# US 10,308,127 B2 · Electric vehicle charging pile control system and method considering grid frequency safety

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- Number: US 10,308,127 B2
- Document ID: US10308127B2
- Status: Granted
- Kind: B2
- Application number: 15/570,489
- Filed: 2016-05-05
- Published: 2018-05-31
- Granted: 2019-06-04
- Earliest claimed: 2015-05-08
- Assignees: Shandong University
- Applicants: Shandong University
- Inventors: Hengxu Zhang; Zongshuai Jin; Yingle Fan
- Web page: https://patentgrep.com/patent/US10308127B2

## CPC

- B60L 53/63: in response to network capacity
- B60L 55/00: Arrangements for supplying energy stored within a vehicle to a power network, i.e. vehicle-to-grid [V2G] arrangements
- G01S 19/13: Receivers
- H02J 3/14: by switching loads on to, or off from, the networks, e.g. progressively balanced loading
- H02J 7/34: Parallel operation in networks using both storage and other DC sources, e.g. providing buffering (H02J7/14 takes precedence)
- B60L 2240/622: by satellite navigation
- H02J 2105/12: supplying households or buildings
- H02J 2105/37: exchanging power with electric vehicles [EV] or with hybrid electric vehicles [HEV]
- Y02B 70/3225: Demand response systems, e.g. load shedding, peak shaving
- Y02E 60/00: Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02T 10/70: Energy storage systems for electromobility, e.g. batteries
- Y02T 10/7072: Electromobility specific charging systems or methods for batteries, ultracapacitors, supercapacitors or double-layer capacitors
- Y02T 10/72: Electric energy management in electromobility
- Y02T 10/92: Energy efficient charging or discharging systems for batteries, ultracapacitors, supercapacitors or double-layer capacitors specially adapted for vehicles
- Y02T 90/12: Electric charging stations
- Y02T 90/16: Information or communication technologies improving the operation of electric vehicles
- Y02T 90/167: Systems integrating technologies related to power network operation and communication or information technologies for supporting the interoperability of electric or hybrid vehicles, i.e. smartgrids as interface for battery charging of electric vehicles [EV] or hybrid vehicles [HEV]
- Y04S 10/126: the energy generation units being or involving electric vehicles [EV] or hybrid vehicles [HEV], i.e. power aggregation of EV or HEV, vehicle to grid arrangements [V2G]
- Y04S 20/222: Demand response systems, e.g. load shedding, peak shaving
- Y04S 30/12: Remote or cooperative charging
- B60L: PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES (arrangements or mounting of electrical propulsion units or of plural diverse prime-movers for mutual or common propulsion in vehicles B60K1/00, B60K6/20; arrangements or mounting of electrical gearing in vehicles B60K17/12, B60K17/14; preventing wheel slip by reducing power in rail vehicles B61C15/08; dynamo-electric machines H02K; control or regulation of electric motors H02P); SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES (electric coupling devices combined with mechanical couplings of vehicles B60D1/64; electric heating for vehicles B60H1/00); ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL (control or regulation of electric motors H02P); MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
- G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- H02J: ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- Y02B: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y04S: SYSTEMS INTEGRATING TECHNOLOGIES RELATED TO POWER NETWORK OPERATION, COMMUNICATION OR INFORMATION TECHNOLOGIES FOR IMPROVING THE ELECTRICAL POWER GENERATION, TRANSMISSION, DISTRIBUTION, MANAGEMENT OR USAGE, i.e. SMART GRIDS

## Abstract

The invention discloses an electric vehicle charging pile control system and method considering grid frequency safety. The electric vehicle charging pile control system comprises a grid single-phase power input port, a voltage transformer, an AD conversion chip, a first data processor and a second data processor connected successively; the first data processor is further connected with a data real-time display device and a GPS/Beidou signal receiver respectively; the second data processor communicates with an electric vehicle charging pile and an electric vehicle battery pack respectively; and the second data processor is further connected with a man-machine interaction device. The invention has the beneficial effects that: the frequency of a power system can be monitored in real time; when the frequency is relatively low after a fault of the power system, part of unimportant electric vehicle charging loads are cut off to reduce the active power vacancy of the system; low-frequency load reduction is effectively prevented; and the time for restoring the frequency of the power system is shortened.

## Claims

### Claim 1

An electric vehicle charging pile control system considering grid frequency safety, comprising a grid single-phase power input port, a voltage transformer, an AD conversion chip, a first data processor, a second data processor, a data real-time display device, a GPS or Beidou signal receiver and a man-machine interaction device, wherein
the grid single-phase power input port, the voltage transformer, the AD conversion chip, the first data processor and the second data processor are connected successively; the first data processor is further connected with the data real-time display device and the GPS or Beidou signal receiver respectively; the second data processor communicates with an electric vehicle charging pile and an electric vehicle battery pack respectively; and the second data processor is further connected with the man-machine interaction device.

### Claim 2 (depends on 1)

The electric vehicle charging pile control system considering grid frequency safety according to claim 1, wherein the first data processor comprise a main program, second interrupt and sampling interrupt; the main program is used for calculating a frequency and sending frequency data to the second data processor via a serial port; the second interrupt is used for processing a GPS or Beidou time signal and calculating time; and the sampling interrupt is used for updating a sampling sequence and triggering frequency calculation.

### Claim 3 (depends on 1)

The electric vehicle charging pile control system considering grid frequency safety according to claim 1, wherein operations of the second data processor comprise a parameter setting interrupt program and a serial port interrupt program;
wherein the parameter setting interrupt program is triggered by the man-machine interaction device, reads parameter data sent by the man-machine interaction device after being triggered, and then changes corresponding parameters of the charging control system; the serial port interrupt program is triggered by the first data processor, reads frequency data and time information sent by the first data processor after being triggered, then reads electric quantity data of the electric vehicle battery pack, and finally sends a power control signal to the charging pile according to a charging pile output power control strategy to adjust the output power of the charging pile in real time.

### Claim 4

A method for controlling an electric vehicle charging pile control system,
wherein the electric vehicle charging pile control system comprises a grid single-phase power input port, a voltage transformer, a AD conversion chip, a first data processor, a second data processor, a data real-time display device, a GPS or Beidou signal receiver and a man-machine interaction device, and wherein the grid single-phase power input port, the voltage transformer, the AD conversion chip, the first data processor and the second data processor are connected successively; the first data processor is further connected with the data real-time display device and the GPS or Beidou signal receiver respectively; the second data processor communicates with an electric vehicle charging pile and an electric vehicle battery pack respectively; and the second data processor is further connected with the man-machine interaction device,
the method comprising:
(1) converting a grid alternating-current voltage signal into a digital signal and storing the digital signal in the AD conversion chip, thus accomplishing sampling of voltage;
(2) reading voltage sampling data and current geographic information data, calculating the frequency of voltage based on the voltage sampling data and displaying the frequency of voltage using the first data processor;
(3) superimposing the frequency data onto the current geographic information data and then sending the superimposed data to the second data processor; and
(4) reading the frequency data of the first data processor, the geographic information data and the electric quantity data of the electric vehicle battery pack using the second data processor, and sending a power control signal to the charging pile according to a charging pile output power control strategy to adjust the output power of the charging pile in real time.

### Claim 5 (depends on 4)

The method according to claim 4, wherein said calculating the frequency of voltage based on the voltage sampling data in step (2) comprises:
(2-1) supposing that the frequency updating number is cal_num, the initial value of cal_num is 0, the current frequency estimated value is fold, the initial value of fold is 50 Hz, the sampling number of each cycle of waves at the frequency is N and N is a positive integer;
(2-2) supposing a sampling sequence is V[M+N], wherein M+N is the length of the sampling sequence and M is a positive integer;
(2-3) calculating a phase sequence θ[M] using a recursive discrete Fourier phasor analysis method, wherein M is the length of the phase sequence;
(2-4) calculating a phase difference sequence Δθ[M] according to the phase sequence, wherein M is the length of the phase sequence; setting the phase difference as a constant quadratic equation: Δθ(k)=a0+a1k+a2k2, wherein a0, a1 and a2 are constant coefficients, and k=0, 1, 2, . . . , M; then indicating the phase difference sequence in a matrix form:
[
Δ
⁢
⁢
θ
0
Δ
⁢
⁢
θ
1
…
…
Δ
⁢
⁢
θ
M
-
1
]
=
[
0
0
0
0
2
-
1
2
2
-
1
…
…
…
…
…
…
0
(
M
-
1
)
-
1
(
M
-
1
)
2
-
1
]
⁡
[
a
0
a
1
a
2
]
;
abbreviating as Δθ=Xa, and calculating a coefficient matrix a=[XTX]−1XTΔθ, wherein
a
=
[
a
0
a
1
a
2
]
;
(2-5) calculating a frequency offset Δf, and updating the frequency estimated value fnew=fold+Δf;
(2-6) supposing fold=fnew; adding 1 to the frequency updating number, namely cal_num=cal_num+1; if cal_num is equal to 2, ending the frequency calculation, wherein the calculation result is the newest frequency estimated value fnew; if cal_num is smaller than 2, entering step (2-7);
(2-7) adaptively reconstructing the waveform of the sampling sequence based on the newest frequency estimated value fnew to obtain a sampling sequence V[M+N] corresponding to the newest frequency estimated value fnew;
(2-8) returning to step (2-2) for further calculation.

### Claim 6 (depends on 5)

The method according to claim 5, wherein said adaptively reconstructing the waveform of the sampling sequence in step (2-7) comprises:
(2-7-1) setting α as a phase interval of two sampling points at the new frequency fnew, calculating variants
oriInterval
×
1
N
×
f
old
⁢
⁢
and
⁢
⁢
newInterval
=
1
N
×
f
new
;
wherein fnew is the newest frequency estimated value, fold is the previous frequency estimated value, and N is the sampling number of each cycle of waves;
(2-7-2) supposing that the current sampling sequence is Vold, a new sampling sequence to be calculated is Vnew, and i=0;
(2-7-3) calculating a phase interval coefficient
x
=
i
×
newInterval
oriInterval
-
resampleIndex
;
wherein resampleIndex is a maximum integer not greater than
i
×
newInterval
oriInterval
,
(2-7-4) supposing z1=Vold(resampleIndex), z2=Vold(resampleIndex+1), i.e., z1 and z2 are respectively a resampleIndex element and a resampleIndex+1 element of the sampling sequence Vold;
(2-7-5) calculating the ith element value of Vnew, wherein
V
new
⁡
(
i
)
=
z
1
⁢
cos
⁢
⁢
x
⁢
⁢
α
+
(
z
2
-
z
1
⁢
cos
⁢
⁢
α
)
⁢
sin
⁢
⁢
x
⁢
⁢
α
sin
⁢
⁢
α
;
(2-7-6) supposing i=i+1, if i is equal to M+N, ending the calculation, and obtaining a new sampling sequence Vnew[M+N]; if i is smaller than M+N, returning to step (2-7-3) for further calculation.

### Claim 7 (depends on 4)

The method according to claim 4, wherein said superimposing the frequency data in step (3) comprises:
triggering, by a signal sent from the GPS or Beidou signal receiver to the first data processor, a second interrupt program of the first data processor; parsing, by the first data processor, data sent by the receiver to obtain time information of a whole second; then combining the frequency data and the time information into a data packet, and sending the data packet to the second data processor.

### Claim 8 (depends on 4)

The method according to claim 4, wherein the charging pile output power control strategy in step (4) comprises:
(4-1) judging whether a charging control function considering grid frequency safety is enabled, if so, entering step (4-2);
otherwise, judging whether the previous control signal is of “100% Ps state”, if so, not sending a control signal, otherwise, sending a control signal of “100% Ps state”;
(4-2) judging whether the time is within a charging control enabling time period according to the time information sent by the first data processor, if so, entering step (4-3);
otherwise, judging whether the previous control signal is of “100% Ps state”, if so, not sending a control signal, otherwise, sending a control signal of “100% Ps state”;
(4-3) judging whether the current electric quantity of the battery pack is greater than an electric quality limit value of the battery pack according to the electric quantity data information of the electric vehicle battery pack, if so, entering step (4-4);
if the current electric quantity is smaller than or equal to the electric quality limit value of the battery pack, judging whether the previous control signal is of “100% Ps state”, if so, not sending a control signal, otherwise, sending a control signal of “100% Ps state”; and
(4-4) judging a frequency safety state according to the frequency data sent by the first data processor in combination with a charging power control logic, and sending a power control signal to a charging circuit;
wherein Ps is the rated output power of the electric vehicle charging pile; and the “100% Ps state” indicates controlling the output power to be 100% of Ps.

### Claim 9 (depends on 8)

The method according to claim 8, wherein the method of step (4-4) comprises:
a) when the previous control signal is of “0% Ps state”, if the current frequency is smaller than or equal to a hysteresis upper limit frequency 1, not sending a control signal; if the current frequency is greater than or equal to the hysteresis upper limit frequency 1 and smaller than or equal to a hysteresis upper limit frequency 2, sending a control signal of “25% Ps state”; if the current frequency is greater than or equal to the hysteresis upper limit frequency 2 and smaller than or equal to a hysteresis upper limit frequency 3, sending a control signal of “50% Ps state”; if the current frequency is greater than or equal to the hysteresis upper limit frequency 3 and smaller than or equal to a hysteresis upper limit frequency 4, sending a control signal of “75% Ps state”; if the current frequency is greater than or equal to the hysteresis upper limit frequency 4, sending a control signal of “100% Ps state”;
b) when the previous control signal is of “25% Ps state”, if the current frequency is smaller than or equal to a hysteresis lower limit frequency 1, sending a control signal of “0% Ps state”; if the current frequency is greater than or equal to the hysteresis lower limit frequency 1 and smaller than or equal to the hysteresis upper limit frequency 2, not sending a control signal; if the current frequency is greater than or equal to the hysteresis upper limit frequency 2 and smaller than or equal to the hysteresis upper limit frequency 3, sending a control signal of “50% Ps state”; if the current frequency is greater than or equal to the hysteresis upper limit frequency 3 and smaller than or equal to the hysteresis upper limit frequency 4, sending a control signal of “75% Ps state”; if the current frequency is greater than or equal to the hysteresis upper limit frequency 4, sending a control signal of “100% Ps state”;
c) when the previous control signal is of “50% Ps state”, if the current frequency is smaller than or equal to the hysteresis lower limit frequency 1, sending a control signal of “0% Ps state”; if the current frequency is greater than or equal to the hysteresis lower limit frequency 1 and smaller than or equal to a hysteresis lower limit frequency 2, sending a control signal of “25% Ps state”; if the current frequency is greater than or equal to the hysteresis lower limit frequency 2 and smaller than or equal to the hysteresis upper limit frequency 3, not sending a control signal; if the current frequency is greater than or equal to the hysteresis upper limit frequency 3 and smaller than or equal to the hysteresis upper limit frequency 4, sending a control signal of “75% Ps state”; if the current frequency is greater than or equal to the hysteresis upper limit frequency 4, sending a control signal of “100% Ps state”;
d) when the previous control signal is of “75% Ps state”, if the current frequency is smaller than or equal to the hysteresis lower limit frequency 1, sending a control signal of “0% Ps state”; if the current frequency is greater than or equal to the hysteresis lower limit frequency 1 and smaller than or equal to the hysteresis lower limit frequency 2, sending a control signal of “25% Ps state”; if the current frequency is greater than or equal to the hysteresis lower limit frequency 2 and smaller than or equal to a hysteresis lower limit frequency 3, sending a control signal of “50% Ps state”; if the current frequency is greater than or equal to the hysteresis lower limit frequency 3 and smaller than or equal to the hysteresis upper limit frequency 4, not sending a control signal; if the current frequency is greater than or equal to the hysteresis upper limit frequency 4, sending a control signal of “100% Ps state”;
e) when the previous control signal is of “100% Ps state”, if the current frequency is smaller than or equal to the hysteresis lower limit frequency 1, sending a control signal of “0% Ps state”; if the current frequency is greater than or equal to the hysteresis lower limit frequency 1 and smaller than or equal to the hysteresis lower limit frequency 2, sending a control signal of “25% Ps state”; if the current frequency is greater than or equal to the hysteresis lower limit frequency 2 and smaller than or equal to the hysteresis lower limit frequency 3, sending a control signal of “50% Ps state”; if the current frequency is greater than or equal to the hysteresis lower limit frequency 3 and smaller than or equal to a hysteresis lower limit frequency 4, sending a control signal of “75% Ps state”; if the current frequency is greater than or equal to the hysteresis lower limit frequency 4, not sending a control signal;
wherein the frequency of the first turn of action of low-frequency load reduction of the power system is smaller than the hysteresis lower limit frequency 1, which is smaller than the hysteresis upper limit frequency 1, which is smaller than the hysteresis lower limit frequency 2, which is smaller than the hysteresis upper limit frequency 2, which is smaller than the hysteresis lower limit frequency 3, which is smaller than the hysteresis upper limit frequency 3, which is smaller than the hysteresis lower limit frequency 4, which is smaller than the hysteresis upper limit frequency 4, which is smaller than 50 Hz; Ps is the rated output power of the electric vehicle charging pile, the “100% Ps state” indicates that the output power is 100% of Ps.