阅读说明：本技术 一种基于fpga的三相电网基波信号快速提取算法实现方法 (FPGA-based three-phase power grid fundamental wave signal rapid extraction algorithm implementation method ) 是由 李国丽 王群京 袁庆庆 钱喆 于 2018-06-08 设计创作，主要内容包括：本发明公开了一种基于FPGA的三相电网基波信号快速提取算法实现方法,属于电力电子技术领域。本发明的实现平台为FPGA,采用硬件描述语言实现,包括鉴相器、环路滤波器、压控振荡器和方波生成器。所述鉴相器、环路滤波器和压控振荡器组成三相电网基波信号快速提取算法的前向通道,所述的方波生成器为反馈通道。本发明可以在复杂电网环境下及时、有效地跟踪并锁定三相电网电压的基波信号,计算简便,动态和静态跟踪特性良好,以纯硬件的方式实现并行处理,响应时间短。(The invention discloses a method for realizing a rapid extraction algorithm of fundamental wave signals of a three-phase power grid based on an FPGA (field programmable gate array), and belongs to the technical field of power electronics. The implementation platform of the invention is FPGA, which is implemented by hardware description language and comprises a phase discriminator, a loop filter, a voltage-controlled oscillator and a square wave generator. The phase discriminator, the loop filter and the voltage-controlled oscillator form a forward channel of a three-phase power grid fundamental wave signal rapid extraction algorithm, and the square wave generator is a feedback channel. The invention can effectively track and lock fundamental wave signals of three-phase power grid voltage in time under a complex power grid environment, has simple and convenient calculation and good dynamic and static tracking characteristics, realizes parallel processing in a pure hardware mode and has short response time.)

1. A three-phase power grid fundamental wave signal fast extraction algorithm implementation method based on FPGA is characterized in that an implementation platform is the FPGA and is implemented by hardware description language, and the algorithm implementation method comprises the following steps: the phase detector comprises a phase discriminator, a loop filter, a voltage-controlled oscillator and a square wave generator; the input of the phase discriminator is a voltage signal of a three-phase power grid to be detected; the output of the voltage-controlled oscillator is an extracted fundamental wave signal of the three-phase power grid voltage to be detected; the phase discriminator, the loop filter and the voltage-controlled oscillator form a forward channel of a three-phase power grid fundamental wave signal rapid extraction algorithm, and the square wave generator is a feedback channel.

2. The method for realizing the rapid extraction algorithm of the fundamental wave signals of the three-phase power grid based on the FPGA according to claim 1, wherein the method comprises the following steps: the phase discriminator comprises a multiplier and an integrator module, and the calculation formula is as follows:

φ_d＝φ₁+φ₀ (5)

Wherein u is_i(t) is the three-phase network voltage signal u input by the phase discriminator_f(t) is the output signal of the phase detector, u_os(t) is the output signal of the square wave generator, u_mult(t) is the output signal of the multiplier in the phase detector, u_mult(t) is u_i(t) and u_os(t) inthe output result of the multiplication in the multiplier of the phase detector u_f(t) is the output signal of the integrator in the phase detector, u_f(t) is u_mult(t) output of the integration operation in the integrator of the phase detector, A_kFor inputting the amplitude of the kth harmonic in the three-phase mains voltage signal, phi_kFor the initial phase, omega, of the kth harmonic of the input three-phase mains voltage signal₁The angular frequency of a fundamental wave signal in an input three-phase power grid voltage signal.

3. the method for realizing the rapid extraction algorithm of the fundamental wave signals of the three-phase power grid based on the FPGA according to claim 1, wherein the method comprises the following steps: the loop filter adopts a proportional-integral regulator, and the calculation formula is as follows:

Wherein u is_f(t) is the input signal of the loop filter, u_p(t) is the signal output by the loop filter, K_pIs a proportionality coefficient, T_II is the integration time constant and I is the integration time.

4. The method for realizing the rapid extraction algorithm of the fundamental wave signals of the three-phase power grid based on the FPGA according to claim 1, wherein the method comprises the following steps: the voltage controlled oscillator is integrated by first orderand (5) realizing.

5. The method for realizing the rapid extraction algorithm of the fundamental wave signals of the three-phase power grid based on the FPGA according to claim 1, wherein the method comprises the following steps: the square wave generator adopts a pulse signal generator, the square wave generator provides square wave signals for the phase discriminator, and the calculation formula is as follows:

Wherein u is_os(t) is the output signal of the square wave generator, u_o(t) is the output signal of the voltage controlled oscillator and the input signal of the square wave generator, α_iRepresenting the angle values of harmonic signals in a set of input three-phase grid voltage signals.

Technical Field

The invention relates to a method for realizing a rapid extraction algorithm of fundamental wave signals of a three-phase power grid based on an FPGA (field programmable gate array), and belongs to the technical field of power electronics.

Background

With the development of energy internet technology, various new energy sources are accessed to an electric power system in different ways. The phase-locked loop is a circuit unit which enables an output signal and a reference signal to keep synchronous in frequency and phase, plays a vital role in a single-phase and three-phase grid-connected system, obtains frequency and phase information of power grid voltage, and directly concerns the control performance of the whole system with the accuracy of the phase-locked loop, thereby influencing the effectiveness of the grid-connected system; particularly, under a complex and non-ideal power grid environment, the phenomena of three-phase imbalance, phase mutation, serious harmonic wave, voltage drop and the like exist, and the frequency and the phase of the power grid voltage need to be accurately and quickly detected to ensure the correctness of calculation in order to ensure that the system has good stability, so that the phase-locked loop is the basis for the reliable operation of the system.

The phase-locked loop is generally divided into an open-loop phase-locked loop and a closed-loop phase-locked loop, wherein the open-loop phase-locked loop mainly comprises a zero-crossing phase discrimination phase-locked loop, a phase-locked loop based on a low-pass filter, a phase-locked loop based on a space vector filter and the like, and most of the open-loop phase-locked loop has the problems of low phase-locking precision, slow response, insensitivity to system frequency. In order to effectively improve the phase-locking precision and the quick response of the phase-locked loop, a closed-loop phase-locked loop technology is generally adopted.

in the field of three-phase grid-connected phase-locked loop design, common methods include: (1) the method is effectively applied to amplitude, frequency and phase detection during power grid balance, and has good dynamic and steady response performance; however, when the power grid is unbalanced, the 2-frequency multiplication fundamental component exists in the output phase of the SSRF-SPLL, so that the subsequent processing is complicated. (2) A symmetrical component based single synchronous coordinate system software phase locked loop (EPLL-SSRF) that suppresses the effects of negative sequence components in unbalanced voltages; however, when the frequency of the grid voltage changes suddenly, it is difficult to perform real-time 90 ° deviation on the input voltage; meanwhile, the problem of long response time exists when the voltage phase or frequency of the power grid is suddenly changed. (3) The phase-locked loop adopts a double-synchronous coordinate system structure based on positive and negative sequence components, realizes the decoupling of positive and negative sequences, effectively solves the phase-locking problem when three phases are unbalanced, but cannot meet the requirement of high-performance phase-locking on rapidity due to long response time. (4) The phase-locked loop (DSOGI-PLL) based on the biquad generalized integrator can generate orthogonal signals and filter harmonic waves through the biquad generalized integrator, can realize synchronous signal extraction under the conditions of asymmetrical and distorted grid voltage, and is not ideal in filtering effect when the grid voltage contains multiple harmonic waves.

Aiming at the complex and non-ideal power grid environment existing in the grid connection process of the energy Internet system, the invention researches an FPGA-based method for realizing the rapid extraction algorithm of the fundamental wave signals of the three-phase power grid, greatly simplifies the calculation process of extracting the fundamental wave signals of the three-phase power grid, and is convenient for the FPGA to realize; meanwhile, the method can ensure that the fundamental wave signal can be effectively tracked under the complex and non-ideal power grid environment, has good dynamic and static tracking performance, and can be simultaneously suitable for single-phase and three-phase grid-connected systems.

Disclosure of Invention

Aiming at the difficult problem in the extraction process of the fundamental wave signal of the three-phase power grid in the prior art, the invention provides the method for realizing the rapid extraction algorithm of the fundamental wave signal of the three-phase power grid based on the FPGA, the method can track and lock the fundamental wave signal of the power grid voltage in time and effectively under the complex power grid environment, has simple and convenient calculation and good dynamic and static tracking characteristics, realizes parallel processing in a pure hardware mode, and has short response time.

The technical scheme of the invention is as follows: the FPGA-based three-phase power grid fundamental wave signal rapid extraction algorithm implementation method comprises a phase discriminator, a loop filter, a voltage-controlled oscillator and a square wave generator; the input of the phase discriminator is a voltage signal of a three-phase power grid to be detected; the output of the voltage-controlled oscillator is an extracted fundamental wave signal of the three-phase grid voltage to be detected: the phase discriminator, the loop filter and the voltage-controlled oscillator form a forward channel of a three-phase power grid fundamental wave signal rapid extraction algorithm, and the square wave generator is a feedback channel.

the phase detector includes a multiplier and an integrator module.

The loop filter adopts a proportional-integral regulator.

The voltage controlled oscillator is integrated by first orderAnd (5) realizing.

The square wave generator adopts a pulse signal generator, and provides a square wave signal for the phase discriminator.

The invention has the beneficial effects that:

(1) According to the method for realizing the rapid extraction algorithm of the fundamental wave signals of the three-phase power grid based on the FPGA, the low-order harmonic waves with the same times as the power grid can be eliminated through the phase discriminator in the forward channel and the square wave generator in the feedback channel, and the problem of phase deviation is effectively avoided.

(2) Compared with the conventional phase-locked loop based on a synchronous coordinate system, the three-phase power grid fundamental wave signal fast extraction algorithm based on the FPGA does not need coordinate transformation, and three sine and cosine multipliers are omitted, so that a large amount of storage space is saved, and the three-phase power grid fundamental wave signal can be better tracked under the non-ideal power grid condition.

(3) the phase discriminator in the method for realizing the rapid extraction algorithm of the fundamental wave signals of the three-phase power grid based on the FPGA can be well applied to a three-phase grid-connected phase-locked loop system and can also be well applied to a single-phase grid-connected phase-locked loop system.

(4) The method for realizing the rapid extraction algorithm of the fundamental wave signals of the three-phase power grid based on the FPGA processes the fundamental wave signals in a pure hardware mode in parallel, does not occupy CPU resources, greatly shortens the processing time, has good dynamic and static characteristics under complex and non-ideal power grid environments, and can meet the requirements on the instantaneity and the accuracy of voltage and phase information.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate an embodiment of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:

FIG. 1 shows a flow chart of an implementation method of a three-phase power grid fundamental wave signal fast extraction algorithm based on an FPGA;

FIG. 2a is a graph showing the input three-phase grid voltage over time for a sudden change in magnitude according to one embodiment of the present invention;

FIG. 2b is a graph showing the frequency of the fundamental wave signal output with time in the case of an abrupt change in amplitude according to an embodiment of the present invention;

FIG. 2c is a graph showing the phase of the fundamental wave signal output with time in the case of an abrupt change in amplitude according to an embodiment of the present invention;

FIG. 3a is a graph showing the input three-phase grid voltage over time in the phase-loss condition of phase A in accordance with one embodiment of the present invention;

FIG. 3b is a graph showing the frequency of the fundamental wave signal output in the case of phase-A loss according to an embodiment of the present invention;

FIG. 3c is a diagram showing the phase of the fundamental wave signal output in the case of phase-loss of phase A according to an embodiment of the present invention;

FIG. 4a is a graph showing the input three-phase grid voltage versus time for a phase jump event according to one embodiment of the present invention;

FIG. 4b is a diagram showing the frequency of the output fundamental wave signal with time in case of a phase jump according to an embodiment of the present invention;

FIG. 4c is a diagram showing the phase of the output fundamental wave signal over time in the case of a phase jump according to an embodiment of the present invention;

FIG. 5a is a graph showing the input three-phase grid voltage versus time for a sudden change in frequency according to one embodiment of the present invention;

FIG. 5b is a graph showing the frequency of the output fundamental wave signal with time in the case of a sudden change in frequency according to an embodiment of the present invention;

FIG. 5c is a graph showing the phase of the fundamental wave signal output with time in the case of a sudden change in frequency according to an embodiment of the present invention;

FIG. 6a is a graph showing the input three-phase grid voltage versus time for harmonic interference in accordance with one embodiment of the present invention;

FIG. 6b is a graph showing the frequency of the output fundamental signal versus time for harmonic interference in accordance with one embodiment of the present invention;

Fig. 6c shows a graph of the phase of the output fundamental wave signal over time in the case of harmonic interference according to an embodiment of the present invention.

Detailed Description

the invention will be further described with reference to the accompanying drawings and specific embodiments.

A three-phase power grid fundamental wave signal fast extraction algorithm implementation method based on FPGA comprises a phase discriminator, a loop filter, a voltage-controlled oscillator and a square wave generator; the input of the phase discriminator is a voltage signal of a three-phase power grid to be detected; the output of the voltage-controlled oscillator is an extracted fundamental wave signal of the three-phase power grid voltage to be detected; the phase discriminator, the loop filter and the voltage-controlled oscillator form a forward channel in the rapid extraction process of the fundamental wave signals of the three-phase power grid, and the square wave generator is a feedback channel.

The phase detector includes a multiplier and an integrator module.

The loop filter adopts a proportional-integral regulator.

The voltage controlled oscillator is integrated by first orderand (5) realizing.

The square wave generator adopts a pulse signal generator, and provides a square wave signal for the square wave phase discriminator.