aP coordinate system on the a and P axes, respectively; hn denotes an effective value of the phase current of the expected grid current; Qg denotes a grid angle; (p denotes a power factor angle between the grid voltage signal and the grid current signal; L2 denotes a second inductance value of the battery energy storage converter; Ls and Cf denote an inductance value and a capacitance value of an intermediate branch of the battery energy storage converter, respectively.

[0015] In one embodiment, the error model includes:

[0016] defining eia— ha -h, eip— hp -hp, indicating an error between a reference value and an actual value of the inner current;

[0017] defining &2a— ha -ha, &2p— hp -hp, indicating an error between a reference value and an actual value of the outer current;

[0018] defining e^a = Uca-Uca, e^p = ucp -Ucp, indicating an error between a reference value and an actual value of the filter capacitor voltage;

[0019] deriving that: C —I — I 2a la la = — \(u + L (i* -f ))- (u +L (i -i )) y- \ ca 3^1« 2a J 1 \ ca 3^1« 2a J / ^2 = —(e, + 4X ~ L.^ ) j- \ 3« 3 1« 2 2a J ^2 • r* * e = / — / 2 / ? 2 / ? 2 / ? = [K+A (t - C)) - +A - x)) ^2 — + L3eip — L2e2p ) where eia and eip, C2a and e2p, esa and esp denote errors of components of the inner current, the outer current and the filter capacitor voltage on the a and P axes, respectively; ila and i*p denote reference values of the components of the inner current on the a and P axes, respectively; ila and ilfi denote actual values of the components of the inner current on the a and P axes, respectively; e, and e,„, e. and e,„, e, and e,„ denote differentials of errors of the components of the inner current, the outer current and the filter capacitor voltage on the a and P axes, respectively; uma and Um / j denote components of the voltage of the intermediate branch in the aP coordinate * * system on the a and P axes, respectively; uma and u denote reference values of the components of the voltage of the intermediate branch in the a / p coordinate system on the a and P axes, respectively; uia and utp denote the components of the output voltage at an alternating current side in the aP coordinate system on the a and P axes, respectively; Ls and Cf denote an inductance value and a capacitance value of the intermediate branch of the battery energy storage converter, respectively; Li and L2 denote inductance values of a first inductor and a second inductor in the battery energy storage converter, respectively; Uca and up denote components of the filter * * capacitor voltage on the a and P axes, respectively; uca and u denote reference values of the ’* * * components of the filter capacitor voltage on the a and P axes, respectively; i2a and i denote differentials of reference values of the components of the outer current on the a and P axes, respectively; ila and i denote differentials ofthe components ofthe inner current on the a and P axes, respectively; Uca and u denote components of the filter capacitor voltage on the a and P axes, respectively; uca and u denote differentials of reference values of the components of the filter capacitor voltage on the a and P axes, respectively.

[0020] In one embodiment, calculating the components of the voltage of the intermediate branch in the aP coordinate system on the a and P axes and the reference values of the components specifically includes: u =u + L± =u + LAL -L ) ma ga 2 2a ca 3 \ la 2a / < * ’ * / ’* '* \ u =u + =u + LAi. -1. ma ga 2 2a ca 3 y la 2a / ~ UgP + ^2^2P ~ UcP + ^3 — Kp ) u = u B + Lj2B = u + L Ai* — i*) t mP gP 2 2p cP 3 \ 1 / 3 2p / where a dot above a variable denotes the differential operation; uma and ump denote components of the voltage of the intermediate branch in the aP coordinate system on the a and P axes, respectively; u and u a denote reference values of the components of the voltage of the intermediate ma mp 0 branch in the a / p coordinate system on the a and P axes, respectively; i2a and i* denote differentials of reference values of the components of the outer current on the a and P axes, respectively; ila and i denote differentials ofthe components ofthe inner current on the a and P axes, respectively; Uca and u denote components of the filter capacitor voltage on the a and P axes, respectively; and Ls denotes an inductance value of the intermediate branch.

[0021] In one embodiment, the error model further includes:

[0022] setting a vector ea=[eia e^a £3a]T and a vector ep=[e\p ezp e^, and defining Ll=LiL2+L2L3+LiL3, and solving a state space equation of the error model by an elimination method, wherein a standard form of the state space equation of the error model is as follows: e = Ae + Bu +D a a 1a a ep = Aep + Bu.p + Dp where r-(4+A) ,B = 0 ( ; 1 . 1, H--U la -r ma \ J 1 . + ,Dp~- H--U L, where uia and denote the components of the output voltage at an alternating current side in the aP coordinate system on the a and P axes, respectively.

[0023] In one embodiment, the process of solving an output voltage at an alternating current side in finite convergence time includes:

[0024] defining the function N(x) as: defining the function ^[x] as: 0 = k | x |“° sgn(x), where x denotes an independent variable of the function; ao, Po, y, k and o are all control parameters that are adjustable as required; and sgn(x) denotes a sign function;

[0025] selecting the expression of a sliding surface in the aP coordinate system as: s = e + A e + f dr + 2 f e dr fa la p 3a Jo ) ‘ Jo 3“ AMA , f , s,f=e^++£ N(e +a £ where Sfa and Spp denote a sliding surface of an a-axis subsystem and a sliding surface of a P-axis subsystem, respectively; t denotes the current time; ki and ai both denote control parameters that are adjustable as required; eyaand eip, e^and esp denote errors of the components of the inner current and the filter capacitor voltage on the a and P axes, respectively; kp and Ai both denote adjustable control coefficients;

[0026] calculating the derivative of the sliding surface in the aP coordinate system to obtain: = e, Ue, . P "1 = e +Ae + 2e where s and s denote differentials of the sliding surface of the a-axis subsystem and the sliding surface of the P-axis subsystem, respectively; eia and e, e3a and e3 / } denote differentials of the errors of the components of the inner current and the filter capacitor voltage on the a and P axes, respectively;

[0027] the expected reaching laws of the two coordinate axis subsystems in the aP coordinate system are the same, which are expressed as: where k2 denotes a control parameter that is adjustable as required; a.2 denotes a control parameter that is adjustable as required, which is different from ay; s and s denote the expected reaching laws of the a-axis subsystem and the P-axis subsystem, respectively;

[0028] assuming that the sliding surface of each axis subsystem in the aP coordinate system is equal to the expected reaching law of the corresponding subsystem, and substituting into the error model to obtain the expression of the output voltage at the alternating current side of the battery energy storage converter in the aP coordinate system as: ’ * * * Uta = 4Z1« + + U ga + 4 Utp = w , k2[sfar> WiJ N(sfa) N(eip) + N(sfp) ^2S2p where J 4 + 4’ A L t _ p z -A i. K — p s ¢2 — r r ’ L1 +L3 3 (4 + 4)< = A^2 + ^2^3 + AAs where eia and eip, e2a and €2 / :, esa and esp denote errors of the components of the inner current, the outer current and the filter capacitor voltage on the a and P axes, respectively; Ls and Cf denote an inductance value and a capacitance value of the intermediate branch of the battery energy storage converter, respectively; Li asx&L2 denote inductance values of a first inductor and a second f * ’ * inductor in the battery energy storage converter, respectively; l2a and i denote differentials of reference values of the components of the outer current on the a and P axes, respectively; ila and z denote differentials of the components of the inner current on the a and P axes, respectively; Uca and uc / } denote components of the filter capacitor voltage on the a and P axes, respectively.

[0029] In one embodiment, the method further includes: obtaining a voltage controlled amount in the abc coordinate system using inverse Clark transformation on the output voltage at the alternating current side in the aP coordinate system; and obtaining a pulse control signal of the battery energy storage converter through Sinusoidal Pulse Width Modulation (SPWM).

[0030] In one embodiment, the voltage and the current in the battery energy storage converter in the abc coordinate system are detected by sensors.

[0031] According to another aspect of the invention, there is provided an electronic device, including a memory and a processor, wherein a computer program is stored in the memory, and the processor, when executing the program, implements the method.

[0032] Compared with the prior art, the invention has the following beneficial effects.

[0033] 1) The invention establishes an error model of the battery energy storage converter. The error model describes the error relationship between the reference values and the actual values of the inner current, the outer current and the filter capacitor voltage, which effectively reflects the dynamic characteristics of the battery energy storage converter in the convergence process. Thereafter, based on the error model, the calculation equation of the sliding mode control of the output voltage is derived, which achieves convergence control of the battery energy storage converter in finite time, has strong rapidity and robustness, tracks the reference values rapidly, thereby improving the dynamic response performance of the battery energy storage converter, and ensuring the quality of the grid current.

[0034] 2) According to the invention, first, a three-phase variable in the abc coordinate system is converted into a two-phase variable in the aP coordinate system by Clark transformation. After the output voltage in the aP coordinate system is output by sliding mode control based on the error model, the error model makes the structure of the controlled amount simple, which is convenient for popularization and practical application. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] FIG. 1 is a schematic diagram of an overall circuit structure of a battery energy storage converter according to the invention.

[0036] FIG. 2 is a schematic diagram of a control principle of a battery energy storage converter according to the invention.

[0037] FIGs. 3 A-3C together form a schematic flowchart of a control method of a battery energy storage converter based on an error model according to the invention.

[0038] FIG. 4 A is a schematic diagram of a discharging waveform of an energy storage converter in the control method experiment according to the invention.

[0039] FIG. 4B is a schematic diagram of a charging steady-state waveform of the energy storage converter in a control method experiment according to the invention.

[0040] FIG. 4C is a schematic diagram of a dynamic switching waveform from charging to discharging of the energy storage converter in the control method experiment according to the invention.

[0041] FIG. 4D is a schematic diagram of a dynamic switching waveform from discharging to charging of the energy storage converter in the control method experiment according to the invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0042] The technical scheme in the embodiment of the invention will be clearly and completely described with reference to the accompanied drawings hereinafter. Obviously, the described embodiments are some of the embodiments of the invention, rather than all of the embodiments. Based on the embodiments in the invention, all other embodiments obtained by those skilled in the art without creative efforts should fall into the scope of protection of the invention. Embodiment 1

[0043] This embodiment relates to a control method of a battery energy storage converter based on an error model, which improves the existing finite time convergence sliding mode control theory and applies it to the battery energy storage converter.

[0044] First, according to the topology of the battery energy storage converter, a new error model of the controlled object is established. The error model is different from a traditional converter state space model. This model describes the relationship between the difference between the given amount and the actual amount and the system input, for describing the dynamic characteristics of the control convergence process of the battery energy storage converter, which is the design basis of various control systems. Thereafter, based on the error model, the design of the control method is completed such that the structure of the controlled amount is simple, and convenient for practical application. The control algorithm designed based on the error model can converge in finite time, tracks and controls the reference current rapidly, improves the dynamic response performance of the system, ensures the quality of the grid current, and controls the battery energy storage converter efficiently.

[0045] For the convenience of description, the overall circuit structure of the battery energy storage converter is given at first. As shown in FIG. 1, the battery energy storage converter introduces an inductor and a capacitor to filter the grid current based on a two-level voltage source bidirectional inverter circuit. The first inductor and the second inductor with inductance values Li and L2 are the main inductors of the battery energy storage converter, which filter out the high order harmonics generated by the switching process of a voltage source converter based on the high-frequency inductive reactance. The intermediate branch consisted of the third inductor L3 and the capacitor Cf is used to perform notch filtering on the harmonics near the switching frequency, which can optimize the filtering performance. The grid voltage can be expressed by the three-phase alternating current power supply with instantaneous values denoted as uga, ugb and ugc. The remaining variables are defined as follows.

[0046] uia, utb and uic denote instantaneous values of the phase voltage output at the alternating current side of the voltage source bidirectional inverter circuit obtained by sinusoidal pulse width modulation. iia, iib and iic denote instantaneous values of the inner currents of the battery energy storage converter (that is, flowing through the first inductor Li), in which the current flowing to the grid side is positive. i2a, hb and 12c denote the outer currents of the battery energy storage converter (that is, flowing through the second inductor L2), that is, the instantaneous values of the current at the grid side, in which the current flowing to the grid side is positive. uma, umb and umc denote the instantaneous values of the voltage from the upper end of Ls-Cf branch to N2 point. uca, Ucb and ucc denote the instantaneous values of the filter capacitor voltage, isa, isb and isc denote the instantaneous values of the current flowing through the Ls-Cf branch.

[0047] Among the above variables, all three-phase variables can be converted into variables in the aP coordinate system (that is, the two-phase stationary coordinate system) by Clark transformation, and the variables in the aP coordinate system can also be converted into variables in the abc coordinate system (that is, the three-phase stationary coordinate system) by inverse Clark transformation. For example, iia, iib and iic are converted into iia and hp through Clark transformation, whereas iia and hp can be converted into iia, iib and iic through inverse Clark transformation. By analogy, the expanded variables can be further defined as follows: uga and ug / j denote the grid voltage in the aP coordinate system. uia and denote the output voltage at the alternating current side of the bidirectional inverter circuit in the aP coordinate system. iia and hp denote the inner current of the battery energy storage converter in the aP coordinate system. 12a and i2p denote the outer (network-si de) current of the battery energy storage converter in the aP coordinate system. uma and um / j denote the voltage of the Ls-Cf branch in the aP coordinate system. uca and ucp denote the components of the filter capacitor voltage on the a and P axes, ha and hp denote the component of the current flowing through the Ls-Cf branch on the a and P axes.

[0048] Among the above variables, ha, hb, he, ha, hb and he can all be detected by a current sensor, while uga, ugb, ugc, uca, ucb and ucc can be detected by a voltage sensor and can be sent to the control circuit for operation.

[0049] In the following, the control algorithm and the modeling method described in the application of the invention are all carried out in the aP coordinate system, which will not be described in detail.

[0050] The reference value of the variable is indicated by the star-shaped upper corner mark *, and the reference value of the grid current can usually be expressed as: K = sin (0+^) (1), sin(0+^-9O ) where hn denotes an effective value of a phase current of an expected grid current; 9g denotes a grid angle, and 9g = 0 when the phase A voltage of the power grid crosses zero; (p denotes a power factor angle between the grid voltage signal and the grid current signal, (p denotes discharging at the unity power factor when being set as 0, and (p denotes charging at the unity power factor when being set as 180°; i2a and i* denote reference values of the components of the grid current on the a and P axes, respectively.

[0051] Further, for the inductance-capacitance circuit, based on the phasor method, the reference values of the filter capacitor voltage and the inner current can be derived from the above equation: u =---------(u + CD L J21 cos(0 ca 1-oLC^ sa V S '' 1 (2), = 1_ + C°S(^ + ^)) I 1 • ( ® L,C. , i. = 1--f y 21, sin (d la 1 2 t 2R \ g < i.. = 1--f -^21, sin (O i 2 T 2R \ S I where cd denotes the grid angular velocity; uca , <dC + (p ) + u ’ \-aL2Cf g“ (3), , coC + cp I + u ' ) 1 2 t gP l-o L^C and u denote reference values of the components of the filter capacitor voltage on the a and P axes, respectively; ila and i* denote reference values of the components of the inner current on the a and P axes, respectively; uga and ug / j denote the components of the grid voltage in the aP coordinate system on the a and P axes, respectively; hn denotes an effective value of the phase current of the expected grid current; Qg denotes a grid angle; (p denotes a power factor angle between the grid voltage signal and the grid current signal; L2 denotes a second inductance value of the battery energy storage converter; Ls and C / denote an inductance value and a capacitance value of an intermediate branch of the battery energy storage converter, respectively, and the intermediate branch is used to perform notch filtering on the harmonics near the switching frequency.

[0052] The voltage of the intermediate branch of the output filter circuit of the battery energy storage converter has the follow quantitative relationship, Uma = Uga + Lj2a = Uca + 4 (ha ~ ha ) i . . . (4), u =u + Lk =u +LAl ma ga 2 2a ca 3 \ la 2a / Um / 3 ~ U gP + L2i2 / 3 - Ucp + L3 — i2 / 3) u =u + Lj* = u +L (i* - L) t mP gP 2 2P cR 3 \ 1 / 3 2P / where a dot above a variable denotes the differential operation; uma and um / 2 denote components of the voltage of the intermediate branch in the aP coordinate system on the a and P axes, respectively; u and m' „ denote reference values of the components of the voltage of the intermediate branch in the a / p coordinate system on the a and P axes, respectively; i2a and i denote differentials of the components of the outer current of the battery energy storage converter in the * * * * a / p coordinate system on the a and P axes, respectively; i2a and i denote differentials of the reference values of the components of the outer current of the battery energy storage converter in the a / p coordinate system on the a and P axes, respectively; ila and i denote differentials of the components of the inner current of the battery energy storage converter on the a and P axes, respectively; ila and i* denote differentials of the reference values of the components of the inner current of the battery energy storage converter on the a and P axes, respectively; Uca and uc / } denote components of the filter capacitor voltage on the a and P axes, respectively.

[0053] e\a= ha-h, ei / 2= are defined, indicating an error between a reference value and an actual value of the inner current, and it can be derived that: Z" • * * e, = I, * * (u —u \ 1 1 I * * + u —u I = 1, - )— = 1,--(u -u 1« 1« * * 1« 1« 1 * \ la ma 1 1 / y 1« \ ia ma ( * \ ma ma = A + —u -ma 1 * —u-- A m A 1 1 \u -u \ ma ma / = € + —u - —u-- A m A 1 * 1 1 7 — L,e,„ ) = I _ 1 — 1 H- ZZ — —u „--(e, „ + L,ey „ \p \p ip ip mp £ ip £ 3 2p / (6).

[0054] Similarly, da= ha-ha, ezp= hp*-hp can also be defined, and it can be derived that: • r* * € —l — l 2« 2« 2a = —+ L (i* -r ))- (u +L (i -i )) -r \ ca 3^1« 2a } 1 \ ca 3^1« 2a / / ^2 = —(e, + LA -LA ) j- \ 3a 3 1« 2 2a / ^2 • .* * e — 1 — / 2p 2p 2p = J- [K + A ft - C)) - ft. + A ft - 4.)) ^2 — ~ + — L2e2p) (7).

[0055] Finally, £3«= ucA-uca, dp = ucp*-ucp are defined, and it can be derived that:

[0056] Setting a vector ea=[eia da £3a]T and a vector ep=[e\p dp dp^, Ll=LiL2+L2L3+LiL3 is defined, and a state space equation of the error model is solved by an elimination method, wherein a standard form of the state space equation of the error model can be as follows: e = Ae + Bu +D a a 1a a ep = Aep + Bu.p + Dp where where uia and utp denote the components of the output voltage at an alternating current side of the bidirectional inverter circuit in the aP coordinate system on the a and P axes, respectively.

[0057] At this point, the error model of the battery energy storage converter has been established. Based on the error model, the convergence control of the battery energy storage converter in finite time can be further achieved, and the specific scheme will be described later. First, the function N(x) is defined as: 7V(x) = c> +(1-^-)        (10)

[0058] The function 1 -I is defined as: £[xp = k | x |“° sgn(x) (h)

[0059] In the above two equations, x denotes an independent variable of the function; ao, Po, y, k and a are all control parameters that are adjustable as required; and sgn(x) denotes a sign function, which outputs 1 when the independent variable x is greater than zero, outputs -1 when x is less than zero, and outputs zero when x is equal to zero.

[0060] The expression of a sliding surface in the two-phase stationary coordinate system (the aP coordinate system) is selected as: s = e + 2 e + [ ^—^—dz + A [ e dr fa la p 3a Jo ) <Jo 3“ 5 = e + A e + f-----—dz + A. f e dz fP ^P P ^P Jo ) ‘Jo 3 / 7 (12), where Sfa and Sfp denote a sliding surface of an a-axis subsystem and a sliding surface of a P-axis subsystem, respectively; t denotes the current time, and the starting time of system operation is zero; ki denotes an adjustable control coefficient, which is similar to k in Equation (11); kp and Ai both denote adjustable control coefficients. The derivative of the sliding surface is taken to obtain: = + 2 e + + 2 e3 P N(eJ 1 — S + 2 € "I---1 A, 6 IP P 3P N((;^ , 3. (13).

[0061] The expected reaching laws of the two coordinate axis subsystems in the static coordinates are the same, which can be expressed as: ■ ^faP Sfa N(sf ) J (14), ^p) where k2 denotes an adjustable control coefficient (similar to k in Equation (11)); a2 denotes an adjustable control coefficient, which is different from ai and is also derived from Equation (11).

[0062] Assuming that Equation (13) is equal to Equation (14), Equation (13) is substituted into the specific expression of the error model to obtain the expression of the output voltage of the converter circuit in the aP coordinate system as: ti. — Ld + Ldn + u + L ia 1 la 3 2a ga s + ^l^la + ^2^2a + ^3^3, A(e1 / ?) + ^1^1 / 3 ^2^2 / 3 ^3^3 / 3 (15), — L,i, a + o + u o + L 11 / ? 3 2 / ? gp s where 2 L £ _ _____P ____ '~(4 + 4)c / -A !. z — p s ^2 ~ l2 + 4 ’ . A4 3 (L^QC / I. = L^L2 + L2L2 + where eia and eip, e2a and e2p, esa and esp denote errors of the components of the inner current, the outer current and the filter capacitor voltage on the a and P axes, respectively; Ls and Cf denote an inductance value and a capacitance value of the intermediate branch of the battery energy storage converter, respectively; Li and L2 denote inductance values of a first inductor and a second inductor * * * * in the battery energy storage converter, respectively; i2a and i denote differentials of reference values of the components of the outer current on the a and P axes, respectively; ila and i denote differentials of the components of the inner current on the a and P axes, respectively; Uca and u denote components of the filter capacitor voltage on the a and P axes, respectively.

[0063] For the a-axis component, the Lyapunov function Vcan be defined as: =1 (16).

[0064] It can be proved that the upper limit of the corresponding convergence time tc is bounded, as shown in the following equation: (17), where Vo denotes the initial value of Lyapunov function V at zero time. It can be proved that the convergence time of the P subsystem also has a clear upper limit based on the same principle. To sum up, taking the a-axis subsystem as an example, the specific block diagram of the control algorithm of the battery energy storage converter can be shown in FIG. 2.

[0065] According to the above figures, the specific operation process of the algorithm is shown in FIGs. 3A-3C.

[0066] The sliding mode control of the battery energy storage converter can be achieved by executing the above algorithm with the sampling rate of the controller as the cycle period. In addition, in some cases, the V module in FIG. 2 can also be replaced by the proportional resonant regulator Gpr(s), and the Laplace domain (5 domain) expression of the regulator is as follows: GPR^ = kp + 2ka>cs s2 + 2a> cs + cd2 where kp denotes the proportional coefficient of the proportional resonant regulator, coc denotes the bandwidth, coo denotes the resonant frequency of the regulator, and kr denotes the resonant term coefficient.

[0067] Based on the above theory, a prototype of the battery energy storage converter is constructed to implement and experimentally verify the algorithm. The experimental results at different times are presented in FIG. 4 (a) to FIG. 4(d) in the form of oscilloscope voltage / current waveforms, which denote the discharging and charging steady-state waveform, the charging-> discharging dynamic switching waveform, and the discharging-> charging dynamic switching waveform of the energy storage converter, respectively. In each figure, the signal marked as uga denotes the phase voltage of phase A of the power grid, and the signal marked as ugb denotes the phase voltage of phase B of the power grid. Because of a three-phase three-wire power grid, ugc does not need to be measured, and can be inferred from the voltages of phase A and phase B. Similarly, 12a denotes the grid current of phase A, and 12b denotes the grid current of phase B. It can be seen that the steady-state output current of the prototype of the energy storage converter is sinusoidal without obvious harmonic distortion, which can confirm the correctness of the modeling and the algorithm. During given changes, the switching can be completed in a relatively short time, and the dynamic response process has finite time convergence.

[0068] After the feedback amount required by the sliding mode control strategy of finite time convergence is sent to the control circuit, the voltage controlled amount is calculated through the error model shown in Equation (9) and the method shown in Equation (15). The voltage controlled amount of the abc phases is obtained through inverse Clark transformation. The pulse control signal of the converter can be obtained through Sinusoidal Pulse Width Modulation (SPWM). The error model of the system enables the structure of the controlled amount to be simple, which is convenient for popularization and practical application. The control method can achieve the finite time convergence of the controlled object, and has strong rapidity and robustness, so as to achieve the optimal control of the battery energy storage converter. Embodiment 2

[0069] An electronic device of the invention includes a central processing unit (CPU), which can perform various appropriate actions and processes according to computer program instructions stored in a Read-Only Memory (ROM) or loaded into a Random Access Memory (RAM) from a storage unit. In the RAM, various programs and data required for device operation can also be stored. The CPU, the ROM and the RAM are connected to each other through a bus. An input / output (VO) interface is also connected to the bus.

[0070] A plurality of components in the device are connected to the VO interface, including: an input unit, such as a keyboard, a mouse, etc.; an output unit, such as various types of displays, speakers, etc.; a storage unit, such as a magnetic disk, an optical disk, etc.; and a communication unit, such as a network card, a modem, a wireless communication transceiver, etc. The communication unit allows a device to exchange information / data with other devices through computer networks such as the Internet and / or various telecommunication networks.

[0071] The processing unit performs various methods and processes described above. For example, in some embodiments, a method may be implemented as a computer software program tangibly stored in a machine-readable medium, such as a storage unit. In some embodiments, part or all of the computer programs may be loaded and / or installed on a device via a ROM and / or a communication unit. When the computer program is loaded into the RAM and executed by the CPU, one or more steps of the method described above can be performed. Alternatively, in other embodiments, the CPU may be configured to execute the method in any other suitable manner (for example, by means of firmware).

[0072] The functions described above herein may be at least partially performed by one or more hardware logic components. For example, without limitation, exemplary types of hardware logic components that can be used include: a Field Programmable Gate Array (FPGA), an Application Specific Integrated Circuit (ASIC), an Application Specific Standard Product (ASSP), a System on Chip (SOC), a Complex Programmable Logic Device (CPLD) and so on.

[0073] The program code for implementing the method of the invention can be written in any combination of one or more programming languages. These program codes may be provided to a processor or controller of a general-purpose computer, a special-purpose computer or other programmable data processing devices, so that the program codes, when executed by the processor or controller, cause the functions / operations specified in the flowcharts and / or block diagrams to be implemented. The program code can be completely executed on a machine, partially executed on a machine, partially executed on a machine as a separate software package and partially executed on a remote machine or completely executed on a remote machine or a server.

[0074] In the context of the invention, a machine-readable medium may be a tangible medium, which may contain or store a program for use by or in combination with an instruction execution system, apparatus or device. The machine-readable medium may be a machine-readable signal medium or a machine-readable storage medium. The machine-readable medium may include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus or device, or any suitable combination of the above. More specific examples of the machine-readable storage medium may include an electrical connection based on one or more lines, a portable computer disk, a hard disk, a Random Access Memory (RAM), a Read-Only Memory (ROM), an Erasable Programmable Read-Only Memory (EPROM or a flash memory), an optical fiber, a Compact Disk Read-Only Memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above.

[0075] The above is only the detailed description of the invention, but the scope of protection of the invention is not limited thereto. Those skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed by the invention, and these modifications or substitutions should fall into the scope of protection of the invention. Therefore, the scope of protection of the invention should be governed by the scope of protection of the claims.

Claims

1. A control method of a battery energy storage converter based on an error model, comprising: acquiring voltage and current values in the battery energy storage converter in an abc coordinate system, and converting the voltage and current values into voltage and current values in an aP coordinate system through Clark transformation;calculating reference values of the voltage and current values in the aP coordinate system, respectively, according to the voltage and current values in the aP coordinate system;calculating errors between the reference values and actual values of the voltage and current values in the aP coordinate system, respectively, and constructing an error model; andsolving an output voltage at an alternating current side in the aP coordinate system in finite convergence time based on the error model to achieve control of the battery energy storage converter;wherein the voltage and current values include a filter capacitor voltage, an inner current and an outer current.

2. The control method of the battery energy storage converter based on the error model according to claim 1, wherein calculating a reference value of the outer current in the aP coordinate system comprises:= sin (0+^) |€ sin-90 )where hR denotes an effective value of a phase current of an expected grid current; 9g denotes a grid angle; (p denotes a power factor angle between a grid voltage signal and a grid current signal; ■ * *i2a and i denote reference values of components of the outer current on a and P axes, respectively.

3. The control method of the battery energy storage converter based on the error model according to claim 1, wherein calculating reference values of the filter capacitor voltage and the inner current in the aP coordinate system comprises:u —----------(u + co L L „ cos(# + (pca 1-02Z3C / g“ V g<P = :---7-— (ugp + (DL24il2R cos(0 + cp 1-0 L^C vwhere uca and u denote reference values of components of the filter capacitor voltage . * *ona and P axes, respectively; iia and i denote reference values of components of the inner current on the a and P axes, respectively; co denotes a grid angular velocity; uga and ugp denote components of a grid voltage in the aP coordinate system on the a and P axes, respectively; hn denotes an effective value of a phase current of an expected grid current; Qg denotes a grid angle; (p denotes a power factor angle between a grid voltage signal and a grid current signal; L2 denotes a second inductance value of the battery energy storage converter; Ls and Cf denote an inductance value and a capacitance value of an intermediate branch of the battery energy storage converter, respectively.

4. The control method of the battery energy storage converter based on the error model according to claim 1, wherein the error model comprises:defining e\a= ha*-h, e\p= i\p*-hp, indicating an error between a reference value and an actual value of the inner current;defining eia= ha-ha, e2p= hp*-hp, indicating an error between a reference value and an actual value of the outer current;defining e^a = uCa-uca, e^p = ucp*-ucp, indicating an error between a reference value and an actual value of the filter capacitor voltage;deriving that:where eia and eip, e2a and e2p, esa and esp denote errors of components of the inner current, the . * *outer current and the filter capacitor voltage on the a and P axes, respectively; ila and iip denote reference values of components of the inner current on the a and P axes, respectively; ila and i denote actual values of components of the inner current on the a and P axes, respectively; eio ande, e2a and e , e3a and e denote differentials of errors of components of the inner current, the outer current and the filter capacitor voltage on the a and P axes, respectively; uma and ump denote components of a voltage of an intermediate branch in the aP coordinate system on the* *a and P axes, respectively; uma and u denote reference values of the components of the voltage of the intermediate branch in the a / p coordinate system on the a and P axes, respectively; uia and utp denote components of the output voltage at the alternating current side in the aP coordinate system on the a and P axes, respectively; Ls and Cf denote an inductance value and a capacitance value of the intermediate branch of the battery energy storage converter, respectively; Li and L2 denote inductance values of a first inductor and a second inductor in the battery energy storage converter, respectively; Uca and u denote components of the filter capacitor voltage on the a and P axes, respectively; uca and w’ denote reference values of components of the filter’ * * *capacitor voltage on the a and P axes, respectively; i2a and i denote differentials of referencevalues of components of the outer current on the a and P axes, respectively; ila and i denote differentials of the components of the inner current on the a and P axes, respectively; Uca and u denote the components of the filter capacitor voltage on the a and P axes, respectively; uca and w’ denote differentials of the reference values of the components of the filter capacitor voltage on the a and P axes, respectively.

5. The control method of the battery energy storage converter based on the error model according to claim 4, wherein calculating the components of the voltage of the intermediate branch in the aP coordinate system on the a and P axes and the reference values of the components comprises:u =u + L.i. =u + L.(i. -i, ) ma ga 2 2a ca 3 y la 2a / <u = u + Li = u + LAI - L ma ga 2 2a ca 3 y la 2a / 5u = u + Li = u + L (i — i \ m(3 g / 3 2 2(3 c(3 3 y 1(3 2(3 )* _ * * / ’* '* \u = u+Li=u+LAi—i] gP lip cP 3 \ ip ip ) 5where a dot above a variable denotes a differential operation; uma and ump denote the components of the voltage of the intermediate branch in the aP coordinate system on the a and P 24* *axes, respectively; uma and u denote the reference values of the components of the voltage of the intermediate branch in the a / p coordinate system on the a and P axes, respectively; i2a and i* denote the differentials of the reference values of the components of the outer current on the a and P axes, respectively; ila and i denote the differentials of the components of the inner current on the a and P axes, respectively; Uca and u denote the components of the filter capacitor voltage on the a and P axes, respectively; and Ls denotes an inductance value of the intermediate branch.

6. The control method of the battery energy storage converter based on the error model according to claim 5, wherein the error model further comprises:setting a vector ea=[eia e^a £3a]T and a vector e^\e\p ezp e^]7, and defining Ll=LiL2+L2L3+LiL3, and solving a state space equation of the error model by an elimination method, wherein a standard form of the state space equation of the error model is as follows:e = Ae + Bu +Da a 1a aep=Aep+Buip + Dpwhere~l30where uia and utp denote the components of the output voltage at the alternating current side in the aP coordinate system on the a and P axes, respectively.

7. The control method of the battery energy storage converter based on the error model according to claim 1, wherein solving the output voltage at the alternating current side in the finite convergence time comprises:defining a function N(x) as:N (x) = a + (1defining a function &[xp as:= k | x p sgn(x) ,where x denotes an independent variable of the function; ao, Po, y, k and a are all control parameters that are adjustable as required; and sgn(x) denotes a sign function;selecting an expression of a sliding surface in the aP coordinate system as:s = e + 2 e + f dr + 2.( e dr fa la p 3a Jo ) ‘ Jo 3“9where Sfa and Spp denote a sliding surface of an a-axis subsystem and a sliding surface of a P-axis subsystem, respectively; t denotes a current time; ki and ai both denote control parameters that are adjustable as required; eia and eip, esa and esp denote errors of the components of the inner current and the filter capacitor voltage on the a and P axes, respectively; + and k both denote adjustable control coefficients;calculating a derivative of the sliding surfaces in the aP coordinate system to obtain:s + 2 e + + 2 efa la p 5a r / x i ^asffi - eifi++Tppy9where s and s denote differentials of the sliding surface of the a-axis subsystem andthe sliding surface of the P-axis subsystem, respectively; eio and e, e3a and e denotedifferentials of the errors of the components of the inner current and the filter capacitor voltage on the a and P axes, respectively;expected reaching laws of the two coordinate axis subsystems in the aP coordinate system are same, which are expressed as:r.sf =-------s fa ’. _where k2 denotes a control parameter that is adjustable as required; a.2 denotes a control parameter that is adjustable as required, which is different from ay; s and s denote the expected reaching laws of the a-axis subsystem and the P-axis subsystem, respectively;assuming that the sliding surface of each axis subsystem in the aP coordinate system is equal to the expected reaching law of the corresponding subsystem, and substituting into the error model to obtain expressions of the output voltage at the alternating current side of the battery energy storage converter in the aP coordinate system as:u — LA, + LA,, + u + L la 1 la 3 2a gav.p =+N(el / 3) + N(sf / 3)where2 L£ _ _____P ____'~(4 + 4)c / -3 L,p — p s~ 4 + 4 ’3 (4+4)<Ly = 44 + 44 + 44where eyaand eip, e2a and e2p, e^and epp denote errors of components of the inner current, theouter current and the filter capacitor voltage on the a and P axes, respectively; L3 and Cy denote an inductance value and a capacitance value of an intermediate branch of the battery energy storage converter, respectively; Li and L2 denote inductance values of a first inductor and a second inductor* * * *in the battery energy storage converter, respectively; i2a and i denote differentials of reference values of components of the outer current on the a and P axes, respectively; ila and i denote differentials of components of the inner current on the a and P axes, respectively; Uca and u denote components of the filter capacitor voltage on the a and P axes, respectively.

8. The control method of the battery energy storage converter based on the error model according to claim 1, wherein the method further comprises: obtaining a voltage controlled amount in the abc coordinate system using inverse Clark transformation on the output voltage at the alternating current side in the aP coordinate system; and obtaining a pulse control signal of the battery energy storage converter through Sinusoidal Pulse Width Modulation (SPWM).

9. The control method of the battery energy storage converter based on the error model according to claim 1, wherein the voltage and the current in the battery energy storage converter in the abc coordinate system are detected by sensors.

10. An electronic device, comprising a memory and a processor, wherein a computer program is stored in the memory, and the processor, when executing the computer program, implements the control method of the battery energy storage converter based on the error model according to any one of claims 1 to 9.IntellectualPropertyOfficeApplication GB2502799.6Search report under Section 17 of the Patents Act 1977Date search completed: 17 September 2025Claims searched: 1-10International classificationSubclass and subgroup Valid from G06F17 / 10 01 / 01 / 2006 H02J3 / 32 01 / 01 / 2006Field of searchWorldwide search of patent documents classified in the following areas of the IPC: H02J, G06FDatabases used in the preparation of this search report:SEARCH-PATENTDocuments considered to be relevantPatent literatureCategory Relevant claims Document of relevance A - CN 112803461 A (UNIV SHANGHAI MARITIME), see whole documentIntellectual Property Office is an operating name of the Patent Office www.gov.uk / ipoA - CN 116683520 A (UNIV SHANGHAI MARITIME), See whole document Non-patent literature Category Relevant claims Document of relevanceCategoriesLetter or DescriptionsymbolX Document indicating lack of novelty or inventive step.Y Document indicating lack of inventive step, if combined with anotherdocument of the same category.& Member of the same patent family. A Document indicating technological background. P Document published on or after the priority date but before the fling date of the present application. E Earlier application published on or after the filing date of the present application.

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