type
  TOrderState = (stCreating, stCreated, stRequestAdditional, stEstimation, stNegotiations,
                 stWorkingPRV, stRepairSchedulePre, stRV, stRepairSchedule, stWithdraw, stExecList, stFinancialPackage,
                 stGeneralPackage, stClosed);
.................

function StateToString(AState: TOrderState): string;
begin
  case AState of
    stCreating: Result := 'stCreating';
    stCreated: Result := 'stCreated';
    stRequestAdditional: Result := 'stRequestAdditional';
    stEstimation: Result := 'stEstimation';
    stNegotiations: Result := 'stNegotiations';
    stWorkingPRV: Result := 'stWorkingPRV';
    stRepairSchedulePre: Result := 'stRepairSchedulePre';
    stRV: Result := 'stRV';
    stRepairSchedule: Result := 'stRepairSchedule';
    stWithdraw: Result := 'stWithdraw';
    stExecList: Result := 'stExecList';
    stFinancialPackage: Result := 'stFinancialPackage';
    stGeneralPackage: Result := 'stGeneralPackage';
    stClosed: Result := 'stClosed';
    else Result := 'stCreating';
  end;
end;

function StringToState(AString: string): TOrderState;
begin
  if AString = 'stCreating' then Result := stCreating
  else if AString = 'stCreated' then Result := stCreated
  else if AString = 'stRequestAdditional' then Result := stRequestAdditional
  else if AString = 'stEstimation' then Result := stEstimation
  else if AString = 'stNegotiations' then Result := stNegotiations
  else if AString = 'stWorkingPRV' then Result := stWorkingPRV
  else if AString = 'stRepairSchedulePre' then Result := stRepairSchedulePre
  else if AString = 'stRV' then Result := stRV
  else if AString = 'stRepairSchedule' then Result := stRepairSchedule
  else if AString = 'stWithdraw' then Result := stWithdraw
  else if AString = 'stExecList' then Result := stExecList
  else if AString = 'stFinancialPackage' then Result := stFinancialPackage
  else if AString = 'stGeneralPackage' then Result := stGeneralPackage
  else if AString = 'stClosed' then Result := stClosed
  else Result := stCreating;
end;

  Result := GetEnumName(TypeInfo(TOrderState), ord(AState));

uses
	System.TypInfo;
type
  TOrderState = (stCreating, stCreated, stRequestAdditional, stEstimation, stNegotiations,
                 stWorkingPRV, stRepairSchedulePre, stRV, stRepairSchedule, stWithdraw, stExecList, stFinancialPackage,
                 stGeneralPackage, stClosed);

function StateToString(AState: TOrderState): string;
begin
	Result := GetEnumName(TypeInfo(TOrderState), Ord(AState));
end;

function StringToState(AString: string): TOrderState;
begin
	Result := GetEnumValue(TypeInfo(TOrderState), AString);
end;

	Result := TOrderState(GetEnumValue(TypeInfo(TOrderState), AString));