Coordinated control method for a distribution network with DER and EV and control system thereof

1. A coordinated control method for a distribution network with distributed energy resource (DER) and electric vehicle (EV) and a plurality of transformers, wherein said coordinated control method comprises:

acquiring information from a DER controller, an EV controller and a load controller structured to control a load;

as a result of the acquiring information, calculating total active/reactive power (P/Q) references and circuit breaker control commands for said DER, said EV and said load based on active/reactive power balance, voltage and frequency requirement;

allocating said references and said control commands to said DER, said EV and said load based on their locations and available capacity; and

outputting the allocated references and the control commands to said DER, said EV and said load;

wherein at least one of said calculating active/reactive power (P/Q) references, or circuit breaker control commands further comprises:

calculating said transformers permissible overloading capacities based on condition indicators; and

calculating P/Q constrains for a point of common coupling (PCC) of said distribution network, said DER, said EV and said load in which said P/Q constrains include both maximum constrains and minimum constrains based on at least one of:

said transformers permissible overloading capacities, a given range of P/Q exchange between said distribution network and said main grid, or forecast results.

2. The coordinated control method according to claim 1 , wherein said information includes voltages, currents, condition indicators, forecast results, status of circuit breakers and acceptable voltage levels, in which said voltages are used to calculate the actual frequency;

said voltages and said currents are used to calculate an actual P/Q;

said condition indicators include transformer condition monitoring data for a first transformer of the plurality of transformers for at least one of said distribution network, said DER, said EV or said load;

said forecast results include at least one of a DER generation capacity, an EV charging/discharging capacity or a loading level; and said status of circuit breakers include “on/off” status.

3. The coordinated control method according to claim 1 , wherein said acquiring information step further comprises:

acquiring main grid references from a distribution management system (DMS), in which said main grid references comprise a given range of voltage level of the point of common coupling (PCC) of said distribution network and the given range of P/Q exchange between said distribution network and said main grid.

4. The coordinated control method according to claim 3 , wherein said coordinated control method further comprises:

feeding back the distribution network information to said DMS, in which said distribution network information includes the total active/reactive power consumption of said distribution network, the voltage level of the point of common coupling (PCC) of said distribution network and a status of circuit breaker which connects said distribution network to said main grid.

5. The coordinated control method according to claim 4 , wherein said circuit breaker is composed of a single circuit breaker or a number of parallel circuit breakers.

6. The coordinated control method according to claim 1 , wherein said coordinated control method further comprises:

identifying whether said calculated actual P/Q satisfy the P/Q constrains; and

if not, calculating at least one of incremental P/Q references, or the circuit breaker control commands for at least one of said DER, said EV or said load.

7. The coordinated control method according to claim 1 , wherein said coordinated control method further comprises:

identifying whether an actual frequency satisfies a preset frequency range; and

if not, calculating at least one of incremental P references, or the circuit breaker control commands for at least one of said DER, said EV or said load.

8. The coordinated control method according to claim 1 , wherein said coordinated control method further comprises:

identifying whether actual voltages satisfy the acceptable voltage levels; and

if not, calculating at least one of incremental Q references, or the circuit breaker control commands for at least one of said DER, said EV or said load.

9. The coordinated control method according to claim 6 , said total P/Q references for at least one of said DER, said EV or said load, are updated by adding up said incremental P/Q references.

10. The coordinated control method according to claim 6 , wherein at least one of said calculating incremental P/Q references, or the circuit breaker commands for at least one of said DER, said EV or said load further comprises:

if at least one of said actual P of PCC of said distribution network is higher than said P maximum constrain of said distribution network, or said actual frequency of said distribution network is lower than said preset frequency range, then at least one of said incremental P reference, or the circuit breaker control commands of said DER increase the power generation based on the forecast results and P constrains of said DER;

if at least one of the P/Q constrains still not satisfied or said actual P of said DER reaches said P constrain of said DER, then at least one of said incremental P reference, or said circuit breaker control commands of said EV perform at least one of decrease charging power, or increase discharging power based on the forecast results and P constrains of said EV; and

if at least one of the P/Q constrains still not satisfied or said actual P of said EV reaches said P constrain of said EV, then at least one of said incremental P reference or said circuit breaker control commands of said load decrease loading level based on the forecast results and P constrains of said load.

11. The coordinated control method according to claim 6 , wherein at least one of said calculating incremental P/Q references or said circuit breaker control commands for at least one of said DER, said EV or said load further comprises:

if at least one of said actual P of PCC of said distribution network is lower than said P minimum constrain of said distribution network, or said actual frequency of said distribution network is higher than said preset frequency range, then at least one of said incremental P reference or said circuit breaker control commands of said load increases the loading level based on said forecast results and P constrains of said load;

if at least one of the P/Q constrains still not satisfied or said actual P of said load reaches said P constrains of said load, then at least one of said incremental P reference or circuit breaker commands of said EV perform at least one of increase charging power, or decrease discharging power based on the forecast results and P constrains of said EV; and

if at least one of the P/Q constrains still not satisfied or said actual P of said EV reaches said P constrain of said EV, then said at least one of incremental P reference or said circuit breaker control commands of said DER decrease the power generation based on the forecast results and P constrains of said DER.

12. The coordinated control method according to claim 6 , wherein at least one of said calculating incremental P/Q references or said circuit breaker control commands for at least one of said DER, said EV or said load further comprises:

if at least one of said actual Q of PCC of said distribution network is higher than said Q constrain of said distribution network, or said actual voltages inside said distribution network are lower than said acceptable voltage levels, then at least one of said incremental Q reference of said circuit breaker control commands of said EV at least one of decrease inductive Q or increase capacitive Q based on said Q constrains of said EV;

if at least one of the P/Q constrains still not satisfied or said actual Q reaches said Q constrain of said EV, then at least one of said incremental Q reference or said circuit breaker control commands of said DER perform at least one of decrease inductive Q or increase capacitive Q based on said Q constrains of said DER; and

if the P/Q constrains still not satisfied or said actual Q reaches said Q constrain of said DER, then at least one of said incremental Q reference or said circuit breaker control commands of said load perform at least one of decrease inductive Q or increase capacitive Q based on said Q constrains of said load.

13. The coordinated control method according to claim 6 , wherein at least one of said calculating incremental P/Q references or said circuit breaker control commands for at least one of said DER, said EV or said load further comprises:

if at least one of said actual Q of PCC of said distribution network is lower than said Q constrain of said distribution network, or said actual voltages inside said distribution network are higher than said acceptable voltage levels, then at least one of said incremental Q reference or said circuit breaker control commands of said EV perform at least one of increase inductive Q, or decrease capacitive Q based on said Q constrains of said EV;

if at least one of the P/Q constrains still not satisfied or said actual Q reaches said Q constrain of said EV, then at least one of said incremental Q reference or said circuit breaker control commands of said DER perform at least one of increase inductive Q, or decrease capacitive Q based on said Q constrains of said DER; and

if at least one of the P/Q constrains still not satisfied or said actual Q reaches said Q constrain of said DER, then at least one of said incremental Q reference or said circuit breaker control commands of said load perform at least one of reduce inductive Q, or decrease capacitive Q based on said Q constrains of said load.

14. The coordinated control method according to claim 1 , wherein said P/Q constrains include both maximum constrains and minimum constrains based on at least one of: said transformers permissible overloading capacities or a range of P/Q exchange between said distribution network and said main grid.